In response to serious technical errors in the 18th edition, the committee voted in January 2003 to withdraw the 18th edition, and reissue the 17th edition. The issue was safety, and API had no choice but to take this action. The next edition of 6A will be called the 19th edition.

API Specification 6A specifies requirements and gives recommendations for the performance, dimensional and functional interchangeability, design, materials, testing, inspection, welding, marking, handling, storing, shipment, purchasing, repair and remanufacture of wellhead and christmas tree equipment for use in the petroleum and natural gas industries. This edition of API spec 6A is the national adoption of ISO 10423:2001 (E), MOD, Petroleum and natural gas industries-Drilling and production equipment-Wellhead and christmas tree equipment. An informative annex is included covering the requirements of the API Monogram Program for equipment covered in the specification.