Symmetrical Group

Policies and Procedures

OHS&E\SAFETY PROCEDURES

SG-PR-33-05 Hot Work Procedure

1. iNTRODUCTION

This guide manual describes the steps to be taken before carrying out hot work in any confined space or in a potentially explosive/hazardous area.

before any hot work is carried out in a
confined space or potentially hazardous area:

• a permit shall be obtained
• consideration shall be given to conducting a job safety analysis (jsa) to identify and assess all the risks associated with the work

The provisions of this instruction apply to any activity that contains hot work, as defined in 2.3.  If there is any doubt, the activity is to be treated as hot work.

Hot work precautions depend on the type of work being performed, and it is important to try to eliminate ignition sources.  Before carrying out hot work, ask the following questions:

• Can hot work be avoided altogether by selecting non-ignition-type tools, such as air-powered or hydraulic-powered tools and hand tools?
• Can the work be moved out of the confined space, hazardous or restricted area?
• Is there an increased possibility of fire because of the presence of combustible material, such as long grass or wooden pallets?
• Can the design be altered to avoid or minimise hot work?
• Can the work site be shielded from potential vapour sources?
• Are the risks associated with the hot work justified?

Before any hot work commences, permission and work permits shall be obtained from the person responsible for the area or equipment to be worked on and where appropriate, a special permit obtained.

2. definitions

2.1. hazardous zones

AS 2430 defines hazardous area zones for gases and vapours as:

Note:        Hazardous Area Zone classifications purely consider flammable atmospheres.  The classification provides no indication of the probable ability of the atmosphere to sustain life.

• Zone 0 - an area where an explosive gas atmosphere is present continuously, or is expected to be present for long periods, or for short periods which occur with high frequency.
• Zone 1 - an area where an explosive gas atmosphere can be expected to occur periodically or occasionally during normal operation.
• Zone 2 - an area in which an explosive gas atmosphere is not expected to occur in normal operation, and if it occurs, is likely to be present only infrequently and for short duration, but where an explosive atmosphere may be expected to be present due to an abnormal or transient condition.

This includes hazardous pipelines that potentially could contain combustible gases, even though the pipeline would not normally contain such gases, e.g. hydrogen gas in a dormant sulfuric acid line.

• Non-hazardous Area - an area in which an explosive atmosphere is not expected to be present in such quantities as to require special precautions.

1.        HOT WORK IS NOT PERMITTED IN ZONE 0 AREAS.

2.        EQUIPMENT THAT IS NOT INTRINSICALLY SAFE IS NOT PERMITTED IN ZONE 0 AREAS.

3.        SPECIFIC AREAS WITHIN THE SODIUM CYANIDE, CHLOR - ALKALI AND AMMONIA PLANTS HAVE BEEN DESIGNATED ZONE 0 AND ZONE 1 AREAS.

2.2. restricted areas

Whist not defined as Hazardous Zones under AS 2430, various sites have specific operations and areas where flammable, oxidising or explosive materials are present.  Because of the nature of these materials, a permit for hot work shall be obtained before any hot work is started.

2.3. hot work

Hot work is defined as any work which involves the use of tools, equipment or techniques that could generate heat of sufficient intensity to ignite flammable or combustible gases, liquids, dusts or materials within a confined space, a hazardous zone or restricted area.

The following are examples of hot work:

• Welding,
• Thermal and oxygen cutting,
• Heating,
• Fire-producing and spark-producing operations,
• Grinding,
• Abrasive blasting,
• Concrete chipping and drilling,
• Metal drilling,
• Use of flash cameras within a defined hazardous zone or restricted area,
• Use of electrically powered cameras or instruments within a defined hazardous zone or restricted area,
• Use of electrical equipment (such as pagers and mobile phones) which requires batteries or any form of power, within a defined hazardous zone or restricted area, unless they are intrinsically safe,
• Use of internal combustion engines unless they are specifically manufactured and certified for use in explosive gas atmospheres.

3. planning and preparation

3.1. minimum requirements for hot work

3.1.1. Confined Spaces

The minimum requirements for hot work in a confined space are:

• Consideration for carrying out a Job Safety Analysis (JSA) to identify and assess all risks associated with the work.
• To carry out a gas test to establish if flammable / explosive gases are present.

