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Hygienic design of piping for food processing support systems in food factories
21 Hygienic design of piping for food processing support systems in food factories F. Moerman, European Hygienic Engineering and Design Group, Belgium
Abstract: In this chapter, current, modified and innovative engineering practices with respect to the hygienic design and installation of food processing support and utility systems services within a food factory are discussed. Recommendations are given to prevent contamination of food products by badly engineered and installed process (support) piping. A description is given of the materials of construction that are appropriate in the design of these piping systems. Further explanation is given how these pipes can be hygienically insulated and supported; and how piping should run in food processing areas and throughout walls, floors and ceilings within the food factory building. We will make these considerations in relation to the process activities and cleaning operations accomplished and for both medium and high hygienic process areas. Key words: process support and utility systems, hygienic piping, wall, ceiling, floor.
21.1
Introduction
Where a factory and equipment are intended to prepare foodstuffs, these operations are supported by several systems that do not fall under the category of food processing equipment as such. These are support systems, that is systems that deliver or remove components to/from food products during processing or that permit food processing equipment to accomplish these process operations. According to Bhatt (1998) and ISPE (1999), the pharmaceutical industry makes a distinction between process, process support and utility systems and building services:
•
Process systems are systems delivering components that are in direct contact with the product. These components usually become part of the product.
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According to this definition these are systems that produce, distribute and supply ingredients (e.g. process water, carbon dioxide in soft drinks), food additives (e.g. packaging gases) or processing aids (cryogenic agents, cooling air). Systems that are in direct contact with the product and that remove a component are also process systems (e.g. process vacuum, clean and process steam to extract or heat food products). Process support systems are systems that directly support the food manufacturing process operation but do not contact the product and do not become part of the product. Utility systems are systems that do not contact the product but that contain material that becomes part of the product or that is removed from it. They directly affect the manufacturing process. Building services are infrastructure that improve the welfare or safety of the personnel.
According to these definitions, an inventory could be made as in Table 21.1. Support systems are primary in nature (process, process support and utility systems) or have rather a secondary function (building services). Primary support systems are essential – ‘a conditio sine qua non’ – for the preparation, preservation, packaging, inspection and storage of food; or they support the cleaning and disinfection of the food processing equipment, the food production environment and the product storage areas; or they maintain or improve the hygienic working conditions that are so typical of the food industry. Secondary support systems are more ancillary, to guarantee the safety of the personnel or to increase personal comfort during plant operations. In the past, several authors have described guiding principles in the hygienic engineering of food processing support systems, such as water production and distribution (Van Buren et al., 2004; Winkler et al., 2004), air handling (Brown et al., 2005), compressed air production and distribution (Brown et al., 2005), electrical equipment (Uiterlinden et al., 2005), lighting (Mager et al., 2003), cleaning and sanitation systems (Marriott and Gravani, 2006), pest control systems (Füchs and Faulde, 1997; Bell, 2003; Marriott and Gravani, 2006), dust control systems (Brown et al., 2005; Mager et al., 2005), drains (Holah and Thorpe, 2000; Mager et al., 2003; Clark, 2009), steam production and supply (FAO, 1984) and, sanitary facilities (Graham, 2005; Holah, 2005). This chapter will be a review of some of the existing recommendations with regard to the hygienic design and installation of food processing support systems within a food factory. However, based on recent evolutions in food factory engineering, some new or modified hygienic design and installation practices with regard to such systems will be covered. However, not all support systems mentioned in Table 21.1 will be treated in depth. Some are covered by other authors in this book: sewer systems (Ch. 26), drains (Ch. 18), waste handling (Ch. 11), steam distribution (Ch. 23), cleaning facilities (Ch. 28) and filtrated air supply (Ch. 14), electrical equipment/installations and lighting (Chs. 19 and 20).
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Table 21.1 Service systems in the food industry Process systems – Process water (hot, cold, chilled, purified or softened) – Food gases (e.g. nitrogen, carbon dioxide, oxygen, ethylene) – Cryogenic agents (e.g. liquid nitrogen, dry ice) – Process air (e.g. foaming, cooling, heating or drying of food products) – Process vacuum (e.g. packaging operations) – Clean steam and process steam (product extraction or heating) – Ventilation and air conditioning (e.g. to maintain a room temperature ≤13°C) – High-efficiency particulate air (HEPA)-systems Process support systems – Plant cooling and heating water – Plant heating steam – condensate removal traps – Thermal oil service and distribution – Brine water – ethylene glycol (supply and distribution) – Compressed air (instrument air, etc.) – Lighting, electrical service and distribution, emergency power systems – Electromechanical and computer assisted instruments – Process control systems, automation and pneumatics – Data communication systems (monitors, recorders, displays, alarms, etc.) – Pest control systems (UV light traps, etc.) – Furnace gas to heat deep fat fryers, ovens, cooking vessels, etc. Utility systems – Cleaning and sanitizing systems (hose stations, cleaning-in-place, etc.) – Steam for sterilisation purposes (e.g. SIP) – Effluent drainage (equipment, area floor, sink and condensate drains) – Exhaust systems to extract vapour, smoke, heat, etc. – Dust control by means vacuum (in dry areas) – Sanitary waste removal routes & waste disposal systems Building services – Site drainage, storm water collection system, waste water plant – Heating, ventilating and air conditioning (HVAC)-systems for personal comfort – Fire protection and control (smoke detectors, fire extinguishers, sprinkler heads, etc.) – Emergency systems – Security systems – Sanitary systems (washbasins, hand sinks, foot baths, showers, toilets) – Telecommunication systems
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We will describe where and how these food processing support systems must be integrated in the food factory, according to the current principles of good and hygienic manufacturing practice. We will discuss these considerations in relation to the process activities and cleaning operations accomplished in production environments with different hygienic requirements.
21.2
Location of support systems and building services within the food factory
It is the general philosophy of GMP (good manufacturing practice) to locate all process services away from the production areas, in lower technical grade locations. Mechanical, electrical, pneumatic, hydraulic and electronic components, together with distribution conduits, valves, pumps, pressure reducers, gas cylinders, vacuum sources, compressors, etc. should be isolated in a technical room or technical corridor adjacent to the production room. If this is done, the size of the production room can be reduced and concomitantly the size of the air conditioning installation, because most of the heat is transferred to technical areas where it can be eliminated at a reduced cost, sometimes by natural ventilation. Process support systems, such as plant steam production installation and the infrastructure to heat thermal oil, can be placed in a building adjacent to the food production plant, while services like chillers, condensers and water cooling towers can be placed in open air in the neighbourhood or on the roof of the food production plant. Other services like water treatment systems, electrical cabinets, vacuum pumps, compressors, etc., are usually placed in service rooms, close to the point of use.
21.3
General hygienic requirements for food processing support piping within the factory
Unless mounted such that dust and other foreign matter cannot enter, overhead food processing support systems (lighting, piping and ducts) should be avoided. It is preferable that ceilings do not support any items or structures that have inaccessible horizontal surfaces, since dust will invariably accumulate on such surfaces. Food processing support piping should preferably run in technical corridors or – in zone H areas – it should be integrated into wall-compartments or the ceiling. If this is not possible, the use of open racks is recommended. These should be fixed to the ceiling or to the walls and columns close to the ceiling. However, sufficient clearance must be provided between pipe runs and adjacent surfaces (walls and ceiling), so that both the pipe and the adjacent surfaces are readily accessible for cleaning and maintenance (Fig. 21.1). The anchor points of support racks should be sealed to the building (floor, walls, columns, ceiling). Racks must be designed hygienically to minimize the presence of horizontal ledges, crevices or gaps where inaccessible dirt can accumulate and pipe connections between supporting racks and process equipment should be short.
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Fig. 21.1
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Hygienically designed pipe-construction through a wall (Mager et al., 2003).
Allowance must be made for the fact that all pipeline dimensions change with changes in temperature, increasing when heated and decreasing when cooled. As a result, whole pipeline systems move and all hangers and supports have to be designed in such a way that they either move together with the pipe (roll or slide) or can swing without placing any stress on either the pipe or on parts of the supporting anchoring structure. Welding of attachments to food processing support piping is not recommended, as the attachments can stress the pipe and parts of the supporting anchoring structure. Hanging supports should be free of projecting bolts, screws, etc., to avoid or reduce the accumulation of debris, pests and microorganisms. Hence, overhead pipes or conduits should not be supported by angle irons, unistruts or all-threads (threaded rods) (Fig. 21.2). These supports introduce flat surfaces and crevices that can collect dust and soil (Cramer, 2003). Pipe hanger suspension rods should be smooth and round and suspended braces should have round tubing sealed at the ends (Fig. 21.3). A very nice example of a hygienic support pipe hanger can be observed in Fig. 21.4. Expansion pipe bends in process piping are not often used since the ‘spring effect’ of an expansion bend is usually achieved through the frequent change of direction of the line. However, expansion bends are often in use on steam lines. In vertical runs, the expansion of the pipe can cause a change in the even distribution of the weight of the cold pipe on all rigid hangers in such a way that the entire load is shifted to the bottom hanger (FAO, 1984). Food processing support piping should be directly routed from service rooms to process areas and this piping routing should always be logical and simple. Ancillary equipment, control systems and services connected to the process equipment should be located so as to allow easy access for inspection, cleaning and maintenance. The number of service pipes should be reduced to a minimum. The support piping layout should provide space beneath ducts to install temporary structures that allow access to exterior duct surfaces for removal of accumulated dust. Cleaning and drainage requirements and procedures for interior and exterior
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Fig. 21.2 Overhead pipes or conduit should not be supported by angle iron, unistrut (left) or allthread (all-threaded rods suspending from the ceiling).
