Size ： 1/2”~56”（DN15~DN1400）
Rating ： 150~2500LB（PN16~PN420）
Body Materials ： Carbon Steel, Stainless Steel, Alloy Steel, Duplex Steel
Trim ： Carbon Steel, Stainless Steel, Duplex Steel
End Connection ：RF，BW
Qilong fully welded ball valves are used mainly in Gas transmission and distribution pipeline (Mid-stream), typical for underground and buried installation The ball is fixed and the seat rings are floating, free to move along the valve axis.
Side load generated by pressure acting on the ball is absorbed by bearings.
At low pressure the seat sealing acting is achieved by the thrust of the springs acting on the seat. As the pressure increases the fluid pressure pushes the seat rings against the ball, making the sealing more reliable.
Automatic Internal Relief of Body Pressur Relief of excess body cavity pressure is automatic, avoiding dangerous pressure buildup. Any pressure exceeding downstream line pressure by approximately 200 psi pushes the downstream seat away from the ball, allowing the pressure to relieve into the pipeline.
Rotating Seat Rings The exclusive rotating seat feature is standard in the Qilong fully welded ball valve sizes 14” (350 mm) and larger. Both seats rotate 15 degrees each time the valve is closed, exposing a new pinch point and evenly
Distributed Seat Wear
The pinch point is the area of the seat insert that experiences an increased velocity when the valve is seated closed and unseated open. This is where the seat seal experiences the most wear, and in most valves, where a leak path begins. By rotating the seat ring, the pinch point wear is distributed throughout the seat seal, providing an increase in seat life.
In some services, a valve can experience harmful sediment buildup around the seat ring. This can cause the seat to stick and not seal properly. The QiLong fully welded ball valves, with exclusive rotating seat, can handle these harsher services. As the seat rotates, it will prevent any buildup, or breaks up existing buildup.
Delta seals and lip seals made of PTFE are incorporated in the upper stem area. PTFE is a low-friction, non-deteriorating material that is not subjected to rapid decompression explosion. Most valve sizes have a provision for sealant injection to establish a secondary seal.
Trunnion-supported Ball Allows
Regardless of size or pressure rating, every QiLong fully welded ball valve is trunnion mounted. High-strength forged stems are located in PTFE impregnated stainless steels bearings for smooth operation. Trunnion mounted stems absorb the thrust from line pressure, preventing excess friction between the ball and seats, so even at full rated working pressure, operating torque stays low.
Whether in the fully open or fully closed position,pressure on each side of the ball is blocked from the body cavity by the seat ring. The body cavity can then be bled down or drained through the body port. When you block-and-bleed a QiLong fully welded ball valve, the following can be accomplished:
Test Valve Integrity
When the valve body is vented, the seat seal’sintegrity is verified. This test can be performed with the valve open or closed prior to facility maintenance. By verifying valve integrity,unforeseen valve leakage can be prevented.
Secondary Seat Seal
The sealant injection system provides a fast, simple way of restoring tight shutoff if any foreign object should damage the sealing surfaces. The injection system also can be used for routine flushing of the seat ring area in services where this may be required