BHRSolutions sealing performance evaluation – asbestos replacement materials

Citation

(2002), "BHRSolutions sealing performance evaluation – asbestos replacement materials", Industrial Lubrication and Tribology, Vol. 54 No. 2. https://doi.org/10.1108/ilt.2002.01854bab.005

BHRSolutions sealing performance evaluation – asbestos replacement materials

Keywords: Seals

Totally refurbished, BHRSolutions high-duty steam facility reliably imposes real operating conditions on gasketed flanged joints, valve glands, packings and steam control valves to evaluate their performance. Three similar test units provide test steam at conditions up to Class 2500 ie the pressure and temperature at the inlet to power turbines in a modern electric power generating station, 550 C and 180 bar. It is also able to handle more modest conditions, as the test heads are interchangeable and test modules down to Class 150 are routinely used.

The facility provides sealing performance data, which would otherwise be difficult if not impossible to obtain. It has already been used by major manufacturers and end-users to investigate design parameters such as gasket m and y factors, and the Allowable Bolt Load widely used in the design and application of bolted gasketed joints. These parameters arise from the ASME Boiler and Pressure Vessel Code. The Code intends these as design parameters to help achieve an adequately strong structure, but many users treat them as service parameters. Tests on various gaskets with only the Allowable Bolt Load, ca. 25,000psi bolt-stress, compressing them predictably resulted in dramatic blowouts. Bolt stresses of 40,000psi or more are needed to control leakage and avoid such hazards.

BHRSolutions has moved on to determine p-T envelopes for non-asbestos gaskets and has been working with manufacturers to identify maximum operating conditions as some early designs had been previously down rated. Results have shown that excellent performance can be obtained if a thin gasket is used, ca 1.0mm thick, in combination with a high bolt load, 40,000–50,000psi bolt- stress. For bonded fibre gaskets leakage levels can be better than PVRC Tight for Class 600 or Class 900 conditions depending on gasket material. This information has since been widely adopted for user guidance.

With new materials being developed the enhanced facility provides a unique and comprehensive route to sealing product validation coupled with soundly based and independent advice for performance improvement.

For more information contact Ed Bloomfield, BHR Group Limited, The Fluid Engineering Centre, Cranfield, Bedfordshire, MK43 OAJ, UK. Tel: +44 1234 750422;Fax: +44 1234 750074; E-mail: ebloomfield@bhrgroup.com; Website: http:\\www.bhrgroup.com