Sophisticated seals protect against explosive decompression

Louise Smyth

 

Elastomer seals that are used in valves, pipelines, fittings or pig traps have to face exceptionally high requirements. A sudden decrease in pressure is a particularly major challenge for manufacturers and a great responsibility for engineers and operators in these applications. Oil & gas projects are famous for being an area where “time is money”. Projects are planned meticulously against often challenging timescales. As well as being extremely costly, any unplanned downtime can have a knock-on effect on other projects. It is no wonder, then, that when it comes to seals, the oil & gas sector is embracing the next generation of materials that have been designed with durability at their heart.

Sealing compounds used in these applications often create a barrier against gaseous media if highly pressurised gas falls to a very low pressure level within a very short period of time. The result of this process is often damage to the sealing. The elastomer material is either torn in various places or blistered on the surface. This process is called explosive decompression (ED). Only high-tech sealing compounds that were especially tested and designed with excellent physical properties can be used in this sector.

ED-resistant solutions

For the high demands on elastomer seals against ED, the independent manufacturer C. Otto Gehrckens (COG) has developed seven different high-tech compounds that were intensively tested and are resistant against ED. Engineers and operators can choose between four FKM/FPM, two HNBR and one FFKM/FFPM compounds. All seven high-tech compounds fulfil the NORSOK Standard M-710 requirements for resistance against explosive decompression. Furthermore some of the compounds fulfil the important API 6A and 6D standard as well as the American NACE TM 0297 (Explosive decompression) and TM 0187 (sour gas) standard.

In applications for natural gas production, such as pig traps, gate
valves, ball cocks and other regulating valves, the use of all seven AED compounds has been proven successfully in avoiding damages to the sealings caused by explosive decompression –and consequently avoiding costly leakages.l

 

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