Maintaining instrumentation and control equipment and circuits
Overview
This standard identifies the competences you need to carry out corrective maintenance activities on instrumentation and control equipment and circuits, in accordance with approved procedures. You will be required to maintain a range of instrumentation and control equipment such as pressure, flow, level and temperature instruments; fiscal monitoring equipment; smoke, heat, gas, water, chemical and metal detection and alarm systems; industrial weighing systems; linear and rotational speed measurement and control; vibration monitoring equipment; photo-optic instruments; nucleonic and radiation measurement; analysers recorders and indicators; telemetry systems; emergency shutdown systems and other specific instrumentation. This will involve dismantling, removing and replacing a range of instruments and faulty peripheral components down to unit and board/component level, as appropriate.
Your responsibilities will require you to comply with organisational policy and procedures for the maintenance activities undertaken, and to report any problems with the activities, instrument system, tools or equipment used, that you cannot personally resolve, or that are outside your permitted authority, to the relevant people. You will be expected to work with a minimum of supervision, taking personal responsibility for your own actions, and for the quality and accuracy of the work that you carry out.
Your underpinning knowledge will provide a good understanding of your work, and will provide an informed approach to applying maintenance procedures to instrumentation and control equipment and circuits. You will understand the maintenance methods and procedures used, and their application, and will know about the various instrumentation units and peripheral components, their functions and associated defects, in adequate depth to provide a sound basis for carrying out the maintenance activities, correcting faults and ensuring that the equipment operates to the required specification and remains compliant with all standards and regulations. You will also know about the interaction of the other associated integrated technologies, and will have sufficient knowledge to carry out the dismantling and reassembly of the instrumentation system safely and effectively.
You will understand the safety precautions required when carrying out the maintenance activities, especially those for isolating the equipment. You will be required to demonstrate safe working practices throughout, and will understand your responsibility for taking the necessary safeguards to protect yourself and others in the workplace.
Performance criteria
You must be able to:
- work safely at all times, complying with health and safety legislation and other relevant regulations, directives and guidelines
- follow the relevant maintenance schedules to carry out the required work
- carry out the maintenance activities within the limits of your personal authority
- carry out the maintenance activities in the specified sequence and in an agreed timescale
- report any instances where the maintenance activities cannot be fully met or where there are identified defects outside the planned schedule
- complete and store all relevant maintenance documentation in accordance with organisational requirements
- dispose of waste materials in accordance with safe working practices and approved procedures and leave the work area in a safe condition
Knowledge and Understanding
You need to know and understand:
- the health and safety requirements of the area in which the maintenance activity is to take place, and the responsibility they place on you
- the isolation and lock-off procedure or permit-to-work procedure that applies to the system and instruments being worked on, and how to check that any stored energy in pipework and instruments has been released
- the specific health and safety precautions to be applied during the maintenance process, and their effects on others
- what constitutes a hazardous voltage and how to recognise victims of electric shock
- how to reduce the risks of a phase to earth shock (such as insulated tools, rubber matting, isolating transformers)
- the importance of wearing protective clothing and other appropriate safety equipment (PPE) during the maintenance activities, and where this can be obtained
- the procedures and precautions to be adopted to eliminate electrostatic discharge (ESD)
- hazards associated with carrying out maintenance activities on instrumentation and control systems (such as stored pressure/force, electrical supplies, process controller interface, using damaged or badly maintained tools and equipment, not following laid-down maintenance procedures), and how to minimise them and reduce any risks
- how to obtain and interpret drawings, charts, specifications, manufacturers' manuals, history/maintenance reports, symbols used on instrumentation and control documents, other documents needed in the maintenance process
- the basic principles of operation of the instrumentation and control equipment being maintained, how the system functions, its operating sequence, the working purpose of individual units/components and how they interact
- the reasons for making sure that control systems are isolated or put into manual control, and appropriate trip locks, keys or program overrides are inserted, before removing any sensors or instruments from the system
- the identification and selection of instrument sensors (including how to identify their markings, calibration information, component values, operating parameters, working range)
- the correct way of fitting instruments to avoid faulty readings (caused by head correction, poor flow past sensor, blockages, incorrect wiring, poor insulation, incorrect materials)
- the correct and tidy installation and connection of external wiring and components, to avoid electronic interference or mechanical damage
- how to carry out visual checks of the instruments (such as checking for leaks, security of joints, physical damage)
- the procedure for obtaining replacement parts, materials and other consumables necessary for the maintenance process
