Guidance on the repair and overhaul of apparatus intended for use in coal mines susceptible to ...

59 Pages·2015·0.44 MB·English

Health and Safety
Executive
Guidance on the repair and overhaul
of apparatus intended for use in coal
mines susceptible to firedamp
Members of the Deep Mined Coal Industry Advisory Committee
Mr B Langdon Chairman, HM Chief Inspector of Mines HSE
Mr D Bulmer National President BACM
Mr D Flack Senior Vice Chairman, Federation of Independent Mines
Dr B Jones Chief Operating Officer, Mines Rescue Services
(formerly BCC member)
Mr P McNestry General Secretary NACODS
Mr A Dobbs Mining Engineering Consultant UDM
Mr W Rowell Managing Director RJ Budge (Mining) Ltd
Mr J Warwick Coal Investments plc
Assessors
Mr J S Moorhouse Institution of Mining Engineers
Mr J Longden Institution of Mining Engineers
Observers
Mr N Greatrex UDM
Mr R Lees Scottish Coal Co Ltd
Dr A Afacan BCC Occupational Health Service
HSE Advisors
Mr D Mitchell HM Deputy Chief Inspector of Mines HSE
Mr I Todd Head of Branch C Safety Policy Division HSE
Mr G Goodlad HM Principal Inspector of Engineering in Mines HSE
Secretariat
Mr R J Cole HM Principal Inspector of Mines HSE,
Technical Secretary to DMCIAC
Mr G Thomas HM Inspectorate of Mines HSE
Papers only
Mr A Scargill President NUM
This is a web-friendly
version of Guidance on
the repair and overhaul of
apparatus intended for use
in coal mines susceptible
to firedamp, originally
produced by
HM Inspectorate of Mines
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Health and Safety
Executive
© Crown copyright 1996
Applications for reproduction should be made to HMSO
First published 1996
This version published XX/15
All rights reserved. No part of this publication may be reproduced, stored in a
retrieval system, or transmitted in any form or by any means (electronic,
mechanical, photocopying, recording, or otherwise) without the prior written
permission of the copyright owner.
ISBN 0 7176 1249 X
This guidance is prepared, in consultation with the Health and Safety Executive
(HSE), by the Deep Mined Coal Industry Advisory Committee, which was appointed
by the Health and Safety Commission (HSC) as part of its formal advisory
structures. The guidance represents what is considered to be good practice by the
members of the Committee. It has been agreed by the Commission. Following the
guidance is not compulsory 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 as illustrating good practice.
This is a web-friendly
version of Guidance on
the repair and overhaul of
apparatus intended for use
in coal mines susceptible
to firedamp, originally
produced by
HM Inspectorate of Mines
Guidance on the repair and overhaul of apparatus intended for use in coal mines susceptible to firedamp Page 2 of 59
Health and Safety
Executive
Contents
Part 1: REPAIR AND OVERHAUL OF ELECTRICAL
APPARATUS 5
Part 2: REPAIR AND OVERHAUL OF FLAMEPROOF
RECIPROCATING INTERNAL COMBUSTION ENGINES 38
Foreword 4

Introduction 5

Definitions and terms 5

Background information 7

Statutory requirements/duties 10

Guidance for the manufacturer 11

Guidance for the user 12

Guidance for the repairer 12

Type of protection ‘d’ (flameproof) 20

Application 20
Repair and overhaul 20
Reclamation 24
Modifications 25
Type of protection ‘i’ (intrinsic safety – IS) 26

Application 26
Repair and overhaul 27
Reclamation 29
Modifications 30
Type of protection ‘e’ (increased safety) 30

Application 30
Repair and overhaul 30
Reclamation 33
Modifications 33
This is a web-friendly Annex A: Relevant legislation / standards / documents 35
version of Guidance on
the repair and overhaul of Annex B: List of members of the IAC Electrical Working Group 37
apparatus intended for use
in coal mines susceptible
to firedamp, originally
produced by
HM Inspectorate of Mines
Guidance on the repair and overhaul of apparatus intended for use in coal mines susceptible to firedamp Page 3 of 59
Health and Safety
Executive
Foreword

