Plumbing Gas Fitting SWMS

Natural gas (predominantly methane) and LPG (liquefied petroleum gas—predominantly propane and butane) have fundamentally different properties requiring distinct safety considerations and installation procedures. Natural gas is lighter than air with specific gravity approximately 0.55, so leaked gas rises and accumulates in roof spaces, ceiling voids, and upper building levels. LPG is heavier than air with specific gravity 1.5-2.0, so leaked gas sinks and accumulates in basements, pits, floor voids, and low areas, creating particularly hazardous conditions as explosive concentrations can develop in occupied lower levels before detection. This density difference affects leak detection and atmospheric monitoring procedures—natural gas work requires monitoring of upper levels and roof spaces, while LPG work requires monitoring of ground level and below-ground areas including excavations, pits, and basements where gas can accumulate invisible to normal work area monitoring. Operating pressures differ significantly, with natural gas typically supplied at low pressure (1.13 to 2.75 kPa) or medium pressure up to 210 kPa, while LPG is stored as liquid under pressure (vapour pressure approximately 800-1500 kPa depending on temperature and propane/butane ratio) and supplied to appliances at regulated low pressure. This pressure difference affects pipe sizing, materials, and testing procedures, with LPG storage and supply systems requiring enhanced pressure protection, emergency shutdown provisions, and distance separations from buildings and property boundaries. Natural gas is supplied via underground distribution networks eliminating on-site storage requirements, while LPG requires on-site storage in cylinders or bulk tanks introducing hazards related to storage vessel integrity, location requirements, filling procedures, and emergency response for storage vessel failures or fires. Appliance requirements differ because gas combustion characteristics vary—appliances must be specifically configured for natural gas or LPG with different orifice sizes, burner adjustments, and control settings, with appliance conversion between gas types requiring component replacement and adjustment per manufacturer procedures to prevent dangerous over-firing or incomplete combustion. Purging procedures differ due to density—natural gas purging uses upward venting taking advantage of gas rising characteristics, while LPG purging requires careful attention to vent locations ensuring heavy gas vapour does not accumulate in low areas where ignition sources may exist. These differences make gas fitter training and licensing specific to gas types in some jurisdictions, with separate Type B licences for natural gas and LPG work recognising the distinct safety knowledge required for each gas type.

Emergency response to gas leaks requires immediate action prioritizing life safety, prevention of ignition, and notification of emergency services and gas suppliers. If gas odor is detected or gas leak is suspected, immediately implement emergency procedures without delay for verification or investigation. Evacuate all personnel from the affected area including the building or work site where gas leak is suspected, moving to outdoor assembly point upwind and at safe distance from leak location. During evacuation, prohibit use of any potential ignition sources including light switches, mobile phones, torches, vehicle starting, or any electrical equipment operation—gas leaks can create explosive atmospheres that ignite from tiny sparks or static discharge. If safe to do so without entering the affected area or creating ignition risk, shut off gas supply at the meter or isolation valve outside the affected building or area—never enter gas-affected buildings or confined spaces to shut off internal isolation valves as this exposes you to explosion and asphyxiation risks. From safe location clear of the affected area, immediately call emergency services (000) reporting the gas leak, location, and requesting Fire and Rescue attendance who have appropriate equipment and training for gas leak response. Also notify the gas supply utility using their 24-hour emergency number (typically listed on gas bills and meters, or available through 000 operators), providing location details and leak severity so utility emergency crews can respond to isolate supply and make safe. Establish exclusion zones preventing re-entry to affected buildings or areas until gas emergency responders declare the area safe. Never attempt to locate leaks or make repairs during an active gas emergency—these activities are for trained gas emergency responders with appropriate equipment, not construction workers or even licensed gas fitters without specialised emergency response training and equipment. If casualties occur from gas exposure or explosion, provide first aid if safe to do so, prioritizing rescue from gas-affected areas only if you have appropriate breathing apparatus and confined space rescue training—attempting untrained rescue from gas-affected confined spaces or buildings results in multiple fatalities as rescuers are overcome by oxygen-deficient or toxic atmospheres. For gas fitters who discover leaks during gas fitting work, the same evacuation and emergency notification procedures apply, but additionally document circumstances of the leak discovery, atmospheric monitoring readings if available, and any work activities that may have contributed to the leak to support investigation and prevent recurrence. Following emergency response and site being declared safe by gas emergency responders, conduct formal investigation of leak cause, review procedures and controls that failed to prevent the leak, and implement corrective actions before resuming gas fitting work. Document all gas leak incidents regardless of severity to support analysis of trends, identification of recurring issues, and continuous improvement of gas safety systems.