3.1.2. Zone 1 Hazardous Area

The minimum requirements for hot work in a Zone 1 hazardous area are:

• Consideration for carrying out a Job Safety Analysis (JSA) to identify and assess all risks associated with the work.
• A Special Permit for hot work obtained from the Authorising Officer and any necessary gas testing and monitoring arranged. The permit shall show the need for a gas test and continuous testing.
• Before starting hot work, the area in the vicinity of the task shall be tested for the presence of combustible gases.  Particular attention shall be paid to likely sources of leakage such as flanges and trapped areas such as drains.  If any combustible gases are detected, the hot work shall be stopped immediately and the Authorising Officer shall be notified.
• The time and result of each gas test shall be recorded on the Special Permit for Hot Work. Results of continuous monitoring shall be recorded as arranged by the Authorising Officer

3.1.3. Zone 2 Hazardous Area

The minimum requirements for hot work in Zone 2 hazardous areas are:

• Consideration for carrying out a Job Safety Analysis (JSA) to identify and assess all risks associated with the work.
• A Special Permit for hot work obtained from the Authorising Officer.  The permit shall show the need for any gas test and ongoing monitoring.
• Before starting hot work, the area in the vicinity of the task shall be tested for the presence of combustible gases.  Particular attention shall be paid to likely sources of leakage such as flanges and trapped areas such as drains, and for presence of combustible gases in hazardous pipelines, which would not normally contain such gases, e.g. hydrogen gas in a dormant sulfuric acid line.
• Pipes that may contain combustible gases shall be gas tested at the location where the pipe is to be cut, in accordance with Section 4.1.

If any combustible gases are detected, the hot work shall be stopped immediately and the Authorising Officer notified.

• The gas test shall either be continuous or be repeated every hour while hot work is in, and whenever work is being done in the vicinity which increases the likelihood of explosive gases being present.
• The time and results of gas tests shall be recorded on the back of the Special Permit for hot work.

3.1.4. Restricted Area

The minimum requirements for hot work in a restricted area are:

• Consideration for carrying out a Job Safety Analysis (JSA) to identify and assess all risks associated with the work.
• A Special Permit for hot work obtained from the Authorising Officer.  The Permit shall show the need for any necessary gas test and ongoing monitoring.
• The gas test shall either be continuous or be repeated every hour while hot work is in,  explosive gases being present.
• The time and results of gas tests shall be recorded on the back of the Special Permit for hot work.

Before starting hot work, the area in the vicinity of the task (including above and below) shall be cleared of any flammable or oxidising material and tested for the presence of combustible gases.  Particular attention shall be paid to likely sources of leakage such as flanges and trapped areas such as drains.  If any combustible gases are detected, the hot work shall be stopped immediately and the Authorising Officer must be notified.

3.1.5. Non-Hazardous Area

The minimum requirements for hot work in a non-hazardous area is:

• Permission and a work permit from the person responsible for the area or equipment to be worked on.

4. general precautions

4.1. gas testing

Gas testing is to be carried out as follows:

• The correct response and working order of the testing equipment shall be proved before testing atmospheric conditions.
• For any hazardous pipeline that could potentially contain combustible gases, even though the pipeline would not normally contain such gases, e.g. hydrogen gas in a dormant sulfuric acid line, shall be gas tested through a cold-drilled hole at the location where the pipe is to be cut or by use of a long probed tester, if the probe can reach the cut location.
• The JSA is to identify whether a cold-drilled hole can be safely carried out.
• If a positive result is obtained in any part of the confined space, hazardous zone or restricted area, further ventilation shall be carried out and the test repeated.
• Testing shall be repeated at least 8-hourly and more frequently if a naked flame (such as a gas torch) is being used, or conditions are such that gas/vapour may be evolved during working operations.

4.2. precautions for hot work

The following precautions shall apply during hot work:

• Ensure that firefighting systems in the area are fully operational, or provide a suitable alternative.
• A fire watcher shall be assigned while hot work is in progress, during lunch breaks and similar stoppages, and for at least 30 minutes after hot work has been completed.
• Keep the area clean and free of readily combustible and oxidising materials within 10 metres of the task.
• Prevent sparks and hot material from entering low-lying areas, such as drains.
• Use enclosures to ensure sparks and hot material from work above do not enter hazardous areas on a lower level.
• Ensure that appropriate fire extinguishers are available near possible sources of ignition.
• Keep welding machines and gas cylinders in a well-ventilated position and at least 2 metres from low-lying areas, such as drains and culverts.
• Earth welding machines directly to the equipment being welded, as close to the welding point as possible.
• Do not drape power leads across pipelines or access ways.
• Isolate electrical tracing and heating coils on pipelines.
• When work is suspended for a substantial period such as a lunch break or overnight de-energise the power source; remove electrodes from holders and place holders where they will not produce accidental arcing.
• Isolate valves and remove hoses from gas cutting equipment, when work is suspended for a substantial period, such as lunch break or overnight.
• Site welding machines and oxygen cylinders outside hazardous areas.
• Where hot work is done at height, signpost and barricade the are immediately below to restrict entry.

4.3. Explosive gas atmospheres

An explosive gas atmosphere results from the combination of:

• the concentration of combustible gas or vapour,
• the presence of oxygen (for example, in the air).

5. reference material

5.1. regulations and codes

Occupational Safety and Health Regulations 1996.

5.2. Australian standards

AS 2430  Parts 1, 2 and 3 - Classification of Hazardous Areas

AS 1674 Fire Precautions in Cutting, Heating and Welding Operations.

Forms Relevant to this Procedure

F-S-08- Hot Work Permit

Date published: 25/07/2013

* -25/07/2013 12:27:06 PM