Design Criteria of O-rings under Pressure in Sour Gas Environments

Failure of elastomeric seals due to Rapid Gas Decompression (RGD) under high pressure is a known problem in the oil and gas industry. This phenomenon has significant importance in valves, blow out preventers and compressors. Elastomeric materials because of flexibility, resilience, ability to Self-energize and to compensate for housing tolerances, surface textures and scratches are still the first choice of sealing materials. However O-ring decomposition due to the rapid gas decompression (RGD) is a serious threat for rubbers because of their low tensile strength. In this paper, after studying the effective parameters in design of under pressure seals, design and manufacture of sour gas resistant O-rings applied in high pressure valves of a petrochemical unit (water absorption from sour gas plant of Masjed Soleyman) were investigated. The effect of structural parameters and design variables on the performance of O-rings was also evaluated.