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ISSN 1350-4789
June 2003
www.worldpumps.com
Yellow line to make bolt load checking easier Maintenance engineers will soon be able to check bolt tension at a glance on high integrity applications. The new Rotabolt V Vision system currently under trial has a clear yellow stripe across the bolt head and rotor cap. A continuous yellow stripe indicates that the bolt is correctly loaded. But, if the tension drops below a predetermined level, the cap automatically rotates through 90º to form a yellow cross. The original Rotabolt has now been in use for 20 years. It uses an insert within the bolt attached to a thumb wheel on the head. When the bolt is tensioned to the prescribed load, the thumb wheel is locked. Bolt tension can then be checked periodically by testing the thumb wheel. The standard bolt is factory calibrated and tested to indicate a tension setting within +/–5% accuracy. This is more accurate than using typical torque wrenches or bolt tensioning equipment, and is thus of interest for critical applications where more precise bolt tension is required. The new V Vision system is expected to prove particularly effective where important bolts are difficult to reach or are in hazardous locations.
The company also expects that it will significantly reduce bolt checking times where access equipment is required. Contact: James Walker Rotabolt Ltd, Peartree Business Park, Peartree Lane, Dudley, DY2 OUW, UK. Tel: +44 1384 214442, Fax: +44 1384 455 186, Email:
[email protected], Web: www.rotabolt.co.uk.
Seals manufactured from carboxylated HNBR Parker Hannifin Seal Group is now offering sealing products in carboxylated hydrogenated nitrile elastomer (XHNBR). This material is claimed to offer the heat and chemical resistance of HNBR combined with the abrasion resistance of carboxylated nitrile (XNBR). The temperature range is said to be up to 149°C (300°F), and typical ultimate tensile strength 5000 psi (34.5 MPa) for the 94 shore hardness material. The major applications targeted for this material are in oil and gas operations, including both static and dynamic downhole sealing. Contact: Parker Hannifin Corp, EPS Division, 2220 South 3600 West, Salt Lake City, UT 84119, USA. Tel: +1 801 977 5335, Fax: +1 801 972 4777, Email
[email protected].
Rotabolt V Vision showing the tension indicator line, low tension on the left, and correct tension on the right.
Contents News
DuPont Dow demonstrates new perfluoro- and fluoroelastomers; updates chemical resistance guide To coincide with ACHEMA 2003, DuPont Dow Elastomers is unveiling the most recent high performance grade of Kalrez, Spectrum 7075, together with a range of specialty Viton fluoroelastomers made with the recently announced Advanced Polymer Architecture (APA). An updated Chemical Resistance Guide is also announced. Kalrez Spectrum 7075 is designed as an offering for critical sealing components and builds on the performance of Kalrez 4079. Customers should benefit from a longer seal life because of lower compression set, enhanced sealing force retention and higher thermal resistance, now up to 327°C. This new grade of material offers
broader chemical resistance and better compression set recovery on cool down than the previous 4079 grade. The APA fluoroelastomers are being launched as a new generation of fluoroelastomers. DuPont Dow introduced three of these materials, Vitons TBR-S, ETP-S and GBL-S, at ACHEMA. TBR-S is so named to indicate total base resistance. It is said to provide an optimum balance of resistance to strong basic chemicals and low volume swell in one product. ETP-S represents the best-performing Viton in terms of extreme resistance to oils and bases. Continued on page 2
In Brief
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Conference Focus: 17th International Conference on Fluid Sealing 4–5 Feature: Developing a Finite Element Model of Exfoliated Graphite Valve Packings
6–9
Feature: 2D Numerical Modelling of the TEHD Transient Behaviour of Mechanical Face Seals 10–13 Patents Events Calendar
ISSN 1350-4789/03 © 2003 Elsevier Ltd. All rights reserved. This journal and the individual contributions contained in it are protected under copyright by Elsevier Ltd, and the following terms and conditions apply to their use: Photocopying Single photocopies of single articles may be made for personal use as allowed by national copyright laws. Permission of the publisher and payment of a fee is required for all other photocopying, including multiple or systematic copying, copying for advertising or promotional purposes, resale, and all forms of document delivery. Special rates are available for educational institutions that wish to make photocopies for non-profit educational classroom use.
