DIN 7640 is Compression couplings with spherical liner; equal crosses
DIN 7640 standard is included in DIN Handbook 348. Applies to equal crosses (hereinafter briefly referred to as crosses), which are used for pipe joint assemblies with spherical liner as specified in DIN 3863.
DIN 7601 : 1998 COMPRESSION COUPLINGS WITH BALL-TYPE NIPPLES - COMPLETE UNIONS AND SURVEY
DIN 3850 : 1998 COMPRESSION FITTINGS - SUMMARY
DIN HDBK 348 : 3ED 2015