What material should be used for bolts in hydrogen pipeline flange connections?
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Dear everyone: In hydrogen production plants, are there any requirements regarding the material of bolts used for pipe flange connections? It turns out that our company has been using stainless steel for over a decade. During this year’s inspection, we were suddenly informed that bolts made of stainless steel are not allowed to be used, without any relevant documents provided to explain why. I was wondering if anyone here has any insights on this matter! Thank you!
My device uses fully threaded bolts. 35CrMoA/30CrMo. I think it’s because stainless steel bolts are not suitable for tightening when heated, as this can lead to leakage.
We also use ordinary high-strength bolts for our hydrogen pipelines, in order to reduce installation costs
I agree with the view from the second floor; the pressure in hydrogen production equipment isn’t very high, so 35CrMoA/30CrMo will suffice to meet the requirements. It’s not that stainless steel bolts cannot be used for hydrogen production; rather, in the equipment used, non-stainless steel bolts are preferred, and stainless steel bolts are only used when the temperature of the bolts becomes too high. When stainless steel is heated, its linear expansion is excessive, which can easily lead to leaks.
Our pipelines, flanges, and the like are all made of stainless steel; I’m not sure whether replacing the bolts with alloy steel could lead to chemical corrosion Our temperature is at room temperature, and the pressure is only 4.5 MPA, which would be considered medium pressure – not high pressure!