This guidance on the repair and overhaul of apparatus intended for use in coal
mines susceptible to firedamp is part of a series of publications produced by the
Deep Mined Coal Industry Advisory Committee. The Committee was appointed by
the Health and Safety Commission as part of its formal advisory structure.
This document is in two parts:
Part 1 deals with the repair and overhaul of electrical apparatus
Part 2 deals with the repair and overhaul of flameproof reciprocating internal
combustion engines.
This is a web-friendly
version of Guidance on
the repair and overhaul of
apparatus intended for use
in coal mines susceptible
to firedamp, originally
produced by
HM Inspectorate of Mines
Guidance on the repair and overhaul of apparatus intended for use in coal mines susceptible to firedamp Page 4 of 59
Health and Safety
Executive
Introduction

1 This part of the document gives guidance, principally of a technical nature, on
the repair and overhaul of certified electrical apparatus designed for use in
potentially explosive atmospheres found underground in coal mines. A list of the
members of the IAC Electrical Working Group formed to prepare this part of the
document is included at Annex B.
2 The scope of Part 1 does not cover the use of electrical apparatus,
maintenance (other than where this cannot be disassociated from repair and
overhaul), performance, or the use of accessories such as cable entry systems
(which may require renewal when the apparatus is re-installed). Similarly, it does not
cover other safety related matters such as the prevention of electric shock,
electrical overload, short circuit, earth leakage protection and interlocking between
isolators/enclosure covers. These and other analogous matters, not directly
associated with preventing the ignition of an explosive atmosphere, will need to be
the subject of separate negotiations between the user and repairer.
3 Recommendations regarding routine maintenance, and the selection and
installation of intrinsically safe electrical apparatus for use in potentially explosive
atmospheres in mines, may be found in BS 6704.
4 It is assumed that good engineering practices are adopted throughout.
5 Paragraphs 33 to 113 deal with responsibilities under the Health and Safety at
Work etc Act 1974, and those aspects of the repair and overhaul of explosion proof
apparatus which are common to all equipment. The subsequent paragraphs then
provide specific guidance relevant to the types of protection used in mines, ie
flameproof apparatus, intrinsically safe apparatus and increased safety apparatus.
6 Legislation/standards/documents which are relevant to this guidance are listed
in Annex A.
Definitions and terms

