Precautions for installing butterfly valves
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Precautions for the installation of butterfly valves: As the maintenance work progressed, some minor tasks were also completed as planned. On the morning of the 18th, I had the opportunity to see the site where the butterfly valves were being installed, and the following points summarize those observations: 1. Before installation, it is necessary to verify whether the technical parameters of the valves match the actual conditions of the pipeline, including pressure, temperature, and the type of medium used； 2. During installation, it is particularly important to note the requirements regarding the flow direction of the medium: 1. Centerline-type sealed butterfly valves have no requirement for a specific flow direction, as their sealing structure ensures that the pressure resistance on both sides is equal. 2. Eccentric-sealed butterfly valves have specific flow direction requirements. In order to meet the needs for dual-direction sealing, manufacturers simply increase the sealing pressure, which leads to rapid wear of the seals and a shortened product lifespan. 3. The installation direction of the product does not necessarily have to follow the optimal pressure-bearing direction indicated on the valve body; it should be applied flexibly based on the actual operating conditions. Therefore, the direction indicated by the arrow on the valve housing is not the flow direction of the medium, but rather the optimal pressure-bearing direction of the valve, that is, the direction under which the valve can withstand pressure when it is closed. Another important point to consider when installing butterfly valves is that many pipelines today use pipes made of PE (polyethylene) or similar materials, which are specified by their outer diameter; it is essential to ensure that the butterfly valve can be fully opened without interfering with the pipeline ； Butterfly valves, especially flanged butterfly valves, must be tightened in a uniform and symmetrical manner in conjunction with the pipeline flanges.
Thank you to the original poster for sharing the information; I’ve learned something! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !
1. “So the direction indicated by the arrow on the valve body is not the flow direction of the medium, but rather the optimal pressure-bearing direction of the valve, that is, the direction under which the valve can withstand pressure when it is closed.” I heard this for the first time. 2. What worries me the most regarding the installation of butterfly valves is the use of too small gaskets, which prevent the valve disc from opening.
It depends on the process requirements; some butterfly valves shown in the flow diagrams need to be installed in reverse, such as the outlet valves of parallel expanders
The statement in Article 1 is correct; the reason can be found in what was said on Floor 4. For conventional pipelines, the eccentric butterfly valve can be installed in accordance with the flow direction arrow, as the pressure upstream of the medium is higher than that downstream. In the case of parallel compressor or pump outlets, a normally installed backup butterfly valve is exposed to high pressures downstream, which hinders proper sealing of the eccentric butterfly valve; therefore, it is necessary to install it in reverse.
The flow direction arrow of the stop valve should also be interpreted in this way.