the pin joint 21 a see fig3 and 5 the pin 21 a is severed the portions of drill collar above and below the pin joint have longitudinal cuts therein but due to the wall thickness these cuts do not extend all the way to the outside fig5 shows the cut extending part way into the corresponding box joint thus the box joint and the portions of the drill collar above and below the pin joint are not cut completely through and are unsevered nevertheless when the pin joint is cut it unwinds or springs open the joint decouples and the drill string becomes severed at the joint thus only the pin joint need be cut to sever the drill collar that portion of the drill string that is unstuck the upper portion is retrieved to the surface the drill collar 11 that was cut at its pin joint can be reused referring to fig8 a the pin joint 21 a has a longitudinal cut 23 therein the pin joint 21 a is cut off of the drill collar as well as any damaged portions of the collar to form a clean end 83 see fig8 b the end 83 is remachined to form a new pin joint see fig8 c the drill collar can now be reused each of the torches can be provided with ancillary equipment such as an isolation sub and a pressure balance anchor the isolation sub typically is.