Sleeve Coupler vs Joint Pin (Spigot): Which Standard Covers Which

Scaffold tube is sold in fixed lengths, so a standard or a ledger that has to run further than one tube has to be joined end to end. This guide compares two fittings used for that joint, and they are covered by different documents.

A sleeve coupler grips both tube ends from the outside. A joint pin — spigot, coupling pin — sits inside them. The difference that shows up on the paperwork is not the shape: BS EN 74-1:2022+A1:2025 sets requirements for the sleeve coupler and does not cover the spigot pin, which its own introduction assigns to EN 74-3. Where both fittings sit among the rest is in the coupler types guide.

The two ways to join two tubes end to end

BS EN 74-1:2022+A1:2025 lists four coupler types in its Table 1 — right angle (RA), swivel (SW), parallel (PA) and sleeve (SF) — and the sleeve coupler is the type defined for tubes joined end to end coaxially. It works by friction like the other three types in that table, and its scope is couplers for 48,3 mm outside-diameter steel and aluminium tube meeting EN 12811-1, EN 12811-2 and EN 12810-1.

The sleeve coupler is the external form of that joint, closing around the outside of both tube ends; the joint pin is the internal form, which AS/NZS 1576.2:2016 calls the internal type of end-to-end coupler.

The geometry is easy to see. The naming is where orders go wrong, because several markets and standards use different vocabulary for the same pair of fittings, and one of them inverts the expected translation.

The row to read twice is the Chinese one. 对接 means “butt” or “end to end”, which reads like a pin to an English speaker working from a machine translation, and the fitting it names is the external coupler. A quotation for 对接扣件 is a quotation for sleeve couplers.

Which standard covers which — and why it matters on the order

BS EN 74-1:2022+A1:2025 divides the family in its own introduction. Part 1 covers what it calls the common types of friction couplers; Part 2 covers other, less common types; Part 3 covers plain base plates and loose spigot pins. Its scope clause names the four types Part 1 specifies — right angle, swivel, sleeve and parallel couplers working by friction — and Table 1 lists those same four.

The earlier edition was arranged differently. EN 74:1988, published in the UK as BS 1139-2.1:1991 and superseded, gave its scope as requirements and test procedures for couplers, loose spigots and base-plates, all in one document, and it defined a code for each: RA, SW, PA, SF and SS for couplers, LS for the loose spigot. Table 1 of BS EN 74-1:2022+A1:2025 lists RA, SW, PA and SF; it does not list SS or LS.

So a buyer comparing two product pages is comparing fittings that sit in different documents, and a supplier’s product page does not necessarily say so. London Scaffolding Supplies lists its sleeve coupler as “BS EN 74-1 Class B” and its joint pin as “BS EN 74-1” on the same fittings page (accessed 16 September 2026). The first of those is a coupler type Part 1 specifies and a class Part 1 defines. The second names a part of the standard whose own scope clause and Table 1 do not cover the fitting.

How the coupler standards were renamed from BS 1139 to EN 74, and through their successive editions, is set out in the coupler types guide.

What BS EN 74-1:2022+A1:2025 requires of a sleeve coupler

Table 8 of the current edition holds two rows for the sleeve coupler.

Transcribed from Table 8 of BS EN 74-1:2022+A1:2025. The dash against Class A is what the standard prints: it sets no bending-moment value for that class. The sleeve coupler has Classes A and B, and no AA or BB.

Three things about the shape of that table are worth as much as the two rows in it.

• There is no Δ1 row. The right-angle, swivel and parallel couplers are each given a slipping force at a displacement of up to 7 mm as well as one in the 1–2 mm band. Table 8 gives the sleeve coupler the 1–2 mm row by itself.
• The structural parameters for this type are two. Slipping force in both classes, plus a bending moment for Class B. Failure force, pull-apart force, rotational moment, rotational stiffness and indentation are parameters the standard assigns to other types; it does not set them for the sleeve coupler. A supplier quoting a “failure load” for a sleeve coupler is quoting something Table 8 does not ask for, and should be asked where the figure comes from.
• Class letters mean different things for different types. Class B sleeve is not Class B double. The right-angle coupler’s own four classes are in the double coupler guide.

Clause 7.2.1.5 requires the measured test loads to be analysed statistically to the 5 % quantile, which must not fall below the specified value, and defines the Δ2 figure as the lowest force measured between 1 mm and 2 mm of displacement. Clause 6.2.1 then sends the reader to EN 12811-1 and EN 12812 for the characteristic values and safety coefficients to apply in use.

One line in the European foreword of BS EN 74-1:2022+A1:2025 is specific to this fitting. Of the four changes that foreword lists against the 2005 edition, the third is that the sleeve-coupler bending-moment requirements changed. That is the whole of what we can report: we have not read the 2005 edition, so this page does not say what those requirements were or which way they moved, and no figure anywhere on this site is attributed to that edition.

The superseded edition, edition-labelled

The full EN 74:1988 table, published in the UK as BS 1139-2.1:1991 and edition-labelled, is in the coupler types guide; that standard describes its own requirements as being for the assessment of prototypes of couplers, loose spigots and base-plates, so its figures are not safe working loads. Two points from it belong on this page rather than there.

