What Is a Pup Joint — The Short Lengths That Close the Space-Out

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The definition, and the problem it solves

A pup joint is a short length of casing or tubing — shorter than a standard joint — used to adjust the total length of a string. Wells, meanwhile, are designed to depths that owe nothing to those ranges: a casing shoe must land at a specific formation, a tubing pump must sit at a specific point in the curve, a packer must set opposite a specific interval of competent casing. Pup joints are the remainder in that arithmetic — the short lengths that close the gap between the tally of full joints and the depth on the design.

That is the whole idea, and it is worth stating plainly because a pup joint is easily mistaken for an offcut or an afterthought line on an order. It is neither. The factory behind this site lists pup joints as a family of twelve catalogue entries and states that casing and tubing pup joints of various sizes can be machined to order — made to order being the operative phrase, because a pup joint's length is chosen by your string, not by a shelf.

Casing pup joints versus tubing pup joints

The two branches of the family are specified against different strings. Casing pup joints adjust a casing string so the shoe lands at the programmed depth and the hanger sits correctly in the wellhead. Tubing pup joints space out a completion — the spacing the completion design names. A related item, the perforated pup joint, adds a drilled port pattern so the joint also serves as a flow or circulation point; it sits outside this factory's listed family, so it is handled as an enquiry item confirmed against a drawing. Same concept, three duties — and a combined order should still list them as separate lines. Each line carries its own full specification — size, grade, thread form and length.

Lengths, sets and the spacing calculation

The difference between the full joints available and the target depth from the design — the space-out — is made up from pup joints. When you order, give the target lengths and say they form a set, and state the marking and packing arrangement you need so the quotation can confirm whether it can be accepted and in what scope. And declare the length convention — overall length including a made-up coupling, or pin-to-pin pipe length — because a pup joint that is one coupling-length wrong has failed at its only job.

The set is the unit an enquiry describes. State the target depth from the design, the tally of full joints you expect to run, and the adjustment range you want the set to cover; the lengths in the set are then the lengths your own tally arithmetic calls for, stated as a set rather than as one joint cut to a guessed figure. The catalogue publishes no standard length steps for pup joints — its twelve entries are organised by family, not by length — so no length on an order comes from a shelf list: each length is stated on its enquiry line, with the string's full specification behind it. If the set must be packed and marked as a set, in string order, state that in the enquiry as well; the measured-length marking each joint is to carry is likewise an enquiry item, stated with the convention your tally uses. Each pup joint line states the size, grade and thread form of its string and the length the tally calls for. The published coupling stock sizes run 1.315, 1.66, 1.9, 2-3/8, 2-7/8, 3-1/2, 4 and 4-1/2 in.

Specification checklist

• String identity — casing or tubing, with the full line copied from that string's specification.
• Size, weight and grade — state them exactly as the design names them for the string the joint joins.
• Thread and coupling — STC, LTC, BTC, premium pattern, EUE or NUE, exactly as the design names them for the string.
• Lengths and convention — measured lengths, set logic, and whether coupling length is included.
• Marking — the marking your tally needs, stated in the enquiry for the quotation to confirm; ask for set order to be preserved in packing.

Each item on the checklist answers a specification question — the string identity, the full line, the thread and coupling form, the lengths and convention, and the marking — because a pup joint ordered by size alone, without grade or end finish, is not specified at all. The published thread-type list for the coupling family names NUE, EUE and the special-clearance form, and thread dimensions and tolerances follow API Spec 5CT and 5B.

Where pup joints sit in the catalogue

Pup joints are one family in a 71-entry OCTG catalogue whose centre of gravity is couplings — 26 entries. Each pup joint is machined to the exact length its order states for the string it joins. The company's casing literature states the capability plainly: casing and tubing pup joints of various sizes can be machined to order. The twelve entries carry only those generic titles — the source catalogue gives no distinguishing model names or parameters for them — and the company's published summaries of its own range name short joints among its main products, alongside casing, tubing, couplings and crossover subs.

A brief note on pup joints and well economics

If you remember nothing else, remember that a pup joint is defined by the string it joins and the depth it serves, in that order. Get those two facts onto the enquiry, and the quotation confirms the pup-joint line for that string.

How short can a pup joint be?

The practical minimum is set by the two threaded ends plus handling allowance for that diameter and connection. State your target length in the enquiry and ask for the shortest makeable length for that diameter and connection to be confirmed in the quotation.

Are pup joints pressure-rated like full joints?

This site publishes no pressure rating for a pup joint. State the working duty in the enquiry, and ask for the item to be checked against it in the quotation.