1) Introduction

There are two quite different prime types of isolation or removal from service systems required at Greencore Group plc locations:

• Isolation in order to achieve a safety situation.
  
  
• Isolation for pure operational needs, such as, when a valve has to remain in its present position for an operational (or quality control) reason.

2) Safety Isolation

2.1 General

We are required by various Acts and Regulations to have "safe systems of work" which ensure that when an item of equipment is isolated for safety reasons, there is a positive method of preventing accidental removal of that isolation. It is now generally accepted that a system of locking off is the principle method to be employed to have a system of control that is simple to understand, simple to operate and manage and encompasses all hazardous situations.

2.2 Considerations

The need for isolation of electrical equipment in order to safely carry out maintenance and installation work is generally accepted, but the need for similar procedures for work on items such as:

a) Steam
b) Air
c) Water and hazardous product lines i.e. caustic based cleaners
d) Remote starters and confined spaces e.g. silo are not so widely appreciated.

The placing of loose warning signs and the removal of fuses alone are not considered adequate. Systems locating removed fuses in a secure cupboard are flawed by the fact that there are usually many similar fuses available which can be substituted. When withdrawal of fuses has to be used, such as when only one way of a distribution board is required to be isolate, then the board must be locked with an isolation lock so that fuses cannot be replaced until the lock is removed.

The system adopted has to be tailored to the type of Greencore Group location its operation and maintenance methods. One which is designed for a complex manufacturing plant with fully staffed departments in all disciplines would be very difficult to apply to a smaller Greencore Group factory and would prove almost unworkable.

The person or persons whose safety depends on the isolation should be involved in the isolation process if they are not wholly responsible for its application. Even with a formal isolation system in place, those responsible for the running of the factory should retain overall control. This operational control must be via the "Permit to Work System". The generation of a maintenance request by Production would be considered adequate control of small routine repairs.

Each factory must decide which persons, or grade of personnel, are to operate the system, taking into consideration the local circumstances. These decisions must be formally recorded on the factories "Safety Policy".

A major contribution to inherent safety will be achieved by the clear labelling of equipment. This is also a clear requirement of The Electricity at Work Regulations.

3. Principles of a Safety Isolation System

a) Locks and signs are to permanently attached together as numbered units.

b) Adequate number of locks and signs are to be available at points of use i.e.. main switch rooms, control rooms, manufacturing areas and remote locations.

c) One universal system and sign for all safety isolation needs, electrical, mechanical and operational.

d) All equipment foreseen to be used as an isolator has to be able to accept the standard lock and numbered sign. This is particularly important for electrical distribution boards. some existing equipment will have to be modified to meet this requirement.

e) Multi lock adapters are to be available for multi discipline or combined contractor/maintenance use.

f) The written instructions on the use of the system must be clear and brief, ideally not more than a single page, and readily available at points of use.

g) The persons or graders who are authorised to operate the system must be formally trained and recorded.

h) The safety isolation system must be easy to distinguish from other systems such as the "Do not operate" system described later.

i) Only the factories authorised system and signs must be used (contractors must not use their own system). Keys of isolation locks must be readily identifiable by the use of special tags.

j) Central isolation key cabinet provides long term isolation key control.

4. Description of a typical Greencore Group Company isolation system based on the previously described principles

The signs are white letters on a red background (see British Standard 5378) numbered consecutively (see appendix 2). The padlock is attached to the sign by a short (75mm long) welded link chain (non-brass) and is individually keyed. The key is tagged with the same number as the sign using 30mm red disc with white lettering. A spare key for each lock is kept secure preferably in the company safe.

A group of at least 10 locks/signs are held on a board in each manufacturing area, 10 in the engineering workshop. An adequate number must be kept in the main switch room and 2 at remote switch rooms. A record log must be kept at each location containing Responsible Care Form No. with a set of written instructions inside the front cover (see appendix 1 for instructions and details of action to be taken by the authorised person). The keys are kept with the padlock when not in use. Multi lock adapters are kept at each location for use when isolation is required for more than one activity.

The isolation key cupboard is located in the previously identified areas where the isolation keys are logged in and out using a separate control book kept at the cupboard. Any person booking out a key takes responsibility for ensuring that work has been completed and it is safe to remove the isolation (see appendix 2 for key cupboard label detail, see appendix 3 for control book detail).

5. Operational Isolation ("Do not operate" system)

This formal system must be used for purely operational requirements, for example, to indicate that a valve must not be changed for its present position or in order to prevent the wrong diesel/derv tank being drawn from. It replaces the odd bits of rope or wire which have traditionally been used for this purpose. It must be clearly identified as a totally separate system from that for safety isolation is controlled by a specific log book.

This notices to conform with British Standard 5378 must be black letters on a yellow background, each numbered consecutively for easy reference and control (see appendix 2). They are attached to a short length of welded link chain (not brass) which has a hook at one end for convenience length adjustment.

NOTE
It must be stressed that these notices must not be used for safety isolation.

APPENDIX 1

Suggested Isolation Instructions
Hazard Warning Sign/Lock System

Factory Name :

The following system is in operation:

1) Universal Hazard Signs/Locks and keys will be kept on boards at the following locations:

MAIN SWITCH ROOMS :

PRODUCTION AREAS :

ENGINEERING WORKSHOP :

A Hazard sign/lock record book will be attached to each board.

2) When isolation is required prior to electrical or mechanical work or for operational safety reasons, the following steps must be taken:

a) lock of isolation or valve etc. using the combined lock/sign

b) Fill in and sign the hazard sign/lock record book.

c) if the need for isolation is for a short period, retain the key in your possession. For longer periods or if you have to leave the site put the key in the isolation key cupboard located at and sign the key record book attached.

3) Multi lock adapters are provided for use when more than one discipline/team protected by the same isolator.

4) A person withdrawing a key from the cupboard must be satisfied that all repairs etc. have been completed and it is safe to remove the isolation.

5) If you are in doubt do not remove the isolation before confirmation the situation.

APPENDIX 2

Examples of Hazard Warning Signs

APPENDIX 3