Safe isolation of plant and equipment – Part 1

Introduction

The safe isolation of plant and equipment is essential to allow various processes to take place, such as: cleaning, maintenance, repair and modification. Although no health and safety legislation covers this area specifically, there are several general legal drivers, such as the Health and Safety at Work Etc Act 1974 (Section 2: duty to ensure the health, safety and welfare of employees, Section 3: duty to ensure the health and safety of non-employees), the Management of Health and Safety at Work Regulations 1999 (Regulation 3: duty to carry out risk assessments) as well as the Control of Substances Hazardous to Health Regulations 2002 (COSHH) and the Dangerous Substances and Explosive Atmospheres Regulations 2005 (DSEAR), etc. Failures during the isolation and re-instatement of plant and equipment are a significant cause of loss of containment incidents and can lead to major accidents. In some cases, the isolation may take place a long way from where the work is being carried out. Suitable procedures need to be implemented, managed, monitored, reviewed and revised. The effectiveness of an isolation system depends on the adequacy of other arrangements, including work control systems (especially permit-to-work), operating procedures, training and competence, management of change and contingency plans.

The safe isolation of plant and equipment can be considered in three sections:
• The management of isolation of plant and equipment
• The safe systems of work for the isolation of plant and equipment
• The key stages for the safe isolation of plant and equipment
The management of isolation of plant and equipment is considered in outline in this article, while the other items will be considered in a future article.

The management of isolation of plant and equipment

As with nearly all aspects of modern health and safety management, risk assessment is central to the safe isolation of plant and equipment. Although the actual mechanics of isolating plant and equipment may be carried out a range of people, it must be managed effectively, and several points should be considered:
• The safe isolation of plant and equipment should form part of the organisation’s Health and Safety Policy
• Suitable and sufficient assessments of the risks arising from (operations requiring) the isolation of plant and equipment must be carried out (by a competent person) and suitable measures implemented
• Suitable policies and procedures must be established and implemented to either avoid the risk entirely or, where this is not reasonably practicable, to reduce the risk to as low a level as is reasonably practicable
• Consideration must be given to the isolation procedures under both normal operating conditions and other foreseeable conditions
• A process for assessing and implementing any variations from existing procedures should be established
• Procedures to monitor and, where appropriate, improve the effectiveness of isolation procedures should be introduced

In order to manage the isolation of plant and equipment in a safe and effective manner, consideration should be given to:
• The design (of plant and equipment)
• Human factors
• Roles and responsibilities
• Training and competence
• Monitoring, auditing and reviewing

Design
Good initial design of plant and equipment is the most effective way to maximise the inherent safety and, as such, is fundamental to achieving safe and effective isolation of the plant and equipment without creating unnecessary constraints on plant operation. Intrusive repair and maintenance work or internal inspection tasks will require the plant or equipment to be shutdown (or at least certain sections of it). Where isolation is required to enable such tasks, suitable isolation arrangements on the plant should be identified and specified at the design stage. Similarly, consideration of plant isolations should be considered if the plant or equipment is to be modified. Design considerations should include:
• Positive isolation requirements (where vessel entry may be required, where isolation of toxic or dangerous substances is requires and to control segregation of parts of plant and equipment)
• Plant identification (A scheme to identify all process plant, piping, and valves should be drawn up. All items should be readily identifiable on the plant and referenced on the piping and instrumentation diagrams. Additionally, key items of equipment labelled permanently)
• Pipework
• Valves
• Pressure safety valves
• Spared equipment (Isolation arrangements should allow complete segregation from on-line plant and equipment for operational and/or maintenance reasons)
• Location of isolation and testing facilities (Unless contraindicated by risk assessment, isolation and bleed points should be as close as possible to the plant item. Concentration of maintenance work in one place aids control of the isolation arrangements and minimises the inventory of fluid to be depressurised and drained)
• Access and lighting (the design should allow safe access and adequate lighting to allow isolations to be made safely)

Human factors
A review and accidents and incidents involving failures to isolate plant and equipment show that human failure is an important consideration. The performance of isolations depends not only on the integrity of the isolation hardware, but also on the adequacy of the arrangements for identifying each isolation point, securing the isolation, proving/monitoring and maintaining overall control of work. Human failures can be divided into two groups:
• Errors, and
• Violations.

Roles and responsibilities
It is important to ensure that key staff are given (and understand) clearly defined roles and responsibilities for drawing up, maintaining, monitoring and improving the policies, procedures and systems for the safe isolation of plant and equipment.

Training and competence
All personnel involved in the isolation of plant and equipment must be competent to carry out their designated tasks and to discharge their responsibilities. They should:
• Understand the purpose, principles and practices of the organisation’s isolation procedures and safety rules
• Have an understanding of the consequences of any release of hazardous substances

Consideration should be given to the training and competence of staff who:
• Plan the isolations
• Authorise the isolations
• Authorise variations (or any other non-standard isolations)
• Install and remove isolations
• Check and test the isolations
• Work on the plant and equipment

Monitoring, auditing and Reviewing
The processes of monitoring, audit and review enable an organisation to confirm that it actually does what its policies and procedures say that it does, and helps to ensure that this is what it should do. Effective monitoring, audit and review systems:
• Help to identify any deficiencies in the policies and procedures for the isolation of plant and equipment
• Identify and implement any necessary corrective action before these lead to incidents
• Identify of how well the isolation of plant and equipment is are controlled within the organisation

Summary
Safe isolation of plant and equipment is an important part of the management of health and safety at work and, as such, should form part of the documented policies and procedures of the company (including the Health and Safety Policy). Risk assessments must be carried out to determine the range of control measures required. These control measures may include items such as Permit to Work Systems, etc. All policies, procedures and risk assessments must be kept up to date and should be monitored and reviewed regularly and should be revised as necessary.


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