Fig. 21.3
Hygienically designed piping fixture where pipe can roll or slide.
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Fig. 21.4 Sanitary pipe hanger (a) with tension ring connection (b) that allows the hanger body to adjust 7° to tube slope and to rotate 360° (courtesy of Behringer Systems).
duct surfaces should be defined at the duct arrangement design stage. The support piping must be inclined to avoid the formation of standing ‘pools’ of liquid that can support the growth of microorganisms, especially in process water, hot water and process steam piping. The food processing support piping should have a slope of 1/200 to 1/100. Like process piping, service piping should be grouped together in easily accessible pipe trains whenever possible. The points of use should also be grouped, in an attempt to minimize individual ceiling drops. Vertical entrance of piping into the equipment or equipment jacket is more hygienic than horizontal service piping runs. Running of process and service piping over open equipment in food preparation areas cannot be accepted and nesting of ductwork should be avoided. Support piping should not clutter the ceiling. When necessary, any suspended racks that run over a product zone should be equipped with drip pans which protect the product zone and can be readily removable for cleaning. To prevent drip of condensate, grease, carbon or other extraneous substances from falling into the product zone, food processing support piping can be completely enclosed in a canopy (Fig. 21.5). Food processing support systems and building services should be designed, constructed and finished to prevent the accumulation of dirt and to reduce condensation, the growth of undesirable moulds and the shedding of particles. Sanitary design should be applied to minimize the risk of product contamination with oil, mould, dirt, mildew, grease, flaking material, etc. Screws, bolt heads,
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Fig. 21.5 To prevent drip of condensate, grease or other extraneous substances falling into the product zone, food processing support piping can be completely enclosed in a canopy.
nuts, rivets and similar projections should not form pockets or areas difficult to clean. It is recommended that the use screws, nuts, rivets, etc, is avoided as much as possible. Overhead areas should be examined for flaking paint, obstructions to cleaning, dust accumulation and condensation. The geometry of the service piping can destroy the desired air pattern. Service piping with a square or rectangular profile is less favourable than ones with circular profiles. Obstacles with square and rectangular shape create more turbulence and depressions where dust can accumulate. Moreover, cylindrical profiles make cleaning easier (Marriott and Gravani, 2006). Support piping that transports dirty fluids should not run near or cross services that transport process aids, especially if these process aids (process water, process system, food gases, etc.) are in direct contact with the food to be processed. Like process piping, food processing support piping should run unidirectionally, with the support piping running from the cleanest area toward the less clean areas. Support systems should deliver a certain process aid first to the process area with the highest hygienic risk (zone H) and last to a zone of low hygienic risk (zone L). Hot piping (hot water, steam, etc.) should not run in the neighbourhood of piping that transports cold food products, cold process water, etc, as warming up these cold liquids could give raise to the growth of spoilage microorganisms and foodborne pathogens. Insulation around hot water and steam piping is required, not only to economize on energy, but also to prevent excessive heating of the food production environment
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above a temperature whereby the food safety becomes compromised. The insulation should be protected by fully, but not necessarily vapour tight, welded cladding. Poorly insulated ethylene glycol and cold/chilled water piping can sweat or can become evenly covered with ice. A lot of water can drip from poorly insulated cold piping. Moreover, sweating pipes are prone to external corrosion. When moisture from the air condenses on the surface of piping that is colder than the ambient dew point at which that air moisture condenses, air and other gases will also dissolve in the condensate and cause corrosion. A watertight covering applied directly to the pipe (e.g. asphaltic coats, thermal insulation, spiral wrapping with strong fabrics) is the simplest remedy to avoid that corrosion (FAO, 1984). Where preference is given to thermal insulation, it is recommended that an insulating material is selected that does not absorb and retain water. Styrofoam, foam glass or another rigid foam are better choices over fibrous materials. The problem with fiberglass batting is that this material has already proven to be an excellent harbour for dust, insects and rodents. Therefore, it is highly recommended to install fully welded, vapour tight, metal cladding or plastic covering. The exterior of the insulation should be smooth and properly sealed to avoid ingress of dust and liquor and it should be installed correctly so that dust traps are avoided, i.e. joints facing downwards. It should be impossible to walk on the insulation during maintenance. The cladding of insulated piping is regularly damaged by maintenance personnel walking on it. Insulated pipes can become a sanitation problem if the insulation becomes torn. Not only is there then an increased risk that insects and rodents will live and thrive in it; it can also absorb sufficient moisture from the air or spills to permit the growth of moulds. Damage to insulation can be inhibited by covering the pipe insulation with a smooth, hard, non-electrostatic, plastic cover, rather than steel sheet cladding. Recommended for that purpose are polypropylene (PP) or polyvinylchloride (PVC) with seams sealed with PVC cement. Pipe cladding should be applied in both dry and wet areas. Asbestos may never be used (Marriott and Gravani, 2006). The materials used for pneumatic hoses and tubing and their connectors must be resistant to all conditions of intended use especially to the cleaning and disinfection agents. The external design must be easy to clean. Pneumatic joints have to be tight to avoid the leakage of contaminated air. Also the venting of pneumatic air into aseptic areas presents a hygienic risk as it is a possible vector of contamination and also creates uncontrolled airflows. This must be avoided e.g. by transferring pneumatic joints out of the aseptic area. Hydraulics require inspection for leakage, level and fouling. Bumper guard constructions or ramps can be installed in heavy traffic areas (e.g. corridors) to protect support piping from external mechanical forces (e.g. from vehicle impact). Such constructions should be accessible and cleanable. For that purpose, there exist removable ramps (Mariott and Gravani, 2006).
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21.4 Specific hygienic design requirements for food processing support piping in rooms of different hygienic class 21.4.1 Zoning concept Food factories can be divided in zones with different hygienic classification: zone B (basic hygienic requirements), zone M (medium hygienic requirements) and zone H (high hygienic requirements). A zone B is an area where products are produced that are not susceptible to contamination or that are protected in their final packages. A zone M is an area where products are produced that are susceptible to contamination, but where the consumer group is not especially sensitive and where also no further growth is possible in the product in the supply chain. The objective for a zone M is to control or reduce the creation of hazardous sources. A zone H in food is the equivalent to clean room in pharmaceutical facilities. During open processing, even short exposure of product to the atmosphere can result in a food safety hazard. Products and ingredients are processed or stored that are destined for a highly susceptible consumer group (e.g. infant nutrition). The objective for this zone classification is to control all product contamination hazards and to protect the interior of food processing equipment from exposure to atmosphere. Chapter 13 describes the zoning concept in more detail.
21.4.2
Hygienic design requirements for food processing support piping as determined by the hygienic class of a given food factory area
Installation requirements for medium hygiene areas Minimize pipeline penetration through walls, ceilings and floors, as holes in these walls, floors and ceilings can lead to sanitation problems and can invite the entry of insects and rodents. Such flaws can also provide areas where microorganisms can proliferate. Pipes that pass through ceilings or walls should pass through a protection pipe section at the point of traverse to allow for expansion or contraction. Piping running through walls, ceilings or floors shall be installed so that all joints are located at least 300 mm from the surface opening through which it runs (Fig. 21.1). Openings in floors for pipes should be guarded with a sleeve extending far enough above the floor, to avoid spillage of cleaning solutions to a lower floor (Fig. 21.6). That sleeve guarding opening on the floor should be coved to permit efficient cleaning. It is even recommended that there should be no floor openings left. The use of a sleeve boot for single pipe floor penetrations is a possible solution (Fig. 21.7). When several pipes penetrate the floor, a larger curbed floor can circumvent several pipe sleeves to improve the cleanability of the surrounding process environment. However, that curbed floor may not create a large opening where pests may harbour and where dirt, water, etc. may accumulate. It must be a completely
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Fig. 21.6 In both drawings openings in floors for pipes should also be guarded with a sleeve. (a) Cleaning solutions can spill to a lower floor; (b) the sleeve is extended far enough above the floor, excluding any possibility for spills of cleaning solutions to the lower floor.
