PTW/General/TBT-PTW-011

Breaking Into Systems (Process) Permits

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Breaking Into Systems (Process) Permits

Toolbox Talk Record

Ref: TBT-PTW-011  |  Issue: 1  |  Date: March 2026
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What?

  • A breaking-into-systems permit controls work that opens pipelines, vessels, or process equipment.
  • Breaking into a system can release pressurised fluids, hazardous chemicals, or flammable gases.
  • The permit ensures the system has been isolated, drained, depressurised, and made safe before opening.
  • Common activities requiring this permit include pipe cutting, flange breaking, valve removal, and filter changes.
  • Residual pressure, trapped liquids, and stored energy can remain even after isolation is confirmed.
  • COSHH hazards may be present from process chemicals, sludge, or biological material within the system.
  • The permit must specify the exact break point, isolation method, and PPE requirements for the task.
  • Cross-referencing with other permits such as LOTO, hot works, and confined space may be required.
  • Only competent and authorised persons may issue and accept breaking-into-systems permits.
  • The permit system is essential on water treatment works, chemical plants, and mechanical installations.

Why?

Prevent injuryOpening pressurised or chemical-containing systems without controls causes scalding, chemical burns, and toxic exposure.
Control residual energyEven isolated systems may contain residual pressure, trapped liquids, or hazardous atmospheres.
Legal dutyCDM 2015 and PUWER require safe systems of work for maintenance on pressurised and process equipment.
Do Don't
  • Obtain a breaking-into-systems permit before opening any pipeline or vessel
  • Confirm the system is isolated, drained, depressurised, and vented before work
  • Identify the exact break point and method specified on the permit
  • Wear the PPE specified on the permit including face shield and chemical gloves
  • Slacken flange bolts gradually and unevenly to release residual pressure safely
  • Check for cross-referencing with LOTO, confined space, and hot works permits
  • Ensure a COSHH assessment covers any chemicals that may be present in the system
  • Keep emergency eyewash and spill equipment within reach during the operation
  • Brief all team members on the permit conditions and emergency procedures
  • Close out the permit formally once the system is reassembled and tested
  • DON'T open any pipeline, vessel, or process equipment without a valid permit
  • DON'T assume the system is empty or depressurised because a valve is closed
  • DON'T remove all flange bolts at once — loosen gradually to check for pressure
  • DON'T break into systems containing unknown substances without COSHH assessment
  • DON'T carry out the work without the correct PPE as specified on the permit
  • DON'T ignore cross-references to other permits — all conditions must be met
  • DON'T allow unauthorised persons to issue or accept the permit
  • DON'T dispose of drained fluids without following the correct waste procedures
  • DON'T re-pressurise the system until the permit is formally closed out
  • DON'T rush the isolation verification — trapped pressure kills without warning

See also: Permit to Work Awareness | Process Isolation (Valves and Blinds)
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