Permit to Work (PTW)

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Overview

A PTW is a documented authorization that forces hazard identification and sign-off before high-risk work.

It ties together risk assessment, isolation, gas testing and supervision.

When a permit is required

Hot work — welding, cutting, grinding, ignition sources.
Confined space entry — tanks, vessels, pits.
Excavation and ground disturbance.
Electrical isolation and live work.
Working at height and lifting operations.

Step-by-step procedure

Identify the permit type and define scope, location and duration.
Attach the JSA and method statement covering every step.
Perform and record isolations (LOTO), gas tests and controls on site.
The issuer verifies controls physically before approving.
Issuer and receiver sign; permit displayed at the work front.
Work proceeds only within the permit's scope and validity.
Suspend and re-validate if conditions change or at shift change.
Make the area safe, remove isolations and formally close the permit.

Key controls

One permit per task, with a defined validity period.
Cross-referenced isolation certificates and gas-test records.
SIMOPS reviewed so conflicting permits don't clash.

Roles & responsibilities

Role	Responsibility
Permit Issuer / Area Authority	Verifies controls, authorizes and cancels.
Permit Receiver / Supervisor	Accepts permit, briefs crew, works to conditions.
Workers	Follow the permit; stop work if unsafe.

Common mistakes to avoid

Signing without verifying controls on site.
Work drifting beyond the permitted scope or time.
Failing to re-validate after a break or alarm.

Legal requirements (Thailand)

Occupational Safety, Health and Environment Act B.E. 2554 (2011) — the governing workplace-safety law in Thailand.
Ministerial Regulation on the standard for a safety management system B.E. 2565 (2022).
High-risk tasks (hot work, confined space, electrical, lifting) are each governed by their own ministerial regulations.

Frequently asked questions

What is Permit to Work (PTW)?

A Permit to Work (PTW) is a documented authorization issued before a high-risk task starts. It forces the team to stop, identify the hazards, confirm that controls are in place, and obtain sign-off from an authorized person. The permit is a live document displayed at the work front and cancelled when the job is complete.

Who is responsible?

Permit Issuer / Area Authority: Owns the area, verifies controls, authorizes and cancels the permit.; Permit Receiver / Supervisor: Accepts the permit, briefs the crew and works to its conditions.; Workers: Follow the permit, stop work if conditions change or feel unsafe.

What are the most common mistakes to avoid?

Signing the permit from the office without verifying controls on site. Letting work drift outside the permitted scope or past its validity time. Not re-validating after a break, shift change or alarm.

References — Company PTW procedure; Thai OSH Act B.E. 2554 and related regulations.