Home > Case Studies > Case Four Quality control of pipe for oilfield operations The Problem A conflicting metallurgical requirement exists for the pipes used to convey crude oil and other materials on drilling and production sites. Steel piping needs to be very strong and ductile, but at the same time resistant to the very aggressive and abrasive fluids passing through it. The engineering solution is to manufacture the pipe from strong material, and the deposit a hard abrasion-resistant coating to the interior by weld deposition. It is obviously essential that this internal coating is correctly applied, with no weak (or missing) spots, and no excessive thickness. The pipe is approximately 100mm bore, and up to 8 metres long. Ideally, inspection should be concurrent with the actual welding process so that immediate corrective action can be taken as the process proceeds. Real-time manual observation is obviously out of the question, so the product is examined after the welding process and subsequent cooling time by using an endoscope system. The Solution A real-time monitoring system for the observation of weld metal transfer was designed using our furnace camera experience. The system comprised a special water cooled probe which contained an optical system providing a close-up view of the welding plasma and allowed the metal transfer to be clearly seen. Although the process is very clean, it was still necessary to provide a gas purge to keep the viewing lenses clear and cool. The probe was only 25mm square, but carried the optical system, cooling water flow and return for both the optical assembly and the welding torch and purge gas. The probe had a working length of 4 metres, allowing monitoring of the entire 8 metre pipe by working from both ends. Any variation in weld quality could be immediately observed and corrective action taken to avoid faulty production.