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Fig. 21.7 With the use of a sleeve boot for single pipe floor penetrations there is no floor opening left (courtesy of Central States Industrial, http://www.pipetite.us).
closed curb with a cover that leaves no gap around the penetrating piping (Fig. 21.8). Holes in walls for pipe traverse do not need to be sealed water and airtight when both sides of the wall are in rooms of the same hygienic zoning. But any opening should be large enough for access and cleaning. However, if a wall separates rooms of different hygienic zoning, all holes for pipe traverse must be sealed. The exterior surfaces of the pipes that traverse walls or ceilings should then have water and airtight contact with the wall or ceiling. Foaming-in-place is an appropriate method to close the gaps formed between pipe surface and wall. Other alternatives to close the open gaps in the walls and ceiling are the application of plastic caps around the piping (Fig. 21.9). Like process piping, food processing support piping should preferably be positioned in a way that all exterior surfaces are readily accessible. They must permit cleaning from all sides. Support piping should also be set off the wall for better cleaning (Fig. 21.10). Piping should be installed at least 6 cm from walls and floors to encourage thorough cleaning around it. Process equipment shall be installed such that enough space is provided to facilitate support pipe cleaning or to prevent the support piping from being splashed during wet cleaning of that process equipment. Equipment service connections should also be accessible for maintenance, not obstructed by walls, door openings, etc. Hence, support piping in corners must be avoided, as its cleanability is then hampered. Moreover, piping which is situated in the corners of the plant facilitates mould growth. In corners, moulds can grow easily when there is not enough ventilation, especially in cold stores and against cold surfaces. Cold surfaces are likely to cause condensation, which promotes mould growth and other contamination. Cleaning of service piping should be done periodically, preferably dry by means of vacuum cleaning. Also large cable assemblies in areas far away from the process
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Fig. 21.8 When several pipes penetrate the floor, shown in (a), several pipe sleeves can be circumvented by a larger curbed floor can circumvent several pipe sleeves to improve the cleanability of the surrounding process environment. However, the open curbed floor like one may observe in (b) creates an area where pests may harbour, and where dirt, water, etc, may accumulate. Hence, like in a completely closed curb with drainable cover that leaves no gap around the penetrating piping.
equipment should better be cleaned dry than wet. Wet cleaning can promote sticking of dust as a dirt film on service piping and electrical cables, making cleaning very difficult or even impossible. Moreover, bacterial growth starts where water does not dry. Ingrained dirt refers to material which has dried onto a surface making it difficult to clean. Often, ingrained dirt attracts other dirt and debris by sticking to it, thus causing an accumulation of dirt which attracts microbes and pests. Therefore, service piping and electrical cabling shall preferably run in a dry area rather than in a wet area. In the latter case, they can become splashed with water, cleaning agents and soil. In dry material handling plants, pipe trains and cable ensembles that collect a lot of dust should be enclosed in a containment area. After dry cleaning, a wet cleaning is conducted with a limited amount of liquid to remove the brushed-up dust (soil). Here the liquid is not considered a cleaning liquid, but just a carrier. Usually this procedure is applied in dry areas where only
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Fig. 21.9 Pipetite is a silicone wall boot which attaches to the wall and forms a flexible seal around the pipe (courtesy of Central States Industrial, http://www.pipetite.us).
Fig. 21.10
Service piping should be set off the wall for better cleaning (courtesy of Central States Industrial, http://www.csidesigns.com).
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Fig. 21.11 Incorrect and correct installation of hoses on fixed pipes (a) shows a hose, incorrectly connected to at Red pipe. In (b) the hose is clamped correctly at the very end of the pipe, minimizing the amount of dead space between the clamped portion and end of the pipe. (courtesy of H. Lelieveld, personal communication).
a small part of that area needs to be cleaned. Such limited areas need to be dried out immediately after a controlled wet cleaning operation (Mager et al., 2003). Because of the flexible nature of most secondary packaging in zone M, and tertiary packaging in zone B operations, stubbing up of utility service through the floor is not practical. Packaging equipment should be fed from strategically located stainless steel process piping and extruded aluminium power poles that extend up into the suspended ceiling and can be relocated as necessary as packaging process layouts change (Bergey, 2005). Flexible hoses are sometimes used for performing transfers within a given process area. Flexible transfer hoses are also used to connect skid mounted or portable equipment to service stations. Hoses shall be fabricated from food-grade materials which are non-toxic, non-absorbent, corrosion-resistant and smooth and shall not affect or be affected by product and cleaning compounds. Hoses should not exceed 3 m in length. When not in use, the ends of the hoses should be capped. Worm drive clips and snap-on connector unions are in common use to secure flexible hose to metal pieces and adaptors. Notice that hoses attached to stainless steel pipes should be clamped at the very end of the pipe to minimize the amount of dead space between the clamped portion and the end of the pipe (Fig. 21.11). Hoses should be placed at least 0.5 m above the floor. However, hoses are impractical to perform transfers between rooms, especially if these rooms have a different level of ‘cleanliness’. In that case, open doors or openings through the walls between both areas may result in air flowing from the dirty area towards the cleaner area. Moreover, by using fixed piping, the chance that leakage of liquid occurs is much less than when hoses are used.
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To make connections between different processing units in adjacent rooms, transfer panels with fix-welded behind-the-panel-jumpers (connections behind the panel) are used. These transfer panels are composed of a series of nozzles or ports (‘plug-in’ parts with tri-clamp ends) welded into a 316L stainless steel plate. Transfer panels are free standing with legs and foot plates or wall integrated (Huang et al., 2000). The nozzles are connected by hard sanitary stainless tubing to the inlets and outlets of process vessels or other process functions in an allwelded construction. The interconnection between the different ports is made with sanitary U- and J-bends. When jumpers are out of use, they should be stored in jumper holders (Fig. 21.12). The ports of the food process support system are preferably located at the centre of the transfer panel, with all other port connections positioned at the same distance along an arc around them. In that case, U- and J-bends of the same length can be used. That minimizes the number of different sized jumpers. With the addition of proximity switches, transfer panels enable electronic confirmation of proper line connections before a particular process circuit is initiated, thus preventing accidental mistransfers (Fig. 21.13) (Louie and Williams, 2000). The U- and J-bends can be provided with a drain valve, particularly useful as condensate drains during sterilization-in-place (SIP) operations. Low point automatic drain valves can be employed to ensure full transfer line drainage. Drains for capturing residual liquids from the transfer lines when panel connections are broken may be either a trough attached to the transfer panel or a separate floor pit at the base of the front panel. When a drain pan is used, it should be sloped to a low point (typically located in the centre of the pan) and should have a sufficient pan holding volume (Huang et al., 2000). But drains can present contamination concerns. Residual liquid captured in the trough can be piped to a covered drain that is only open during the draining process or it can be piped to an open drain, that is afterwards sanitized with hypochlorite or caustic. At a minimum, an air gap between the panel drain and the building drainage system is advisable. The drain port on the panel trough must be sized generously to avoid overflow. To guarantee proper drainage of all piping connected to the transfer panel, they should be sloped towards the transfer panel, that must be installed at the lowest point of the system. Piping behind the transfer panel and the panel ports must be sloped to ensure proper drainage. There should be no non-draining pockets to, from or within the transfer panel (Louie and Williams, 2000). Supplementary, the whole panel can tip a little bit forward to give the connecting piping a drain angle into the panel spill basin. Ports should be capped with caps when not in use, to prevent a potential spill or contamination. In general, maintenance to transfer panel systems is minimal and can be largely confined to non-classified areas behind the panel. Installation requirements for high hygiene areas In zones with the highest hygiene requirements (zone H) support piping should preferably be integrated in wall compartments (Fig. 21.14) or the ceiling. Technical service shafts should be well ventilated, to prevent accumulation of dust out off the clean room in overpressure.
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Fig. 21.12 View of the front (a) and the back (b) of a transfer panel (courtesy of Central States Industrial, http://www.csidesigns.com).
Like clean rooms in the pharmaceutical industry, zone H food production/ packaging areas can have interstitial space above the room to house piping services, large-volume heating, ventilation and air conditioning (HVAC) ducts, instruments, pumps and valves. The larger that clear ceiling space is, the better. With larger clear ceiling space, layering of services, duct crossings and installation of large horizontal HVAC and piped service distribution systems are possible. The latter also help to minimize the number of vertical shafts and the floor space they
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Fig. 21.13
U- and J-bends of the same length can be used (Louie and Williams, 2000).
