Main circulation pipelines welded in record time at the power unit no. 2 of Novovoronezh NPP-2
Energospecmontazh, PJSC assembly unit at the power unit no. 2 under construction of Novovoronezh NPP-2 completed welding of the main circulation pipelines of the VVER-1200 reactor facility on September 15, 2016. Installation of the main circulation pipelines is an important stage of the nuclear power plant reactor construction. The diameter of the pipes is 990 mm, the wall thickness is 70 mm, and the total weight of the pipe blocks is 238 tons. The pipelines are made of high-quality alloy steel with a layer of stainless metal welded from the inside. Highly qualified welders, who passed the appropriate certification, performed welding. In accordance with the requirements of the technology, pre-heating of the metal with special induction units was carried out before the welding, the necessary metal temperature was also maintained and controlled during the welding process, and after the welding was completed, the welded joints were heat-treated. Work on main circulation pipelines welding was carried out in record short time - 72 days. Previously, similar work at other sites was performed in 96 - 140 days. Process duration reduction was achieved due to the optimization of the work schedule (works were conducted simultaneously on 4 loops of pipelines), time reduction auxiliary operations, clear workplace management , and, of course, the skills and professionalism of installers and welders. Conducted mandatory monitoring with radiographic, ultrasound, capillary and other methods showed no defects, i.e. ensured the high quality of welded joints in full compliance with technology and safety requirements.