How to perform pressure testing on welded valves
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After the installation of the equipment, pipelines, and valves in the chemical plant was completed, the project was put on hold. Once work resumed, how can one inspect welded valves while under pressure testing?
On both sides of the valve, find a flange and remove it. Then the pipes on both sides of the valve are filled with water, and the valve is closed. Apply pressure from one side to check if the valve is leaking, that is, to see if there is any change in the liquid level on the other side ； Then release the pressure, apply pressure from the other side, and observe the change in liquid level on the opposite side.
The method mentioned above works. But what if the flanges on either side of the pipe are very far apart and the pipe is extremely long? What should be done in that case?
Follow the steps for conducting a hydrostatic test on the pipelines along with the equipment. Remove instruments and safety valves from the pipeline, install temporary restraining devices, and conduct tests in the order of main pipes, trunk pipes, and branch pipes; for pipelines that are long, blind flanges can be used to divide them into sections for testing. After the test, check the parallelism and coaxiality of the flanged pipeline in its free state :)