Valve dehydrogenation treatment
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A newcomer is facing some new problems and would like to ask everyone for advice. I encountered PN100 high-pressure hydrogen valves. I already knew that oil and grease had to be removed from high-pressure hydrogen systems, but this time it was mentioned that dehydrogenation is also necessary, in order to prevent hydrogen embrittlement. I would like to ask, under what circumstances is dehydrogenation necessary? Do we need high-pressure hydrogen, or do we need all high-pressure valves?
Media under high pressure or high temperature, as well as those containing hydrogen ions, require treatment to resist SSCC and HIC
Thank you, I’ve learned it. Is there some general standard, such as a certain temperature or pressure threshold above which anti-SSCC and anti-HIC treatments are required?
Both anti-HIC and SSCC are designed to address low-temperature wet hydrogen sulfide corrosion, not hydrogen corrosion. Oil-free degreasing is intended for oxygen-based media; as for the dehydrogenation process, it is up to the party who requests it to specify how it should be carried out – this term is not mentioned in any standards. For requirements regarding high-pressure hydrogen valves, reference can be made to JBT11484-2013, Technical Specifications for Valves Used in High-Pressure Hydrogenation Units
I have another question: besides oxygen, I’ve also encountered situations where, due to the need to use clean media and avoid contamination, oil-free degreasing was required. In such a situation, is oil-free degreasing a suitable treatment method?
Degreasing is generally done using specialized degreasing agents, with the specific components varying from one valve manufacturer to another. The ban on oil refers to the prohibition of coming into contact with oily substances, such as applying anti-rust oil or injecting lubricants. There is no need to specify in detail how the procurement process should be carried out; it is sufficient to state the requirements. If one wants to know more, they can ask the supplier to provide an explanation.