API TR 934-B pdf download Fabrication Considerations for Vanadium-Modified Cr-Mo Steel Heavy Wall Pressure Vessels 4 Design and Fabrication 4.1 Background Vanadium-modified 2 1 / 4 Cr-1Mo and 3Cr-1Mo alloys used for the fabrication of heavy wall pressure vessels offer definite advantages over conventional Cr-Mo alloys. The advantages include increased resistance to hydrogen attack, a lower susceptibility to hydrogen embrittlement,...