Transportable Pressure Equipment Directive

Directive 2010/35/EU, the Transportable Pressure Equipment Directive (TPED) is one of a series of measures implementing ADR - the European agreement on the International Carriage of Dangerous Goods. 

It is implemented in the UK along with ADR by The Carriage of Dangerous Goods and Use of Transportable Pressure Equipment Regulations.

The purpose of TPED is to provide for a legal structure whereby pressure equipment to be transported under pressure can be manufactured and sold and used throughout the European community without having to go through a local approval regime in every member state and can be transported between EU member states and beyond. The means by which this is achieved is to ensure common standards of design, manufacture, testing and certification in all transportable pressure equipment sold and used within the European Economic Area. Manufacturers, and owners of cylinders for compressed gases 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 all 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 as well as suppliers of compressed gases, who transport their goods in cylinders.

The Directive applies to the design, manufacture, conformity assessment and periodic reassessment of transportable cylinders, tubes, cryogenic vessels and tanks for transporting gases as well as hydrogen cyanide, hydrogen fluoride and hydrofluoric acid. It also covers their associated valves and other pressure equipment. Most of this equipment was subject to earlier national regulations.

Both refillable and non-refillable cylinders are included.

It applies not only to new equipment but also to existing equipment which must be reassessed at the time of its periodic inspection under the ADR regulations.

Typical examples of pressure equipment covered include:

• Fuel gas cylinders
• Welding gas cylinders
• Road tankers for transport of compressed gases
• Battery vehicles containing bundles of cylinders joined by a manifold
• Containerized vessels for compressed gases
• Cylinders incorporated in life rafts and lifejackets
• Vessels for cryogenically cooled gases

Pressure vessels and apparatus used for non-transport related applications will usually be within the scope of the Pressure Equipment Directive 97/23/EC instead.

Equipment placed on the market before 1st July 2001 does not require initial conformity assessment but must be reassessed at the time of its periodic inspection under the ADR regulations as defined in the ADR packing instruction P200 and dependent on the gas carried.

Other specific exclusions are:

• Vessels for non-hazardous gases under 2 bar
• Vessels incorporated into vehicles for their operation
• Vessels for pressurized foodstuffs or fizzy drinks
• Vessels not being used for work
• Aerosol dispensers covered by 2008/47/EC
• Gas cartridges
• Lighters and refills
• Refrigerators with less than 12kg of refrigerant
• Shock absorbers and gas springs with a volume less then 1.6 litres and a P.V not exceeding 80 bar.litres subject to certain provisions
• 2 sparklets of limited pressure and size (derogation 584)
• Unpressurised flasks of certain cryogenic inert gases for cooling of medical and biological specimens.
• Fire extinguishers (which are covered by PED)
• Equipment designed principally to withstand forces due to other functions than the containment of pressure.
• Gas cylinders for breathing apparatus (which are covered by PED)

The Directive defines 3 categories for pressure equipment, based on its pressure volume product (P.V) in bar.litres and hence its stored energy.

Assessment and conformity procedures are different for each category, ranging from occasional auditing of test procedures for the lowest (category I) hazard up to full ISO9001 quality management and/or notified body type examination for category 3 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.

National conformity assessment is still allowed as an alternative with approval by an approved body and conformity assessment by A1, C1, F & G. These products cannot bear the pi mark and cannot be used for international transport. 

The Directive itself contains no safety requirements. Instead it refers to the requirements set out in Chapter 6.2 of Annex A of ADR. These are set out according to the 'old approach' with detailed technical requirements covering design, materials, openings, fittings, etc as well as a list of standards giving presumption of conformity with the requirements of ADR.

The filling pressure of cylinders is to a large extent defined in the packaging instructions of ADR. It should not be assumed that gases can be transported at a pressure chosen by the cylinder manufacturer or user.

In addition to ensuring that the equipment is capable of meeting the performance requirements of the directive, manufacturers must also complete a specified declaration of conformity and they must compile and maintain a technical file of information about how the equipment was designed and manufactured and supply it to the Notified body.

There is no requirement for instructions. Instead, detailed instructions for use, transport, filling, regular inspection, training of drivers etc. are contained in ADR, particularly in packaging instruction P200 concerning gas cylinders.

According to ADR section 6.2.1.7, new cylinders must be marked with following particulars in clearly legible and durable characters:

• manufacturer's name or mark
• approval number (if the design type of the receptacle is approved)
• manufacturer's serial or batch number
• tare of the receptacle without fittings and accessories, when the check of wall thickness required during the periodic inspection is performed by weighing
• test pressure (gauge pressure)
• date (year) of the initial inspection and month where the inspection interval is less than 10 years
• stamp of the expert who carried out the tests and inspections
• water capacity in litres
• for compressed gases filled by pressure, the maximum filling pressure at 15 °C allowed for the receptacle
• For dissolved acetylene, the permitted filling pressure and the total of the mass of: the empty receptacle, the fittings and accessories, the porous mass and the solvent
• In addition, TPED and UK regulations require the Pi mark

Non-refillable receptacles must also be marked with:

• The words “DO NOT REFILL” - this marking shall be a minimum of 6 mm in height.
• UN number and the technical name of the gas or in the case of mixtures, the two constituents which most predominantly contribute to the hazards

Safety related valves are required to be pi marked or CE marked for PED. Other valves require no special markings.

Old cylinders must be marked with the Pi mark, Notified or Approved Body number and inspection date when they pass their first periodic inspection after the introduction of TPED.

Although the wording of the Pressure Equipment Directive (PED) 97/23/EC and TPED is not clear, European Commission guidelines interpret that although it is permissible to incorporate pi-marked pressure equipment into a CE marked pressure system without further assessment, it is not permissible to use CE marked cylinders for transporting compressed gases. They must be re-assessed to TPED and pi-marked.

The reason for this is that the Conformity Assessment Procedures for TPED are stricter and always require notified body certification whereas pressure vessels in the lower categories of PED can be self-assessed and certified by the manufacturer. 

Overall, the requirements of the directive are difficult to understand because much of its detail comes from ADR, which is a very detailed directive running to nearly 1000 pages of prescriptive technical requirements. There is a lack of information available to the uninitiated. However, if the manufacturer of the equipment designs it according to approved design standards and follows the instructions of his chosen notified body for manufacture, testing and final inspection, then the equipment will comply. 

The European Commission have a special section on transportable pressure equipment on their EUROPA server with links to the guidelines and the text of the directive. The most up-to-date requirements of ADR can be found at The United Nations Economic Commission for Europe (UNECE) web site.

Useful information may also be found on the Health and Safety Executive web site, particularly a list of notified and approved bodies in the UK.

The Department for Transport has some background reading.

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