- organisational policy on the repair/replacement of components during the maintenance process
- the techniques used to dismantle/assemble integrated equipment (such as release of pressures/force, proof marking to aid reassembly, plugging exposed pipe/component openings, dealing with soldered joints, screwed, clamped and crimped connections)
- methods of attaching identification marks/labels to removed components or cables, to assist with reassembly
- methods of checking that components are fit for purpose, and the need to replace electronic modules, sensors, transmitters, transducers, electronic boards, other failed items
- how to check that tools and equipment are free from damage or defects, are in a safe and usable condition, and are configured correctly for their intended purpose
- the generation of appropriate documentation and/or reports following the maintenance activity
- the equipment operating and control procedures to be applied during the maintenance activity
- the problems that can occur during the maintenance of the instrumentation and control system, and how they can be overcome
- the organisational procedure to be adopted for the safe disposal of waste of all types of material
- the extent of your own authority and to whom you should report if you have problems that you cannot resolve
Scope/range
Carry out all of the following during the maintenance activities:
- plan and communicate the maintenance activities so as to minimise any disruption to the process/system operation
- obtain and use the correct issue of organisational and/or manufacturers' drawings and maintenance documentation
- adhere to procedures or systems in place for risk assessment, COSHH, personal protective equipment (PPE) and other relevant safety regulations
- where appropriate, ensure the insertion, or program override, of any relevant system trip defeats (such as fire extinguishant, emergency shutdown)
- ensure the safe isolation of instruments (such as process, electrical, hydraulic, pneumatic, mechanical)
- where applicable, ensure that appropriate decontamination procedures are used for instruments that have been used with hazardous (such as toxic, corrosive, inflammable, explosive, radioactive) substances
- provide and maintain safe access and working arrangements for the maintenance area
- carry out the maintenance activities, using appropriate techniques and procedures
- record the results of the maintenance activity and report any defects found
- dispose of waste materials in accordance with safe working practices and approved procedures, and leave the work area in a safe condition
Carry out maintenance activities on four of the following types of instrumentation and control equipment:
- pressure (such as absolute, gauge, vacuum)
- flow (such as orifice plate, venturi tube, electromagnetic, ultrasonic, differential pressure cell, positive displacement)
- level (such as floats, displacer, differential pressure cells, load cells, ultrasonic, conductivity)
- temperature (such as bi-metallic, thermocouples, resistance, infra-red, thermal imaging)
- weight (such as mechanical systems, load cells/strain gauges, transducers)
- fiscal metering (such as gas, electricity, water, fuel)
- detection and alarm (such as smoke, heat, gas, chemical, water, metal)
- speed measurement (such as mechanical, electrical, stroboscopic)
- emergency shutdown
- speed control (such as mechanical governors, electrical governors, DC speed controller, AC motor control systems, stepper motors, invertors)
- vibration monitoring (such as vibration switches, proximity probes, seismic velocity transducer, linear variable differential transformers, portable data collectors)
- nucleonic and radiation (such as Geiger-Muller tube, neutron counter, photomultiplier tube, proportional counter)
- analysers (such as gas detection, spectroscopy, oxygen analyser, water analysis, moisture measurement, density)
- recorders and indicators
- telemetry systems (such as master station, outstation, stand-alone systems)
- valves and valve mechanisms (such as control valves, valve actuators and positioners)
- other specific instrumentation or control equipment
Carry out ten of the following maintenance activities, as appropriate to the equipment being maintained:
- disconnecting electrical/pneumatic supply
- replacing mechanical components
- disconnecting signal transmission
- replacing electrical components
- disconnecting process pipework
- replacing complete instruments
- removing instruments from the system
- tightening fastenings to the required torque
- replacing peripherals (such as sensors, actuators, relays, switches)
- replacing `lifed' items (such as seals, gaskets, batteries)
- proof marking/labelling of removed wires or components
- taking electrostatic discharge (ESD) precautions when handling components and circuit boards
- setting, aligning and adjusting replaced instruments
Use four of the following types of test equipment:
- analogue or digital meters
- oscilloscope
- signal sources/generator
- standard test gauges
- current injection devices
- pressure sources
- logic probes
- digital pressure indicators
- signal tracer
- special purpose test equipment
Return instruments and systems to service, to include carrying out all of the following:
- connecting up process impulse pipework
- connecting up electrical/pneumatic supply
- connecting up signal transmission (such as electrical, electronic, pneumatic, mechanical)
- confirming that signal measurement and transmission are satisfactory
- final re-commissioning of the system and removal of any trip defeats
Maintain instrumentation and control equipment in compliance with one of the following:
- organisational and/or customer standards and procedures
- BS, ISO or BSEN standards and procedures
- equipment manufacturer's operation range
Complete and store all relevant maintenance documentation in accordance with organisational requirements, using one of the following:
- job cards
- maintenance log or report
- permits to work/formal risk assessment
- organisational-specific documentation
- electronic reports