TESTING BUTTWELD END VALVES

TESTING BUTTWELD END VALVES

To perform a pressure test of a butt­weld end valve on site requires the valve to be welded into a piping system or caps welded to the valve buttweld ends. Seat leaks detected on a valve body once a valve is installed in a piping system can be very expensive since the valve needs to be cut from the line and sent to a repair facility. Because of this, many end users request that butt­weld valves for critical service have an independent pressure test performed to ensure the valves meet respective design pressure test requirements.

Valve manufacturers and repair/modification facilities use hydrostatic test stands that can seal buttweld end valves by using test plate adapters to seal the buttweld ends through a retained O-ring seal . These test plates are energized by means of a hydraulic ram. As the internal hydrostatic valve pressure is increased, hydraulic ram pressure also is increased on the test plates to equalize the external force against the valve buttweld ends with the internal valve hydrostatic force. This means an independent pressure test can be performed on a buttweld-type valve to ensure no defects without having the expense of finding a leak after it has been welded in a piping system.

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