Trunnion Mounted Ball Valve Operation Instruction
To assure maximum valve performance, only use a trunnion mounted ball valve that is suitable for the rated pressure / temperature and corrosive environment.
For your safety and normal operation, please read the following trunnion mounted ball valve operation procedures:
4.1 Trunnion mounted ball valve must be kept either in the fully open or fully closed position. Never throttle or leave the trunnion mounted ball valve at the half-open position as erosion of the ball and seating surface may occur and damage will result.
4.2 Trunnion mounted ball valve open and closed positions are indicated on the valve gear box or lever. Rotating the trunnion mounted ball valve hand wheel clockwise will close the valve; counter-clockwise operation will open the trunnion mounted ball valve, this is also applicable to gear or motor actuated operation.
4.3 There are position stops for the trunnion mounted ball valve at the fully open and fully closed position. When the trunnion mounted ball valve lever or hand wheel will not rotate any further it means the valve is already at the fully open or fully closed Installation, Operation and Maintenance Trunnion Mounted Ball Valve. The open/close stroke is 90°.
4.4 Lever operated valves are in the open position when the lever is in-line with the flow centerline. Conversely when the lever is perpendicular to the flow centerline the trunnion mounted ball valve is in the closed position. Gear operated trunnion mounted ball valve will have a position indicator on the gear.
4.5 Never operate the trunnion mounted ball valve without authorization and a full understanding of the safe operation procedures, inspections and proper handling instructions.
4.6 The trunnion mounted ball valve vent and drain should never be opened unless safety procedures are followed to ensure it is safe to open those connections.
4.6.1 Ensure the operator is aware of the body vent fitting location. Inspect and determine the direction of the hole on the side of the vent fitting. Caution should be taken as any debris within the valve or the fitting will be exhausted at a high velocity through the hole on the drain fitting.
4.6.2 Personnel safety is the most important factor when opening the vent fitting. Ensure that the vent fitting is fully CLOSED. Place a backup wrench on the body of the fitting to prevent accidental loosening or removal of the body vent fitting. Carefully open the vent fitting all the way to drain/vent the ball valve.
4.7 DBB Operation: Trunnion mounted ball valve will have two uni-directional seats (SPE seat), which can seal both the upstream and downstream pressure at the same time. When the trunnion mounted ball valve is at the closed position, opening the drain valve will release the body cavity pressure and allow observation of any potential leakage from the valve seats.
4.8 DIB Operation: DIB trunnion mounted ball valves have two configurations: DIB-1 and DIB-2. The DIB-1 configuration has two bi-directional seats (DPE seat), which can seal both upstream and downstream pressure at the same time while providing the seal between the body cavity and both upstream and downstream seals. The DIB-2 configuration has one uni-directional seat (SPE seat) on the upstream side and on bi-directional seat (DPE seat) on the downstream side which can seal on both upstream and downstream pressure at the same time and can only provide the seal between the body cavity and the downstream seal.
4.9 Trunnion mounted ball valve body cavity pressure relief: When the trunnion mounted ball valve is in the closed position, the body cavity is sealed between both upstream and downstream seal due to the cavity temperature increase (specifically for a liquid medium). The cavity pressure will increase rapidly and could exceed the rated valve pressure. To prevent this from happening, trunnion mounted ball valves provide the following two methods to assist in relieving excessive body cavity pressure (depending on type of seat design):
Self-pressure relief seat (SPE): When cavity pressure reaches the pre-set design pressure, the ball and seat will separate and release the pressure to the pipeline. Therefore, when the valve has a SPE x SPE seat design (normal valve design), or SPE x DPE seat design (DIB-2), no other pressure relief system is required.
Bi-directional seats (DIB-1): For liquid service, install a pressure relief by-pass line (liquid port) between the body cavity and the upstream or downstream side as per client order. When cavity pressure reaches Installation, the pre-set design pressure, the pressure relief valve in the by-pass line will open and release the extra cavity pressure back to the upstream side to maintain the cavity pressure within the safety limits.
Trunnion mounted ball valveis designed and manufactured as per API6D. Unless otherwise specified, hydrostatic shell test shall be 1.5 times pressure rating, minimum duration shall not be less than that specified in table-1. hydrostatic seat test shall be 1.1 times pressure rating, minimum duration test shall not be less than that specified in table-2.Site acceptance test shall be carried out as per above specification by design institute, the user, the construction company.
Table-1: minimum duration of hydrostatic shell test
| Valve Size |
Test duration/min |
| NPS |
DN |
| ≦4 |
≦100 |
2 |
| 6 to 10 |
150 to 250 |
5 |
| 12 to 18 |
300 to 450 |
15 |
| 20 and larger |
500 and larger |
30 |
Table-2: minimum duration of hydrostatic seat test
| Valve Size |
Test duration/min |
| NPS |
DN |
| ≦4 |
≦100 |
2 |
| 6 to 18 |
150 to 450 |
5 |
| 20 and larger |
500 and larger |
10 |
info@shxvalve.com
