What do Q2, BK2 and the manufacturer qualification mean?
Anyone buying welded components for defence applications soon meets terms such as DIN 2303, Q1, Q2, BK2 and manufacturer qualification. They are often named side by side – but they do not mean the same thing.
One point above all: Q2 is not a component class. And BK2 is not a welder qualification.
DIN 2303 looks at several levels: the manufacturer, the materials and procedures used, the classification of the component, and the qualification required of personnel and processes.
What does DIN 2303 govern?
DIN 2303 is titled “Welding and allied processes – Quality requirements for manufacturing and repair companies for defence products”.
Companies that use thermal joining processes – welding, brazing, thermal spraying – in the manufacture or repair of defence products for the German armed forces need a certificate of manufacturer qualification to DIN 2303. The standard applies to armed forces establishments and to civilian companies alike. It does not apply to commercially available products that can be used in civilian and military settings without substantial modification. A certificate is required for component classes BK1 to BK3.
So the standard does not cover every part that will at some point be put to military use – what decides the matter is the defence product specification and the procurement situation. The provisions of the A-Z collection compiled by the recognised bodies apply in addition, by way of explanation and correction. Information sheet on DIN 2303 (PDF, in German)
What is a manufacturer qualification?
A DIN 2303 certificate does not refer to an individual welder: it describes the qualification of a manufacturing company for a defined scope. That includes requirements for:
welding coordination
qualified staff carrying out the work
approved welding procedure specifications
the materials used
welding procedures
testing
traceability
quality assurance
Qualified welders and operators to DIN EN ISO 9606, 14732 and 14918 are required, together with approved procedure specifications; for classes Q2 to Q4 their approval generally rests on procedure qualification tests, while for Q1 approval to DIN EN ISO 15610 is also permissible.
DIN 2303 therefore qualifies not just the weld but the manufacturer’s organisational and technical prerequisites.
What does Q2 mean?
This is where a misunderstanding most often arises: Q1 and Q2 are not grades in the sense of “good” and “better”.
The manufacturer qualification class describes how materials are grouped, taking account of the conditions under which they are joined with heat (Q1 to Q3) or of their fitness for the product concerned (Q3 and Q4).
Q2 therefore describes a scope of qualification for particular materials – not a higher level of quality than Q1. A company holding both classes covers both groups of materials.
Q1 to Q4 – simply put
Manufacturer qualification class
Underlying principle
Q1
independent of product: material groups 1.1, 1.2, 1.4, 21, 22 and 8.1 to DIN CEN ISO/TR 15608
Q2
independent of product: all remaining groups in that technical report
Q3
product-dependent: only selected materials to technical delivery conditions – armour function
Q4
product-dependent, to aerospace standards of its own such as DIN ISO 24394, DIN ISO 11745, DIN ISO 16338
More important than the statement “we hold Q2” is therefore the certificate itself: what counts is which materials and procedures the scope actually covers.
What does BK mean – and why is Q2 not BK2?
BK stands for component class and is to be distinguished from the manufacturer qualification class Q. A defence product is assigned to a component class according to the type of loading, its safety significance and its operational capability.
Q – for which materials and manufacturing areas is the manufacturer qualified?
BK – what significance does the particular component have for safety and operation?
The labels look similar but describe different things. A certificate may show manufacturer qualification Q1/Q2 and component class BK2 – that does not mean Q2 automatically belongs with BK2. The combination follows from the manufacturer’s scope of certification and from how the components are classified.
Why are the welding procedures listed on the certificate?
A DIN 2303 qualification does not cover every conceivable welding procedure. The certificate states which procedures the manufacturer may use within the qualified scope, with their standardised process numbers. These can include:
The same applies to materials. Holding a DIN 2303 certificate does not mean a company may weld every metal within the standard – the certificate names the qualified material groups. That matters above all with:
special stainless grades
non-magnetisable materials
highly alloyed materials
aluminium alloys
special defence materials
When choosing a supplier, the actual scope of the certificate should therefore always be compared with the component specification. All parent materials must be evidenced by certificates to DIN EN 10204; for filler metals, CE marking, certificates to DIN EN 10204 and approval certificates or data sheets are required in addition.
