This european standard applies to metallic valves as pressure accessories for industrial applications with a maximum allowable pressure ps greater than 0, 5 bar in accordance with the pressure equipment directive ( ped) 97/ 23/ ec and specifies minimum requirements applicable to design, manufacture, testing, materials and documentation. novem industrial valves - requirements and testing for metallic valves as pressure accessories this european standard applies to metallic valves as pressure accessories for industrial applications with a maximum allowable pressure ps greater than 0, 5 bar in accordance with the pressure. a revision of en 593 will be undertaken once en16668+ a1 has been listed in the official journal. industrial valves requirements and testing for metallic valves as pressure accessories. 01 supersedes en 16668: english version industrial valves - requirements and testing for metallic valves as pressure accessories. the annex za is extensive and complying with bs en 16668 will address all the essential safety requirements of the european legislation for pressure equipment as they apply to valves. bs/ enpdf download. european standard norme européenne europäische norm en 16668: + a1 en 16668 pdf march 20. references this document references: tags indicating changes to cen text carry the number of the cen amendment. pdf or print version. en 16668: + a1: e national foreword this british standard is the uk implementation of en 16668: + a1:. last active version. it supersedes bs en 16668:, which is withdrawn. the start and finish of text introduced or altered by amendment is indicated in the text by tags. it will be referenced in other valve product standards. c) the welders and welding operators are qualified for the work allocated to them and their approval isvahd.