Regarding valve installation
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Dear experts, are there any relevant standards and specifications regarding the prohibition of installing valves in reverse? If inversion is possible, are there any specific requirements?
I understand that by inversion you mean installing the valve stem downward on a horizontal pipe; it’s not the kind of inversion where it’s installed against the flow direction of the fluid, right? That kind of inversion is definitely not acceptable. Based on the above, there is no concept of inversion for the valves on the vertical pipe. It is recommended to consult the valve supplier to determine whether a specific valve can be installed with its stem facing downward. However, in general, whether due to the valve’s opening and closing mechanism or the requirements for sealing at the stem location, it is not possible to install the valve with the stem facing downward.
By inversion, do you mean the situation where the valve flow direction arrow is perpendicular to the fluid flow, or the inversion of a valve on a vertical pipe? GB50235 and SH3501 contain relevant provisions; stop valves can also be installed in the reverse direction, but this requires specific design requirements
Inversion is not allowed; the valve stem must be directly below. This is part of basic safety knowledge, and there’s no need to include it in the standards. After all, at the lowest point, there may be slight leaks of fluid from the pipes, as well as condensation, which can corrode the valve stem – and this is definitely not permitted
Inverted installation can lead to the deposition of impurities due to gravity, which affects the sealing performance; it also increases the difficulty of maintaining the valve.
GB50235-2010 and SH3501-2021 require that valves be installed vertically.
When cut-off valves are installed on the inlet and outlet pipes of the safety valve, a single-plate gate valve should be used, and it should be sealed with lead. The valve stem must be positioned horizontally to prevent the valve plate from sliding down in case the pins that connect the valve stem to the valve plate become corroded or loose. When a safety valve is equipped with a bypass valve, this valve should be sealed with lead.
It should only specify that the safety valve be installed vertically
Since horizontal installation (vertical pipes) is allowed and common, inverted installation should not either be prohibited; it is simply not widely used due to convenience, habit, etc. (it is used in certain special situations)
Only 3D model drawings were found; what the design institute provided was one that could be inverted.