CSN EN ISO 669 This International Standard defines and specifies certain identified electrical and mechanical characteristics of equipment used for - resistance spot welding, - projection welding, - resistance seam welding, - upset welding, and - flash welding. This International Standard specifies the information to be given in equipment specifications and the test methods to be used for measuring those characteristics. Not all requirements apply to all types of equipment. Original English text of CSN EN Standard. The price of the Standard included all amendments and correcturs.