Flowline
Swivel joints
Swivel joints let rigid iron turn in one, two or three planes while it carries full pressure, so lines can be rigged between pumps, manifolds and wellheads that never sit in quite the same place.
A swivel joint is a section of high-pressure pipe with one or more swivels, each a pair of ball races that lets one part of the joint rotate on the other, combined with elbows so the line can turn in one, two or three planes. Swivels absorb the movement and misalignment between pumps, manifolds and wellheads that rigid iron cannot. We supply them in the standard styles 10 to 80, long and short radius, with hammer union, threaded or butt weld ends, for standard or sour service.
Styles
Swivel joints are ordered by style number, which fixes how swivels and elbows are arranged and so how many planes the joint can turn in:
| Planes of rotation | Styles | What it allows |
|---|---|---|
| 1 | 20, 30, 40 | The line turns about one axis |
| 2 | 50, 60, 70 | The ends move in two planes |
| 3 | 10, 80 | The ends move freely in three planes |
Planes of rotation as published by swivel makers, for example OPW Engineered Systems; each plane has two ball races. Check the configuration drawing against your layout before ordering.
Styles with the same number of planes differ in where the swivels and elbows sit, which changes the shape of the joint and where its ends land. Send your rig-up sketch or the style your current iron uses, and we match it.
Long radius or short radius
| Long radius | Short radius | |
|---|---|---|
| Elbow radius | Several times the bore | Close to a standard elbow |
| Typical rating | 10,000 to 20,000 psi; sour versions 7,500 to 15,000 psi | Around 6,000 psi for high-pressure threaded swivels |
| Erosion | Lower wear at the elbows in sand-laden and high-velocity flow | Faster wear; not for abrasive frac service |
| Ends | Hammer union, FIG 1002, 1502 or 2002 | Threaded, hammer union or butt weld |
| Used for | Frac, flowback, cementing and test lines | Cement and mud lines, plant and low-pressure connections |
Ratings as published by swivel makers, for example TechnipFMC for its Chiksan and Longsweep swivels. The rating of each joint is stamped on it.
How a swivel is built
Each swivel has a male and a female body joined by two rows of hardened steel balls running in ball races, which carry the pressure end load and let the bodies turn. Packing between the bodies seals the bore, and a grease fitting lubricates the races. Bodies and elbows are made from AISI 4130, quenched and tempered for the rating. Packing is chosen for the fluid: nitrile for standard service, fluoroelastomer or HNBR for sour gas.
For hydrogen sulfide service, swivels are made from material within the hardness limits of NACE MR0175 / ISO 15156-2, fitted with sour-service packing and rated at the sour version of the figure. Order the service on every line.
Inspection and testing
Each swivel is hydrostatically tested to the test pressure on your order, often 1.5 times the cold working pressure, and stamped with its style, size, rating and heat number. The EN 10204 3.1 certificate gives chemistry, heat treatment, tensile and hardness results. In service, swivels are greased, repacked and checked for elbow wall loss on the schedule your procedure sets.
We make these parts to the API 6A and API 16C 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
Swivel joint, style 50, 3 in, long radius, FIG 1502 male by female, AISI 4130, 15,000 psi CWP standard service, hydrostatic test at 22,500 psi, EN 10204 3.1, 6 pcs
Swivel joint, style 10, 2 in, long radius, FIG 1502 male by female, sour service to NACE MR0175 / ISO 15156, 10,000 psi CWP, HNBR packing, EN 10204 3.1, 4 pcs
Frequently asked questions
Long radius or short radius swivel?
For frac, flowback and other abrasive or high-pressure service, long radius. The larger bend radius slows erosion at the elbows, and long radius designs carry 10,000 to 20,000 psi. Short radius threaded swivels are compact and are generally rated around 6,000 psi, for lower-pressure lines and connections.
What do the style numbers mean?
They describe the arrangement of swivels and elbows, and so the number of planes the joint can turn in: one, two or three. The numbering is shared across the industry, but always check the configuration drawing against your own layout before ordering.
How are swivel joints maintained?
Grease the ball races through the grease fittings on a schedule, replace packing when it leaks or after the number of jobs your procedure sets, and inspect the elbows for erosion by wall thickness measurement. Swivels for sour gas are rebuilt with packing suited to hydrogen sulfide.
Can you supply hose loops made from swivels?
Yes. Swivels and pup joints assembled into loops for the pump-to-manifold connection are covered on the pup joints and hose loops page.