Operating procedures

This Technical Measures Document refers to Operating Procedures.

Related Technical Measures Documents are:

The relevant Level 2 Criteria are:

General principles

There have been numerous recorded incidents where failings by operators have been the major contributing cause of major accidents. Provision of clear, concise and accurate operating procedures is the most effective measure to prevent, control and mitigate such events.

Operating procedures should clearly lay down instructions for operation of process plant that take into consideration COSHH, manual handling, permit to work, PPE Regulations, quality, HAZOP, and SHE requirements. The procedure should represent a definition of good or best practice that should be adhered to at all times. Process operatives should be provided with guidance concerning the required operating philosophy to ensure that they comply with procedural requirements.

Adequate training should be provided to ensure that operators are fully conversant with written procedures. This is covered in the Technical Measures Document on Training.

It is important that operating procedures should always reflect plant practice, and vice versa.

Provision of Comprehensive Written Operating procedures

Comprehensive written operating procedures should be generated where applicable that address:

  • Standard operating procedures and operating philosophy;
  • Abnormal operating procedures;
  • Temporary operating procedures;
  • Plant trials;
  • Emergency operating procedures;
  • Commissioning;
  • Plant Start-up;
  • Plant Shut-down;
  • Bulk loading and unloading;
  • Process change;
  • Plant change.

These procedures should cover the following:

  • Material safety data (COSHH);
  • Plant operatives should have an awareness and understanding of material safety data for raw materials, intermediates, products and effluent / waste;
  • Control measures and personal protective equipment;
  • Location of plant where process to be undertaken;
  • Roles and responsibilities of individuals involved in plant operations;
  • Plant fit for purpose;
  • The condition of main process plant and equipment (clean, empty etc. as appropriate) should be established as being fit for purpose;
  • The condition of ancillary process plant and equipment (clean, empty etc. as appropriate);
  • Plant correctly set-up for processing;
  • Process monitoring and recording;
  • Monitoring and recording of key process parameters (temperature, pressure etc.) in plant logs;
  • Quality;
  • Sampling of raw materials, intermediates, products and effluent/waste;
  • Packaging of final product.

Operating procedures should be controlled documents, generally covered under the company's quality system and thus kept fully up to date. Any changes should be fully controlled and documented and should be subject to company change procedures (see Technical Measures Document on Plant Modification / Change Procedures). Standard operating procedures may be revised for the following reasons:

  • Introduction of new equipment into the process;
  • Introduction of new chemicals into the process;
  • Significant change to process, task, personnel or equipment covered by the procedure;
  • Plant trials have been successful and need to be incorporated into standard operating procedures.

Limits of Intervention, Control Systems Interface

Clear demarcation of where limits of intervention cease and reliance upon the control systems interface begins is a critical step in defining the operating procedures for a given plant or process. During the hazard and operability stage, the justification of reliance upon human intervention rather than automated systems should be established. This should be assessed in more depth in a subsequent risk assessment.

Commissioning procedures

Commissioning of process plant is the practical test of the adequacy of prior preparations, including training of operating personnel and provision of adequate operating instructions. Since the possibility of unforeseen eventualities cannot be eliminated during this period when operating experience is being gained, the need for safety precautions should be reviewed. This should form part of the HAZOP / Risk Assessment processes applied to the installation. Full written operating instructions should be provided for all commissioning activities.

Commissioning Procedures document a logical progression of steps necessary to verify that installed plant is fully functional and fit for purpose. A general sequence of steps in commissioning may typically include:

  • System Configuration Check;
    The purpose of this activity is to trace all pipework and connections to verify the system configuration, and to visually inspect items of equipment to ensure that they are clean, empty and fit for purpose as appropriate prior to undertaking water trials.
  • Instrumentation System Check - Verification of Alarms and Trips;
    The purpose of this activity is to ensure that all instrumentation, alarm settings, microprocessor signals and hardwire trips pertaining to the installation are functional. This will also check that signals from the field instrumentation are displayed locally and are being correctly relayed to the computer interface rack, as well as to the computer system.
  • Flushing and Cleaning of Lines and Vessels with Water;
    The purpose of this activity is to clean all items of pipework and the vessels that make up the installation. This task shall also ensure that there are no obstructions, blockages or any potential contaminants in any of the process lines or vessels that may have resulted from materials being left inside the system from the construction phase. If chemicals incompatible with water are to be used, it is important that the pipelines and equipment are thoroughly dried prior to introduction of the chemicals. This is normally done by passing dry air through the plant.
  • Assessment of Ancillary Equipment;
    The main aim of this assessment is to verify the performance of all ancillary equipment. This may include pumps, fans, heat exchangers, condensers etc.
  • Calibration of Vessels and Instrumentation;
    The purpose of this activity is to check the calibration and performance of all vessels and instrumentation pertaining to the installation. To a certain extent this will be carried out in conjunction with the system pre-checks to ensure that the correct set points and alarm points have been established for use in the water trials.
  • Start Up Protocol;
    The purpose of this procedure is to provide guidance for bringing the installation online starting from an empty non-operational system.
  • Shut Down Protocol;
    The purpose of this procedure is to provide guidance for taking the installation offline starting from a fully operational system.
  • Chemical Trials;
    The aim of this activity is to verify the performance of the installation by simulating 'live' conditions by following standard procedures.
  • Handover

Each section should be read in detail to gain understanding about the particular requirements of the activity prior to undertaking the activity itself and completing the associated check list. The checklist will serve as a permanent record of the activity, and can be reviewed if future modifications are undertaken.

It is assumed that prior to the commencement of commissioning activities that full support from plant personnel has been obtained.

