Good Coiled Tubing Welds, Properly Managed, Do Not Break

摘要

Butt welding of coiled tubing performed routinely in both newrnand used tubing extends life or increases application versatilityrnof existing strings. Welds are commonly made to replacernoverly fatigued sections, remove mechanical damage, extendrnstring length, and attach special application strings or tools tornwork reels and repair tubing imperfections. Properly designedrnand executed butt welds provide the same load bearingrnproperties of the surrounding tubing. The weld integrity isrnverified by non-destructive testing, insuring sound joints. Thernfatigue properties of the weld must be understood and properlyrnmanaged. This has resulted in an extremely successful recordrnfor butt welds placed in coiled tubing for field application.rnThe paper documents the steps required to insure the bestrnweld quality is being placed into a string of coiled tubing.rnData on properties of welds from manual and machine welds,rnin both new and used tubing verify the load carrying capabilityrnof the welds. The down rating of fatigue life and potentialrncorrosion implications are handled through continuous stringrnmanagement. The field experience of butt welds performed inrnboth factory and field environments are reviewed. Resultsrnindicate the clear cost effectiveness of currently available,rnproperly installed butt welds combined with systematicrnmonitoring by the relevant service companies.