Right Angle Scaffold Coupler
A double coupler is the main load-bearing fitting in tube-and-coupler scaffolding. It clamps two scaffold tubes together at a fixed 90° right angle, joining a standard to a ledger or transom and carrying the load between them. Lengge makes the drop forged version: forged from steel rather than pressed or cast, so the body has no blowholes, grips the tube harder, and holds its slip load. It fits 48.3 mm scaffold tube and is made to BS1139 and EN74, closing with a T-bolt and nut.
We hold double couplers in bulk, galvanized or painted, and ship by the thousand, factory-direct for scaffold contractors, hire fleets and dealers worldwide.
| Item | Specification |
|---|---|
| Type | Fixed double coupler (90° right angle) |
| Material | Drop forged steel |
| Tube size | 48.3 mm (Ø48) |
| Joins | Standard to ledger or transom |
| Bolt | T-bolt with nut |
| Tightening torque | Around 50 N·m |
| Standard | BS1139 / EN74 |
| Finish | Hot-dip galvanized or painted |
Tube size, finish and bolt grade can be set to your specification. Couplers are supplied loose in bulk for scaffold assembly.
A double coupler is the load-bearing fitting that joins two scaffold tubes at a fixed 90° right angle, normally a standard (vertical) to a ledger (horizontal). It carries the load from one tube into the other, which makes it the main structural connector in tube-and-coupler scaffolding. It is also called a right angle coupler or a fixed coupler.
A double coupler holds a fixed right angle and is rated to carry load, so it is used for the main standard-to-ledger joints. A swivel coupler rotates to any angle and is used for diagonal braces, where the tubes do not meet square. The fixed coupler bears load; the swivel mainly ties the brace in. They are not interchangeable for structural joints.
Drop forged is the stronger of the three common types. Forging shapes the steel under a hammer, so the body has no blowholes and a denser grain, which gives higher slip resistance and better grip on the tube. Pressed steel couplers are stamped from sheet, lighter and cheaper, but carry less load. Cast malleable iron can be brittle under a shock load. For load-bearing joints, forged is the safe pick.
It fits Ø48 scaffold tube, the standard size, and is made to BS1139 and EN74. That means it works in standard tube-and-coupler scaffolds across the markets that use those standards. Tell us your tube size if it differs and we confirm the fit.
The two halves close around the tubes with a T-bolt and nut. Tighten the nut to about 50 N·m and the joint reaches its rated slip resistance; that torque is what the standard tests against. A torque wrench on site keeps every joint consistent, and a galvanized thread keeps tightening cleanly after reuse.
We supply in bulk, galvanized or painted, and ship by the thousand. Stock moves quickly; large or custom orders we confirm at the time. Couplers pack dense into containers so freight per ton stays low, and we handle export packing, marking and documents for overseas projects.
In a tube-and-coupler scaffold, the double coupler is the fitting that actually holds the structure together and carries the load. Get the wrong type or a weak coupler and every joint in the scaffold is affected. This page explains what the double coupler does, how it sits among the other couplers, why the forged version is the load-bearing choice, and what tube size and standard it has to meet.
Tube-and-coupler scaffolding is built from plain steel tubes joined by fittings. The double coupler is the fitting that clamps a vertical tube (the standard) to a horizontal tube (the ledger) at a fixed right angle. Because it is rated to carry load, it is what transfers the weight of the platform and the working level down through the standards. It shows up at almost every main joint, so a scaffold uses a lot of them, and the strength of each one matters.
A scaffold uses several coupler types, and they are not interchangeable. The double coupler is the load-bearing one; the others each do a specific job:
| Coupler | What it joins | Angle |
|---|---|---|
| Double (right angle) coupler | Standard to ledger / transom | Fixed 90°, load-bearing |
| Swivel coupler | Tube to tube for braces | Adjustable, any angle |
| Sleeve / joint coupler | Tube end to tube end | In-line join |
| Putlog / single coupler | Transom to ledger | Non-load-bearing |
The key split is load-bearing versus non-load-bearing. The double coupler and the swivel both grip hard, but only the fixed right angle is used to carry structural load; the swivel is for braces, and the putlog or single coupler is for light connections that do not take weight.
The same double coupler is made three ways, and the manufacturing method decides how much load it can take:
| Type | Made by | Strength and notes |
|---|---|---|
| Drop forged | Hammer-forged steel | Highest strength, no blowholes, best slip resistance |
| Pressed steel | Stamped sheet steel | Lighter and cheaper, lower load capacity |
| Malleable iron | Cast iron | Can be brittle under shock load |
Drop forging works the steel under a hammer, which closes up any voids and lines up the grain. The result is a body that grips the tube tightly and resists slipping under load, with no blowholes to start a crack. Pressed couplers are fine for lighter, non-structural duty, but for the main load-bearing joints the forged coupler is the one rated for the job.
Standard scaffold tube is 48.3 mm in outside diameter, and the double coupler is sized to clamp it. The fitting is made to BS1139 and EN74, the two standards most tube scaffolds are built to. The two halves close with a T-bolt and nut, and the nut is tightened to around 50 N·m. That torque is not arbitrary: it is the figure the slip-resistance test uses, so a joint tightened to it reaches its rated capacity. On site, a torque wrench keeps every coupler consistent.
For load-bearing joints, specify a drop forged double coupler, not a pressed one. Confirm the tube size against your scaffold (48.3 mm is standard), the standard it must meet, and the finish, galvanized for outdoor and long-cycle work, painted for shorter use. Couplers are bought in bulk, so check the supplier can hold volume and ship by the thousand without the price per piece climbing on a large order.
