Grooved pipe couplings are used to join pipes after grooves have been applied with a roll-grooving machine. When installing couplings, always lubricate the gasket exterior and lip as well as the inside of the coupling to avoid pinching the gasket. Stretch the gasket over the pipe ends then place the coupling segments over the gasket and fasten the nuts and bolts. Tighten until there is metal to metal contact on the bolt pads, then tighten another 1/4 to 1/2 turn.