Repair of underwater risers on offshore rigs are an inherently safer project if you can do it without welding.  It’s also a faster and less expensive.  A product called the Riser Weld+End from PLIDCO is designed to simplify the replacement of underwater risers on offshore gas and oil lines–without welding underwater.  This fitting has additional clamping and thrust screws to provide a seal for high pressure and for resisting extreme end-pull. Installation is rapid. It’s socket-welded at the surface to the new replacement riser and lowered into the water. A diver cuts out the old riser, stabs the new fitting over the cut-off pipe, then tightens the clamping and thrust screws for a complete leakproof seal without welding.  The short video below tells you more.