Safety of pressure systems

Health and Safety

Safety of pressure systems Pressure Systems Safety Regulations 2000

Approved Code of Practice and guidance The Pressure Systems Safety Regulations 2000 (PSSR) cover the safe design and use of pressure systems. The aim of PSSR is to prevent serious injury from the hazard of stored energy (pressure) as a result of the failure of a pressure system or one of its component parts.

The revised PSSR ACOP and guidance is aimed at dutyholders under PSSR who are involved with pressure systems used at work. It is for users, owners, competent persons, designers, manufacturers, importers, suppliers and installers of pressure systems used at work.

Since the last edition, the ACOP and guidance has been updated for clarity. The content has not been radically changed, as it was fit for purpose. The main changes to this publication are as follows:

L122 (Second edition) ■■ The decision tree on whether PSSR applies has been moved to the front of Published 2014 the book and explanatory notes have been added to it, to help readers decide if PSSR applies to them or not ■■ A new Appendix has been added to provide clarity on how to apply PSSR in a proportionate manner to small pressure vessels in schools ■■ The section on the legal background to PSSR and related legislation has been removed as it was out of date

The Regulations themselves have not changed at all, so dutyholders’ responsibilities remain unchanged.

HSE Books

© Crown copyright 2014

First published 2000 Second edition 2014

ISBN 978 0 7176 6644 7

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Approved Code of Practice

This Code has been approved by the Health and Safety Executive, with the consent of the Secretary of State. It gives practical advice on how to comply with the law. If you follow the advice you will be doing enough to comply with the law in respect of those specific matters on which the Code gives advice. You may use alternative methods to those set out in the Code in order to comply with the law.

However, the Code has a special legal status. If you are prosecuted for breach of health and safety law, and it is proved that you did not follow the relevant provisions of the Code, you will need to show that you have complied with the law in some other way or a Court will find you at fault.

Guidance

This guidance is issued by the Health and Safety Executive. Following the guidance is not compulsory, unless specifically stated, and you are free to take other action. But if you do follow the guidance you will normally be doing enough to comply with the law. Health and safety inspectors seek to secure compliance with the law and may refer to this guidance.

Contents

Preface 5 Introduction 7 PART I Introduction 10 Regulation 1 Citation and commencement 10 Regulation 2 Interpretation 10 Regulation 3 Application and duties 18 PART II General 20 Regulation 4 Design and construction 20 Regulation 5 Provision of information and marking 24 Regulation 6 Installation 25 Regulation 7 Safe operating limits 27 Regulation 8 Written scheme of examination 29 Regulation 9 Examination in accordance with the written scheme 35 Regulation 10 Action in case of imminent danger 40 Regulation 11 Operation 41 Regulation 12 Maintenance 44 Regulation 13 Modification and repair 46 Regulation 14 Keeping of records etc 46 Regulation 15 Precautions to prevent pressurisation of certain vessels 48 PART III Miscellaneous 49 Regulation 16 Defence 49 Regulation 17 Power to grant exemptions 49 Regulation 18 Repeals and revocations 50 Regulation 19 Transitional provision 50 SCHEDULE 1 51 Part 1 Pressure systems excepted from all regulations 51 Part 2 Pressure systems excepted from certain regulations 57 SCHEDULE 2 Modification of duties in cases where pressure systems are supplied by way of lease, hire, or other arrangements 59 SCHEDULE 3 Marking of pressure vessels 61

Appendix 1 Notice of Approval 62 Appendix 2 Equivalent measurements to 1 bar 63 Appendix 3 Interface between the Pressure Equipment Directive (PED), the Pressure Equipment Regulations 1999 (PER) and the Pressure Systems Safety Regulations 2000 64 Appendix 4 Application of PSSR to small pressure vessels in schools 66 References and further reading 67 Further information 69

Preface

This publication contains the full text of the Regulations, the Approved Code of Practice (ACOP) and guidance on the Pressure Systems Safety Regulations 2000 (SI 2000/128) (PSSR).

ACOPs are approved by the HSE Board with the consent of the Secretary of State (see Appendix 1: Notice of Approval for details).

The ACOP describes preferred or recommended methods that can be used (or standards to be met) to comply with the Regulations and the duties imposed by the Health and Safety at Work etc Act.1 The accompanying guidance also provides advice on achieving compliance, or it may give information of a general nature, including explanation of the requirements of the law, more specific technical information or references to further sources of information.

The legal status of ACOP and guidance text is given on the copyright page.

The ACOP text is set out in bold and the accompanying guidance in normal type, the text of the Regulations is in italics. Coloured borders also indicate each section clearly.

Introduction

1 This Approved Code of Practice (ACOP) and guidance, produced in support of the Pressure Systems Safety Regulations 2000 (SI 2000/128) (PSSR), was reviewed in 2014. It is aimed at dutyholders under the Regulations, which includes users, owners, competent persons, designers, manufacturers, importers, suppliers and installers. To work out whether PSSR applies to your pressure system, see Figure 1.