Start-up / shutdown procedures

Many potential hazards can be realised during start-up or shut-down of plant or process. Specific operating procedures should be provided which take account of all eventualities. For some specific plant items, start-up is know to present particular additional hazards; some examples of these are:

  • Dryers – when starting up a drying system after maintenance or a plant shutdown, the actual temperature the dryer might reach before settling out with the control system may result in an increased chance of a dust explosion;
  • Furnaces – explosions may occur if ignition of fuel is delayed;
  • Vessels, Tanks, Reactors – ignition of flammable vapours introduced may occur for systems relying on elimination of oxygen to prevent explosions, unless inert gas purging is carried out effectively;
  • Reactors – start-up of batch reactors after agitator failure may cause an uncontrollable exothermic reaction.

The start-up and shut-down procedures should be ordered and phased so that interlinked plant operations can resume or cease in a safe and controlled manner.

Emergency procedures

Further information can be found in the Technical Measures Document Emergency Response / Spill Control.

Any potential deviations to normal operation that cannot be addressed by design or control identified in the Hazard and Operability studies should be covered by emergency procedures. These should detail how to make plant and process safe, minimising risks to operators at all stages. They should cover PPE, the level of intervention which is safe and when to evacuate. The procedures will need to tie in closely with the on and off-site emergency plans provided under COMAH.

Management / supervision

A clear management structure should be in place that defines competent responsible person(s) for generation of operating procedures and supervision of plant and personnel. The role of the supervisor in terms of training of operators, overseeing certain critical operations and checking of logs and other activities to ensure compliance with operating procedures. This should fulfil the requirements of the company's health and safety policy.

Human factors

The appropriate design of a procedure is critical in the reduction of human error within process operations. The benefits of procedures are that they can aid an operator when they are faced with a complex diagnosis, or they can act purely as an aide memoir during non-critical routine operations.

The following section provides human factors guidance on the production and implementation of procedures.

Generally there are four types of procedure:

  • Procedures that provide general operating guidance;
  • Procedures that provide an aid to meeting operating aims;
  • Procedures that are mandatory and prescribe behaviour; and
  • Procedures that are used as a training tool.

Each of the procedure types listed above all conform to the same general human factors principals. These are discussed below.

Task analysis

The content of important procedures should be based on some form of formal task analysis method to ensure that the procedure accurately describes the task it refers to. On some plants a process may have a safety-related action or task that has become an accepted 'unofficial' part of the procedure, but which is not documented anywhere. In this situation the task analysis will pick up on this and allow it to be incorporated into the procedures. Conversely, any dangerous actions that an operator might routinely carry out will also be detected.

The most commonly used method of task analysis is Hierarchical Task Analysis (HTA). Further information on this method and others can be found in ' A Guide to Task Analysis edited by B. Kirwan and L. K. Ainsworth.

Operating instructions should be close to the user and kept up to date. The following issues should be considered in assessing operating procedure documentation:

  • There should be no easier, more dangerous alternatives than following the procedure.
  • There should be a suitable QA system in place to ensure that the procedures can be kept up to date and that any errors are quickly detected and hence corrected.
  • The procedures should not be needlessly prescriptive. The best way of ensuring that procedures do not become overly prescriptive is through involving the operator during the design stage.
  • Procedures should contain information on the requirements for the wearing of personal protective equipment during the task.
  • Any risks to the operator should be documented at the start of the procedure, based on a risk assessment of the task.
  • An appropriate method of coding each procedure should be used.
  • Each time a procedure is produced it should be dated and also marked, where appropriate, with a shelf life, ie 'This procedure is only valid for six months after the date hereon'.
  • There should be no ambiguity between which procedures apply to which situations.
  • Procedures do not always have to be paper based.
  • At the start of the procedure an overview of the task should be provided.
  • Prerequisites should presented clearly at the start of the procedure to ensure that the operator can check that it is safe to proceed.
  • The most important information on the page should be identified and this should be designed to be the most prominent information.
  • Separate headings should be used to differentiate clearly between sub tasks.
  • Any warnings, cautions or notes should be placed immediately prior to the instruction step to which they refer.
  • Language should be kept as simple as possible, ie use nomenclature familiar to the operator.
  • The nomenclature should be consistent with that on controls or panels.
  • Symbols, colours, and shapes used for graphics should conform to industry standards.

More detailed information can be obtained from the Further Reading Material outlined in the section below.


A procedure should always be formally validated prior to it being issued. The best method to achieve this is a comprehensive walk-through assessment of the procedure in the plant, or with reference to the relevant plant drawing when an in plant assessment is not possible.

Status of guidance

Guidance related to operating procedures tends to be non-specific, ie operating procedures are covered in sections of existing guidance. However, no guidance is currently available that specifically addresses operating procedures and related issues. Consequently the quality and standard of operating procedures can vary between different companies, and also within the same company if multi-process plants are in operation.

Codes of Practice relating to Operating procedures

Further reading material

  • ILO, PIACT, Major Hazard Control: A practical manual, 1988.
  • ILO, Conditions of work digest, Preventing Stress at Work, 1992.
  • Lees, F.P., 'Loss Prevention in the Process Industries: Hazard Identification, Assessment and Control', Second Edition, 1996.
  • Section 6.5 provides guidance on Systems and Procedures;
  • Section 13 provides guidance on Control System Design;
  • Section 14 provides guidance on Human Factors and Human Error;
  • Section 19 provides guidance on Plant Commissioning and Inspection;
  • Section 20 provides guidance on Plant Operation;
  • Section 24 provides guidance on Emergency Planning.
  • Kirwan, B. and Ainsworth, L. K. eds., 'A Guide to Task Analysis', Taylor and Francis, London, 1993.
  • Ball, P. W. ed., 'The Guide to Reducing Human Error in Process Operations', HFRG, The SRD Association, AEA Technology, 1985.

Case studies illustrating the Importance of Operating procedures

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