Designing a Permit-to-Work System for Overlapping Work

Overlapping work happens whenever operations, maintenance, construction, commissioning or emergency response share a process area, asset, isolation or access route. Examples include a turnaround with mechanics working beside riggers, hot work near a live pipeline, or an electrician isolating equipment while another crew tests hydraulics. Designing a permit-to-work system for overlapping work activities must treat each interaction as a controlled work interface rather than a separate job. The objective is to prevent incompatible work from starting together while allowing safe productivity when coordination is strong.

A permit is only the visible part of the control system. It records hazards, isolations, conditions and responsibilities, but it cannot replace competent planning, physical safeguards or effective supervision. Australian sites also operate under state and territory variations of the Safe Work Australia model laws, with additional requirements for electrical work, confined spaces, construction and high-risk activities. A reliable system therefore combines regulatory compliance, site-specific rules and a clear process for managing simultaneous operations.

Map work interfaces before permits are issued

Build a complete inventory of planned and reactive work, including maintenance, structural work, drilling, excavation, lifting, testing, cleaning, painting and material movement. Record the exact workfront, equipment boundary, access route and operating condition. Work extending beyond the immediate task area can create overlooked interactions, particularly when contractors use temporary lighting, generators, gas cylinders or portable extraction equipment.

Map these activities against each other rather than reviewing them one at a time. A simultaneous operations, or SIMOPS, register can show which crews depend on the same isolation, atmosphere, traffic route or emergency resource. This is particularly important during turnarounds and major construction programmes in Melbourne’s industrial precincts, Pilbara mining operations, the Port of Newcastle and LNG facilities around Gladstone. A common look-ahead planning meeting should review upcoming work several weeks ahead, with daily confirmation of changes.

Convert the inventory into a work interface risk assessment using the hierarchy of control. Eliminate interference where possible, physically segregate incompatible activities and introduce administrative controls only after higher-order measures have been considered. The assessment should identify who owns each shared system and which permit must remain suspended until the conflicting task ends. Dynamic risk assessments are valuable, but they must not allow an informal decision to bypass a planned compatibility check.

Define authority, accountability and permit content

Give the system clear decision rights through defined roles such as permit issuer, permit receiver, area authority, isolation authority, gas tester and site supervisor. One person may hold several roles, but the actual authority must be explicit. A permit issuer should be competent, present for the task and able to verify the controls described in the permit. A principal contractor, supervisor or person responsible for the workfront should coordinate contractors where their activities intersect.

Each permit should describe the scope, location, equipment, work method, hazards, isolations, test results, controls, sequencing, communications and emergency arrangements. It should state when the permit starts, expires, requires suspension or needs reauthorisation. Drawings and isolations must identify the precise boundary rather than referring vaguely to equipment “near” the work area. Add fields for nearby operations and the crews that could affect the task, including other permit holders and operational personnel.

Use linked or multiple permits where separate workfronts share a dependency. A mechanical isolation permit may depend on an electrical isolation, while a hot-work permit may depend on process draining, purging and atmosphere monitoring. Each permit should identify the permits on which it relies, and each permit issuer must confirm that the prerequisite is still valid. Changes to the work method, isolation boundary, gas-test result, personnel or equipment require review and formal reissue. A permit must never be transferred informally to another crew.

Coordinate sequencing, isolations and live conditions

Schedule competing activities around shared constraints. A permit register or coordinated permit board should show the status, location, ownership and dependencies of every open permit. Create a sequencing plan for high-risk combinations, including priority rules for emergency work and shutdown work. When two activities cannot safely coexist, assign an exclusive zone, establish a clear hold point or move one task to a later window. Brief the affected workers before work starts, not after a conflict becomes visible.

Protect isolation boundaries throughout the permit period. Lockout and tagout arrangements should identify every energy source, including electrical, hydraulic, pneumatic, thermal, gravity and stored pressure. The isolation certificate must be accepted by the permit receiver before work begins, with equipment proved dead or safe in the required condition. Electrical work remains subject to jurisdictional requirements such as Queensland’s electrical safety rules, the NSW Electricity Safety Rules and the Victorian Electricity Safety Rules, together with applicable Australian standards and licensing requirements.

