Permit to Work and Plant Isolation Procedure

Purpose. Sets out how work on plant is authorised by permit and how process, electrical and mechanical energy sources are isolated, proven and recorded so that hazardous materials and energy cannot reach the people doing the work.

1.Scope

This procedure applies to all work on or near operating plant at Hydra sites, including maintenance, inspection, modification, cleaning and contractor work. It covers the permit to work, the isolation certificate, blinding, draining, purging and de-isolation. Routine operating tasks described in an operating procedure do not require a permit unless the procedure states otherwise.

2.Permit types

A cold work permit covers work that does not create an ignition source. A hot work permit covers welding, grinding, cutting and any work that creates an ignition source, and requires gas testing and a fire watch. A confined space entry permit covers entry to vessels, tanks and pits. Every permit must be attached to an isolation certificate where the work requires isolation.

3.Process isolation standard

Process isolation must be positive. The minimum standard for hazardous service is double block and bleed or a spade or blind. A single closed valve is not an acceptable isolation for entry, hot work or breaking of containment on hazardous service. Every isolation point must be locked and tagged and listed on the isolation certificate with its tag number.

• Double block and bleed with the bleed open and visible
• Spade or blind installed with a numbered tag and entered on the blind list
• Physical disconnection with the open end blanked
• Electrical isolation at the switchboard with the isolator locked and tested for dead

4.Preparing the plant

After isolation the equipment must be depressurised, drained to a closed system, flushed and purged as required by the chemical and the work. The outside operator must gas test where flammable or toxic vapour is possible and must record the results on the permit. The plant is not ready for work until the permit issuer has verified zero energy at the work location.

5.Roles

The permit issuer is the shift supervisor or an authorised operations person who owns the plant. The isolation authority is an authorised operator who applies the process isolations. The permit holder supervises the work and must fit a personal lock to the isolation lockbox before starting. Every person working under the permit must sign on and off.

6.De-isolation and return to service

When work is complete the permit holder must confirm all people, tools and temporary equipment are clear and all joints have been remade and tagged for leak testing. The isolation authority must remove isolations in the order on the certificate, reconcile the blind list and record the de-isolation. The equipment must be leak tested before hazardous material is reintroduced.

7.Audit

The Process Safety Manager will audit at least six live permits each month against this procedure and will record the results in the permit and isolation register. Repeated findings must be raised as a process safety event.