Flowline
Plug valves
Quarter-turn valves that open and shut flowline iron under high pressure and abrasive flow, with hammer union ends, a handle, gear or actuator, and seals that can be rebuilt in the field.
A flowline plug valve is a quarter-turn valve: a plug with a bore through it turns 90° between replaceable inserts in the body, lining the bore up with the line to open it and turning it across to shut it. It is the standard isolation valve on frac, flowback, cementing and well test iron. We supply plug valves from 1 x 2 in to 4 in with hammer union or flanged ends, rated 10,000 or 15,000 psi, for standard or sour service, operated by handle, gear or actuator.
Sizes, ratings and ends
| Size | Bore | Ends | Usual operation |
|---|---|---|---|
| 1 x 2 in | 1 in | 2 in hammer union | Handle |
| 2 in | 2 in | 2 in hammer union | Handle or gear |
| 3 in | 3 in | 3 in hammer union or flange | Gear or actuator |
| 4 in | 4 in | 4 in hammer union or flange | Gear or actuator |
Ratings follow the union figure and the service, for example 15,000 psi with FIG 1502 ends in standard service and 10,000 psi in sour service. Flanged ends to API 6A to order.
How a plug valve is built
The body is a forging with the union subs integral or attached. The plug sits between two inserts, often called segments, which carry the seals that close against the plug face. A stem connects the plug to the handle or gear, and grease fittings feed sealant and lubricant to the plug. Because the inserts and seals carry the wear, a valve can be rebuilt many times by replacing them, without changing the body.
Plug valves isolate; they do not throttle. Partly open, sand-laden flow cuts the plug and inserts in minutes. Control rate and pressure with a choke, and keep plug valves fully open or fully shut.
Sour service
For hydrogen sulfide service, the body, plug and stem are made within the hardness limits of NACE MR0175 / ISO 15156, seals are chosen for sour gas, and the valve carries the sour rating and marking. Order the service on every line.
Testing and documents
Each valve is shell tested and seat tested to the pressures on your order, and stamped with size, figure, rating and heat number. The EN 10204 3.1 certificate gives the body material results; test records list the shell and seat test pressures and hold times. Repair kits, gear operators and actuator mounting are quoted on the same order.
We make these parts to the API 6A requirements your order calls up: material, dimensions, tests and marking as specified. We do not hold an API license, so the parts do not carry the API Monogram. If your specification requires monogrammed equipment, the quotation says so plainly.
Ordering
Plug valve, 2 in, FIG 1502 male by female, 15,000 psi CWP standard service, handle operated, shell and seat tested, EN 10204 3.1, 6 pcs, plus 6 repair kits
Plug valve, 3 in, FIG 1502 male by female, sour service to NACE MR0175 / ISO 15156, 10,000 psi CWP, gear operated, EN 10204 3.1, 2 pcs
Frequently asked questions
What does 1 x 2 mean on a plug valve?
The first figure is the bore through the plug and the second the size of the union ends. A 1 x 2 in plug valve has a 1 in bore and 2 in union ends, so it fits into 2 in iron while keeping the body small.
Handle or gear operator?
Small valves are turned with a handle or wrench. Larger bores and higher pressures need more torque, so 3 in and 4 in valves, and valves that are cycled under pressure, are usually gear operated or actuated.
Can the seals be replaced in the field?
Yes. Plug valves are built to be rebuilt: the seals and the inserts that the plug turns against are replaceable, and repair kits for each size and rating can go on the same order as the valves.
Can I throttle flow with a plug valve?
No. Flowline plug valves are for fully open or fully closed service. Partly open, the high-velocity flow erodes the plug and the inserts. Use a choke to control flow.