Valve structural length
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Dear teachers； In GB/T 12221-2005, when looking at Table 1 which lists the structural lengths of flanged valves, I see that there are many different series of lengths for each diameter. How should one choose the appropriate length from these series? I previously saw in a selection catalog that the flanged butterfly valve with a 250 caliber is 165mm. But I don’t understand how to choose other lengths?
The national standards are chaotic; bold text is the preferred option, but some manufacturers do not follow this
Generally, the length of gate valves, globe valves, and ball valves should be relatively consistent, but some manufacturers intentionally make them a bit longer or shorter; therefore, attention should be paid when replacing them. There are actually standards for the connection length of butterfly valves, but many manufacturers produce them without following these standards. In short, the structural length depends on the actual site conditions; this is especially true when replacing valves in existing pipes. If it’s the first time installing pipes, then it doesn’t have much impact.
Choose long-type valves directly when formulating procurement requirements
Valve sizes vary among different manufacturers
Take a look at ASME b16.10
The length is not standard; next time I’ll have to turn to them for a replacement :D So it’s clear that the quality of valves produced by such companies must also be poor.
The long series belongs to the ISO standard system, while the short series falls under the American standard system; there are also some similar series, which are the result of China’s standards being copied from foreign standards.
There is indeed no mandatory standard for this; if you’re worried, simply specify the valve length when submitting the purchase plan!
It’s best to specify in the purchase contract that a certain size must be followed, and the same standard should apply to spare parts as well; otherwise, there will be numerous problems later on
Based on my own needs, I think the most important factors are diameter, width, and pressure rating. Regarding the external dimensions, if you have any specific requirements, please mention them directly; or if you think the drawings submitted by the supplier don’t affect the use of the space in question, that’s fine. Standards are there for later reference, hahaahaha