Furmanite On Site Machining,Welding, Stress Relief and NDT Case Study Steel Tube Mill Hydrotester
The 15,000 PSI Hydrostatic Tube and Pipe testing mill sealing surface heads, at a major manufacture of pipe and tube, had become cracked. The surface of the fill and purge head blocks in the hydrotester require a fine, indication-free finish on the sealing surfaces. The surfaces had become cracked to such an extent that, while the testing machine could still maintain a 15,000 PSI hydrostatic test pressure, excessive amounts of water were being wasted during the test process. The material of the head blocks, AISI 4340 Nickel – Chrome –Moly, requires specialized weld media and pre and post weld heat treatment procedures in order to prevent cracking. During the preliminary client interview Furmanite learned that the prior vendor’s repair was completed using local torch preheat only, standard carbon steel compatible electrodes and without post weld stress relief. Furmanite advised the client to be prepared for indications of discontinuity deeper than expected due to the uncontrolled processes previously used which we expected to be revealed after the initial pre-machining process.