Why is it specified this way in the technical specifications for the construction of petrochemical instrumentation projects?
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Why is it specified this way in SH/T 3521-2013, Technical Specifications for the Construction of Petrochemical Instrumentation Projects? Thank you, Haiyou, for answering this question ? ? 、
Plug-welded valves should be in the open position during welding; if they are closed, it is very likely that they will not be able to be opened after welding.
The flange is connected by threads, and the valve is kept closed to prevent installation debris from damaging the internal components of the valve, especially the seals； Welded connections, with the valve open – it’s to prevent thermal expansion of the valve’s internal components.
It seems to me that this wasn’t done at all during the actual installation process
You think everyone understands this kind of knowledge? Even those in charge of construction don’t know it; how could the workers know then?
What he meant was welded valves; by opening the valve during installation, it is possible to prevent welding slag from remaining inside the valve and affecting its performance. After welding in an open manner, purging should be carried out
I’m not very familiar with the first one. Regarding the second one, the valve needs to be fully open during welding, mainly to avoid damaging the valve’s sealing surface; this is especially true for ball valves, so they must be in an open position during welding
That makes a lot of sense. During welding, there is high temperature, which may cause the internal components of the valve to stick together. As for threaded connections, one concern is that debris might enter the valve and damage its internal components.
Considering the impact of slag on valve internals and seals.