What does DIN CEN ISO/TR 15608 mean?
The numbers given on DIN 2303 certificates, such as 8.1, 8.2, 22 or 23, are material groups to DIN CEN ISO/TR 15608. That system groups metals by their metallurgical and welding properties, which saves a certificate from having to list every individual material number.
Even so, belonging to a group does not mean every particular application is covered without further review. The drawing, the technical delivery conditions, the welding procedure specification and the project’s own requirements remain decisive.
Why does welding coordination matter?
In qualified welding production it is not enough to employ good welders – the company also needs suitable welding coordination. The qualification required of it follows the component class: on the basis of DIN EN ISO 14731, levels A to C are defined, with level A the highest. Companies must have both responsible and deputy coordination personnel.
Welding coordination helps to ensure, among other things, that:
suitable procedures are used
valid welding procedure specifications are in place
qualified personnel are deployed
materials and filler metals are correctly allocated
testing and documentation requirements are met
DIN 2303 is therefore a good deal more than an individual welder test. Our specialist welders
What does Q2 mean in day-to-day production?
For a manufacturing company, a qualification of this kind shapes how the whole process is organised:
Material – must be unambiguously identified and allocated to the order.
Filler metal – must suit the procedure and the parent material, and be evidenced.
Personnel – only appropriately qualified staff may carry out the work concerned.
Welding procedure specification – the process must rest on an approved procedural basis.
Testing – prescribed tests must be carried out and documented to a qualified standard; for the quality of the joints, DIN EN ISO 5817 and DIN EN ISO 10042 generally apply.
Documentation – the manufacturing process must remain traceable.
The real qualification therefore shows in the process behind the certificate.
What has DIN 2303 to do with traceability?
With defence components it is often important to be able to establish:
which material was used
which material certificate belongs to it
which filler metal was used
which procedure was applied
who did the welding
which tests were carried out
Which documentation is required in a given case follows from the component, the drawing, the standards, the technical delivery conditions and the contract. DIN 2303 provides a qualified organisational framework for it. Quality & certifications
What does DIN 2303 mean for non-magnetisable components?
Certain naval and defence applications call for very low magnetic properties. Here it is not enough to buy a stainless steel specified as non-magnetisable: machining, and thermal joining processes in particular, can affect a material’s properties. The following can therefore matter:
a defined material
controlled material handling
suitable filler metals
qualified welding parameters
defined forming
suitable records and tests
Non-magnetisable is therefore not only a question of material: it can become a requirement on the process. How to proceed in a given case always follows from the defence specification concerned. Defence & marine
May a manufacturer holding Q2 make any defence component?
No – and this is one of the most important points. A DIN 2303 certificate applies only within its defined scope. What has to be checked is:
Component class – does the BK shown suit the project?
Material – is the relevant material group covered?
Welding procedure – is the intended procedure part of the qualification?
Welding procedure specification – is the actual process qualified?
Component specification – what additional requirements do the drawing or the technical delivery conditions contain?
Customer requirements – are additional approvals needed?
The certificate defines the prerequisites. The product specification defines the order.
What should a buyer check on a DIN 2303 certificate?
A short checklist:
Is the certificate still valid? Certificates are issued with a maximum validity of three years.
Which manufacturer qualification classes are recorded?
Which component class is shown?
Which welding procedures are included?
Which material groups are included?
Which body issued the certificate?
Does that scope really match your own drawing and specification?
Even where a DIN 2303 qualification is in place, the first step should be to check whether component class, material, welding procedure, design, test requirements and documentation are covered by the existing scope and by the customer’s requirements.
For a first assessment, the technical drawing, the material designation, the intended component class and the relevant technical delivery conditions all help. What belongs in a manufacturing enquiry?
Q2 is a qualification – what counts is the scope behind it
DIN 2303 creates a qualified framework for the manufacture and repair of welded defence products. Whether a manufacturer suits a particular component, though, can only be judged once component class, material group, procedure and project specification are considered together.
Send us your drawing or CAD data by email – together with material, batch size and your requirements. We will come back to you with a sound assessment.
