Flowline
Positive and adjustable chokes
Chokes control the rate and pressure of a flowing well. Positive chokes hold a fixed bean; adjustable chokes move a stem against a seat with a handwheel while the well flows.
A choke is a valve that restricts a flowing well to control its rate and the pressure downstream. A positive choke has a fixed orifice, the bean, that is changed to change the rate; an adjustable choke moves a tapered stem towards or away from a seat with a handwheel, so the opening can be changed while the well flows. We supply both in 2 and 3 in bodies, with FIG 1502 hammer union ends for test and flowback iron or API 6A flanged ends for wellheads and manifolds, with steel, tungsten carbide or ceramic trim.
Positive and adjustable chokes
| Positive | Adjustable | |
|---|---|---|
| Restriction | Fixed orifice in a replaceable bean | Stem tip and seat, opening set by a handwheel |
| Changing the rate | Shut in, then change the bean | Turn the handwheel while flowing |
| Orifice indication | Bean size, stamped on the bean | Indicator marked in 64ths of an inch |
| Typical use | Steady production and long flow periods | Cleanup, flowback, well testing and kick control |
| Wear parts | Beans | Stem tips and seats |
Bodies and end connections
Union-end chokes, with a FIG 1502 male or female inlet and outlet, go into well test, flowback and cleanup iron. API 6A flanged chokes bolt into wellheads and choke manifolds and are ordered by end flange size and pressure rating, material class, temperature class and product specification level. Both are made with a body cavity that accepts the bean or seat and stem for the orifice range you need, and with a bleed or blanking cap so the choke can be opened safely for a bean change.
Isolate the choke upstream and downstream and bleed off trapped pressure before opening the cap. Never back off a cap while pressure may be trapped behind a plugged bleed port.
Trim materials
The restriction sees the full pressure drop and any sand in the flow, so it wears fastest. Steel trims suit clean fluids; tungsten carbide and ceramic lined beans and seats last much longer in erosive flow. Bean and seat options, and how sizes in 64ths convert to inches, are on the choke beans, seats and stems page.
Sour service and testing
For hydrogen sulfide service, bodies and trims are made within the limits of NACE MR0175 / ISO 15156 and the choke carries the sour rating. Each choke is shell tested to the pressure on your order and stamped with type, size, end connections, rating and heat number; EN 10204 3.1 certificates cover the body and bonnet material.
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
Adjustable choke, 2 in body, FIG 1502 female inlet by male outlet, 15,000 psi CWP standard service, tungsten carbide stem tip and seat, maximum orifice 64/64 in, EN 10204 3.1, 2 pcs
Positive choke, 2 in body, API 6A 2-1/16 in 10,000 psi flanged ends, material class DD, temperature class P, PSL 2, with 16/64 and 24/64 in ceramic beans, EN 10204 3.1, 1 pc
Frequently asked questions
Positive or adjustable choke?
A positive choke holds one fixed orifice and is changed by swapping the bean, which suits steady flow such as production or a long flow period in a test. An adjustable choke changes the opening with a handwheel while flowing, which suits cleanup, flowback and testing, where the rate changes often. Many manifolds carry one of each.
How are choke sizes given?
In 64ths of an inch of orifice diameter. A 32/64 choke has a 1/2 in orifice, and a 64/64 choke a 1 in orifice. Adjustable chokes have an indicator marked in 64ths.
Can I use a choke as a shut-off valve?
No. A choke controls flow; it is not built to seal tight. Isolate the line with a gate or plug valve upstream.
Do you supply the beans and seats separately?
Yes. Positive beans and adjustable seats and stems are wear parts and are covered on the choke beans, seats and stems page.