In the superseded EN 74:1988, published in the UK as BS 1139-2.1:1991, the first of those two points is what the class letters meant for this fitting. Its clause 3.5 defined the two sleeve classes as sharing requirements except that Class B added a minimum bending-strength requirement and a higher tensile-strength requirement, and its foreword put the friction sleeve coupler’s Class A 50 % below its Class B. The same foreword also sets out the right-angle relationship. Both place Class B above Class A, but the percentage relationship and the type-specific requirements differ — which is why a bare “Class B” on an order means nothing without the fitting type beside it.

The second is that the two editions’ bending rows are not the same quantity. The 1988 table expresses its bending requirement as a force in kN: 19,0 kN, Class B only, with permissible displacement δ below 5,0 mm, in EN 74:1988, published in the UK as BS 1139-2.1:1991 and superseded. The bending row of Table 8 in BS EN 74-1:2022+A1:2025, the current edition, is a moment in kNm: 1,4 kNm for Class B. Different quantities from different procedures; neither is the successor value of the other, and the two cannot be set side by side as old and new values of one requirement.

Why there is no equivalent table for a joint pin

The absence of a joint pin table on this page is a fact about how the documents are split, not a verdict on the fitting. BS EN 74-1:2022+A1:2025 does not set requirements for a spigot pin because its own introduction places loose spigot pins in Part 3 of the same standard family. A standard that does not cover a product is not a standard that has judged it.

Three different kinds of silence are worth separating, because a comparison page that leaves a cell blank invites readers to fill it in as “weaker”.

1. The standard prints a dash. Table 8 gives Class A of the sleeve coupler an en dash in the bending-moment row. That is an explicit statement that the standard sets no value there.
2. The parameter is not in the type’s set. The structural parameters the standard assigns to the sleeve coupler are a slipping force in both classes and a bending moment for Class B. Table 8 does not set the sleeve coupler a failure force or a pull-apart force. That is a statement about the standard’s structure, and can be reported as such.
3. Our sources do not record it. Our transcription of the 1988 Table 1 holds rows for right-angle, swivel, friction sleeve, shear-pin sleeve and parallel couplers. It holds no loose-spigot row, and we have not obtained EN 74-3. That is a gap in what we hold — not evidence that either document sets no requirement.

Everything this site can say about a spigot pin under a European standard sits in the third category. EN 74:1988 plainly covered the fitting: its scope named loose spigots and it issued them the code LS. Our ledger contains no requirement row for LS; an applicable requirement would need to be located and entered before it could be reported. The practical move for a buyer is the same either way: ask which document the supplier’s type-test report is written to, and read the report rather than the label.

Where both fittings are tested under one procedure: AS/NZS 1576.2:2016

The Australian and New Zealand standard takes a different route: rather than splitting the two fittings between documents, it treats them as one category with two variants. Clause 4.2.2.5 calls both an end-to-end coupler and distinguishes an external type from an internal type. Both are assessed under Appendix E, and at least six couplers are tested for each relevant test appendix under clause 4.2.1.

Both rows are Australian and New Zealand type-test acceptance thresholds under Appendix E; neither is a safe working load, neither is a European requirement, and neither is comparable with the BS EN 74-1:2022+A1:2025 Table 8 rows above, which are characteristic 5 % quantile values from a different procedure on a different reference tube. The clause text we hold states the load to be reached and the deflection limit; it does not name the direction in which the load is applied, so this page does not name one either.

This page also publishes no ratio between the two figures. They are acceptance thresholds for two different products under one procedure, and AS/NZS 1576.2:2016 does not state a ratio between these two thresholds. What that standard asks of a right-angle coupler instead — its slip test, the rule that a test for a higher slip resistance uses twice the intended working load limit, the check coupler threshold and the clause 1.6 equivalence with couplers tested to EN 74-1:2005 — is summarised in the coupler types guide.

China: the 对接扣件 is a sleeve coupler, not a pin

GB 15831-2006, the Chinese national standard for steel tube scaffold couplers, gives four type codes: Z for the 直角扣件, U for the 旋转扣件, D for the 对接扣件 and DZ for the 底座. The standard’s own English glosses in clause 3.1 render 对接扣件 as sleeve coupler — the same English words EN 74 uses. There is no internal-joint type among its four codes, although the international standard its foreword names as a reference, ISO 4054—1980, carries 对接销 (spigot pins) in its title.

GB 15831-2006 was withdrawn on 1 December 2023 and replaced by GB/T 15831-2023, which we have not read; every figure in this section is the 2006 edition’s. Its 表1 gives the 对接扣件 a single mechanical row: a 抗拉 (tensile) test in which the displacement must not exceed 2.00 mm at a load of 4.0 kN. Its conditions travel with it. For this 对接扣件 test the bolt is tightened to 40 N·m, the tube is a GB/T 3091 tube of 48.3 mm outside diameter and 3.5 mm wall painted with red lead, the load is applied at 300–400 N/s, and the 1.0 kN preload is counted inside the total load.

