the production casing nipple 26 the coupling 24 and a valve 32 a the coupling is welded to the production casing plate in such a manner that it will not effect the fillet weld around the circumference of the plate to the production casing the system further includes a surface casing plate 28 having a surface casing nipple 30 attached to the surface casing plate 28 through an appropriate bore 30 a in the surface casing plate 28 generally the production casing plate 22 includes a threaded coupling to allow the production casing nipple 26 to be removed to allow welding around the circumference of the production casing plate and then re installed the surface casing plate 28 does not require as long a nipple and thus does not interfere with the weld around the circumference of the surface casing plate the surface casing plate 28 is also provided with a second bore 30 b to allow the production casing nipple 26 to pass through the surface casing plate the surface casing nipple 30 is provided with appropriate threads on the upper outer surface to enable threaded connection with a valve 32 b each of valves 32 a and 32 b may be provided with a rubber stopper 34 a 34 b that may be inserted within the valve as an indicator of gas release as may be required by regulators the system further includes a surface casing cap 36 dimensioned to fit over the surface casing 12.