Make atmospheric and physical conditions part of the permit, not an informal assumption. Gas testing may need continuous monitoring during hot work, draining, purging, confined-space entry and pressure testing. Hot-work permits should identify fire protection, a dedicated watch and the response to an alarm or elevated reading. Confined-space permits should confirm isolation, ventilation, rescue arrangements and attendant duties. Excavation work should account for buried services, while lifting permits should manage overhead power lines, suspended loads and exclusion zones. A shift handover must transfer permit status, outstanding tests and suspended work without resetting accountability.

Build competence and assurance into the system

Competence must be assessed for the task, site and permit role involved. Toolbox talks should explain the actual work interface, the reason for each control, stop-work triggers and the location of isolation points and emergency equipment. Workers new to the site, temporary staff, labour-hire personnel and apprentices need clear supervision and appropriate authorisation. Australian licence requirements, white-card training and recognised vocational qualifications should be checked alongside site competency, since formal qualifications do not automatically demonstrate site-specific permit knowledge.

The kind of realistic live-process-plant environment used at HCF CATCH demonstrates why practical rehearsal is valuable. Trainees can practise receiving a permit, checking isolations, responding to changed conditions and handing work back. Scenarios should include distracting alarms, incomplete permits, unexpected pressure and conflicting crew requests. Training should assess behaviour as well as knowledge, because a technically correct permit can still fail when communication is poor or authority is unclear.

Audit the complete permit lifecycle, including planning, briefing, issue, acceptance, changes, suspension, close-out and handback. Look for permits issued just before work, unclear isolation boundaries, overdue tests and repeated conflicts at the same location. Pair safety indicators with operational information, such as late permit changes, repeated work-front conflicts and time spent managing interfaces. Review incidents and near misses with crews, supervisors, contractors and isolation owners so corrective actions reach schedules and technical documentation.

Test emergency decisions as part of the permit system. A gas alarm, medical emergency, failed isolation or sudden process change should trigger a defined response. Workers need to know when work stops, who authorises resumption and how affected crews are informed. Plain-language permits, visible responsibility boards and accessible radio protocols are especially important where FIFO rosters, rotating shifts, multiple languages and mixed contractor crews make informal communication unreliable.

Turn the permit system into a daily site routine

Decide compatibility before the shift begins, using an approved matrix that separates prohibited, conditional and routinely compatible work combinations. Conditional work requires named controls and a release condition that can be verified by the relevant authority. Prohibited combinations should be blocked through the schedule or an exclusive work zone. The matrix should be supported by the permit form and live register so that the rule remains consistent from planning room to workfront.

A compatibility matrix makes these decisions explicit:

Work combination	Principal clash	Required permit controls	Release condition
Hot work and confined-space entry	Ignition source may meet a flammable or toxic atmosphere	Gas testing, ventilation, fire watch, entry controls and rescue readiness	Readings remain within site criteria and both permits identify the shared controls
Electrical and mechanical work	Unexpected energisation or stored mechanical energy	Lockout, tagout, isolation certificates, discharge and stored-energy control	Isolation holder and permit receiver confirm the boundary before either task starts
Hot work and hydrocarbon draining	Ignition source may contact released hydrocarbon	Drain or depressurise first, use continuous monitoring and establish a fire watch	Conflicting release stops or hot work moves until conditions are verified
Excavation and live services	Service strike, electric arc or process release	Service records, detection, safe exposure, isolation and exclusion barriers	Workfront controller and service owner approve the excavation boundary
Lifting and electrical work	Dropped loads or contact with energised overhead conductors	Lift plan, exclusion zone, tag lines and electrical clearance or isolation	Lift area is released and confirmed electrically safe by the authority
Pressure testing and adjacent work	Stored energy or released fluid may cross the boundary	Independent barricade, exclusion zone, staged restart and communication protocol	Test boundary is isolated before adjacent work is released

Convert the matrix into shift-level controls by assigning an accountable coordinator for each high-risk interface. Review the compatibility decision again if the sequence, crew composition or operating condition changes, and record the reason for any authorised exception. Capturing these decisions helps the next shift understand why work was paused, which condition must be restored and who can authorise release.

Choose one planned work overlap, gather the relevant permit issuers, supervisors and contractors, and walk the shared systems before the next shift. Treat the result as a practical test of the system, not a paperwork exercise. HCF CATCH’s hands-on training, safety qualifications and facility options can support realistic rehearsal of permit discipline, helping teams turn coordination into a consistent site routine before conflicting work reaches the field.