Because the sealing rings of soft-seal butterfly valves are mostly made of rubber or PTFE, excessive pressure can damage them. Therefore, if the actual operating pressure is low, the shell pressure test can be reduced, and only the seal pressure test needs to be performed.

Shell pressure testing increases equipment and time costs. Therefore, for small- and medium-diameter, low-pressure butterfly valves, the process can be simplified, omitting the shell test and focusing on the seal test to reduce the risk of valve damage due to excessive testing.

For soft-seal butterfly valves with a diameter of PN10 or less and DN600 or greater than or equal to, and containing non-flammable and non-toxic media, the shell pressure test can be completed simultaneously with the system pressure test. The system pressure test satisfies both the shell and seal pressure tests, eliminating the need for repeated pressure testing.