Fig. 21.14
Support piping can be integrated in wall compartments in a zone H.
require. However, if the clear ceiling space is small, service duct diameter sizes are obliged to be much smaller. In that case, multiple duct runs will be required and the necessary vertical shaft space will enlarge. Concomitantly, the amount of available space for production activities will decrease. Walkable ceilings where personnel can stand erect, make maintenance operations of service piping that is set out of the process areas much easier. Moreover, these walkable ceilings permit the change-over of high efficiency particulate air (HEPA) filters and the service of piping and valves without disruption of the cleanliness of the high hygiene space below. And finally, maintenance personnel can access the technical area without special gowning. Notice that support pipe infrastructure integrated in walls or the ceiling must be checked for leaks on a regular basis, to avoid contamination of certain process aids like process water, food gases, compressed air, etc. If connections to equipment in zone H rooms needs to be done neatly, service panels (Fig. 21.15) and piping hook-up panels (Fig. 21.16) can be considered. These panels allow
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Fig. 21.15 If connections to equipment need to be done neatly, service panels should be considered (courtesy of Central States Industrial, http://www.csidesigns.com).
Fig. 21.16 If connections to equipment need to be done neatly, also piping hook-up panels should be considered (courtesy of Central States Industrial, http://www.csidesigns.com).
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Fig. 21.17 The apertures through the ceilings shall be properly closed.
piping drops to installed equipment with the piping system remaining behind a wall, running in a shaft or in an service duct chase. Support pipe service for packaging equipment in zone H packaging areas should stub up through the floor whenever possible to maintain clean uncluttered walls and to prevent conduit or pipe drops from the ceiling. Pipes and conduits are preferably not buried into the concrete floor. The problem of dusty and dirty pipes is solved, but if alterations or maintenance to buried support piping is required, it gives rise to expensive renovation work, costly obstruction or shut down of normal processing activities and a lot of hygienic problems (Barr and Montalvo, 2005). However, if running of process and service piping through walls or ceilings in zone H rooms cannot be excluded, the apertures through the walls and ceilings (Fig. 21.17) shall be properly closed for air leakage, as they give excessive air volume losses or affect the product. As piping (service and process) can affect or disrupt the airflow pattern in zone H rooms, a fog test can control airflow pattern. In high hygienic rooms (clean room), food processing support systems can also be supplied via pendant services (Fig. 21.18). In zone H areas, painting of piping services is not acceptable, as there is a continuous exposure of food products to the atmosphere making contamination with flaking paint realistic.
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Fig. 21.18 Food processing support systems can also be supplied via pendant services. (a) A pendent service system is shown, (b) shows a cross section outlining in detail how services are supplied from the ceiling to the point of use. As shown in (c), pipes supplying steam, hot and cold water must be insulated. (courtesy of Industrial EquipWash Inc.).
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21.5
References
BARR, D.
and MONTALVO, M. (2005), ‘API Facilities’, Ch. 13, in Signore, A. and Jacobs, T. (eds.), Good Design Practices for GMP Pharmaceutical Facilities. Drugs and Pharmaceutical Science series, Boca Raton, United States, Taylor and Francis Group, Vol 146, pp. 313–356. BELL, C.H. (2003). ‘Pest control: insects and mites’, Ch. 17, in Lelieveld, H.L.M., Mostert, M.A. and Holah, J. (eds.), Hygiene in Food processing, Cambridge, England, Woodhead Publishing, pp. 335–366. BERGEY, M. (2005), ‘Packaging/warehousing’, Ch. 20, in Signore, A. and Jacobs, T. (eds.), Good Design Practices for GMP Pharmaceutical Facilities, Drugs and Pharmaceutical Science series, Boca Raton, United States, Taylor and Francis Group, Vol 146, pp. 515–538. BHATT, V. (1998). GMP Compliance, Productivity and Quality: Synergy in Healthcare Manufacturing. Buffalo Grove, United States, Informa Healthcare, 524 p. BROWN, K.L., AICHINGER, K., BURFOOT, D., FAHLDIECK, A., FREUND, M. et al. (2005), ‘Air handling in the food industry’, EHEDG Guideline No 30, EHEDG subgroup Air Handling, EHEDG, Frankfurt, Germany, pp. 1–43. CCFRA (2003), ‘Guidelines for the Hygienic Design, Construction and Layout of Food Processing’, in Holah, J. (ed.), 2nd edition, Guideline No 39 of Campden and Chorleywood Food Research Association, Chipping Campden, United Kingdom, 94 p. CLARK, P.J. (2009), Practical Design, Construction and Operation of Food Facilities, San Diego, United States, Academic Press Inc., 317 p. CRAMER, M.M. (2003), ‘Building the Self-cleaning Food Plant: Six Steps to Effective Sanitary Design for the Food Plant’, Food Safety Magazine, Feb/March. FAO (1984), ‘Maintenance systems for the dairy plant’, FAO Animal Production and Health Paper No 45, 73 p. FÜCHS M. and FAULDE M. (1997), Kompedium der Schädlingsbekämpfung, Schriftenreihe, Präventivmedizin – PM6, Bundesministerium der Verteidigung, Referat Hygiene, Arbeits-, Umweltmedizin, Bonn, Deutschland, 358 p. (in German). GRAHAM, D.J. (2005), ‘Improving Building Design’, Ch. 7, in Lelieveld, H.L.M., Mostert, M.A. and Holah, J. (eds.), Handbook of hygiene control in the food industry, Cambridge, England, Woodhead Publishing, pp. 123–147. HOLAH, J. and THORPE, R.H. (2000). Hygienic design of chilled food plants, Ch. 13, in Stringer, M. and Colin Dennis, C. (eds.), Chilled Food: a comprehensive guide, 2nd edition, Cambridge, England, Woodhead Publishing, pp. 355–396. HOLAH, J. (2005), ‘Improving zoning within food processing plants’, Ch. 8, in Lelieveld, H.L.M., Mostert, M.A. and Holah, J. (eds.), Handbook of hygiene control in the food industry, Cambridge, England, Woodhead Publishing, pp. 148–167. HUANG, W., ATTENBOROUGH, G. and COTTER, R. (2000), Integrated Transfer Panel Design for the Biopharmaceutical Industry, Pharmaceutical Engineering, 20 (3), 56–70. ISPE (1999), ‘Sterile Manufacturing Facilities’, Baseline® Pharmaceutical Engineering Guides for New and Renovated Facilities, Vol. 3, Tampa, Florida, United States, 166 p. LOUIE, E. and WILLIAMS, B. (2000), ‘Transfer Panel Design: Aseptic Solution handling in Biopharmaceutical Facilities’, Pharmaceutical Engineering, 20 (4), 48–58. MAGER, K., DUFFEY, J.L., HAUSER, G., HUTTEN, H., MASTERS, K. et al. (2003), ‘Hygienic Engineering of Plants for the Processing of Dry Particulate Materials’, EHEDG Guideline No 26, EHEDG subgroup Dry Materials Handling, EHEDG, Frankfurt, Germany, pp. 1–28. MAGER, K., HUTTEN, J.G.H., JACOB, M., MASTERS, K., MEESTERS, G.M.H. et al. (2005), ‘Hygienic Engineering of Fluid Bed and Spray Dryer Plants’, EHEDG Guideline No 31, EHEDG subgroup Dry Materials Handling, EHEDG, Frankfurt, Germany, pp. 1–19. MARRIOTT, N.G. and GRAVANI, R.B. (2006), Principles of Food Sanitation, 5th edition, Food Science Text Series, New York, United States, Springer Science and Business media, 413 p.
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UITERLINDEN, L., VAN EIJK, H.M.J. and GRIFFIN, A. (2005), ‘Improving the Hygienic Design of
Electrical Equipment’, Ch. 15, in Lelieveld, H.L.M., Mostert, M.A. and Holah, J. (eds.), Handbook of hygiene control in the food industry, Cambridge, England, Woodhead Publishing, pp. 237–262. VAN BUREN, A.M., MILLIGAN, J.A., VAN EIJK, H.M.J., O’BRIEN, J., WINKLER, A. et al. (2004), ‘Safe storage and distribution of water in Food Factories’, EHEDG Guideline No 27, EHEDG subgroup Process Water, EHEDG, Frankfurt, Germany, pp. 1–16. WINKLER, A., HOPMAN, R., MILLIGAN, J.A., NAPPER, D., O’BRIEN, J. et al. (2004), ‘Safe and hygienic water treatment in Food Factories’, EHEDG Guideline No 28, EHEDG subgroup Process Water, EHEDG, Frankfurt, Germany, pp. 1–21. WIRCHANSKY, D. (2004), ‘Developing a Process for aseptic Facility Design and Validation’, in Williams, K.L. (ed.), Microbial Contamination Control in Parenteral Manufacturing, Good Design Practices for GMP Pharmaceutical Facilities. Drugs and Pharmaceutical Science series, Boca Raton, United States, Taylor and Francis Group, Vol 140, pp. 157–171.
