Installation of reverse-mounted spool control valves
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In SH3012-2011, the installation of control valves has the following requirement: the clear distance from the bottom of the control valve to the ground or platform surface should not be less than 400 mm. For single- and double-seat control valves with reverse-mounted spools, it is advisable to leave space below the valve body for removing the spool; SH3012-20 should be changed to: 10.4.6 The clear height from the bottom of the control valve to the ground or platform surface should not be less than 300 mm. When the control valve requires core extraction, space for core extraction should be reserved. Which control valves require core pulling, and how can this information be obtained?
In terms of the standard updates, the requirements regarding the installation height of control valves have indeed been relaxed; however, the critical aspect of the clearance for removing the inverted valve core still requires special attention. It is recommended to pay attention to two points when carrying out actual operations: 1. Although the new standard allows a clearance of 300 mm, it is safer to reserve 400 mm when it comes to valve core maintenance ； 2. When determining the core-pulling space, one must consider not only the height but also the lateral operating space. In our project, we encountered a situation where pipes located beneath the valve body made it impossible to perform core pulling. For specific implementation suggestions, review the space dimensions in conjunction with the on-site pipeline layout diagram~
One really does need to pay attention to the details in these installation specifications! Regarding the space requirements for installing control valves, here are two practical suggestions: For large-diameter valves of DN50 or larger, it is advisable to increase the available clearance to 500 mm, as more operating space may be needed during actual maintenance tasks. When considering the space required to remove the valve core, in addition to ensuring sufficient space below the valve body, it is also important to leave at least 1.5 times the length of the valve body on the sides to facilitate the removal of the valve stem. In one of our previous projects, insufficient space led to the need to remove pipe supports when replacing the valve core, which significantly delayed the project timeline. It is recommended to conduct a BIM collision check before construction for greater safety.
To determine whether it is a valve core installed in reverse, it is necessary to consult the valve manufacturer; currently, valves with reverse installation are quite rare.
In such a situation, is the only option to reverse-install the film head?