7 The following definitions apply to this part of the document:
Serviceable condition – A condition of the apparatus, such that it is fit for use,
unlikely to be an igniting source for an explosive atmosphere, and is in accordance
with the relevant explosion protection concept standard.
Relevant standard – This means the standard to which the apparatus was
originally certified.
This is a web-friendly Repair – An action to restore apparatus to its serviceable condition, where an
version of Guidance on examination and inspection has established that the apparatus is faulty or
the repair and overhaul of damaged, or parts are replaced which can affect explosion protection.
apparatus intended for use
in coal mines susceptible Overhaul – An action to restore apparatus to its serviceable condition, where an
to firedamp, originally examination and inspection has established that the apparatus is not faulty or
produced by damaged, and parts are not replaced which can affect explosion protection.
HM Inspectorate of Mines
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Health and Safety
Executive
Maintenance – Routine actions taken to preserve the serviceable condition of the
installed apparatus.
Component part – An indivisible item from an assembly of such parts which may
form an apparatus.
Reclamation or recovery – A means of repair involving the removal or addition of
material to restore component parts, which have sustained damage, to a
serviceable condition.
Modification – A change to the design of the apparatus which may affect material,
fit, form or function.
Manufacturer – The maker of the apparatus (who may also be the supplier, the
importer or the agent) in whose name usually the certification (where appropriate) of
the apparatus was originally registered.
User – The user of the apparatus.
Repairer – The repairer of the apparatus, who may be the manufacturer, the
user,or a third party (repair agency).
Certification – The issue of a document by a recognised body, or notified body,
testifying that a type of apparatus or a type of component or a procedure conforms
with the requirements of a European Directive, a European Harmonised Standard, a
published national or recognised international standard.
Approval – The issue of a document by the Health and Safety Executive (HSE)
indicating that a type of apparatus meets the requirement of a particular legal
obligation, using powers given to them under legislation relating to that type of
apparatus.
Certificate references – A certificate reference number may refer to a single
design or a range of apparatus of similar design. The suffix ‘X’ or ‘B’ when added
to the certificate number indicates special conditions of use and that the
certification documents need to be studied before such apparatus is installed,
repaired, overhauled, reclaimed, or modified.
Copy winding – Process by which a winding is totally or partially replaced by
another, the characteristics and properties of which are at least as good as those
of the original.
Type of protection ‘d’ (flameproof) – As defined in the protection concept
standard relating to the type of apparatus being repaired, ie BS 229, BS 4683,
BS 5501, EN 50018. This is generally a type of protection in which parts which can
ignite an explosive atmosphere are placed in an enclosure which can withstand an
internal explosion of flammable gas without damage and without transmitting
incendive flames from the interior to the explosive atmosphere surrounding the
enclosure.
This is a web-friendly
version of Guidance on Type of protection ‘i’ (intrinsically safe) – As defined in the protection concept
the repair and overhaul of standard relating to the type of apparatus being repaired, ie BS 1259, BS 5501,
apparatus intended for use EN 50020. This is generally a type of protection in which no spark or any thermal
in coal mines susceptible effect produced in the test conditions prescribed in the relevant standard(s) (which
to firedamp, originally include normal operation and specific fault condition) is capable of causing ignition
produced by of a given explosive atmosphere.
HM Inspectorate of Mines
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Health and Safety
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Type of protection ‘e’ (increased safety) – As defined in BS 5501, EN 50019.
This is generally a type of protection by which measures are applied so as to
prevent, with a higher degree of security than normal industrial type apparatus, any
parts from producing arcs or sparks in normal operation or from exceeding
specified temperature limits..
Background information
Statutory requirements for mines
8 Electrical equipment intended for use in a potentially explosive atmosphere is
legally required to be of such construction, or so protected as to prevent danger
arising from such use.
9 The legal requirements for zoning and explosion protection in mines are covered
by The Electricity at Work Regulations 1989 which require the manager of every mine
in Great Britain to assess the risk of flammable gas occurring in the mine workings
and to indicate, on plans, those places where flammable gas is likely to occur.
10 Such places are defined as “zones in which firedamp, whether or not normally
present, is likely to occur in a quantity sufficient to indicate danger”. The same
regulations define “firedamp” as “a mixture of flammable gases naturally occurring
in mines”.
11 Having designated the zones on a plan, the manager must ensure that those
places are identifiable underground so that workers know where the zones start
and finish. The manager must also ensure that mine workers are made aware of
the requirement that any electrical apparatus is not to be energised inside a zone
unless it is protected in such a way as to prevent it from being an igniting source
for an explosive firedamp/air atmosphere.
12 The above Regulations contain a list of the various types of apparatus which
may be energised in the zones. With the exception of mining type cables and