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Abstract: In this chapter, current, modified and innovative engineering practices with respect to the hygienic design and installation of food processing support and utility systems services within a food factory are discussed. Recommendations are given to prevent contamination of food products by badly engineered and installed process (support) piping. A description is given of the materials of construction that are appropriate in the design of these piping systems. Further explanation is given how these pipes can be hygienically insulated and supported; and how piping should run in food processing areas and throughout walls, floors and ceilings within the food factory building. We will make these considerations in relation to the process activities and cleaning operations accomplished and for both medium and high hygienic process areas. Key words: process support and utility systems, hygienic piping, wall, ceiling, floor.
21.1
Introduction
Where a factory and equipment are intended to prepare foodstuffs, these operations are supported by several systems that do not fall under the category of food processing equipment as such. These are support systems, that is systems that deliver or remove components to/from food products during processing or that permit food processing equipment to accomplish these process operations. According to Bhatt (1998) and ISPE (1999), the pharmaceutical industry makes a distinction between process, process support and utility systems and building services:
•
Process systems are systems delivering components that are in direct contact with the product. These components usually become part of the product.
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According to this definition these are systems that produce, distribute and supply ingredients (e.g. process water, carbon dioxide in soft drinks), food additives (e.g. packaging gases) or processing aids (cryogenic agents, cooling air). Systems that are in direct contact with the product and that remove a component are also process systems (e.g. process vacuum, clean and process steam to extract or heat food products). Process support systems are systems that directly support the food manufacturing process operation but do not contact the product and do not become part of the product. Utility systems are systems that do not contact the product but that contain material that becomes part of the product or that is removed from it. They directly affect the manufacturing process. Building services are infrastructure that improve the welfare or safety of the personnel.
According to these definitions, an inventory could be made as in Table 21.1. Support systems are primary in nature (process, process support and utility systems) or have rather a secondary function (building services). Primary support systems are essential – ‘a conditio sine qua non’ – for the preparation, preservation, packaging, inspection and storage of food; or they support the cleaning and disinfection of the food processing equipment, the food production environment and the product storage areas; or they maintain or improve the hygienic working conditions that are so typical of the food industry. Secondary support systems are more ancillary, to guarantee the safety of the personnel or to increase personal comfort during plant operations. In the past, several authors have described guiding principles in the hygienic engineering of food processing support systems, such as water production and distribution (Van Buren et al., 2004; Winkler et al., 2004), air handling (Brown et al., 2005), compressed air production and distribution (Brown et al., 2005), electrical equipment (Uiterlinden et al., 2005), lighting (Mager et al., 2003), cleaning and sanitation systems (Marriott and Gravani, 2006), pest control systems (Füchs and Faulde, 1997; Bell, 2003; Marriott and Gravani, 2006), dust control systems (Brown et al., 2005; Mager et al., 2005), drains (Holah and Thorpe, 2000; Mager et al., 2003; Clark, 2009), steam production and supply (FAO, 1984) and, sanitary facilities (Graham, 2005; Holah, 2005). This chapter will be a review of some of the existing recommendations with regard to the hygienic design and installation of food processing support systems within a food factory. However, based on recent evolutions in food factory engineering, some new or modified hygienic design and installation practices with regard to such systems will be covered. However, not all support systems mentioned in Table 21.1 will be treated in depth. Some are covered by other authors in this book: sewer systems (Ch. 26), drains (Ch. 18), waste handling (Ch. 11), steam distribution (Ch. 23), cleaning facilities (Ch. 28) and filtrated air supply (Ch. 14), electrical equipment/installations and lighting (Chs. 19 and 20).
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Table 21.1 Service systems in the food industry Process systems – Process water (hot, cold, chilled, purified or softened) – Food gases (e.g. nitrogen, carbon dioxide, oxygen, ethylene) – Cryogenic agents (e.g. liquid nitrogen, dry ice) – Process air (e.g. foaming, cooling, heating or drying of food products) – Process vacuum (e.g. packaging operations) – Clean steam and process steam (product extraction or heating) – Ventilation and air conditioning (e.g. to maintain a room temperature ≤13°C) – High-efficiency particulate air (HEPA)-systems Process support systems – Plant cooling and heating water – Plant heating steam – condensate removal traps – Thermal oil service and distribution – Brine water – ethylene glycol (supply and distribution) – Compressed air (instrument air, etc.) – Lighting, electrical service and distribution, emergency power systems – Electromechanical and computer assisted instruments – Process control systems, automation and pneumatics – Data communication systems (monitors, recorders, displays, alarms, etc.) – Pest control systems (UV light traps, etc.) – Furnace gas to heat deep fat fryers, ovens, cooking vessels, etc. Utility systems – Cleaning and sanitizing systems (hose stations, cleaning-in-place, etc.) – Steam for sterilisation purposes (e.g. SIP) – Effluent drainage (equipment, area floor, sink and condensate drains) – Exhaust systems to extract vapour, smoke, heat, etc. – Dust control by means vacuum (in dry areas) – Sanitary waste removal routes & waste disposal systems Building services – Site drainage, storm water collection system, waste water plant – Heating, ventilating and air conditioning (HVAC)-systems for personal comfort – Fire protection and control (smoke detectors, fire extinguishers, sprinkler heads, etc.) – Emergency systems – Security systems – Sanitary systems (washbasins, hand sinks, foot baths, showers, toilets) – Telecommunication systems
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We will describe where and how these food processing support systems must be integrated in the food factory, according to the current principles of good and hygienic manufacturing practice. We will discuss these considerations in relation to the process activities and cleaning operations accomplished in production environments with different hygienic requirements.
21.2
Location of support systems and building services within the food factory
It is the general philosophy of GMP (good manufacturing practice) to locate all process services away from the production areas, in lower technical grade locations. Mechanical, electrical, pneumatic, hydraulic and electronic components, together with distribution conduits, valves, pumps, pressure reducers, gas cylinders, vacuum sources, compressors, etc. should be isolated in a technical room or technical corridor adjacent to the production room. If this is done, the size of the production room can be reduced and concomitantly the size of the air conditioning installation, because most of the heat is transferred to technical areas where it can be eliminated at a reduced cost, sometimes by natural ventilation. Process support systems, such as plant steam production installation and the infrastructure to heat thermal oil, can be placed in a building adjacent to the food production plant, while services like chillers, condensers and water cooling towers can be placed in open air in the neighbourhood or on the roof of the food production plant. Other services like water treatment systems, electrical cabinets, vacuum pumps, compressors, etc., are usually placed in service rooms, close to the point of use.
21.3
General hygienic requirements for food processing support piping within the factory
Unless mounted such that dust and other foreign matter cannot enter, overhead food processing support systems (lighting, piping and ducts) should be avoided. It is preferable that ceilings do not support any items or structures that have inaccessible horizontal surfaces, since dust will invariably accumulate on such surfaces. Food processing support piping should preferably run in technical corridors or – in zone H areas – it should be integrated into wall-compartments or the ceiling. If this is not possible, the use of open racks is recommended. These should be fixed to the ceiling or to the walls and columns close to the ceiling. However, sufficient clearance must be provided between pipe runs and adjacent surfaces (walls and ceiling), so that both the pipe and the adjacent surfaces are readily accessible for cleaning and maintenance (Fig. 21.1). The anchor points of support racks should be sealed to the building (floor, walls, columns, ceiling). Racks must be designed hygienically to minimize the presence of horizontal ledges, crevices or gaps where inaccessible dirt can accumulate and pipe connections between supporting racks and process equipment should be short.
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Fig. 21.1
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Hygienically designed pipe-construction through a wall (Mager et al., 2003).
Allowance must be made for the fact that all pipeline dimensions change with changes in temperature, increasing when heated and decreasing when cooled. As a result, whole pipeline systems move and all hangers and supports have to be designed in such a way that they either move together with the pipe (roll or slide) or can swing without placing any stress on either the pipe or on parts of the supporting anchoring structure. Welding of attachments to food processing support piping is not recommended, as the attachments can stress the pipe and parts of the supporting anchoring structure. Hanging supports should be free of projecting bolts, screws, etc., to avoid or reduce the accumulation of debris, pests and microorganisms. Hence, overhead pipes or conduits should not be supported by angle irons, unistruts or all-threads (threaded rods) (Fig. 21.2). These supports introduce flat surfaces and crevices that can collect dust and soil (Cramer, 2003). Pipe hanger suspension rods should be smooth and round and suspended braces should have round tubing sealed at the ends (Fig. 21.3). A very nice example of a hygienic support pipe hanger can be observed in Fig. 21.4. Expansion pipe bends in process piping are not often used since the ‘spring effect’ of an expansion bend is usually achieved through the frequent change of direction of the line. However, expansion bends are often in use on steam lines. In vertical runs, the expansion of the pipe can cause a change in the even distribution of the weight of the cold pipe on all rigid hangers in such a way that the entire load is shifted to the bottom hanger (FAO, 1984). Food processing support piping should be directly routed from service rooms to process areas and this piping routing should always be logical and simple. Ancillary equipment, control systems and services connected to the process equipment should be located so as to allow easy access for inspection, cleaning and maintenance. The number of service pipes should be reduced to a minimum. The support piping layout should provide space beneath ducts to install temporary structures that allow access to exterior duct surfaces for removal of accumulated dust. Cleaning and drainage requirements and procedures for interior and exterior
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Fig. 21.2 Overhead pipes or conduit should not be supported by angle iron, unistrut (left) or allthread (all-threaded rods suspending from the ceiling).
