Drill Stem Testing Tools Tubing String Testing (TST) Valve with ball
The tubing string testing (TST) valve is a full-opening valve used to pressure-test the workstring while running in the hole. The valve is operated after it is stung into a permanent packer or after a retrievable packer is set. The TST valve requires a differential pressure between the annulus and the tubing to shear. The TST valve can also be used for pipe flexing if it is run below an annulus pressure-responsive circulating valve.
The ball valve can be locked in the open position before coming out of the hole applied to the annulus will shear a set of shear pins, which caused the shear pin be upward, dropping flue locking dogs into a groove, once the locking dogs have falled groove, the ball valve will be locked open. Allowing fluid trapped lnside the well drain out while the stiing is retrieved from the hole.
Top and Bottom Differential of Flapper Valve
Shear Value of single screw
Shear Value of single shear pin
NACE MR-0175 Sour gas service (> 175F°)