The scaffold framework is built from varying lengths of metal tubes which are joined together by a variety of fittings called couplers or clips. The design of the the framework will be determined by the intended purpose of the scaffold and the expected load it is to bear.

Sleeve couplers often just called sleeves can be used to connect scaffold tubes end to end. Unlike joint pins this fitting has a resistance to bending and has a safe working tension of 315kg.

There is a wide range of scaffold couplers available and how they are used maintained will depend on the type of fitting and its application. All fittings should be regularly oiled and kept free from rust.

To connect scaffold tubes end to end a joint pin (or expanding spigot can be used). The joint pin or spigot is inserted into the end of the scaffold tubes and a centre bolt is tightened. This tightening causes the two parts of the joint pin to expand gripping the ends of the scaffold tubes. It is essential not to use this fitting in situations where it will be subject to tension or bending.