Couplings for tubing and casing are made from seamless hot deformed pipe. Pipes go to the warehouse of coupling stock where they go through the incoming inspection including visual inspection, size inspection, sampling for mechanical testing, chemical composition and metallographic analyses.
Pipes are cut into coupling blanks using band saws. The machining of the couplings is made at the coupling threading machines that allow us to thread different types of thread (round, buttress, gas-tight).
The visual inspection of the coupling surfaces and geometry inspection are performed at the inspection workplaces. The thread parameters inspection is made by means of universal measuring devices and/or special equipment.
After finishing, the nondestructive testing of couplings is performed using magnetic particle method to detect the outside and inside imperfections. The magnetizing process and magnetic suspension washing are carried out automatically. In case of the unacceptable defects, couplings are rejected.
In order to minimize wear and achieve maximum properties as for leak-resistance of the joint, the final couplings go through phosphating. The accepted pipe are stacked in special containers and transferred from the phosphating section to the coupling screwing machine or the coupling warehouse.