GC1 or GC2? Just how much of a difference will this actually make? ?

Should the classification of sulfuric acid pipelines be upgraded to GC1? https://bbs.hcbbs.com/thread-2844942-1-1.html (Source: Haichuan Chemical Industry Forum)

Just in terms of materials, once the temperature and pressure conditions of the medium are determined, the material to be used is also fixed. When creating a database of pipeline material data, it is standard practice to consider GC1 as the appropriate material; it is rare to see cases where the material changes due to differences between GC1 and GC2. If such a change does occur, it indicates that the design was not properly thought through and that sufficient care was not taken during database creation. Regarding construction, the main differences between GC1 and GC2 lie in the flaw detection ratio and the acceptable level for flaw detection. I remember that in GB20801, the lowest values are 20% and 5%; of course, the value increases depending on the type of medium used. As for the costs, since we are not a construction team but have only been involved in general contractor projects, I asked the project manager – there isn’t much difference in welding and installation costs; even in case of rework, the cost is roughly double. But for flaw detection, the ratio is much higher; it can be 4 to 5 times as much.

During the period from the issuance of HG/T20660 until the release of Document No. 3 in 2019, sulfuric acid was classified as GC1; once Document No. 3 was issued, it was classified as GC2. There are significant differences between GC1 and GC2: the grade of piping, valve flanges, and fasteners, weld inspection, inspection costs, etc. Additionally, GC1 requires registration with the General Administration of Quality Supervision, Inspection and Quarantine.

GC1 will result in significantly higher costs for future routine inspections