Pressure Vessel Regulations and The Law

The information below covers some of the legislation and regulations relating to Relating to Pressure Vessels in the UK – as seen by the HSE 2013

Pressure Equipment Directive (Directive 97/23/EC) (PED)
This European Single Market Directive covers pressure equipment and assemblies with a maximum allowable pressure PS >0.5 bar. Adopted 29 May 1997; came into force 29 November 1999.
See information below under the Pressure Equipment Regulations 1999.

Pressure Equipment Directive

Pressure Equipment Regulations 1999
(SI 1999/2001) (PER)
The Pressure Equipment Directive has been implemented in the UK by the Pressure Equipment Regulations 1999 (SI 1999/2001). PER came into force on 29 November 1999 and was amended by SI 2002 No 1267 which came into force on 30 May 2002.

For a list of Conformity Assessment Bodies accredited under PED follow links on the Department for Business, Innovation and Skills (BIS).

HSE and local authorities are responsible for enforcing PER.

The Regulations apply to:
design, manufacture and conformity assessment of pressure equipment and assemblies of pressure equipment with a maximum allowable pressure >0.5 bar

The Regulations do not apply to:

excluded pressure equipment and assemblies (specified in Schedule 1 to PER)
pressure equipment and assemblies placed on the market before 29 November 1999
pressure equipment or assemblies placed on the market on or before 29 May 2002 if they comply with the safety provisions in force in the UK on 29 November 1999 and do not bear a CE marking (unless required by another Community Directive or any indication of compliance with PED)


Pressure equipment – vessels, piping, safety accessories and pressure accessories.
Where applicable, includes elements attached to pressurised parts such as flanges, nozzles, couplings, supports, lifting lugs etc.
Vessel – a housing designed and built to contain fluids under pressure.
Includes its direct attachments up to the coupling point connecting it to other equipment. A vessel may be composed of more than one chamber.
Piping – piping components intended for the transport of fluids when connected together for integration into a pressure system.
Includes a pipe or system of pipes, tubing, fittings, expansion joints, hoses, or other pressure-bearing components as appropriate. Heat exchangers consisting of pipes for the purpose of cooling or heating air are considered as piping.
Safety accessories – devices designed to protect pressure equipment against the allowable limits being exceeded.
Such devices include devices for direct pressure limitation, such as safety valves and bursting discs etc, and limiting devices which either activate the means for correction or provide for shutdown or shutdown and lock out, such as pressure switches or temperature switches etc.
Pressure accessories – devices with an operational function and having pressure-bearing housings.
Assemblies – several pieces of pressure equipment assembled by a manufacturer to constitute an integrated and functional whole.
Schedule 2 of PER details the essential safety requirements (ESR) that qualifying vessels must satisfy. Additionally, there are details of how the different products are classified, the technical requirements that must be satisfied, and the conformity assessment procedures that must be followed.

See FAQ section for advice on how to comply with the ESRs – essentially, by either producing a technical file that addresses each ESR in turn, or manufacturing using standards that have been listed in the EU’s Official Journal which give a ‘presumption of conformity’ to specific ESRs.

The Department for Business, Innovation and Skills (BIS) has produced a very useful guide to the Pressure Equipment Directive (PER) . Annex C has an easy-to-use flow chart showing how equipment should be classified depending on, for example, what it is designed to contain and the operating pressure; also the conformity assessment procedure to be followed before placing the equipment on the market.

Note: The Regulations do not apply to the assembly of pressure equipment on the site and under the responsibility of the user, as in the case of industrial installations. In such cases, the Pressure Systems Safety Regulations 2000, which contain ‘in use’ provisions, will apply.
The Simple Pressure Vessels Directive (Directive 87/404/EEC) (SPVD)
SPVD is one of the ‘New Approach’ Directives that set out ‘essential requirements’ (for safety, for example), written in general terms, which must be met before products are placed on the market in the UK or elsewhere in the EC. European standards fill in the detail and are the main way for businesses to meet the ‘essential requirements’. The Directives also say how manufacturers are to show that products meet the ‘essential requirements’.

Products meeting the requirements are to carry CE marking, which should mean that they can be supplied anywhere in the EC, provided they are safe.

The Simple Pressure Vessel (Safety) Regulations 1991 implement the Directive in the UK.

