Selection of material for hydrogen pipelines
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For a 4” hydrogen pipeline with an operating pressure of 0.1 Mpag and an operating temperature of 120°C, a design pressure of 0.5 Mpag and a design temperature of 160°C, it is intended to use pipes in accordance with standard 20 GB/T 8163; is it feasible not to use pipes based on standard 9948?
For pipelines operating in hydrogen environments, or those working in conditions prone to stress corrosion, it is also advisable to use the GB9948 or GB6479 standards.
I would like to ask whether there is an authoritative definition for hydrogen-handling pipelines, such as one specified in standards or something similar. Can it be considered that the presence of hydrogen means there is a hydrogen pipeline?
I think those with hydrogen should be hydrogen pipelines
Brother upstairs, do you have a standard in mind? Is the presence of hydrogen, regardless of the proportion, considered to be in the presence of hydrogen?
The Design Code for Hydrogen Stations GB50177-2005 only sets limits on the flow rate of hydrogen; it can be seen that for carbon steel, this value is around 15 m/s at such pressure. GB/T8163 can also be used. The temperature is still far from reaching levels that could cause hydrogen embrittlement. As for valves, globe valves and ball valves are recommended. For the pressure valve body, carbon steel is sufficient; for the sealing surfaces, materials such as 13Cr9948 or 6479 can be used. This is mainly because if the pipeline pressure becomes high enough, GC1 materials would be required
1. Under normal circumstances, for carbon steel and alloy steel pipes operating at temperatures equal to or above 200°C and containing H2 in the medium, hydrogen service conditions must be taken into consideration. At this time, an appropriate hydrogen-resistant material should be selected by referring to the Nelson curve, taking into account a margin of 20°C to 40°C added to the highest operating temperature of the pipeline and the hydrogen partial pressure in the medium. 2. For pipelines operating at temperatures of 250°C or higher, with H2S and H2 present in the medium, the selection of pipeline material should be determined by referring to the Couper curve, taking into account both the operating temperature and the H2S content in the medium. 3. Based on the operating conditions you provided, the design pressure is 0.5 Mpag and the design temperature is 160°C. Using pipes in accordance with 20 GB/T 8163 is no problem. Of course, if you designate this tube as GC1, then GB/T 8163 is not suitable; at least the GB/T 9948 standard should be used (GB/T 8163 cannot be applied to GC1 according to GB/T 20801).