Manufacturers and subcontractors may be subject to high requirements for traceability and quality of the welds they produce, in particular due to several mandatory manufacturing standards and possible compliance with the EN ISO 3834 standard (welding quality assurance).
EN ISO 3834 is increasingly required by major clients and applies to many products for sensitive markets such as nuclear, oil, natural gas and food processing with pressure equipment (pipes, heat exchangers, containers, etc.), but also rail transport, shipbuilding or steel construction with steel or aluminium structures.
Manufacturers or subcontractors must then comply with a review of the quality of welds that EN ISO 3834 classes as well :- Follow-up of non-conformities and corrective actions.
- Requirements review, technical review and subcontracting
- Workshop organisation, process and qualification management: welders, QMOS, DMOS ...
- Welding monitoring and control: welding, NDT...
In this article, Mathilde NAUMER and Vincent Saling in charge of the Welding line of Sirfull, a company specialized in industrial software edition, share their vision of these welding quality requirements which they divide into 4 main steps.
1- Preparation of the manufacturing process
? PQR and WPQ - welding procedure and welder qualification
When receiving an order, the first step will be to check that the welds can be carried out internally, and that the welders and the company have the necessary qualifications.
Thus, the WPQ (Welder Performance Qualification) ensures the dexterity and skill of a welder in carrying out a particular welding job. And the PQR (Procedure Qualification Record) ensures the range over which the company can achieve specific welded assemblies.
The WPQ and PQR are documents issued by third party certification organisations, such as Apave, the Welding Institute, the Welding Development Centre, Bureau Veritas, etc.
In order to weld a part subject to regulations, the company must have the appropriate PQR and the welder with the right qualification (WPQ).The management of qualifications is complex, on two aspects in particular:
- the follow-up of the updates of the different qualifications for the company and for each welder,
- the valorisation of qualifications in relation to the welds to be made.
Mathilde Naumer explains that "the welding management software enables to automate and centralize the management of qualifications, and in particular the management of qualifications renewals. »
Then Vincent Saling adds that by "indicating the types of welding to be carried out on a project, the software will automatically indicate whether the welding can be carried out, and what qualifications are available to the company to carry them out. »
Indeed, the PQR is a document that consists in verifying that the welding parameters used lead to an assembly whose mechanical characteristics are in accordance with the customer's expectations and manufacturing codes. The PQR is qualified by a third party organisation via a welded coupon that has been inspected, in order to check the conformity of the assembly before it goes into production. This qualification results in a Welding Procedure Specification (WPS) giving the necessary instructions to the welder to carry out the assembly. In addition, the qualification also generates a "Domain of Validity" (DV) which can be interpreted by the manufacturer in the context of future assemblies, thus avoiding in some cases to go through the qualification stage again with the third party organisation.
Digital tools can be an interesting solution to centralize and facilitate all these steps.
? WPS - Welding Procedure Specification
Preliminary WPS - serving as a test for a PQR - and certified WPS are complete and precise descriptions of how a weld should be processed. The European standards NF EN ISO 15609 and NF EN ISO 15614-1 of 2005 with the amendments of 2008 and 2012 specify the modalities of the WPS. These standards are notably invoked by various manufacturing codes.
? Welding book
Then, before the start of production, the drafting of a summary document called 'welding book' is required by various manufacturing codes (CODAP, NF EN 13445 for pressure vessels, CODETI and NF EN 1348 for piping, RCCM and RRCEV for the nuclear sector and many others).
The welding book generally includes :- All the welds planned on the equipment produced,
- A marking plan of each weld with an identification number,
- A weld tracking table listing the numbers of each weld, the associated PQR and WPS.
This document can be submitted to the client for validation.
Vincent Saling points out that "the drafting of the DMOS and the welding book, a document standardized in particular by NF EN ISO 15609, is time-consuming to produce. The documentary research section is an important part of the process. A good welding management and monitoring software should enable this operation to be conducted in a semi-automated manner. »
2- Manufacturing follow-up, production process and traceability of welds
The person in charge of the sector and/or the welding engineer must, on the basis of the previous elements, organise their production, ensure traceability and quality controls. In order to do so, the following information and documents will be necessary:
- The components to be welded,
- The technical characteristics for each weld,
- The welder with the necessary qualification for each weld,
- Certificates of all components and casting numbers to ensure maximum traceability of the production process.
Mathilde Naumer insists on the importance of 'digitalizing' the management at this level as well, "the welding software can gather all this information in order to make it readable to the person in charge of the welding department, allowing him to guarantee the good management of his sector, to follow the quality and to ensure traceability. In the most demanding sectors, the reference standard for welding quality traceability is EN ISO 3834. »
3- NDT - Non Destructive Testing
The non-destructive tests do not alter the weld, and are therefore performed by neutral methods such as : visually, by radiography or radioscopy, by sound, etc.
The NDT inspector may be internal or external to the company, but must be certified in order to sign the NDT report. This report, together with the copy of the controller's certification, is one of the many documents to be provided in the end of manufacture report (see next paragraph).
4- Manufacturing Report or 'Manufacturer/Builder file'
The Manufacturing Report is a complete report given to clients at the time of delivery. It precisely traces the manufacturing history, as well as all qualifications and the numerous documents associated with the assembled equipment. The purpose of this file is to accurately record each step of the manufacturing process of an equipment, so that the origin of any defect can be identified. In addition to the elements mentioned in the two previous paragraphs, the Manufacturing Report integrates :
- A manufacturing follow-up table;
- A list and certificates of the materials used;
- The list and certificates of consumables: coil, wire, etc. ;
- A follow-up of the non-destructive testing (NDT), their results and their reports.
Other elements, which are not exhaustive, can complete it and will depend on the requirements of the manufacturing codes and the clients.
Vincent Saling insists on the time it takes to compile this large type of file: "the information must be gathered, the documents collected in the archives through several services, or even externally for NDT controls. Then the company has to assemble the production information, any repairs, defects, etc." He adds: "The information has to be gathered, the documents collected in the archives from several departments, or even externally for NDT inspections. The centralization of all this information and documents in digital form automates the creation of the Manufacturing Report. The digitalization of a deliverable is not only a time saving for the welding coordinator or the project manager, but above all a real asset in terms of trust towards the client. »
Conclusion
Beyond the technicality of welding, the 'administrative' requirements are important and very time-consuming. Industry 4.0, or in other words digitalisation, is probably a key element in improving productivity. 3 aspects seem to be essential: the digitisation of welding qualification data, the traceability of technical information in a centralised tool and the automation of reports.
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