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Continued from page 1 Viton GBL-S is a special chemical process industry candidate that provides improved resistance to acids such as concentrated sulphuric and also to hot water and steam. This is achieved without the addition of toxic lead oxide to counter material swell. In addition to these three grades considered to be of interest to the chemical process industry, the company has also introduced Viton APA grades to the automotive industry. These were described at the International Conference on Fluid Sealing in York. They include GFLT-S, GF-S and GLT-S. GFLT-S is a high fluorine grade with low-temperature functionality for fuel systems. GLT-S offers the best low-temperature performance, while GF-S provides the best chemical resistance. The best compression set resistance of these grades is provided by GLT-S. The updated and enlarged Chemical Resistance Guide has an established internet advisory service that is intended to help engineers and designers select the best elastomer to meet their specific application and chemical resistance requirements. Contact: DuPont Dow Elastomers S.A., 2 chemin du Pavillon, Case postale, CH-1218 Le GrandSaconnex, Geneva, Switzerland. Tel: +41 22 717 4000, Fax: +41 22 717 4001.
New mixer seal repair programme from Burgmann A new seal care programme being offered by Burgmann Seals America for mixer, reactor and agitator seals offers a fast repair turnaround without having to deal with multiple vendors. The Accelerated Seal Accessibility Program (ASAP) provides a 72hour turnaround for all makes and models of mixer seals. All seal repairs will be completed by experienced Burgmann maintenance personnel at their dedicated repair facilities. In addition to the repair service, ASAP customers will receive a seal observation report analyzing the cause of the seal damage. Seal upgrade and replacement recommendations are also provided when appropriate.
The 72-hour service is available on what Burgmann calls a “Category 1 Repair”. This comprises: clean, inspect, seal observation report with digital pictures, replace carbon face, recondition mating ring, replace gaskets, springs, pins, set screws and snap rings. A new capabilities guide describes similar services for all mechanical seals across the process industry. The company claims to be the only major seal vendor with dedicated facilities for repairs, upgrades and rebuilds of all leading makes of mechanical seals. The MultiVendor Services Group also specializes in root cause failure analysis to predict and prevent seal problems. Contact: Burgmann Seals America, 10035 Brookriver Drive, Houston, TX 77040, USA. Tel: +1 800 303 7765, Fax: +1 713 939 9091, Web: www.burgmann.com.
Chicago Rawhide unveils new rolling mill seal Chicago Rawhide has introduced the new HDL Seal to help solve bearing life problems for large rolling mills. Applications include the paper and primary metals industries. The HDL Seal is intended to provide superior sealing performance while compensating for more severe problems such as roll deflection, shaft misalignment and run-out. It has a stainless steel finger and garter spring, largely eliminating the effects of external forces that cause changes to film thickness under the lip, which is necessary for the sealing function. The design also prevents the loss of lubricant and excludes contaminant particles. The rubber main lip element of the HDL Seal is bonded to the metal case, unlike fully assembled designs, and this provides complete security against internal bypass leakage. This innovative product release coincides with Chicago Rawhide’s 125th anniversary, reflecting the organization’s history of ongoing product development. Contact: CR Industries, 735 Tollgate Road, Elgin, IL 60123, USA. Tel: +1 847 742 7840, Fax: +1 847 742 0291, Web: www. chicago-rawhide.com.
Valve doors manufactured to ultra high purity Parker Hannifin Seal Group has introduced ultra high purity (UHP) valve doors for semiconductor processing equipment. The slit valve and gate valve doors feature fluorocarbon of perfluorinated elastomer seals chemically bonded to aluminium or steel. The doors are designed to replace existing arrangements that use an O-ring in a dovetail groove for sealing. The UHP gate valve door is claimed to reduce both product contamination and maintenance downtime. The advantages are said to include: reduced particle generation, improved abrasion resistance, reduced contamination and increased service life. The doors are processed and packaged in Parker’s ultra-high purity manufacturing cells using a batch traceable statistical process control programme. Contact: Parker Hannifin Seal Group, CSS Division, 7664 Panasonic Way, San Diego, CA 92154, USA. Tel: +1 619 671 3376, Fax: +1 619 671 3206, Web: www.parofluor.com.
Gasketing materials comply with FDA regulations Garlock Sealing Technologies has issued a statement for the Gylon gasketing material range confirming compliance with Food and Drug Administration (FDA) regulations. This statement, which will be available on request, covers not only the raw gasket material but also a wide range of proprietary Garlock sealing products that contain Gylon. The statement has been issued in particular response to recent increased pressure on customers of Garlock in the pharmaceutical sector to verify that animal-derived materials, such as beef extracts, are not contained within the product.
Sealing Technology June 2003