Simple Pressure Vessels (Safety) Regulations 1991 (SPV)
Simple pressure vessels have the following characteristics or limitations:

intended to contain air or nitrogen at a gauge pressure >0.5 bar but less than or equal to 30 bar
not intended to be exposed to flame
manufactured in series, ie more than one vessel of the same type is manufactured during a given period by the same continuous manufacturing processes, in accordance with a common design
of welded non-alloy steel or non-alloy aluminium construction or non-age hardening aluminium alloy
a maximum working pressure (PS) of not more than 30 bar, and a PS.V (the product of PS and the vessel’s capacity expressed in litres) of not more than 10,000 bar.litres
a minimum working temperature of not lower than -50°C, and the maximum working temperature is not >300°C for steel vessels and not >100°C for aluminium or aluminium alloy vessels
Additionally, vessels consist either:

of a cylindrical component with circular cross-section, closed at each end, each end either outwardly dished or flat and also co-axial with the cylindrical component; or
of two co-axial outwardly dished ends
Exclusions SPV does not apply:

where vessels are designed specifically for nuclear use, and where vessel failure might or would result in an emission of radioactivity
where vessels intended specifically for installation in, or for use as part of the propulsion system of, a ship (as defined in relevant merchant shipping legislation) or aircraft
for fire extinguishers
Schedule 1 of SPV details the essential safety requirements that qualifying vessels must satisfy. It also gives details of how the vessels should be categorised, the technical requirements to be satisfied, and the conformity assessment procedures to be followed.
Pressure Systems Safety Regulations 2000 (PSSR)
The duties imposed by PSSR relate to pressure systems for use at work and the risk to health/safety.

The aim of these Regulations is to prevent serious injury from the hazard of stored energy as a result of the failure of a pressure system or one of its component parts.

Before using any qualifying pressure equipment (new or otherwise), a written scheme of examination (WSE) must be in place, and an examination undertaken.

Pressure systems are defined as:

a system comprising one or more pressure vessels of rigid construction, any associated pipework and protective devices
the pipework with its protective devices to which a transportable pressure receptacle is, or is intended to be, connected
a pipeline and its protective devices
A relevant fluid is:

steam at any pressure
any fluid or mixture of fluids which is at a pressure >0.5 bar above atmospheric
a gas dissolved under pressure in a solvent (acetylene)
Relevant fluids do not include hydraulic oils. Hydraulic systems, while using high pressures, do not store energy in the system and so are not covered by this legislation.

The PSSR Approved Code of Practice (ACOP), Safety of pressure systems (L122), provides a useful flow chart to help determine which regulations (if any) apply.


There are many exceptions to PSSR, including:

a pressure system which forms part of, or is intended to form part of, a weapons system
any pressure system which is the subject of a research experiment
any tyre used or intended to be used on a vehicle
Twenty-five complete exceptions are detailed in PSSR Schedule 1 Part I.

Three partial exceptions are detailed in PSSR Schedule 1 Part II.

If in doubt, the useful and instructive ACOP Safety of pressure systems provides additional information and advice.

Pipeline v pipework

There is a difference between a pipeline and pipework. The easiest way to distinguish between the two terms is to remember that pipelines cross boundaries and pipework does not (except where there is a common supply to a number of units). The terms also include associated protective devices, valves, compressors etc.

The PSSR ACOP Safety of pressure systems (page 4) provides useful definitions of pipework and pipelines as these can vary between different regulations (specifically PSSR, PER and the Pipeline Safety Regulations 1996).

Who has duties under PSSR?
Employers (also known as ‘dutyholders’), including:

the owner of a mobile system, ie one that can be easily moved, such as an air compressor taken from site to site
the user of an installed system, ie one that is not a mobile system, such as a steam boiler
Competent person

The user of hired or leased equipment should make sure that the WSE is in place and that the certificate of examination is also current.

PSSR Schedule 2 allows a supplier of an installed system to assume responsibility in writing for the WSE, the operation, the maintenance and the record keeping.

Competent person

In general terms, the role and responsibilities of the competent person can be summarised as follows:

carry out examinations in accordance with the WSE including:
review WSE and confirm it is suitable
produce a written report for each examination
notify user/owner of repairs required
identify action in case of imminent danger
agree postponements of examination, where appropriate
draw up or certify written schemes of examination
An important feature of the in-house competent person is that they should be independent from the operating functions of the organisation, and they must have sufficient authority to stop the use of the pressure equipment should the need arise.

For more detail about the role and responsibilities of the competent person see the Approved Code of Practice (L122) Safety of pressure systems, particularly paragraphs 35 to 43 and 104 to 108.

Further reading should include any and all of the publications and documents referred to above.