Two further features separate the Chinese regime from the European one. GB 15831-2006 carries no class letter at all — there is no A/B system in it — so a coupler cast to that standard legitimately has none. And its 表2 ticks 对接扣件抗拉性能 for both 型式检验 (type inspection) and 出厂检验 (factory inspection), where the European type test is an assessment of a prototype.

No figure on this page is attributed to the 2023 edition. The three sets of numbers on this page — Table 8, Appendix E and 表1 — come from three procedures with different test tubes, different bolt torques and different acceptance rules. They are not interchangeable, and a quotation that mixes them is worth a question. The rest of the Chinese picture, including materials and inspection, is in the double coupler guide.

Choosing between them, and what to put on the order

No source in our ledger compares the two fittings or ranks one above the other, and this page does not. The designer’s question is what the joint has to transmit and under which rules the scaffold is being designed; the buyer’s is narrower — which document the fitting is certified to, and whether the paperwork matches the label.

Five lines on a purchase order are specific to this pair. The eight points common to every fitting are in the purchase-order list in the coupler types guide.

1. Name the type, the edition and the class together. “Sleeve coupler, BS EN 74-1:2022+A1:2025, type SF, Class B” — or the clause 8 designation form, EN 74-1 SF B C2 M, which carries type, class, corrosion class and production-inspection level in one string. “EN 74” alone does not identify the part, edition, fitting type or class.
2. Decide the class on the bending row, not on a general idea of strength. Class B is the class for which Table 8 sets a bending moment, 1,4 kNm; the Class A cell against that row is a dash. If the design leans on that row, the order has to say Class B.
3. Ask whether the product manual carries the spigot-pin statement. Clause 13 lists what a product manual must state for a coupler, and a spigot-pin requirement for sleeve couplers is one of the listed items. Ask to see the manual itself, and read that item against the pins you intend to use.
4. For a joint pin, ask which document the test report is written to. A listing that says “BS EN 74-1” against a joint pin is naming a part whose scope clause and Table 1 cover four coupler types, and whose introduction sends loose spigot pins to EN 74-3. The useful request is the report and the name of the assessing body, not a label.
5. Ask about production-control frequency by type. Annex B of BS EN 74-1:2022+A1:2025 is informative rather than mandatory, and its Table B.2 sets a different internal test frequency by type. For parallel and sleeve couplers it gives 1 per production run, with 2 couplers per third-party inspection. For right-angle and swivel couplers it gives 1 per 50 000 couplers, with a minimum of 1 per week, and 5 per third-party inspection. A factory’s answer for its doubles does not describe what it does for its sleeves.

What suppliers list today

Our ledger currently contains product-specific entries from two supplier pages; only Altrad Generation lists weights for both fittings.

Altrad Generation’s scaffold fittings catalogue lists a pressed sleeve coupler, code 26005, at 1.02 kg, and a pressed joint pin, code 26006, at 0.79 kg (accessed 16 September 2026). That is one supplier’s catalogue for both figures. Our ledger requires at least three independent vendors before a weight may be published as a typical figure or a range, so these two numbers are cited as Altrad Generation’s own listing and nothing more; this page publishes no typical weight for either fitting. The other supplier page in our ledger, London Scaffolding Supplies (accessed 16 September 2026), publishes no weights and no per-product load figures for either fitting.

For freight planning, take the catalogue weight of the exact SKU quoted rather than a figure for the fitting in general — and if the quotation is for 对接扣件, confirm that it is the sleeve coupler before pricing the container.

In an end-to-end fitting enquiry, identify the external sleeve or internal pin and the document your specification requires for it.

Sources

1. BS EN 74-1:2022+A1:2025 Couplers, spigot pins and baseplates for use in falsework and scaffolds — Part 1: Couplers for tubes (current edition; European foreword, clause 1 and introduction, Table 1, Table 2, Table 8, clauses 6.2.1, 7.2.1.5, 8, 13, Annex B). BSI product page — accessed 2026-09-17
2. BS 1139-2.1:1991 (EN 74:1988) Metal scaffolding — Part 2: Couplers — Section 2.1: Specification for steel couplers, loose spigots and base-plates. Superseded; cited for its scope wording, its coupler codes and its Table 1 sleeve coupler rows. Current edition sold by BSI — accessed 2026-09-16
3. AS/NZS 1576.2:2016 Scaffolding — Part 2: Couplers and accessories (clauses 4.2.1 and 4.2.2.5, Appendix E end-to-end coupler test). Standards New Zealand product page — accessed 2026-09-16
4. GB 15831-2006 《钢管脚手架扣件》 Steel tube scaffold couplers — 对接扣件 type code D, 表1 tensile row, 表2 inspection items; withdrawn 2023-12-01 and replaced by GB/T 15831-2023. Official catalogue record, 全国标准信息公共服务平台 — accessed 2026-09-16
5. Altrad Generation — Scaffold fittings catalogue (pressed sleeve coupler code 26005, pressed joint pin code 26006, with catalogue weights) — accessed 2026-09-16
6. London Scaffolding Supplies — Scaffold fittings range (the standard and class each fitting is listed against; no weights or per-product load figures published) — accessed 2026-09-16