2 Although only the courts can give an authoritative interpretation of law, in considering the application of these Regulations and guidance to people working under another’s direction, the following should be considered:

If people working under the control and direction of others are treated as self- employed for tax and national insurance purposes, they are nevertheless treated as their employees for health and safety purposes. It may therefore be necessary to take appropriate action to protect them. If any doubt exists about who is responsible for the health and safety of a worker, this could be clarified and included in the terms of a contract. However, remember, a legal duty under section 3 of the Health and Safety at Work etc Act 1974 (the HSW Act)1 cannot be passed on by means of a contract and there will still be duties towards others under section 3 of the HSW Act. If such workers are employed on the basis that they are responsible for their own health and safety, legal advice should be sought before doing so.

3 Each section of this ACOP gives practical guidance on a specific regulation, the number, title and content of which appear at the head of each section.

4 Words and expressions which are defined in the HSW Act or in PSSR have the same meaning in this ACOP and guidance unless the context requires otherwise. Where the expression ‘user/owner’ is used in the ACOP and guidance, it should be read as an abbreviated form of ‘user of an installed system or owner of a mobile system’.

5 The aim of PSSR 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.

6 The Regulations are concerned with steam at any pressure, gases which exert a pressure in excess of 0.5 bar above atmospheric pressure and fluids which may be mixtures of liquids, gases and vapours where the gas or vapour phase may exert a pressure in excess of 0.5 bar above atmospheric pressure. A list of equivalent measurements to 1 bar is given in Appendix 2 of this ACOP.

7 With the exception of the scalding effects of steam, the Regulations do not consider the hazardous properties of the contents released following system failure. PSSR does not deal with all the hazards arising from the operation of such a system. The contents may be toxic, or the plant may be part of a major hazard site. These aspects are the subject of separate legislative requirements and dutyholders

must consider these other risks when deciding on the precautions required. In PSSR, the stored contents’ properties are of concern only to the extent that they may be liable to cause a more rapid deterioration in the condition of the system, so leading to an increased risk of failure. The risk from steam includes not only any possible deterioration in the condition of the system, which could increase the risk of failure, but also its scalding effect in the event of release.

8 In the case of some storage systems where gas is kept in liquid form at very low temperatures in a tank, the pressure above the liquid is below 0.5 bar (gauge) and PSSR would not apply unless the pressure rises above 0.5 bar (gauge). The Regulations do not apply simply as a result of pressure exerted by a head of liquid. Also, the Regulations do not aim to deal with vacuum conditions.

9 The amount of stored energy in a vessel is generally considered to be directly related to the volume of the vessel and the pressure of the contents. The measure of the stored energy has been expressed by multiplying the pressure by the internal volume (P x V), ie the pressure-volume product. If the values used are bar for pressure and litres for volume, the measure (or product) is given in bar litres (bl).

Figure 1 User/owner decision tree: Do the Regulations apply to my pressure system?

Start

PSSR does not apply No Is there a relevant fluid in the system?

Yes Is there a pressure vessel that PSSR regs 5(4), 8–10 and 14 No contains steam or has a do not apply pressure x volume product of 250 bl or more?

Yes Is the system mobile or Is the system mobile or subject to a lease/hire subject to a lease/hire agreement? agreement? No Yes No Yes User has Owner has User has Owner has duties duties duties duties

Reg 7 Safe operating limits Reg 7 Safe operating limits

Reg 11 Operation Reg 8 Written scheme of examination Reg 12 Maintenance Reg 9 Examination in Reg 15 Precautions to accordance with the written scheme prevent pressurisation of certain vessels Reg 10 Action in case of (user only) imminent danger

Reg 11 Operation

Reg 12 Maintenance

Reg 14 Keeping of records etc

Reg 15 Precautions to prevent pressurisation of certain vessels (user only) Note: This diagram only covers type (a) pressure systems, as defined in regulation 2(1) under ‘pressure system’, ‘one or more pressure vessels of rigid construction, any associated pipework and protective devices.’

It does not cover a type (b) pressure system, ‘the pipework with its protective devices to which a transportable pressure receptacle is, or is intended to be, connected,’ or a type (c) pressure system, ‘a pipeline and its protective devices.’ If your pressure system is as defined in (b) or (c), this diagram will not work.

See paragraphs 19–24 for a definition of a ‘relevant fluid’ in PSSR, as referred to in the decision tree.

PART I Introduction

Regulation 1 Citation and commencement Regulation 1 (1) These Regulations may be cited as the Pressure Systems Safety Regulations 2000 and shall come into force on 21st February 2000.

