This best practice report complements API 934-A and specifies additional fabrication considerations that should be observed when constructing a new heavy wall pressure vessel using vanadium-modified Cr-Mo materials intended for hydrogen service at elevated temperature and pressure. It applies to vessels that are designed@ fabricated@ certified and documented in accordance with ASME Code Section VIII@ Division 2@ including Paragraph 3.4 of the ASME Code@ Supplemental Requirements for Cr-Mo Steels and ASME Code Case 2151@ as applicable (or equivalent international codes). Nominal material chemistries covered by this report are the vanadium-modified steels including 2?Cr-1Mo-?V@ 3Cr- 1Mo-?V-Ti-B@ and 3Cr-1Mo-?V-Cb-Ca steels. The interior surfaces of these vessels may have an austenitic stainless steel cladding or weld overlay to provide additional corrosion resistance.