Continuously machine-welded tubes, i.e. tubes made from coils as starting materials in an automatic process, which are usually heat treated after welding shall be in the terms of certification procedures considered as materials provided the essential safety requirements (ESRs) of Annex I section 4 “Materials” as well as applicable ESRs of Annex I section 3 “Manufacturing” (in particular 3.1.2 and 3.1.3) are fulfilled.
Further the manufacturer of such tubes shall affirm compliance of the welded tube to the specification.
In general, the inspection document shall take the form of a certificate of specific product control, where shall be found the references to the competent third party approval of welding procedures and personnel and to the recognised third party approval of non destructive personnel (for categories III and IV).
When the use of the welded tube is limited to pressure equipment of category I, a statement in the test report confirming that personnel and welding procedures are qualified according to suitable internal operating procedures is sufficient.
In application of PED Guideline G-16, where the welded tube manufacturer has a certified quality system, this system shall properly cover not only the relevant material properties referred to in the tube specifications, but also the manufacturing process of the welded tubes (in particular welding and NDT).
Note:
This implies that e.g. tubes made from plates are to be considered components, see PED Guideline G-19.