Fig. 21.3
Hygienically designed piping fixture where pipe can roll or slide.
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Fig. 21.4 Sanitary pipe hanger (a) with tension ring connection (b) that allows the hanger body to adjust 7° to tube slope and to rotate 360° (courtesy of Behringer Systems).
duct surfaces should be defined at the duct arrangement design stage. The support piping must be inclined to avoid the formation of standing ‘pools’ of liquid that can support the growth of microorganisms, especially in process water, hot water and process steam piping. The food processing support piping should have a slope of 1/200 to 1/100. Like process piping, service piping should be grouped together in easily accessible pipe trains whenever possible. The points of use should also be grouped, in an attempt to minimize individual ceiling drops. Vertical entrance of piping into the equipment or equipment jacket is more hygienic than horizontal service piping runs. Running of process and service piping over open equipment in food preparation areas cannot be accepted and nesting of ductwork should be avoided. Support piping should not clutter the ceiling. When necessary, any suspended racks that run over a product zone should be equipped with drip pans which protect the product zone and can be readily removable for cleaning. To prevent drip of condensate, grease, carbon or other extraneous substances from falling into the product zone, food processing support piping can be completely enclosed in a canopy (Fig. 21.5). Food processing support systems and building services should be designed, constructed and finished to prevent the accumulation of dirt and to reduce condensation, the growth of undesirable moulds and the shedding of particles. Sanitary design should be applied to minimize the risk of product contamination with oil, mould, dirt, mildew, grease, flaking material, etc. Screws, bolt heads,
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Fig. 21.5 To prevent drip of condensate, grease or other extraneous substances falling into the product zone, food processing support piping can be completely enclosed in a canopy.
nuts, rivets and similar projections should not form pockets or areas difficult to clean. It is recommended that the use screws, nuts, rivets, etc, is avoided as much as possible. Overhead areas should be examined for flaking paint, obstructions to cleaning, dust accumulation and condensation. The geometry of the service piping can destroy the desired air pattern. Service piping with a square or rectangular profile is less favourable than ones with circular profiles. Obstacles with square and rectangular shape create more turbulence and depressions where dust can accumulate. Moreover, cylindrical profiles make cleaning easier (Marriott and Gravani, 2006). Support piping that transports dirty fluids should not run near or cross services that transport process aids, especially if these process aids (process water, process system, food gases, etc.) are in direct contact with the food to be processed. Like process piping, food processing support piping should run unidirectionally, with the support piping running from the cleanest area toward the less clean areas. Support systems should deliver a certain process aid first to the process area with the highest hygienic risk (zone H) and last to a zone of low hygienic risk (zone L). Hot piping (hot water, steam, etc.) should not run in the neighbourhood of piping that transports cold food products, cold process water, etc, as warming up these cold liquids could give raise to the growth of spoilage microorganisms and foodborne pathogens. Insulation around hot water and steam piping is required, not only to economize on energy, but also to prevent excessive heating of the food production environment
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above a temperature whereby the food safety becomes compromised. The insulation should be protected by fully, but not necessarily vapour tight, welded cladding. Poorly insulated ethylene glycol and cold/chilled water piping can sweat or can become evenly covered with ice. A lot of water can drip from poorly insulated cold piping. Moreover, sweating pipes are prone to external corrosion. When moisture from the air condenses on the surface of piping that is colder than the ambient dew point at which that air moisture condenses, air and other gases will also dissolve in the condensate and cause corrosion. A watertight covering applied directly to the pipe (e.g. asphaltic coats, thermal insulation, spiral wrapping with strong fabrics) is the simplest remedy to avoid that corrosion (FAO, 1984). Where preference is given to thermal insulation, it is recommended that an insulating material is selected that does not absorb and retain water. Styrofoam, foam glass or another rigid foam are better choices over fibrous materials. The problem with fiberglass batting is that this material has already proven to be an excellent harbour for dust, insects and rodents. Therefore, it is highly recommended to install fully welded, vapour tight, metal cladding or plastic covering. The exterior of the insulation should be smooth and properly sealed to avoid ingress of dust and liquor and it should be installed correctly so that dust traps are avoided, i.e. joints facing downwards. It should be impossible to walk on the insulation during maintenance. The cladding of insulated piping is regularly damaged by maintenance personnel walking on it. Insulated pipes can become a sanitation problem if the insulation becomes torn. Not only is there then an increased risk that insects and rodents will live and thrive in it; it can also absorb sufficient moisture from the air or spills to permit the growth of moulds. Damage to insulation can be inhibited by covering the pipe insulation with a smooth, hard, non-electrostatic, plastic cover, rather than steel sheet cladding. Recommended for that purpose are polypropylene (PP) or polyvinylchloride (PVC) with seams sealed with PVC cement. Pipe cladding should be applied in both dry and wet areas. Asbestos may never be used (Marriott and Gravani, 2006). The materials used for pneumatic hoses and tubing and their connectors must be resistant to all conditions of intended use especially to the cleaning and disinfection agents. The external design must be easy to clean. Pneumatic joints have to be tight to avoid the leakage of contaminated air. Also the venting of pneumatic air into aseptic areas presents a hygienic risk as it is a possible vector of contamination and also creates uncontrolled airflows. This must be avoided e.g. by transferring pneumatic joints out of the aseptic area. Hydraulics require inspection for leakage, level and fouling. Bumper guard constructions or ramps can be installed in heavy traffic areas (e.g. corridors) to protect support piping from external mechanical forces (e.g. from vehicle impact). Such constructions should be accessible and cleanable. For that purpose, there exist removable ramps (Mariott and Gravani, 2006).
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21.4 Specific hygienic design requirements for food processing support piping in rooms of different hygienic class 21.4.1 Zoning concept Food factories can be divided in zones with different hygienic classification: zone B (basic hygienic requirements), zone M (medium hygienic requirements) and zone H (high hygienic requirements). A zone B is an area where products are produced that are not susceptible to contamination or that are protected in their final packages. A zone M is an area where products are produced that are susceptible to contamination, but where the consumer group is not especially sensitive and where also no further growth is possible in the product in the supply chain. The objective for a zone M is to control or reduce the creation of hazardous sources. A zone H in food is the equivalent to clean room in pharmaceutical facilities. During open processing, even short exposure of product to the atmosphere can result in a food safety hazard. Products and ingredients are processed or stored that are destined for a highly susceptible consumer group (e.g. infant nutrition). The objective for this zone classification is to control all product contamination hazards and to protect the interior of food processing equipment from exposure to atmosphere. Chapter 13 describes the zoning concept in more detail.
21.4.2
Hygienic design requirements for food processing support piping as determined by the hygienic class of a given food factory area
Installation requirements for medium hygiene areas Minimize pipeline penetration through walls, ceilings and floors, as holes in these walls, floors and ceilings can lead to sanitation problems and can invite the entry of insects and rodents. Such flaws can also provide areas where microorganisms can proliferate. Pipes that pass through ceilings or walls should pass through a protection pipe section at the point of traverse to allow for expansion or contraction. Piping running through walls, ceilings or floors shall be installed so that all joints are located at least 300 mm from the surface opening through which it runs (Fig. 21.1). Openings in floors for pipes should be guarded with a sleeve extending far enough above the floor, to avoid spillage of cleaning solutions to a lower floor (Fig. 21.6). That sleeve guarding opening on the floor should be coved to permit efficient cleaning. It is even recommended that there should be no floor openings left. The use of a sleeve boot for single pipe floor penetrations is a possible solution (Fig. 21.7). When several pipes penetrate the floor, a larger curbed floor can circumvent several pipe sleeves to improve the cleanability of the surrounding process environment. However, that curbed floor may not create a large opening where pests may harbour and where dirt, water, etc. may accumulate. It must be a completely
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Fig. 21.6 In both drawings openings in floors for pipes should also be guarded with a sleeve. (a) Cleaning solutions can spill to a lower floor; (b) the sleeve is extended far enough above the floor, excluding any possibility for spills of cleaning solutions to the lower floor.
