What adjustments are needed for valve flow meters under high-temperature and high-pressure hydrogen conditions?
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1. Since hydrogen embrittlement, also known as hydrogen penetration, can occur under high temperature and pressure, pressure transmitters have their diaphragms plated with gold. So what measures need to be taken for other instruments in such operating conditions, such as valves and flow meters? 2. In the design code for hydrogen stations, GB 50177-2005, the terms \"hydrogen embrittlement\" or \"penetration testing\" are not mentioned at all. Why is that? According to relevant information, even without high temperature and pressure, a small amount of hydrogen ions are generated. Over time, won’t these hydrogen ions cause damage by penetrating into the metal? 3. In Section 12 of this specification, which deals with hydrogen pipelines, as shown in Figure 3.1, ball valves and globe valves are recommended for use on hydrogen pipelines. Why cannot butterfly valves be used? Are ball valves and globe valves also used for very large pipelines? And all of them require a hard seal? Can’t ball valves use soft seals? Wouldn’t that result in better sealing? 3.2 What does the phrase “when the sealing surface is directly connected to the valve body” mean, as stated in the annotations above? Similar descriptions have never appeared in the data sheets for control valves and ball valves before.
Regarding hydrogen embrittlement, it depends on the scale involved. The diaphragm is very thin and easy to be penetrated, which can cause it to bulge and affect measurements. Devices like valve flow meters, which are of a relatively heavy construction, don’t pose any such problems
1. Under high temperature and pressure, the materials used for valves and flow meters should be appropriately treated or of high quality. 2. In situations where temperatures are not high, special materials aren’t necessary; otherwise, the cost of hydrogen pressure stations would be extremely high. 3. I think the relevant standards have not kept up with the times – modern triple-eccentric butterfly valves can achieve a shut-off level such that the leakage rate meets the required standards. The sealing surface here should refer to components such as the upper valve cover that compresses the packing.
However, it can be found online that valves exposed to high temperature and pressure in pure hydrogen require forged stainless steel and must also undergo flaw detection; theoretically this makes sense, but it’s not clear whether this practice is actually used in real applications.
When soft seals are used in ball valves, the leakage level is relatively low; their sealing performance is not as good as that of hard seals