Simple pressure vessels are vessels which are intended to contain air or nitrogen at a gauge pressure greater than 0.5 bar but less than or equal to 30 bar and not intended to be exposed to heat. They must be manufactured in series production and be of welded steel or aluminum construction with a total pressure.volume product not exceeding 10,000 bar.litres. The Directive categorizes vessels according to their stored energy, expressed in terms of the product of maximum working pressure in bar and its capacity in litres (PS.V). Different provisions apply to each category of vessel. Category A consists of vessels whose PS.V is more than 50 bar.litres, and is divided into 3 subcategories. Category B consists of vessels whose PS.V is 50 bar.litres or less.
The safety requirements for a vessel in Category A are that it meets the essential safety requirements outlined in Annex 1 of the Directive, it has 'safety clearance, the CE marking and the other specified information is shown on the vessel and it is provided with appropriate instructions. The safety requirements for a vessel in Category B are that It is manufactured in accordance with engineering practice recognized as sound in an EEA State and it bears the specified inscriptions (but not the CE marking). Safety clearance' is the terminology used in the UK Regulations to refer to the successful involvement of a Notified Body. Both category A and B equipment must carry certain markings, however these differ between the categories.
Directive 87/404/EEC, the Simple Pressure Vessels 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, and consumers with similar economies of scale.
The purpose of the SPVD is to provide for a legal structure whereby certain types of pressure vessel 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 for all such vessels 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 vessels 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 market within the EU.
'Simple pressure vessels' are vessels which are intended to contain air or nitrogen at a gauge pressure greater than 0.5 bar but less than or equal to 30 bar and not intended to be exposed to heat. They must be manufactured in series production and be of welded steel or aluminium construction with a total pressure.volume product not exceeding 10,000 bar.litres.
Although the Directive applies to the vast majority of common pressure containers designed for containing air, the scope is actually very strictly defined. Included would be most compressor receivers, but any vessel not designed for air or nitrogen or not made of ordinary steel or aluminium is automatically excluded, as are any vessels with a design pressure greater than 30 bar or over a certain size.
Products falling outside the scope of the Simple Pressure Vessels Directive will almost certainly fall within the scope of the Pressure Equipment Directive.
The Directive applies to any Simple Pressure Vessels 'placed on the market' or 'brought into service' within the EU. This means that they explicitly apply to any vessel which is sold by one company to another, or to a private user, and they also apply to any vessel which is made or imported for the manufacturer/importer's own use.
The Directive required member states of the (then) EEC to introduce the requirements of the Directive from 1 July 1990. In practice, not all member states achieved this - in the UK, for instance, the Regulations implementing the Directive were brought into force on 31 December 1991 and transitional arrangements applied until 30 June 1992.
The Directive catgorises vessels according to their stored energy, expressed in terms of the product of maximum working pressure in bar and its capacity in litres (PS.V). Different provisions apply to each category of vessel.
Category A consists of vessels whose PS.V is more than 50 bar.litres, and is divided into:
• Category A.1, consisting of vessels whose PS.V is more than 3,000 but not more than 10,000 bar.litres;
• Category A.2, consisting of vessels whose PS.V is more than 200 but not more than 3,000 bar.litres; and
• Category A.3, consisting of vessels whose PS.V is more than 50 but not more than 200 bar.litres.
Category B consists of vessels whose PS.V is 50 bar.litres or less.
The safety requirements for a vessel in Category A are that:
1. It meets the essential safety requirements outlind in Annex 1 of the Directive;
2. It has 'safety clearance';
3. The CE marking and the other specified information is shown on the vessel;
4. It is provided with appropriate instructions.
The safety requirements for a vessel in Category B are that:
1. It is manufactured in accordance with engineering practice recognised as sound in an EEA State;
2. It bears the specified inscriptions (but not the CE marking).
1. The essential safety requirements
The essential safety requirements cover the design, manufacturing processes and material requirements. However, if the vessels are made in conformity with a harmonised European standard they will be presumed to comply with the essential requirements.
The relevant harmonised standards include:
• EN 286-1 Simple unfired pressure vessels designed to contain air or nitrogen - Part 1: Design, manufacture and testing.
• EN 286-2 Simple unfired pressure vessels designed to contain air or nitrogen - Part 2: Pressure vessels designed to contain compressed air for air braking and auxiliary systems for motor vehicles and their trailers.
• EN 286-3 Simple unfired pressure vessels designed to contain air or nitrogen - Part 3: Steel pressure vessels designed for airbraking equipment and auxiliary pneumatic equipment for railway rolling stock.
• EN 286-4 Simple unfired pressure vessels designed to contain air or nitrogen - Part 4: Aluminium alloy pressure vessels designed for airbraking equipment and auxiliary pneumatic equipment for railway rolling.
2. Safety clearance
'Safety clearance' is the terminology used in the UK Regulations to refer to the successful involvement of a Notified Body (referred to in the Directive as 'Approved Bodies').
The involvement of a Notified Body is required for two purposes:
• The verification of the design and manufacture of a vessel by type approval or a design assessment;
• Assessment of the manufacturer's arrangements for quality control of series production.
Which of these functions the Notified Body has to perform, and in what way, is a function of the category of the vessel.
3. The CE mark and other specified markings
Vessels in Category A and B must be marked with:
• maximum working pressure in bar;
• maximum working temperature in °C;
• minimum working temperature in °C;
• capacity of the vessel in litres;
• name or mark of the manufacturer;
• type and serial or batch identification of the vessel;
• the CE logo;
• the last two digits of the year in which the CE marking was affixed.
In addition, vessels in Category A must carry the identification number of the Notified Body responsible for quality system assessment.
Vessels in Category B are subject to much less complex requirements than those in Category A and do not require Notified Body involvement. Instead they must be manufactured in accordance with “engineering practice recognised as sound in an EEA state”. In practice, this means that the ASME codes or the former BS 5500 could be used, or any EU member state's pressure vessel code from before harmonisation under the Pressure Equipment Directive.
Vessels in category B must not carry the CE logo, although they should carry all of the other information required for Category A vessels except for the notified body number. This status is analgous to the 'Sound Engineering Practice' category of the PED.
The SPVD predates the Pressure Equipment Directive (PED) by a margin of several years. In practice, the SPVD covers a small sub-set of equipment which would otherwise be within the scope of the PED and the structure and requirements of the SPVD are similar to those of the PED.
There has been discussion about the possibility of repealing the SPVD and simply covering all pressure vessels under the PED (unless they are subject to the Transportable Pressure Equipment Directive) but to date it has been concluded that this would simply be an adminstrative measure to suit the legislators and industry is comfortable with both directives continuing side by side for the foreseeable future.
Pressure equipment (primarily vessels) which is intended to be transported by road, rail or air are the subject of a more specific directive, the Transportable Pressure Equipment Directive (TPED) and so are excluded from the SPVD. The requirements of the TPED are more stringent, particularly with regard to Notified Body involvement
The European Commission have a special section on simple pressure vessels on their EUROPA server. This includes the full text of the directive and lists of the current harmonised standards.
The UK government's Department for Business, Innovation and Skills has a web page on the Directive and publishes a number of useful guides which 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.
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.