High Quality Epdm Lined Butterfly Valves & Gear Operated Wafer Type Valve | Trusted Butterfly Valve Supplier & Factory

Visual and Dimensional Inspection: Step one Determine Take the valve apart in case it is assembled. When processing the valve’s body, disc, stem and sealing material, it is essential to conduct a surface inspection. With regard to those products either made by or purchased from an Epdm Lined Butterfly Valves Factory, significant focus needs to be given to the EPDM (Ethylene Propylene Diene Monomer) lining. The lining must be equally vulcanized, no bubble, no folding and no foreign matters otherwise any defect reduces chemical resistivity and/or sealing performance. Ensure that flange drillings are in accordance with international standards such as ANSI, DIN, JIS and that the face to face dimensions of the valve correspond to ISO 5752 or API 609.

Step two is your Hydrostatic Shell Test (Body Strength Test). That a professional Butterfly Valve Supplier will validate that the test is the following – testing the body and bonnet for integrity. The valve is then set in a partially open position (typically approx 45 degrees) to allow the test medium to fill the entire cavity. Both ends are capped and clean water, usually with a rust inhibitor, is pressurized to 1.5 times the rated pressure of the valve (Cold Working Pressure, CWP) in accordance with the standards of API 598or ISO 5208. The pressure is kept for a certain period of time (e.g. duration of a minute for typical sizes, up to five minutes for large diameters). There can be no visible leaks, sweating, or permanent deformation to the valve body during this phase.

The third step is the Seat Leakage Test (Closure Test). That is key to test the shut-off ability. The shaft operated valve (such as Gear Operated Butterfly Valve) is completely closed through its actuator(s). The valve is pressurized to test pressure (usually 1.1 times the rated CWP) on one side with the other side open to the atmosphere. For Epdm Lined Butterfly Valves that has a resilient soft seat, the standard is normally “no leakage” or “bubble-tight” per API 598 Class VI or ISO 5208 Rate A. There should be no drips or bubbles coming out beyond the disc seal. This test is repeated in the reverse direction for bidirectional valves.

The fourth stage is the Operation and Torque Test.Smooth mechanical operation is preferred for any Gear type butterfly valve Supplier. The valve needs to be exercised several times, open to close (and close to open) without sticking. The handwheel of gear-operated versions should have a smooth rotation and the torque needed to move the valve should be uniform and within the allowed values. This allows for the valve to be either manually actuated or instrumented with an actuator.