A test procedure was developed for screening Electric Resistance Welded (ERW) / High Frequency Welded (HFW) pipe weld seam against the susceptibility to hydrogen embrittlement, mainly after exposure to wet sour environment. This test procedure was evaluated and proven effective as a reliable technique to assure the performance of the HFW pipe weld seam in wet sour environment. The test procedure can be complementary to other testing procedures such as NACE TM0284 and TM0177 [1 & 2]. This procedure was developed, tested and patented by Aramco (U.S. Patent No. 11,235,427) [3 &4].
HFW pipes is considered a cost-effective pipe option for oil and gas pipeline projects. The HFW seam performance is always a concern, especially in challenging environments such as low temperature applications and wet sour services. One of the challenges include the seam properties to resist sulfide stress cracking (SSC) or hydrogen embrittlement (HE) when exposed to hydrogen charging environment such as a wet sour service. HFW pipe seam embrittlement during operation can be catastrophic and detrimental to the oil and gas operations. Hence, quality control measures by pipe specifications and standards, such as API-5L and DNVGL-ST-F101 mandate material qualification for SSC and HIC as per NACE MR0175/ISO-15156 and NACE TM0284, respectively [5, 6 & 7].
Unfortunately, both these material and testing requirements do not address the susceptibility to HE in the HFW pipe seam. Some of these crack features can raise inconclusive concerns and doubts about the seam compatibility to sour service. Accordingly, there is a need for a complementary test procedure that is quick and reliable to screen indications in the HFW seam.
This paper proposes a novel approach to evaluate the seam susceptibility to embrittlement after hydrogen charging that is caused by exposure to an aqueous sulfide solution. The testing procedures can be used as a complementary test for all HFW pipes intended for sour service applications. The proposed testing procedure can be implemented for all HFW pipes orders for sour service procured in accordance with API 5L, ISO-15156/NACE MR0175 and NACE TM0284. The testing procedure can be further qualified and modified to be adopted by API 5L, NACE TM0284 or NACE TM0177 in the future to test the pipe seam susceptibly to HE.
