Structural Steel, CE Marking and ISO 3834
Job Knowledge 120
ISO 3834, Quality Requirements for Fusion Welding of Metallic Materials, is a specification that was first published as an EN specification, EN 729, almost 20 years ago, becoming an ISO specification in 2005. It spells out in Parts 2, 3 and 4 what is regarded as best practice with regard to the control of welding and its associated activities. Not being a mandatory specification it has, to a large extent, been ignored by welding fabricators who have adopted the attitude that they will implement the requirements when they have to. That point has now been reached for many companies with the publication of the Construction Products Regulations (CPR) and a number of related specifications that reference ISO 3834 and will therefore directly affect the structural steel industry.
The CPR is the UK version of the European Construction Products Directive and requires structural steel work that is placed on the market to be CE marked. CE marking may be applied to the steel work provided that the manufacturer can demonstrate that the components comply with the relevant harmonised standards – a harmonised standard being a standard that is regarded by the European Commission as satisfying the Essential Safety Requirements set out in the Directive. The CE marking of construction products becomes mandatory in the summer of 2014 at which time fabricators must be able to demonstrate compliance with BS EN 1090, Execution of Steel Structures and Aluminium Structures, the harmonised standard for construction products.
The CPR requires that the manufacturer implements a factory production control (FPC) system to ensure that products comply with the design and service criteria by means of written procedures and inspections and tests. BS EN 1090 Part 1, clause 6.3, which states that an FPC system conforming to EN ISO 9001 and made specific to the requirements of BS EN 1090 is regarded as acceptable. Welding, however, is identified in ISO 9001 as a “special process” and therefore additional controls are required to ensure that welding and its related activities are competently managed – compliance with the relevant part of ISO 3834 satisfies this requirement and is therefore specified in BS EN 1090. The CPR also requires that the FPC system is accredited by a notified body (NB), an NB being an independent third party approved by the government–in the UK via the UK Accreditation Service (UKAS).
BS EN 1090 Part 2 – Steels – divides construction products into four Execution Classes (EXC). EXC1 includes unwelded items, welded items not subject to dynamic loading and items in steels with a specified minimum yield strength below 355MPa. EXC2, 3 and 4 are for increasingly onerous service conditions and for all steels of S355 grade and above. Manufacturers working to EXC1 are required to comply with ISO 3834 Part 4 Elementary Quality Requirements, to EXC2 with ISO 3834 Part 3, Standard Quality Requirements and to EXC classes 3 and 4 with ISO 3834 Part 2 Comprehensive Quality Requirements. Because of the requirement with respect to S355 steels it is likely that most fabricators will need to comply with ISO 3834 Part 3 as a minimum. In addition to the parts mentioned above ISO 3834 has a further three parts, these being part 1, Criteria for the selection of the appropriate level of quality requirements; part 5, Documents with which it is necessary to conform to claim conformity and part 6 Guidelines on implementing ISO 3834. Table 1 below summarises the requirements contained in parts 2, 3 and 4.
Table 1 summarises the requirements contained in parts 2, 3 and 4.
Most of the work involved in achieving compliance is in the production and implementation of written procedures and the qualification of welding procedures. Whilst there is no mandatory requirement either in the CPR or EN 1090 for the fabricator to have independent accreditation to ISO 3834 it is inevitable that self-certification will not be acceptable and that purchasers will demand third party accreditation.
Although the implementation of a competent FPC system, whilst being time-consuming, is relatively straightforward there is one area that fabricators may have difficulty complying with. EN 1090 Part2 clause 7.4.3 requires welding co-ordination personnel as specified in ISO 14713, Welding Co-ordination – Tasks and Responsibilities, to be appointed when welding EXC2, EXC3 and EXC4 components. Any individual involved in any way with welding activities is regarded as a welding co-ordinator - from the chief designer to the storeman. It is, however, the appointment of an individual called the Responsible Welding Co-ordinator (RWC) that may be problematic. Table 14, taken from EN 1090 Part2, requires the RWC to have either “basic”, B, “specific”, S or “comprehensive”, C knowledge. Table 15 specifies similar requirements for the welding of stainless steels.
Table 2 Copy of Table 14 from EN 1090 Part 2
Table 3 Copy of Table 15 from EN 1090 Part 2
The qualifications of International Welding Specialist (IWS), International Welding Technologist (IWT) and International Welding Engineer (IWE) are quoted in ISO 14713 as examples of qualifications that would be regarded as fulfilling the requirement of B, S and C respectively. Other qualifications of the RWC may be accepted by the accrediting body auditor following a formal interview but the appointment of a suitable qualified and experienced RWC is a potential problem area for many fabricators.
In addition to the requirements of the CPR and EN 1090 there are several additional specifications that require the implementation of ISO 3834 and its related specification ISO 14713. In order to be included in the Register of Qualified Steelwork Contractors (RQSC), administered by UKAS, it is necessary to comply with the National Highways Sector Scheme for Quality Management in Highway Works document 20 - The Execution of Steelwork in Transportation Infrastructure Assets, fortunately known as “NHSS 20”. This document is mandated in Appendix A of the Specification for Highway Works and describes the quality management system requirements for fabricators providing “transportation infrastructure assets” – this includes road side furniture, overhead gantries, crash barriers, bridges etc. NHSS 20 specifies that the quality systems shall comply with both ISO 9001 and the appropriate part of ISO 3834 – including the appointment of an RWC with qualifications and experience in accord with the execution class of EN 1090.
One final specification that should be mentioned is EN 15085-Railway Applications- Welding of Railway Vehicles and Components. This specification is in four parts and adopts a similar approach with respect to the classification of railway components and the quality assurance systems for the control of manufacture as EN 1090. Fabricators are required to be independently third party certified and to comply with either ISO 3834 Part 2, Part 3 or Part 4 depending on the certification level (execution class in EN 1090). There are numerous specific requirements regarding welding and its related activities in EN 15085 – far more that can be covered in a brief article such as this – reference to the specification is therefore essential. It should be remembered that the requirements of EN 15085apply not only to the main contractor but also to any subcontractors - this includes the repair welding of items such as forgings and castings.