Puma were required to take the old Channel End drawings and reproduce a full set of manufacturing drawings, not only using current available materials, but also to ensure that they met current engineering standards. Puma had to follow a QIP (Quality Inspection Plan) throughout the Channel Ends fabrication. To ensure that all the correct procedures were followed the QIP had various witness and hold points which allowed the customer to ensure that all fabrication process and procedures were achieved. Due the materials specifications within the new standards, Puma were required to machine complete branches from solid Inconel Billets. These Branches ranged from ¾” 300# RTJ’s to 8” 300# RTJ’s complete with a 385mm extended Neck.
Pre-Overlay machining on the Inlet and Outlet flanges was complete, which entailed machining only the Weld Prep and the internal diameter of the flanges. This enabled us to weld all parts such as the flanges to the vessel body ensuring that all the bolt holes and flanges would not distort during welding or Overlay. During the welding MPI was required at each stage to ensure no cracks were present, this was completed on the Root, Cap and the entire following weld runs. Pre-Heat was required to achieve the correct welding temperatures were maintained throughout the fabrication. A big part of this process was to apply a Stainless Steel 304 overlay to the internal surfaces.
On completion the unit was subject to PWHT to relieve the induced stresses caused by the manufacturing processes. Only was this required on all internal surfaces and it could only be complete once the vessel body had both flanges welded in position. Finally the flange faces and the bolt holes were machined. This was left to allow us to guarantee that the bolt holes and sealing faces would be correct, which otherwise would not have been possible due to the unavoidable distortion resulting from the hot processes.