Fittings
What is a check coupler?
A check coupler is a second coupler fitted alongside a primary one as a safeguard, so that a single fitting failing or slipping does not release the connection.
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<img src="https://scaffoldoptix.co.uk/glossary/check-coupler/diagram.svg" alt="check coupler — scaffold diagram from ScaffoldOptix" width="880" height="620" loading="lazy">
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<a href="https://scaffoldoptix.co.uk/glossary/check-coupler">What is a check coupler?</a> — diagram by
<a href="https://scaffoldoptix.co.uk">ScaffoldOptix</a>
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</figure>Check couplers appear where the consequence of one fitting letting go is serious — commonly at ties, at cantilevered members and at connections carrying significant load.
The principle is redundancy rather than extra capacity. The check coupler is not there to share the load in normal service; it is there for the case where the primary fitting does not do its job.
Where a design or a compliance sheet calls for check couplers, they are not optional detailing. Leaving them off changes the assumption the structure was assessed on.
What goes wrong on site
- Omitted because the primary coupler looks sufficient.
- Fitted loosely, so they would not hold if the primary slipped.
- Removed during an alteration and not refitted.