Under PRESSURE

Subject to being approved by the European Parliament (having passed its committee and amendment stages) the European Pressure Equipment Directive (PED) will establish a single European market for pressure equipment. It will achieve this end by harmonising the essential safety requirements to which primary and ancillary pressure equipment is designed and constructed.

The PED will bring in a modular approach to conformity assessment, an approach which will put the onus on manufacturers to self-certify so-called lower risk pressure equipment while demanding independent assessment of equipment associated with higher risk operations and environments.

Equipment will be validated under a series of modules for the four categories (I-IV) ranging from low risk to high risk plant. An example of low risk would be a hospital's anaesthetic gas cylinder, while high risk plant would include large boilers in public places.

This combination of self-certification and independent assessment was hard won by safety groups that were concerned that the directive in its original form could have resulted in manufacturers applying self-certification to equipment at all levels of risk.

The PED began its course in about 1988 and the latest estimate of when it could become mandatory is April 2002. As the PED moved closer to becoming legislation, members of the UK Safety Assessment Federation (SAFed) and of the continental European equivalent CEOC (Confederation Europeenne des Organismes de ContrOle, d'Inspection et de Prevention) said that reliance on quality assurance of manufacturing procedures and self-certification of products could have reduced safety levels across Europe.

The groups recommended various amendments, working with Roger Barton, the Labour MEP for Sheffield and `rapporteur' for the PED's conciliation committee. The European Parliament recognised the safety issue at the PED's second reading in July 1996 and passed an amendment to redress the anticipated validation problems.

MORE SAID SOONEST AMENDED

The amended Directive, adopted in February 1997, states that it will:

* create a Single European Market for pressure equipment, which SAFed endorses with a `good news for Britain's exporters' thumbs-up;

* ensure that Quality Assurance systems can be used as attestation of conformity for lower risk, mass-produced pressure vessels and steam generators manufactured to independently verified designs. This is, unquestionably, deregulation, in practice;

* additionally provide for independent product checks on the most potentially hazardous products. This is a desirable safety measure for European society and will also maintain European manufacturers' ability to compete worldwide.

WHAT's all the fuss ABOUT?

To substantiate the safety groups' concerns, SAFed members undertook a study between 1994-6 to identify non-compliance and departures from specification that had escaped manufacturers' own quality assessment systems but were detected during independent design appraisals and stage inspections.

The survey recorded deficiencies found in more than 350 randomly selected vessels manufactured to certified ISO 9000 quality assurance regimes and found that 58 per cent of vessels subjected to design appraisal did not comply with the relevant Standard in some respect; 45 per cent of these were overstressed, some so critically that they presented a high probability of failure.

A similar survey has since been conducted by CEOC member organisations located in 12 other European countries; results are shown overleaf.

CEOC deduced that if pressure vessel design is not independently inspected:

* 10 per cent of pressure vessels/steam boilers constructed to existing designs could incorporate defects of a severity greater than the acceptance criteria prescribed in the Standards. Some of these could undergo catastrophic failure;

* 20 per cent of pressure vessels/steam boilers constructed to these designs could have shortened service lives or other in-service deficiencies;

* At least 50 per cent of designs would go forward to construction stage containing major deficiencies;

The CEOC survey also shows that quality assurance systems alone do not support the reliability of design documentation and therefore do not provide assurance of the safety of vessels produced from these designs.

The British Standards Institution's Claims of Compliance with BS5750/ISO 9000 a Policy Statement describes quality assurance as `a measure of the supplier's capability to meet specific requirements ... it is neither synonymous with product quality nor a substitute.'

The SAFed survey also addressed stage inspection during construction - albeit on a slightly smaller sample size of 212 vessels. More than half of these vessels (51 per cent) exhibited non-compliances with the Standards, of which 21 per cent had significant defects, including cracks or lack of penetration in the welds joining the plates.

It must be said that, had these vessels been commissioned without independent design verification, all of them might not have failed. Nevertheless, the undetected weaknesses would have lowered safety levels and would undoubtedly have reduced the life expectancies of the vessels in question. Comparable data from CEOC was not available from all respondents. However where such data was available, the results showed similar rates of defects detected.

With deregulation issues on the minds of all major policy-makers, the cost of any service must be assessed and justified. SAFed experience indicates that, averaging across the spectrum, independent inspection adds less than 2 per cent to the overall cost of items inspected. In SAFed's view this is hardly excessive and is more than justified by the evidence of what they find.

The PED underwent a second reading in Strasbourg in the summer of 1996 during which many of the above arguments were recognised by MEPs. As a result one of the amendments adopted (amendment 8) aimed to ensure that bespoke fired and unfired pressure vessels falling into the high risk categories III and IV defined in the PED were subject to independent design appraisal and stage inspection during construction. Unfortunately neither the European Commission nor the Council of Ministers could accept the amendment and the PED was referred to the so-called Co-decision Procedure, a consequence of the Maastricht Treaty.

Under this procedure a Conciliation Committee comprising Council of Ministers' representatives and MEPs, with the Commission acting as honest broker, aims to reach a compromise `Joint Text'. If, within the time allowed, they had not succeeded, the entire Directive could have fallen.

Conclusions

A compromise text, drafted by the European Commission, has been accepted by COREPER and, once translated into the necessary languages, will be voted on by the European Parliament in Spring 1997.

All the indications are that Parliament will accept this text and it is likely that the compromise text Directive will be adopted by the Council of Ministers by April 1997.

SAFed/CEOC have good reason to be pleased with the recently agreed compromise text which:

* meets the objective of incorporating the principle that independent inspection is an integral part of conformity assessment for category III and IV pressure vessels/steam generators;

* fulfils what was in the art of the politically possible;

* is acceptable to all parties - including, albeit reluctantly, the European Commission;

* avoids setting a precedent for subsequent `new approach' Directives;

* has enhanced the SAFed/CEOC profile by being clear and understandable by Parliamentarians - and commended by the Rapporteur;

* European events must now take their course and member states should prepare for implementation into nationalstandards.

Tamar Posner is chief executive of the Safety Assessment Federation (SAFed), the trade association established in 1995 to represent the interests of the independent inspection and certification industry

NEW BRITISH STANDARD

In January, the British Standards Institution (BSI) launched BS 5500:1997, the Specification for Unfired Fusion Welded Pressure Vessels.

The standard is intended to be employed in the design, manufacture and testing of pressure vessels for a wide range of chemical, petroleum, process and utility industries. Vessels are produced to BS 5500 by UK industry and throughout the world for domestic and export markets.

First issued in 1976, the standard is published in three-year life cycles, the new edition incorporating amendments and enquiry cases published during the three-year period. The standard gives a basis for the design and construction of a range of vessel types in various materials and deals with pressure vessel and heat exchanger geometries under various steady state and cyclic loading conditions. BS 5500: 1997 contains several annexes which offer guidance on a range of pressure vessel related issues.

BS 5500:1997 includes its own updating service, incorporating amendments and enquiry cases as they are published during its three-year life cycle to the year 2000. The standard contains approximately 600 pages and costs £47 (members) and £84 (non-members).

Copies of BS 5500: 1997 can be purchased through BSI Customer Services. Contact tel. 0181 996 7000.