Regulation 2 Interpretation Regulation 2 (1) In these Regulations, unless the context otherwise requires—

“the 1974 Act” means the Health and Safety at Work etc. Act 1974;

“the CDGCPL Regulations” means the Carriage of Dangerous Goods (Classification, Packaging and Labelling) and Use of Transportable Pressure Receptacles Regulations 1996;*

“competent person” means a competent individual person (other than an employee) or a competent body of persons corporate or unincorporate; and accordingly any reference in these Regulations to a competent person performing a function includes a reference to his performing it through his employees;

“danger” in relation to a pressure system means reasonably foreseeable danger to persons from system failure, but (except in the case of steam) it does not mean danger from the hazardous characteristics of the relevant fluid other than from its pressure;

“examination” means a careful and critical scrutiny of a pressure system or part of a pressure system, in or out of service as appropriate, using suitable techniques, including testing where appropriate, to assess—

(a) its actual condition; and (b) whether, for the period up to the next examination, it will not cause danger when properly used if normal maintenance is carried out, and for this purpose “normal maintenance” means such maintenance as it is reasonable to expect the user (in the case of an installed system) or owner (in the case of a mobile system) to ensure is carried out independently of any advice from the competent person making the examination;

“the Executive” means the Health and Safety Executive;

* S.I. 1996/2092, now superseded by S.I. 2009/1348

Regulation 2 “installed system” means a pressure system other than a mobile system;

“maximum allowable pressure” and “minimum allowable pressure” mean the maximum pressure and minimum pressure respectively for which a pressure vessel is designed;

“mobile system” means a pressure system which can be readily moved between and used in different locations but it does not include a pressure system of a locomotive;

“owner” in relation to a pressure system means the employer or self-employed person who owns the pressure system or, if he does not have a place of business in Great Britain, his agent in Great Britain or, if there is no such agent, the user;

“pipeline” means a pipe or system of pipes used for the conveyance of relevant fluid across the boundaries of premises, together with any apparatus for inducing or facilitating the flow of relevant fluid through, or through a part of, the pipe or system, and any valves, valve chambers, pumps, compressors and similar works which are annexed to, or incorporated in the course of, the pipe or system;

“pipework” means a pipe or system of pipes together with associated valves, pumps, compressors and other pressure containing components and includes a hose or bellows but does not include a pipeline or any protective devices;

“pressure system” means—

(a) a system comprising one or more pressure vessels of rigid construction, any associated pipework and protective devices; (b) the pipework with its protective devices to which a transportable pressure receptacle is, or is intended to be, connected; or (c) a pipeline and its protective devices,

which contains or is liable to contain a relevant fluid, but does not include a transportable pressure receptacle;

“protective devices” means devices designed to protect the pressure system against system failure and devices designed to give warning that system failure might occur, and include bursting discs;

“relevant fluid” means—

(a) steam; (b) any fluid or mixture of fluids which is at a pressure greater than 0.5 bar above atmospheric pressure, and which fluid or mixture of fluids is— (i) a gas, or (ii) a liquid which would have a vapour pressure greater than 0.5 bar above atmospheric pressure when in equilibrium with its vapour at either the actual temperature of the liquid or 17.5 degrees Celsius; or (c) a gas dissolved under pressure in a solvent contained in a porous substance at ambient temperature and which could be released from the solvent without the application of heat;

“safe operating limits” means the operating limits (incorporating a suitable margin of safety) beyond which system failure is liable to occur;

“scheme of examination” means the written scheme referred to in regulation 8;

Regulation 2 “system failure” means the unintentional release of stored energy (other than from a pressure relief system) from a pressure system;

“transportable pressure receptacle” has the same meaning as in regulation 2(1) of the CDGCPL Regulations;*

“user” in relation to a pressure system, or a vessel to which regulation 15 applies, means the employer or self-employed person who has control of the operation of the pressure system or such a vessel or, in the case of a pressure system or such a vessel at or in—

(a) a mine within the meaning of section 180 of the Mines and Quarries Act 1954 it means the manager for the time being of that mine; (b) a quarry within the meaning of regulation 3 of the Quarries Regulations 1999 it means the operator for the time being of that quarry.

(2) Any reference in these Regulations to anything being in writing or written (including any reference to anything being kept in writing) shall include reference to its being in a form—

(a) in which it is capable of being reproduced as a written copy when required; (b) which is secure from loss or unauthorised interference.

(3) In these Regulations, unless the context otherwise requires, any reference to—

(a) a numbered regulation or Schedule is a reference to the regulation or Schedule in these Regulations so numbered; (b) a numbered paragraph is a reference to that paragraph so numbered in the regulation or Schedule in which that reference appears.

*Now superseded by S.I. 2009/1348.

Guidance 2 Competent person

10 The term ‘competent person’ refers not to the individual employee who carries out duties under the Regulations but to the body which employs the person charged with those duties. Thus, the definition of competent person makes it clear that the legal duty to comply rests with a competent person’s employer, and not with an individual, unless that person is self-employed.

Danger

11 The Regulations are concerned with reasonably foreseeable danger to people from the unintentional release of stored energy.