certain apparatus which is constantly supervised under manager’s operating rules,
the majority of electrical apparatus is expected to be of a type which is “certified”
by a third party test house, ie having a certificate testifying that the design conforms
with a recognised published standard relating to the protection of electrical
apparatus intended for use in a potentially explosive atmosphere.
Certification
13 Certificates are usually issued to the manufacturer of the apparatus (or to an
agent) by one of the recognised European Test Houses. With the exception of rare
items of apparatus allowed by ‘special certificates’ (type ‘s’) or ‘inspection
certificates’, the majority of explosion protected electrical apparatus will be of a type
constructed in accordance with recognised national standards (eg British
Standards), or more recently CENELEC European Harmonised Standards.
This is a web-friendly
version of Guidance on 14 In Great Britain, a Government owned mining certification service was set up in
the repair and overhaul of 1931 to issue certificates for explosion protected apparatus intended for use in
apparatus intended for use mines. This service, now known as the Mining Equipment Certification Service
in coal mines susceptible (MECS), has continued to the present day. In 1991 SIRA Test and Certification Ltd
to firedamp, originally (SIRA) set up a privately owned certification service offering the same facilities. Both
produced by test houses in Great Britain have been approved by the Secretary of State for
HM Inspectorate of Mines Employment as notified European Test Houses (under the Electrical Equipment for
Guidance on the repair and overhaul of apparatus intended for use in coal mines susceptible to firedamp Page 7 of 59
Health and Safety
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Explosive Atmospheres (Certification) Regulations 1990 – Statutory Instrument
No. 13 of 1990) and are able to issue European Certificates of Conformity to the
European Harmonised Standards in the series EN 50014 to EN 50039.
15 Until the 1960s, only two types of concept protection certificates were issued
for mining apparatus in Great Britain, these being for flameproof apparatus (FLP)
and intrinsically safe apparatus (IS).
16 In 1977 the British Standards for flameproof apparatus (ie BS 229 and
BS 4683) and intrinsically safe apparatus (ie BS 1259) were joined by, and
co-existed with, the BS 5501: Parts 1-9: series of standards, the latter being
copies of the first editions of European CENELEC standards in the series EN 50014
to EN 50039. This resulted in small quantities of other types of explosion protected
apparatus entering mines in Great Britain, in particular, apparatus known as
increased safety (type ‘e’) and moulded/encapsulated (type ‘m’). When the second
editions of the CENELEC standards replaced the first editions in 1994/95 they were
given BS EN standard designation with European numbering. Thus, the second
edition of the European harmonised standard BS 5501: Part 1 (EN 50014) was
published in Great Britain by BSI as BS EN 50014.
17 A list of the various types of explosion protection, suitable for use in mines
susceptible to firedamp, can be found in Appendix 1 of the Code of Practice
approved under section 16 of the Health and Safety at Work etc Act 1974, entitled
The Use of Electricity in Mines which accompany the Electricity at Work
Regulations (Statutory Instrument No. 635 of 1989).
18 The list in the Approved Code includes the earlier types of protection defined in
British Standards BS 4683, BS 1259, BS 5501, also the types of protection given
in the European Harmonised Standard EN 50014 with the exception of the type of
protection ‘o’ – oil filled apparatus (as defined and described in EN 50015).
19 Restrictions are placed on the use of oil filled electrical apparatus in mines in
Great Britain because of the risk of atmospheric pollution of the mine ventilation
system should the oil catch fire. See regulation 23 of the Electricity at Work
Regulations 1989.
20 The objective of this document, as well as giving guidance on the practical
means of maintaining the electrical safety and performance requirements of
repaired apparatus, is to recommend procedures for maintaining after repair
compliance of the apparatus with the provisions of the Certificate of Assurance or
Conformity or with the provisions of the appropriate explosion protected Standard.
21 The document is divided into separate parts, some of which are concerned
with an individual type of explosion protection. In those cases where an apparatus
incorporates more than one type of protection, reference will need to be made to
all of the relevant parts involved. The reader will, however, note that this guidance
excludes types of protection ‘o’ – oil filling; ‘q’ – sand filling; ‘p’ – pressurised; and
‘m’ – encapsulated which is generally considered to be irreparable.
This is a web-friendly Effects of the Explosive Atmospheres Directive (94/9/EC)
version of Guidance on
the repair and overhaul of 22 On 23 March 1994 an Article 100A Directive for Equipment and Protective
apparatus intended for use Systems intended for Use in Potentially Explosive Atmospheres was published in
in coal mines susceptible the Official Journal of the European Communities. The Directive became effective
to firedamp, originally from 1 March 1996 and included both Electrical and Mechanical Equipment. The
produced by Directive is implemented in GB by the Equipment and Protective Systems Intended
HM Inspectorate of Mines for Use in Potentially Explosive Atmospheres Regulations 1996; SI 1996: 192.
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23 In the case of apparatus intended for use in gassy mines susceptible to
firedamp, the Regulations/Directive do not apply to apparatus placed on the market
or put into service for the first time before 1 March 1996.
24 After that date and up to 30 June 2003, apparatus may be used on the market
