Wall thickness of piping material is related to lifetime of the products and entire facilities. Due to the reason, engineers always consider annual losses of materials and manufacturers must follow specification of what engineer designed. However, there is one thing that causes cretical situation and shorten lifetime of the products. That is Wet H2S corrosion. For the material which would be used in H2S environment, it must be passed the tests HIC and SSCC. How heavy piping material walls are, if the registance of the material to sour environment is poor, there would be cretical failure.
The crack of the picture below was found by Hydrogen Blistering. The materials were passed HIC, and SSCC tests before shipment however, the failure was happened because it was bonded item. In case of explosively clad, roll bonded or fusion-bonded corrosion resistance overlay, it is important that the boundary between two materials are bonded well and the area is firmly welded. Most users regard clad plates(or overlayed) as a permanent solution for hydrogen blistering problem. And actuall it’s very effective to prevent the matter. The issue is that un-bond while we use clad items at site can be found any time, and we don’t know when it would be happened. Un-bond is not related to hydrogen blistering itself but it’s related to quality management at manufacturer side. After clad, RT is necessary to discover air poket between materials.