Stable, well controlled manufacturing processes are of vital importance for the reliable assurance of the qualty requirements which are increasing in several aspects like e.g. pipe geometry and weld seam quality. One particular strength of the UOE process is its high performance and productivity. The UOE pipe mill in Mülheim reaches the highest productivity worldwide implying a competitive advantage for the supply of large linepipe quantities on a high quality level with challenging requirements as requested for big pipeline projects like Nord Stream or others. However this high “speed” production (up to 30 pipes per hour) necessitates that all steps during pipe manufacturing are optimised and controlled in very tight limits. This is important in order to minimise pipe rework or, even worse, pipe rejects. It is EUROPIPE’s general manufacturing philosophy that the linepipe quality is assured via the process control. Subsequent inspections and measurments have both the target to confirm the set process parameters and to ensure the product quality.
To the Nord Stream project EUROPIPE delivered around 1,850km of the total linepipe quantity of 2,440km. Month by month around 40,000t had to leave the pipe mill with consistent quality and in time. Such a challenge can only be mastered by stable processes.
In this paper the main manufacturing steps “Forming” and “Welding” are described and how these processes are optimised and controlled in order to minimise the risk of not fulfilling the quality requirements. Process control starts with the design of tools and the careful set up of all process parameters. The subsequent inspection steps (AUT, digital radiography, dimension control by Laser) are especially designed to cope with this high production speed and also to achieve the best inspection quality and measurement accuracy at the same time. By example, the installed Laser equipment for the measurement of the pipe end dimension has superior accuracy compared with other measurement techniques or the usually applied manual control. Also the AUT inspection of the weld seam is developed for this high productivity and requests specific process know-how.