The Pressure Equipment Directive

Purpose

Directive 97/23/EC, the Pressure Equipment Directive, is one of a series of measures intended to create a single European market in which the technical requirements for goods are identical, thus allowing manufacturers easy access to a market with a spending power greater than that of the Yen or the Dollar.

The purpose of the PED is to provide for a legal structure whereby pressure equipment can be manufactured and sold throughout the European community without having to go through a local approval regime in every member state. The means by which this is achieved is to ensure common standards of safety in all pressure equipment sold within the European Economic Area. Manufacturers are therefore able to meet the requirements for approval in any member state of the EU, and do not have to repeat the process when selling goods in any other state.

In most cases, clearly, manufacturers will have their equipment approved in their home state. Manufacturers outside of the EU may also have approvals and test work undertaken at their own factory (and in many cases this is obligatory) but responsibility for compliance with the requirements of the directive will ultimately rest on the person responsible for placing the product on the EU market place.

Scope

The Directive applies to the design, manufacture and conformity assessment of pressure equipment and assemblies with a maximum allowable pressure greater than 0.5 bar gauge (i.e. 1.5 bar absolute).

Vessels, piping, safety accessories and pressure accessories are all included.

Typical examples of pressure equipment covered include:

• shell and water tube boilers
• heat exchangers
• plant vessels
• pressurised storage containers
• industrial pipework

as would be used in the chemical, petrochemical, biochemical, food processing and energy industries. However, gas cylinders (including cylinders for breathing air) and certain compressed air equipment, as would be used in any general engineering process, are also included.

Typical examples of safety accessories include:

• safety valves,
• bursting disc safety devices,
• buckling rods,
• controlled safety pressure relief systems

  and

• pressure switches
• temperature switches
• fluid level switches

where these are used in safety related applications.

Exclusions

The Directive applies only to components and sub assemblies - it does not apply to the "assembly of pressure equipment on site and under the responsibility of the user, as in the case of industrial installations". There are also a number of other which cover items of equipment for military use, for use in transport, equipment which presents a relatively low hazard from pressurisation and which is within the scope of another CE mark directive (e.g. the Machinery Directive) and several other classes of equipment.

Also excluded from the PED are vessels used for the transport of fluids while under pressure (i.e. containers used for the transport of fluids by road, rail, sea and air). These are subject to another directive, the Transportable Pressure Equipment Directive (TPED), which has different attestation and marking requirements (the "pi-mark"). For certain applications, both the CE mark and the Pi-mark are required.

A further exclusion covers 'simple pressure vessels' which are the subject of a separate directive. This directive essentailly applies to recievers used on compressed air systems.

Implementation dates

The implementation date for the Directive in all member states is 29 November 1999. During a transitional period up to 30 April 2002, member states may permit the placing on the market of any equipment which complies with the legislation in forces in that state on 29 May 1997 (the date of adoption of the Directive).

Structure

The Directive defines a number of classifications for pressure equipment, based on the hazard presented by their application. Hazard is determined on the basis of stored energy (pressure-volume product) and the nature of the contained fluid.

Assessment and conformity procedures are different for each category, ranging from self-certification for the lowest (category I) hazard up to full ISO9001 quality management and/or notified body type examination for category IV equipment. The assessment procedures are arranged in a modular structure and manufacturers have the choice of which modules to select (within pre-determined combinations) in order to best suit their application and manufacturing procedures.

Aspects of the design, production and testing of the equipment are the subject of a large number of harmonised standards, many of which are still in the process of being produced. They cover all aspects of equipment design and production, including dimensions, materials, welding and test methods. In some cases manufacturers will be required to operate strictly within the guidelines imposed by these standards, whereas in other circumstances application of standards, while not compulsory, will considerably simplify compliance with the essential requirements of the directive.

Protection requirements

The Directive defines certain requirements about the design and performance of pressure equipment in a series of Essential Requirements, contained in Annex 1 of the directive itself. Equipment must be:

• Designed for adequate strength taking into account internal/external pressure, ambient and operational temperatures, static pressure and mass of contents in operating and test conditions, traffic, wind, earthquake loading, corrosion and erosion, fatigue, etc.;
  
• Provided with means to ensure safe handling and operation and of examination, draining and venting;
  
• Provided with protection against exceeding the allowable limits of pressure;
  
• Where necessary, pressure equipment must be designed and fitted with suitable accessories to meet damage-limitation requirements in the event of external fire;
  

Non-destructive tests of permanent joints must be carried out by suitable qualified personnel. For equipment in categories III and IV, the personnel must be approved. Suitable procedures must also be established to provide traceability of materials and components from supply to finished product.

Administration requirements

In addition to ensuring that the equipment is capable of meeting the essential performance requirements of the directive, manufacturers must also provide adequate instructions with equipment they sell, they must complete a specified declaration of conformity and they must maintain a technical file of information about how the equipment was designed and manufactured.

Pressure equipment is to be marked with at least:

• identification of the manufacturer
• unique identification of model and serial number
• the year of manufacture
• maximum/minimum allowable pressure limits
• the CE logo

Overall the requirements of the Directive are complex and quite onerous. It is difficult to provide generalised advice about what the specific requirements of the Directive are because these (in common with all CE marking requirements) are very much individual to the product being considered. It is vitally important to carefully consider every item of equipment on an individual basis and in a methodical fashion when trying to decide how best to make it comply with the requirements of the Directive.

Useful links

For details of draft standards, the New Approach web site is a good EU-funded resource.

The UK government's Department for Business, Enterprise and Regulatory Reform (BERR) publishes a number of useful guides on the Directive and these are available for download.

Useful information may also be found on the Health and Safety Executive web site, particularly in relation to the ongoing requirements for pressure equipment after installation (e.g. regular inspections etc.).

Links to some bodies notified under the directive can be found on our Notified Bodies page.

Further advice

As with all CE marking directives, the actual requirements for any piece of equipment under the directive are complex and dependent on not only the design but also the type of user, the intended use and sometimes even what is claimed in the instructions or sales literature.

For further advice specific to your products, please contact us at Conformance and we will be pleased to discuss your needs. If you'd like us to prepare a no-obligation quote for assisting you with CE marking your products, please take a look at our page which gives details of the information required in order to be able to give you an accurate idea of the costs and procedures involved.