Two Common Seating Structures For Stationary Ball Valves.
Date:2019-12-13 Click:1342
Two common seating structures for stationary ball valves.
1. DBB double block and bleed valve
Valves with two seat seating pairs can provide pressure seal at both ends of Forged Steel Reduced Port Ball Valve through a discharge/exhaust method in the body cavity between the two seat surfaces.
2. DIB double isolation and bleed valve
Valves with two seat sealing pairs, each of which can be provided with a single source pressure seal by discharging/emptying the body cavity between the two seat sealing pairs at the closed position.
Valve Pressure Testing Method
1. Double Shutoff and Discharge Valve DBB
Forged Steel Reduced Port Ball Valve is in a semi-open state, and the experimental medium is fully injected into Forged Steel Reduced Port Ball Valve and Forged Steel Reduced Port Ball Valve chamber. Then close Forged Steel Reduced Port Ball Valve and open Forged Steel Reduced Port Ball Valve body drain valve to allow excess test fluid to overflow from Forged Steel Reduced Port Ball Valve chamber test interface. The sealing of the seat should be monitored by the overflow at the test interface ofForged Steel Reduced Port Ball Valve chamber under pressure at both ends of Forged Steel Reduced Port Ball Valve.
2. DIB valves are divided into DIB-1 and DIB-2.
(1) Double Isolation and Discharge Valve DIB-1 (Two-way Two Seats)
Each seat should be tested in two directions. If the chamber relief valve is installed, it should be removed. In order to make Forged Steel Reduced Port Ball Valve semi-open, Forged Steel Reduced Port Ball Valve and Forged Steel Reduced Port Ball Valve chamber should be injected with experimental medium until the test liquid overflows through the test interface of Forged Steel Reduced Port Ball Valve chamber. In order to test seat leakage in the direction of the chamber, Forged Steel Reduced Port Ball Valve should be closed. The test pressure shall be applied to each end of Forged Steel Reduced Port Ball Valve one by one to test the upstream leakage of each seat separately. Leakage shall be monitored for seat tightness by overflow at Forged Steel Reduced Port Ball Valve chamber test interface. Each seat is then tested as a downstream seat. The two ends of Forged Steel Reduced Port Ball Valve are opened to fill Forged Steel Reduced Port Ball Valve chamber with test medium. Then pressurize and observe the leakage of each seat at both ends of Forged Steel Reduced Port Ball Valve.
(2) Double Isolation and Discharge Valve DIB-2 (Single Seat, One Seat, Two Seats)
Two-way seat shall be tested in two directions. If the chamber relief valve is installed, it should be removed. In order to make Forged Steel Reduced Port Ball Valve semi-open, Forged Steel Reduced Port Ball Valve and Forged Steel Reduced Port Ball Valve chamber should be injected with experimental medium until the test liquid overflows through the test interface of Forged Steel Reduced Port Ball Valve chamber. In order to test seat leakage in the direction of the chamber, Forged Steel Reduced Port Ball Valve should be closed. The test pressure shall be applied to each end of Forged Steel Reduced Port Ball Valve one by one to test the upstream leakage of each seat separately. Leakage should be monitored by the overflow at the test interface of Forged Steel Reduced Port Ball Valve chamber. For the bidirectional seal seat test of Forged Steel Reduced Port Ball Valve chamber test, the test pressure is applied to Forged Steel Reduced Port Ball Valve chamber and upstream end in turn. Leak detection is performed at the downstream end of Forged Steel Reduced Port Ball Valve.
The above text is mainly taken from API 6D-2014. Without repeated reading and careful deliberation, it is difficult for non-professionals to fully understand its meaning.
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