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Fig. 21.7 With the use of a sleeve boot for single pipe floor penetrations there is no floor opening left (courtesy of Central States Industrial, http://www.pipetite.us).
closed curb with a cover that leaves no gap around the penetrating piping (Fig. 21.8). Holes in walls for pipe traverse do not need to be sealed water and airtight when both sides of the wall are in rooms of the same hygienic zoning. But any opening should be large enough for access and cleaning. However, if a wall separates rooms of different hygienic zoning, all holes for pipe traverse must be sealed. The exterior surfaces of the pipes that traverse walls or ceilings should then have water and airtight contact with the wall or ceiling. Foaming-in-place is an appropriate method to close the gaps formed between pipe surface and wall. Other alternatives to close the open gaps in the walls and ceiling are the application of plastic caps around the piping (Fig. 21.9). Like process piping, food processing support piping should preferably be positioned in a way that all exterior surfaces are readily accessible. They must permit cleaning from all sides. Support piping should also be set off the wall for better cleaning (Fig. 21.10). Piping should be installed at least 6 cm from walls and floors to encourage thorough cleaning around it. Process equipment shall be installed such that enough space is provided to facilitate support pipe cleaning or to prevent the support piping from being splashed during wet cleaning of that process equipment. Equipment service connections should also be accessible for maintenance, not obstructed by walls, door openings, etc. Hence, support piping in corners must be avoided, as its cleanability is then hampered. Moreover, piping which is situated in the corners of the plant facilitates mould growth. In corners, moulds can grow easily when there is not enough ventilation, especially in cold stores and against cold surfaces. Cold surfaces are likely to cause condensation, which promotes mould growth and other contamination. Cleaning of service piping should be done periodically, preferably dry by means of vacuum cleaning. Also large cable assemblies in areas far away from the process
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Fig. 21.8 When several pipes penetrate the floor, shown in (a), several pipe sleeves can be circumvented by a larger curbed floor can circumvent several pipe sleeves to improve the cleanability of the surrounding process environment. However, the open curbed floor like one may observe in (b) creates an area where pests may harbour, and where dirt, water, etc, may accumulate. Hence, like in a completely closed curb with drainable cover that leaves no gap around the penetrating piping.
equipment should better be cleaned dry than wet. Wet cleaning can promote sticking of dust as a dirt film on service piping and electrical cables, making cleaning very difficult or even impossible. Moreover, bacterial growth starts where water does not dry. Ingrained dirt refers to material which has dried onto a surface making it difficult to clean. Often, ingrained dirt attracts other dirt and debris by sticking to it, thus causing an accumulation of dirt which attracts microbes and pests. Therefore, service piping and electrical cabling shall preferably run in a dry area rather than in a wet area. In the latter case, they can become splashed with water, cleaning agents and soil. In dry material handling plants, pipe trains and cable ensembles that collect a lot of dust should be enclosed in a containment area. After dry cleaning, a wet cleaning is conducted with a limited amount of liquid to remove the brushed-up dust (soil). Here the liquid is not considered a cleaning liquid, but just a carrier. Usually this procedure is applied in dry areas where only
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Fig. 21.9 Pipetite is a silicone wall boot which attaches to the wall and forms a flexible seal around the pipe (courtesy of Central States Industrial, http://www.pipetite.us).
Fig. 21.10
Service piping should be set off the wall for better cleaning (courtesy of Central States Industrial, http://www.csidesigns.com).
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Fig. 21.11 Incorrect and correct installation of hoses on fixed pipes (a) shows a hose, incorrectly connected to at Red pipe. In (b) the hose is clamped correctly at the very end of the pipe, minimizing the amount of dead space between the clamped portion and end of the pipe. (courtesy of H. Lelieveld, personal communication).
a small part of that area needs to be cleaned. Such limited areas need to be dried out immediately after a controlled wet cleaning operation (Mager et al., 2003). Because of the flexible nature of most secondary packaging in zone M, and tertiary packaging in zone B operations, stubbing up of utility service through the floor is not practical. Packaging equipment should be fed from strategically located stainless steel process piping and extruded aluminium power poles that extend up into the suspended ceiling and can be relocated as necessary as packaging process layouts change (Bergey, 2005). Flexible hoses are sometimes used for performing transfers within a given process area. Flexible transfer hoses are also used to connect skid mounted or portable equipment to service stations. Hoses shall be fabricated from food-grade materials which are non-toxic, non-absorbent, corrosion-resistant and smooth and shall not affect or be affected by product and cleaning compounds. Hoses should not exceed 3 m in length. When not in use, the ends of the hoses should be capped. Worm drive clips and snap-on connector unions are in common use to secure flexible hose to metal pieces and adaptors. Notice that hoses attached to stainless steel pipes should be clamped at the very end of the pipe to minimize the amount of dead space between the clamped portion and the end of the pipe (Fig. 21.11). Hoses should be placed at least 0.5 m above the floor. However, hoses are impractical to perform transfers between rooms, especially if these rooms have a different level of ‘cleanliness’. In that case, open doors or openings through the walls between both areas may result in air flowing from the dirty area towards the cleaner area. Moreover, by using fixed piping, the chance that leakage of liquid occurs is much less than when hoses are used.
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To make connections between different processing units in adjacent rooms, transfer panels with fix-welded behind-the-panel-jumpers (connections behind the panel) are used. These transfer panels are composed of a series of nozzles or ports (‘plug-in’ parts with tri-clamp ends) welded into a 316L stainless steel plate. Transfer panels are free standing with legs and foot plates or wall integrated (Huang et al., 2000). The nozzles are connected by hard sanitary stainless tubing to the inlets and outlets of process vessels or other process functions in an allwelded construction. The interconnection between the different ports is made with sanitary U- and J-bends. When jumpers are out of use, they should be stored in jumper holders (Fig. 21.12). The ports of the food process support system are preferably located at the centre of the transfer panel, with all other port connections positioned at the same distance along an arc around them. In that case, U- and J-bends of the same length can be used. That minimizes the number of different sized jumpers. With the addition of proximity switches, transfer panels enable electronic confirmation of proper line connections before a particular process circuit is initiated, thus preventing accidental mistransfers (Fig. 21.13) (Louie and Williams, 2000). The U- and J-bends can be provided with a drain valve, particularly useful as condensate drains during sterilization-in-place (SIP) operations. Low point automatic drain valves can be employed to ensure full transfer line drainage. Drains for capturing residual liquids from the transfer lines when panel connections are broken may be either a trough attached to the transfer panel or a separate floor pit at the base of the front panel. When a drain pan is used, it should be sloped to a low point (typically located in the centre of the pan) and should have a sufficient pan holding volume (Huang et al., 2000). But drains can present contamination concerns. Residual liquid captured in the trough can be piped to a covered drain that is only open during the draining process or it can be piped to an open drain, that is afterwards sanitized with hypochlorite or caustic. At a minimum, an air gap between the panel drain and the building drainage system is advisable. The drain port on the panel trough must be sized generously to avoid overflow. To guarantee proper drainage of all piping connected to the transfer panel, they should be sloped towards the transfer panel, that must be installed at the lowest point of the system. Piping behind the transfer panel and the panel ports must be sloped to ensure proper drainage. There should be no non-draining pockets to, from or within the transfer panel (Louie and Williams, 2000). Supplementary, the whole panel can tip a little bit forward to give the connecting piping a drain angle into the panel spill basin. Ports should be capped with caps when not in use, to prevent a potential spill or contamination. In general, maintenance to transfer panel systems is minimal and can be largely confined to non-classified areas behind the panel. Installation requirements for high hygiene areas In zones with the highest hygiene requirements (zone H) support piping should preferably be integrated in wall compartments (Fig. 21.14) or the ceiling. Technical service shafts should be well ventilated, to prevent accumulation of dust out off the clean room in overpressure.
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Fig. 21.12 View of the front (a) and the back (b) of a transfer panel (courtesy of Central States Industrial, http://www.csidesigns.com).
Like clean rooms in the pharmaceutical industry, zone H food production/ packaging areas can have interstitial space above the room to house piping services, large-volume heating, ventilation and air conditioning (HVAC) ducts, instruments, pumps and valves. The larger that clear ceiling space is, the better. With larger clear ceiling space, layering of services, duct crossings and installation of large horizontal HVAC and piped service distribution systems are possible. The latter also help to minimize the number of vertical shafts and the floor space they
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Fig. 21.13
U- and J-bends of the same length can be used (Louie and Williams, 2000).
