This Technical Measures Document refers to Operating Procedures.
Related Technical Measures Documents are:
The relevant Level 2 Criteria are:
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;
- 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
- 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;
- Sampling of raw materials, intermediates, products and
- 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
- 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 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
- 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
- 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,
- 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
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
- 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
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.
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
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.
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
- There should be no easier, more dangerous alternatives than following
- 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, i.e. ‘This procedure is only
valid for six months after the date hereon’.
- There should be no ambiguity between which procedures apply to which
- Procedures do not always have to be paper based.
- At the start of the procedure an overview of the task should be
- 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
- 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, i.e. 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
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, i.e.
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
- HS(G)65 Successful health & safety
management, HSE, 1997.
Appendix 5 provides guidance on the contribution of procedural failures
on the causes of incidents and methods to mitigate them.
- HSE, ‘Health risk management: A practical guide for managers in
small and medium-sized enterprises’, HSE Books, 1995.
- HS(G)28 Safety advice for bulk chlorine
installations, HSE, 1999.
Paragraphs 190-192 provide guidance on operating instructions for bulk
- BS 5908 : 1990 Code of Practice For Fire
Precautions in the Chemical and Allied Industries, British Standards
Section 8, Paragraph 48.1 provides guidance on the definition and
communication of operating and emergency rules, training and on the job
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