In 1992, a Welder Qualification Sub-Committee in SWS was set up under the Chairmanship of Mr Seiichi Inoue, Managing Director of Chiyoda Singapore Pte Ltd. The objective of this sub-committee was to set up a common welder qualification scheme that would be recognised and accepted by the industry, particularly the oil, gas and petrochemical companies, and their sub-contractors. It was agreed by all parties in the process industry, that welder qualified through this scheme, need not have to undergo repeated welder tests whenever the welders moved from one refinery/plant to another for different jobs and contracts. Hence, this set the stage for the formation of Common Welder Qualification Scheme (CWQS) in 1993.

Currently, there are ten (10) approved Welder Qualification Test Centres (WQTCs) under the SWS CWQS system as follows:

1. ACE Quality Testing & Inspection Services Pte Ltd
2. Atomic Technologies Pte Ltd
3. Cast Laboratories Pte Ltd
4. Cutech Process Services Pte Ltd
5. Element Testing Services Pte Ltd
6. Goodwill Engineering & Inspection Services Pte Ltd
7. Leads Specialist Services Pte Ltd
8. Masterscan Engineering Pte Ltd
9. Setsco Services Pte Ltd
10. Worldscan Engineering Pte Ltd