German pressure vessel code AD 2000-Merkblat
ISO 3834
EN 1090
EN 15085
DIN 2303
AWS D1.1
AWS D1.8
JIS Z 3801,
WES 820
JIS Z 3841,
WES 824
JIS Z 3821,
WES 8221
JIS Z 3805,
WES 8205
JIS Z 3831,
WES 8101
WES 8102
JPI-7S-31,
WES 8102
These three refer to EN ISO 9606 for welder performance qualifications.
Even though EN 287 is long time replaced by the 9606 standard, some companies still refer to it.
Some others, from the top of my head:
EN ISO 17660
EN ISO 24394
EN ISO 14732 (for operators)
There's also the australian/new zealand standards, some of which are very similar to their EN/ISO counterparts.
Dek Dee has it right, what are you building? What welding/fabrication code applies? Where is the end user, i.e., Owner, located? There's a number of considerations to think about before spending the time and money to qualify the welders.
I suggest ASME Section IX if you are working in the chemical, pharma, steam, water chilled or hot, anything that is greater than 15 psig. Section IX is not a stand alone code, it is used with other ASME construction codes that "add to" the basic requirements of Section IX. The construction code will provide additional information such as whether post weld heat treatment is required and when CVN testing is needed.
Section IX provides a comprehensive methodology for qualifying the WPS and the welder for pressure piping and pressure vessels.