Repeated weld joints leaks were observed in newly commissioned non insulated low temperature carbon steel anhydrous ammonia pipes after few months of operations. A detailed investigation was carried out to identify the root cause which found to be usage of high strength filler wire which leads to stress corrosion cracking (SCC) and weld joints failure. Also, An Online advance inspection via Phased Array Ultrasonic Test (PAUT) was conducted to assess the condition of weld joints in anhydrous ammonia pipe loops. Moreover, three different samples of leaked weld joints were submitted for metallurgical failure analysis laboratory. The paper explains the root cause of the damage, Online PAUT inspection and the challenges faced during development of the rectification procedure and implementation.

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