Two of James Walker’s flagship grades of explosive-decompression (ED) resistant elastomers — FR58/90 and Elast-O-Lion 101 — are now qualified to the exacting Norsok M-710 requirements, with one having a sour gas rating of ‘over 800 years’.
Explosive decompression can destroy seals made in standard elastomers — downhole, at the wellhead and upstream. Global operators and equipment manufacturers in the oil and gas sector rely on James Walker’s ED-resistant materials for special oilfield sealing products.
Operators such as Shell and Total have validated James Walker materials against their own specifications. James Walker can now add a world-recognised independent qualification to its expanding portfolio of industry approvals.
The Norsok M-710 standard has been developed by the Norwegian petroleum industry as a qualification for non-metallic sealing materials used in oil industry developments and operations.
Exacting test regimes
The DNV-witnessed rapid gas decompression (RGD) tests were carried out by James Walker Technology Centre — which has a custom test facility specifically for ED work.
‘O’ rings in these materials were housed and soaked in a mixture of carbon dioxide and methane gases for 72 hours at 150bar and 100°C. They were then subjected to ten ED cycles (rapid decompression, dwell for one hour at 100°C, recompression and hold for 24 hours) before being microscopically examined and rated for cracks, holes and blisters.
The Materials Engineering Research Laboratories (MERL) in Hertfordshire performed the accelerated sour gas aging tests. An exceptional service life of 817 years at 80°C has been predicted for FR58/90 for sour gas service under Norsok test conditions, before its tensile strength is halved. For Elast-O-Lion 101 the prediction is 36.7 years.
To obtain these predictions, MERL exposed material samples to a fluid containing H2S for different lengths of time up to 40 days, at a set pressure and a variety of temperatures. Samples were physically tested to different parameters as soon as they left the sour gas test rig. The working life was extrapolated from the resulting time-based curves using Arrhenius techniques. When used in this manner, Arrhenius is a good tool for comparing the relative service lives of different elastomer types and grades.
Well-proven sealing materials
Fluorocarbon (FKM) based FR58/90 and hydrogenated nitrile (HNBR) Elast-O-Lion 101 are renowned for their high integrity fluid sealing capabilities in the oil and gas sector. In addition to ED-resistance, FR58/90 displays excellent chemical and thermal properties; Elast-O-Lion 101 also has exceptional mechanical strength and wear resistance.
Both are nominal 90 IRHD compounds, with the excellent resilience and low compression set characteristics needed for efficient longterm fluid sealing.
Confirmed Trevor Clarke: “Norsok M-710 qualification proves that our materials will survive both harsh explosive decompression and sour gas environments — as well as providing the long-term sealing reliability that oil and gas sector customers need.”