Tubing and casing
API 5CT pup joints
Short joints of tubing or casing used to space out a string, set a tool at the right depth or match a landing height, made to the size, weight, grade and connection of the string they go into.
An API 5CT pup joint is a length of tubing or casing shorter than a standard joint, used to space out a string so that a packer, nipple or hanger lands at the right depth or height. It is made to the same size, weight, grade and connection as the string. We supply tubing pup joints from 2-3/8 to 4-1/2 in with NUE or EUE threads and casing pup joints with STC, LTC or BTC threads, in grades J55 to P110, in the common lengths from 2 to 12 ft or cut to order, pin by box or pin by pin.
Grades
The grade sets the strength and, for the controlled-yield grades, the hardness limit. These are the API 5CT values for the common grades:
| Grade | Yield, min to max | Tensile, min | Hardness, max | Notes |
|---|---|---|---|---|
| J55 | 55 to 80 ksi | 75 ksi | - | General tubing and casing |
| K55 | 55 to 80 ksi | 95 ksi | - | As J55, higher tensile |
| N80 (Type 1 and Q) | 80 to 110 ksi | 100 ksi | - | Higher strength; Q is quenched and tempered |
| L80 Type 1 | 80 to 95 ksi | 95 ksi | 23 HRC | Sour service |
| C90 | 90 to 105 ksi | 100 ksi | 25.4 HRC | Sour service, higher strength |
| T95 | 95 to 110 ksi | 105 ksi | 25.4 HRC | Sour service, higher strength |
| P110 | 110 to 140 ksi | 125 ksi | - | Deep and high-pressure wells; not for sour service |
Yield, tensile and hardness limits per API 5CT. The 4130-type steels behind L80 are explained in 4130 75K, 80K and L80.
Connections
| Connection | Used on | Thread form |
|---|---|---|
| NUE, non-upset | Tubing | Round thread cut in the plain pipe end |
| EUE, external upset | Tubing | Round thread on thickened (upset) ends, for a joint as strong as the pipe body |
| STC, short round thread | Casing | 8 round, short coupling |
| LTC, long round thread | Casing | 8 round, long coupling |
| BTC, buttress | Casing | Buttress thread, highest joint strength of the three |
Threads are cut and gauged to API 5B. Premium connections are made only under the owner's license, so they are not offered here.
How pup joints are made
Pups are cut from seamless tubing or casing of the ordered grade, or machined from seamless stock heat treated to the grade, then threaded, gauged and fitted with a coupling where the order calls for pin by box. Each pup is drifted with an API drift mandrel where your order asks for it, hydrostatically tested to the pressure on your order, and stenciled or stamped with size, weight, grade, connection, length and heat number.
For hydrogen sulfide service, order a sour-service grade such as L80 Type 1, C90 or T95, with its hardness limit and the testing API 5CT sets for it. P110 is not a sour-service grade.
We make these parts to the API 5CT and API 5B 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
Tubing pup joint, 2-7/8 in 6.5 lb/ft, L80 Type 1, EUE 8 round, pin by box with L80 coupling, 6 ft, drifted, EN 10204 3.1, 10 pcs
Casing pup joint, 5-1/2 in 17 lb/ft, P110, BTC, pin by box, 10 ft, EN 10204 3.1, 4 pcs
Frequently asked questions
What lengths do tubing pup joints come in?
The common lengths are 2, 3, 4, 6, 8, 10 and 12 ft, and any other length can be cut to order. Give the length and whether it is measured end to end or excluding the coupling.
Pin by box or pin by pin?
Pin by box is a pup with a coupling made up on one end, ready to run in the string. Pin by pin has threads on both ends and no coupling, for use with couplings you supply or with equipment that has box ends.
Can you match the grade and connection of our string?
Yes. Give the size, weight, grade and connection of the string, for example 2-7/8 in 6.5 lb/ft L80 EUE, and the pup is made to match, including the coupling grade.
Do you supply crossovers between connections?
Yes. Crossover subs between EUE and NUE, or between casing connections, are made to API 5CT and API 5B on the same basis as pup joints.