Back Pressure Valves

Back Pressure Valve

Back pressure valves are installed in the tubing hanger to hold pressure from below during the following operations:
• Nipple down and up the drilling BOP stack.
• Nipple up or down Christmas tree.
• Test the Christmas tree (2-way check).
• Replace the master valve.

The most common types of BPV are the Cameron Type ‘H’ BPV and Petroline ‘ABC’. A BPV is set in a profile provided in the tubing hanger using a special tool and lubricator assembly for threaded BPV models, or by slickline for profile set models. The BPV holds pressure from below to isolate well pressure, but allows flow from above to permit killing of the well if necessary in an emergency, i.e., the BPV functions as a check valve. A two way check valve is designed to fit the same profile as the BPV. It holds pressure from both directions while allowing equalization when required and is used to test the tree and BOP assembly.

Cameron Type ‘H’ Back-pressure Valve

Illustration

Type H back-pressure valves are used extensively in Cameron hangers to safely seal well pressure to 20,000 psi during removal of the blowout preventer and installation of the Christmas tree. Fluid may be pumped through the BPV. If the tree above the BPV is to be pressure tested, the type ‘H’ 2-way check valve may be landed in the tubing hanger for pressures to 20,000 psi. If during the life of the well it becomes necessary to remove the Christmas tree or repair the lower master valve, the back pressure valve can be reinstalled in the hanger without killing the well. The lubricator consists of a rod, which works through a yoke provided with two stuffing boxes. By closing the vent valve and opening the equalizing valve, well pressure acts on both the top and bottom of the rod. The rod can then be moved up or down by means of a friction wrench. Experienced operators can utilize the well pressure in moving the rod by manipulation of the valves.

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For setting, the running tool is inserted into the right-hand thread at the top of the valve, and then attached to the polished rod. When the valve has been lowered into the hanger, the rod is lowered so that the cross pin in the running tool engages in the slot on the top of the valve. Left hand (anti-clockwise) rotation is applied to insert the valve. Once the valve is fully seated, moving the rod up to lift the pin from the slot and continuing a left hand rotation backs out the running tool.

For removal, the pulling tool is attached to the rod and lowered to the valve. Right-hand (clockwise) rotation makes up the pulling tool. The rod is lowered into the slot on the top of the valve and continuing the right-hand (clockwise) rotation removes the valve.