Abstract: A select port chemical injection collar device for selectively discharging and optimizing chemical injection processes is disclosed. The disclosed device comprises a tubing collar having an integral collar fluid flow-through chamber formed in the tubing collar wall. The fluid flow-through chamber houses a chemical injection valve cartridge. The device is arranged and configured for selectively injecting chemical into a production tubing string, annulus, or downhole apparatus.

Abstract: A method and apparatus for welding together two metal workpieces, at least one of which has thereon a coating material which enters a fluid or visco-elastic phase at a temperature below the melting temperature of the workpieces, the method comprising the steps of subjecting the workpieces to a preliminary preparative treatment at a zone to be welded and thereafter applying (preferably be means of a high-energy beam such as a laser beam) sufficient heat to the workpieces at the weld zone to effect there the welding together thereof, wherein the preliminary preparative treatment comprises preheating the workpieces to the said lower temperature and pressing them together, at the zone to be welded with a force sufficiently great to expel coating material from between the workpieces at the weld zone. thereby to improve the quality of the subsequent weld.