Fig. 21.14
Support piping can be integrated in wall compartments in a zone H.
require. However, if the clear ceiling space is small, service duct diameter sizes are obliged to be much smaller. In that case, multiple duct runs will be required and the necessary vertical shaft space will enlarge. Concomitantly, the amount of available space for production activities will decrease. Walkable ceilings where personnel can stand erect, make maintenance operations of service piping that is set out of the process areas much easier. Moreover, these walkable ceilings permit the change-over of high efficiency particulate air (HEPA) filters and the service of piping and valves without disruption of the cleanliness of the high hygiene space below. And finally, maintenance personnel can access the technical area without special gowning. Notice that support pipe infrastructure integrated in walls or the ceiling must be checked for leaks on a regular basis, to avoid contamination of certain process aids like process water, food gases, compressed air, etc. If connections to equipment in zone H rooms needs to be done neatly, service panels (Fig. 21.15) and piping hook-up panels (Fig. 21.16) can be considered. These panels allow
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Fig. 21.15 If connections to equipment need to be done neatly, service panels should be considered (courtesy of Central States Industrial, http://www.csidesigns.com).
Fig. 21.16 If connections to equipment need to be done neatly, also piping hook-up panels should be considered (courtesy of Central States Industrial, http://www.csidesigns.com).
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Fig. 21.17 The apertures through the ceilings shall be properly closed.
piping drops to installed equipment with the piping system remaining behind a wall, running in a shaft or in an service duct chase. Support pipe service for packaging equipment in zone H packaging areas should stub up through the floor whenever possible to maintain clean uncluttered walls and to prevent conduit or pipe drops from the ceiling. Pipes and conduits are preferably not buried into the concrete floor. The problem of dusty and dirty pipes is solved, but if alterations or maintenance to buried support piping is required, it gives rise to expensive renovation work, costly obstruction or shut down of normal processing activities and a lot of hygienic problems (Barr and Montalvo, 2005). However, if running of process and service piping through walls or ceilings in zone H rooms cannot be excluded, the apertures through the walls and ceilings (Fig. 21.17) shall be properly closed for air leakage, as they give excessive air volume losses or affect the product. As piping (service and process) can affect or disrupt the airflow pattern in zone H rooms, a fog test can control airflow pattern. In high hygienic rooms (clean room), food processing support systems can also be supplied via pendant services (Fig. 21.18). In zone H areas, painting of piping services is not acceptable, as there is a continuous exposure of food products to the atmosphere making contamination with flaking paint realistic.
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Fig. 21.18 Food processing support systems can also be supplied via pendant services. (a) A pendent service system is shown, (b) shows a cross section outlining in detail how services are supplied from the ceiling to the point of use. As shown in (c), pipes supplying steam, hot and cold water must be insulated. (courtesy of Industrial EquipWash Inc.).
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21.5
References
BARR, D.
and MONTALVO, M. (2005), ‘API Facilities’, Ch. 13, in Signore, A. and Jacobs, T. (eds.), Good Design Practices for GMP Pharmaceutical Facilities. Drugs and Pharmaceutical Science series, Boca Raton, United States, Taylor and Francis Group, Vol 146, pp. 313–356. BELL, C.H. (2003). ‘Pest control: insects and mites’, Ch. 17, in Lelieveld, H.L.M., Mostert, M.A. and Holah, J. (eds.), Hygiene in Food processing, Cambridge, England, Woodhead Publishing, pp. 335–366. BERGEY, M. (2005), ‘Packaging/warehousing’, Ch. 20, in Signore, A. and Jacobs, T. (eds.), Good Design Practices for GMP Pharmaceutical Facilities, Drugs and Pharmaceutical Science series, Boca Raton, United States, Taylor and Francis Group, Vol 146, pp. 515–538. BHATT, V. (1998). GMP Compliance, Productivity and Quality: Synergy in Healthcare Manufacturing. Buffalo Grove, United States, Informa Healthcare, 524 p. BROWN, K.L., AICHINGER, K., BURFOOT, D., FAHLDIECK, A., FREUND, M. et al. (2005), ‘Air handling in the food industry’, EHEDG Guideline No 30, EHEDG subgroup Air Handling, EHEDG, Frankfurt, Germany, pp. 1–43. CCFRA (2003), ‘Guidelines for the Hygienic Design, Construction and Layout of Food Processing’, in Holah, J. (ed.), 2nd edition, Guideline No 39 of Campden and Chorleywood Food Research Association, Chipping Campden, United Kingdom, 94 p. CLARK, P.J. (2009), Practical Design, Construction and Operation of Food Facilities, San Diego, United States, Academic Press Inc., 317 p. CRAMER, M.M. (2003), ‘Building the Self-cleaning Food Plant: Six Steps to Effective Sanitary Design for the Food Plant’, Food Safety Magazine, Feb/March. FAO (1984), ‘Maintenance systems for the dairy plant’, FAO Animal Production and Health Paper No 45, 73 p. FÜCHS M. and FAULDE M. (1997), Kompedium der Schädlingsbekämpfung, Schriftenreihe, Präventivmedizin – PM6, Bundesministerium der Verteidigung, Referat Hygiene, Arbeits-, Umweltmedizin, Bonn, Deutschland, 358 p. (in German). GRAHAM, D.J. (2005), ‘Improving Building Design’, Ch. 7, in Lelieveld, H.L.M., Mostert, M.A. and Holah, J. (eds.), Handbook of hygiene control in the food industry, Cambridge, England, Woodhead Publishing, pp. 123–147. HOLAH, J. and THORPE, R.H. (2000). Hygienic design of chilled food plants, Ch. 13, in Stringer, M. and Colin Dennis, C. (eds.), Chilled Food: a comprehensive guide, 2nd edition, Cambridge, England, Woodhead Publishing, pp. 355–396. HOLAH, J. (2005), ‘Improving zoning within food processing plants’, Ch. 8, in Lelieveld, H.L.M., Mostert, M.A. and Holah, J. (eds.), Handbook of hygiene control in the food industry, Cambridge, England, Woodhead Publishing, pp. 148–167. HUANG, W., ATTENBOROUGH, G. and COTTER, R. (2000), Integrated Transfer Panel Design for the Biopharmaceutical Industry, Pharmaceutical Engineering, 20 (3), 56–70. ISPE (1999), ‘Sterile Manufacturing Facilities’, Baseline® Pharmaceutical Engineering Guides for New and Renovated Facilities, Vol. 3, Tampa, Florida, United States, 166 p. LOUIE, E. and WILLIAMS, B. (2000), ‘Transfer Panel Design: Aseptic Solution handling in Biopharmaceutical Facilities’, Pharmaceutical Engineering, 20 (4), 48–58. MAGER, K., DUFFEY, J.L., HAUSER, G., HUTTEN, H., MASTERS, K. et al. (2003), ‘Hygienic Engineering of Plants for the Processing of Dry Particulate Materials’, EHEDG Guideline No 26, EHEDG subgroup Dry Materials Handling, EHEDG, Frankfurt, Germany, pp. 1–28. MAGER, K., HUTTEN, J.G.H., JACOB, M., MASTERS, K., MEESTERS, G.M.H. et al. (2005), ‘Hygienic Engineering of Fluid Bed and Spray Dryer Plants’, EHEDG Guideline No 31, EHEDG subgroup Dry Materials Handling, EHEDG, Frankfurt, Germany, pp. 1–19. MARRIOTT, N.G. and GRAVANI, R.B. (2006), Principles of Food Sanitation, 5th edition, Food Science Text Series, New York, United States, Springer Science and Business media, 413 p.
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UITERLINDEN, L., VAN EIJK, H.M.J. and GRIFFIN, A. (2005), ‘Improving the Hygienic Design of
Electrical Equipment’, Ch. 15, in Lelieveld, H.L.M., Mostert, M.A. and Holah, J. (eds.), Handbook of hygiene control in the food industry, Cambridge, England, Woodhead Publishing, pp. 237–262. VAN BUREN, A.M., MILLIGAN, J.A., VAN EIJK, H.M.J., O’BRIEN, J., WINKLER, A. et al. (2004), ‘Safe storage and distribution of water in Food Factories’, EHEDG Guideline No 27, EHEDG subgroup Process Water, EHEDG, Frankfurt, Germany, pp. 1–16. WINKLER, A., HOPMAN, R., MILLIGAN, J.A., NAPPER, D., O’BRIEN, J. et al. (2004), ‘Safe and hygienic water treatment in Food Factories’, EHEDG Guideline No 28, EHEDG subgroup Process Water, EHEDG, Frankfurt, Germany, pp. 1–21. WIRCHANSKY, D. (2004), ‘Developing a Process for aseptic Facility Design and Validation’, in Williams, K.L. (ed.), Microbial Contamination Control in Parenteral Manufacturing, Good Design Practices for GMP Pharmaceutical Facilities. Drugs and Pharmaceutical Science series, Boca Raton, United States, Taylor and Francis Group, Vol 140, pp. 157–171.
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