API 6A CRA is a supplement to API 6A, covering a group of high performance alloys – specifically age-hardened nickel alloys, which includes Alloy 718, Alloy 725 and Alloy 925 as well as Alloys 716, 935 and 945. From a material supplier’s perspective, it covers the most relevant aspects of the metals properties: production route, chemical composition, mechanical properties, microstructure and test conditions.
API is the American Petroleum Institute. Formed in 1919, the trade association aims to promote safety across the natural gas and oil industry globally. One of its main activities is to bring together subject matter experts to develop and maintain standards that cover materials and operational practices.
API 6A is a large document, at over 400 pages, that covers all aspects of materials specification for wellhead and Christmas tree equipment. It goes into great detail to cover the requirements for specific components such as tubing and casing hangers, valve bodies and bonnets, stems, lock screws, flanges, hubs, clamps and connectors. It covers identification and marking of components, general dimensional control and operational parameters.
Langley Alloys stocks a number of these very high-strength nickel alloys, certified to both the relevant API (API 6A and API 6ACRA) and NACE (MR0175 – ISO15156-3) standards. In all cases these alloys develop their high strength through a secondary ageing heat treatment.