What does the manufacturer qualification mean in pressure vessel construction?
Anyone buying pressure vessels or pressure-bearing components soon meets terms such as the Pressure Equipment Directive, AD 2000, HP 0, ISO 3834 and manufacturer qualification. They are related, but they do not mean the same thing.
One point above all: AD 2000 HP 0 is not a general “pressure vessel approval” for any conceivable component. The code sheet sets out the general principles for the design and manufacture of pressure vessels and the testing that goes with them.
For a manufacturer that means above all: it has to be capable, organisationally and technically, of making the pressure-bearing components concerned to assured quality. HP 0 therefore looks not only at the finished weld but at the company behind it.
What is the AD 2000 body of rules?
AD 2000 is a body of technical rules for pressure equipment. It comprises code sheets on subjects such as:
design
materials
manufacture
welding
testing
documentation
The HP series deals with manufacture and testing. Besides HP 0 it includes code sheets of its own: HP 2/1 on welding procedure qualification, HP 3 on welding coordination and welders, HP 4 on inspection supervision and inspectors, and the HP 5 sheets on making and testing the joints.
What has HP 0 to do with the Pressure Equipment Directive?
European Pressure Equipment Directive 2014/68/EU governs the design, manufacture and conformity assessment of pressure equipment and assemblies with a maximum allowable pressure PS above 0.5 bar. AD 2000, by contrast, is a body of technical rules widely used in Germany to put those requirements into practice – alongside DIN EN 13445 for pressure vessels and DIN EN 13480 for pipework.
Level
What is settled there
Pressure Equipment Directive 2014/68/EU
the legal framework for placing pressure equipment on the market
technical rules such as AD 2000 or DIN EN 13445
the technical rules by which equipment is designed, made and tested
HP 0 and the other AD code sheets
requirements for the manufacturer, procedures, personnel and testing
the particular item of pressure equipment
material, pressure, medium, design, scope of testing, documentation
The two levels answer different questions. The Directive says which legal requirements apply when equipment is placed on the market. AD 2000 says by which technical rules it may be designed, made and tested. Directive 2014/68/EU
Does the Directive always apply above 0.5 bar?
In principle it applies to pressure equipment and assemblies with a PS above 0.5 bar – but it also contains exclusions and different classifications. “The vessel runs at 2 bar” is therefore not enough to establish the requirements. What matters includes the maximum allowable pressure, the volume, the fluid, the temperature, the type of construction and the actual use.
What does manufacturer qualification mean?
A manufacturer qualification confirms that a company has suitable prerequisites for a defined field of work. For welded pressure equipment these include in particular:
suitable production facilities
qualified personnel
welding coordination
qualified welding procedures
material control
test methods
documented quality assurance
An HP 0 certificate typically describes a product-related quality assurance system, suitable facilities for processing and testing materials, and responsible supervisory and competent production staff – in other words, evidence of a quality-assured manufacturing process.
What has ISO 3834 to do with it?
DIN EN ISO 3834 sets out quality requirements for the fusion welding of metals – it deals specifically with welding quality assurance and forms the basis on which manufacturer qualifications in the AD 2000 HP 0 context are built.
AD 2000 HP 0 – looks at the building of pressure equipment.
DIN EN ISO 3834 – looks at the quality of the welding process.
On welded pressure equipment the two overlap considerably, but they are not the same. Welding processes compared
What is examined on the welding side?
For pressure vessels, “our people can weld stainless steel” is not enough. Depending on the project and the rules applied, the following must be evidenced:
qualified welding procedures
welding procedure specifications
qualified welders
suitable filler metals
responsible welding coordination
defined testing
AD 2000 has its own code sheets for this, among them HP 2/1 on welding procedure qualification and HP 3 on welding coordination and welders. The welding process has to be under control repeatably – not just work once.
What is a WPS?
WPS stands for welding procedure specification. It sets out the established parameters for a particular welding process, for example:
the process
the parent material
the filler metal
material thickness
joint geometry
current and voltage
shielding gas
preheat or interpass temperature
For qualified processes, such a specification rests on a suitable procedure qualification: the specification, the procedure qualification test and the testing of the test piece afterwards all belong together.
Why does material traceability matter?
A pressure vessel is only traceably documented if it is clear which material was actually used. Depending on the project, the following may be required:
material certificates
unambiguous material marking
allocation of part to certificate
documented transfer of material
re-marking after machining
Where plate is cut and then worked into several components in particular, the identity of the material has to survive the whole process. Documentation therefore begins at goods inwards – not at the finished vessel.
Which tests are involved?
That depends on the equipment and the specification. Possible tests are:
visual inspection
dimensional checks
pressure testing
tightness testing
penetrant testing
radiographic testing
ultrasonic testing
other non-destructive testing
AD 2000 has its own requirements for inspection personnel and methods – HP 4 on inspection supervision and inspectors, and the HP 5 sheets on making and testing the joints, among others. Which tests are actually required is decided by the component specification and the rules applied.
Does HP 0 automatically mean CE marking?
No – and this is an important distinction. The CE marking of a particular item of pressure equipment arises from conformity assessment under the relevant European legislation. A manufacturer qualification to AD 2000 HP 0, by contrast, demonstrates that the company has the technical and organisational prerequisites for the defined field.
Manufacturer qualification and product conformity are two different levels. A qualified manufacturer does not therefore make any item of pressure equipment without a further, project-specific assessment.
May any pressure vessel be made under HP 0?
Again, no. For a particular project the following still have to be checked:
material
dimensions
pressure
temperature
fluid
manufacturing processes
welding procedures
test requirements
the rules applied
the scope of the manufacturer qualification
What decides the matter is therefore the actual scope of the certificate.
AD 2000 or EN 13445?
Several sets of technical rules exist for unfired pressure vessels: AD 2000, widely used in Germany, and DIN EN 13445, the harmonised European standard series for unfired pressure vessels.
Which basis applies to a given project should be settled early between the designer, the manufacturer and, where applicable, the notified body. A finished part should not have to be reinterpreted between different sets of rules after the event.
What should a buyer check?
With a pressure vessel manufacturer, these questions are worth asking:
Is a current manufacturer qualification in place?
What scope of manufacture does it cover?
Which materials are worked?
Are the welding procedures needed qualified?
What welding coordination is in place?
Which tests can be carried out, or arranged?
How is material traceability assured?
What documentation will be supplied?
Under which rules will this particular item be made?
For a first assessment of a pressure vessel, the following help:
drawing or STEP data
vessel volume
maximum allowable pressure
operating and design temperature
medium
material
wall thicknesses
connections
internals
the rules to be applied
test requirements
scope of documentation
The sooner these details are available, the more reliably it can be established what manufacturing and testing process is required. What belongs in a manufacturing enquiry?
AD 2000 HP 0 at stainlesstec
stainlesstec built up its pressure vessel business in 2016 and is certified for pressure vessel construction to AD 2000 HP 0 in conjunction with DIN EN ISO 3834-3.
Typical fields of work are process vessels for pharmaceutical and food applications, pressure vessels, heat exchanger components and vacuum chambers.
The certificate is the prerequisite – the specification defines the vessel
AD 2000 HP 0 shows that a manufacturer has the organisational and technical prerequisites for qualified pressure equipment manufacture within its confirmed scope. Whether a particular project falls under it is decided only by the pressure, medium, temperature, material, design, applicable rules and test requirements.
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.