or put into service for the first time if it is in compliance with either the Directive/
Regulations or the GB statutory requirements/certification arrangements in place on
23 March 1994.
25 After 30 June 2003 apparatus cannot be placed on the market or put into
service for the first time unless it complies with 94/9/EC as meeting the
requirements of categories M1 or M2 (as defined in the Directive).
26 Apparatus which was legally in service on 30 June 2003 may be repaired or
overhauled and put back into service after 30 June 2003 without the need to
comply with 94/9/EC, providing no modifications are made which would require
re-certification, or a supplementary certificate to be obtained to cover the
modifications.
27 To date, two notified bodies have been appointed for the purposes of 94/9/EC
in GB, these are the HSE’s Mining Equipment Certification Service (MECS) and
SIRA Certification Service Ltd.
Repair of apparatus
28 Users are recommended to utilise the most appropriate repair facilities for any
particular item of equipment, whether they be the facilities of the manufacturer or a
suitably competent and equipped repairer.
29 The document recognises the necessity of a required level of competence for
the repair of apparatus.
30 In the case of the repair or overhaul of apparatus which has been the subject of
third party certification, such as by MECS or SIRA, it may be necessary to clarify
the position of the continued conformity of the apparatus with the certificate.
31 Assuming that repairs and overhauls are carried out using good engineering
practices then;
a) if manufacturers’ specified parts or parts as specified in the certification
documentation are used in a repair or overhaul, those aspects of the repair or
overhaul may be presumed to be in conformity with the certificate;
b) if repairs or modifications are carried out on the apparatus in accordance with
details in the certification documents, eg dimensions are within allowable
tolerances, the apparatus may still conform with the certificate;
c) if repair or overhaul is carried out on the apparatus in accordance with the
relevant protection standards and subjected to the relevant tests, then,
This is a web-friendly although not necessarily in accordance with (a) and (b) above, the apparatus is
version of Guidance on acceptable for re-use;
the repair and overhaul of
apparatus intended for use d) if other repair or modification techniques are to be used, then it will be
in coal mines susceptible necessary to seek authoritative advice, eg from the manufacturer or owner,
to firedamp, originally regarding the suitability of the apparatus for continued use in a ‘zone’ in a coal
produced by mine.
HM Inspectorate of Mines
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Health and Safety
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32 In considering the above options, users are strongly recommended to adopt (a)
or (b) where it is possible to do so. Before any repair or overhaul work to (c) or (d)
are undertaken the repairer will need to seek the written permission of the user.
Statutory requirements/duties
33 The relevant statutory requirements for mines are the Health and Safety at
Work etc Act 1974 (HSW Act) and the Mines and Quarries Act 1954. Relevant
regulations are made under these Acts include, the Electricity at Work Regulations
1989, the Provision and Use of Work Equipment Regulations 1992 (PUWER), the
Supply of Machinery (Safety) Regulations 1992, and the Equipment and Protective
Systems Intended for use in Potentially Explosive Atmospheres Regulations 1996.
34 The following references to certain statutory requirements are for guidance only
and the reader’s attention is drawn to the complete requirements of the Act and
relevant regulations.
Manufacturer duties
35 The manufacturer’s responsibilities under the HSW Act 1974 are stated in
section 6 of the Act, in particular, section 6(1)(c) states:
“to take such steps as are necessary to secure that there will be available in
connection with the use of an article at work adequate information about the use
for which it is designed and has been tested, and about any conditions necessary
to ensure that, when put to that use, it will be safe and without risks to health”.
36 It is therefore not acceptable to merely assume that adequate information is or
can be so widely circulated that it is always available where and when it is needed.
Specific steps must be taken to make it available. Sources of adequate information
are users, manufacturers or, under certain circumstances, the certifying authorities.
37 The manufacturer will also need to take into account the Supply of Machinery
(Safety) Regulations 1992 and the Equipment and Protective Systems Intended for
use in Potentially Explosive Atmospheres Regulations 1996 (which implement the
Flammable Atmospheres Directive 94/9/EC).
User duties
38 Apart from the need to comply with section 2 of the HSW Act 1974 (regarding
safe maintenance of plant and systems by the employer), the user is also required
to pay due regard to section 6 of the Act should they wish to undertake the repair
or overhaul of the equipment themselves.
39 The Provision and Use of Work Equipment Regulations 1992 amplify and
makes more explicit the general duties on employers, the self-employed and
people in control to provide safe plant and equipment.
This is a web-friendly
version of Guidance on 40 In particular, regulation 7 of the PUWER 1992 which states:
the repair and overhaul of
apparatus intended for use Where the use of work equipment is likely to involve a specific risk to health or
in coal mines susceptible safety, every employer shall ensure that repairs, modifications, maintenance or
to firedamp, originally servicing of that work equipment is restricted to those persons who have been
produced by specifically designated to perform operations of that description (whether or not
HM Inspectorate of Mines also authorised to perform other operations).
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