Ventilation assessment and provision for gas appliances is critical for preventing carbon monoxide (CO) poisoning from incomplete combustion, with requirements specified in AS/NZS 5601 based on appliance types, input rates, and room volumes. Begin by identifying appliance classifications under AS/NZS 5601 including flueless appliances that discharge all combustion products into the room (limited to low input rates and specific applications), flued appliances that discharge combustion products to outside through flue systems, and outdoor appliances installed in exterior locations with inherent unlimited ventilation. For flueless appliances (primarily domestic cooktops and some decorative gas log fires), calculate required ventilation openings using AS/NZS 5601 formulas based on appliance input rate in megajoules per hour (MJ/h) and room volume in cubic metres. The calculation determines minimum free area of ventilation openings required to provide adequate combustion air and dilute combustion products to safe concentrations. Ventilation openings must communicate directly with outdoors or through adjacent rooms that themselves have adequate ventilation to outdoors. Openings must be positioned to avoid blocking (high-level openings prevent furniture blocking, low-level openings prevent floor coverings or stored items blocking). For flued appliances including water heaters, space heaters, and commercial kitchen equipment, ensure adequate combustion air supply is provided either through natural ventilation openings calculated per AS/NZS 5601 based on appliance input rate and room volume, or through mechanical ventilation systems providing specified air change rates. Additionally, verify flue systems are correctly sized, installed with appropriate materials and slope, supported adequately, provide required clearances from combustible materials, and terminate at locations preventing combustion product re-entry to buildings through windows, doors, or air intakes. Commission flued appliances with spillage testing—temporarily block flue outlet and verify natural draft or fan extraction prevents combustion products from spilling into room, indicating correct flue sizing and adequate replacement air for combustion. For mechanical ventilation systems serving gas appliance rooms (common in commercial installations), verify interlocks prevent appliance operation if ventilation fails, air flow directions prevent combustion product circulation to other building areas, and make-up air is provided replacing exhausted air without creating negative pressures that could affect flue operation. Document ventilation provisions including calculations, ventilation opening sizes and locations, flue system details, and commissioning results to demonstrate AS/NZS 5601 compliance. Educate building owners on critical importance of maintaining ventilation provisions—never blocking ventilation openings, ensuring exhaust fans operate when appliances are in use, and recognizing symptoms of inadequate ventilation including condensation on windows, stuffy air, yellow or sooty flames, and CO alarm activation. Install CO alarms in residential premises with gas appliances providing additional detection of dangerous CO accumulation, though this is supplementary to proper ventilation not a substitute.

Working on live gas services—modifications or repairs to existing gas installations while gas supply remains connected—represents the highest-risk gas fitting activity requiring enhanced competency, specialized training, strict procedural controls, and often additional qualifications beyond basic gas fitting licences. Gas fitters performing live gas work must have extensive experience with gas systems (typically minimum 5-10 years licensed experience), demonstrated competency in high-pressure systems if live work involves pressure above domestic low-pressure ranges, specific training in live work procedures covering gas release control, emergency shutdown methods, fire suppression, and emergency response if immediate ignition occurs. Specialized equipment competency is essential including hot tapping machines that install connections to pressurized pipes through drilling and tapping while maintaining pressure containment, line stopping equipment that provides temporary internal isolation of pipes allowing sections to be isolated for work while maintaining supply to unaffected areas, and pressure monitoring systems confirming actual system pressures and flows match assumptions critical for safe work. Enhanced hazard recognition training is required covering assessment of system pressures through reading meters and gauges, identification of backflow risks where downstream pressure sources could prevent effective isolation, recognition of aging infrastructure deterioration that may cause unexpected failures during live work, and evaluation of building configurations identifying where leaked gas could accumulate creating explosion or asphyxiation hazards. Permit-to-work systems for live gas work should require senior gas fitter or supervisor approval before commencing live work, documented assessment of whether isolation is truly impractical compared to supply shutdown, atmospheric monitoring plan with continuous monitoring throughout live work, emergency response preparation including fire extinguishers and emergency shutdown procedures, and restriction of personnel to minimum required for the work excluding non-essential workers from hazard areas. Pre-work planning for live work involves detailed review of gas system configuration identifying all supply sources and potential backflow paths, verification of actual system pressures and flows through measurements not assumptions, gas utility coordination to verify supply configurations and obtain any required approvals for live work, and preparation of detailed work procedures specifying each step, tools required, atmospheric monitoring points, and emergency procedures. Communication protocols during live work require continuous dialogue between workers performing the work and safety observers monitoring conditions, pre-arranged signals or code words enabling rapid emergency shutdown, and notification to gas utility emergency services that live work is in progress enabling faster emergency response if incidents occur. Following live work completion, pressure testing of modified or repaired sections verifies integrity before returning to service, leak detection confirms no leaks exist at work locations, and formal close-out of work permits documents successful completion and return to normal operations. Many gas supply utilities and large industrial gas users prohibit live work entirely, requiring system shutdown for all modifications and repairs—when clients prohibit live work, gas fitters must not attempt to circumvent these restrictions regardless of apparent inconvenience or client pressure, as the prohibitions reflect understanding of extreme live work risks. Gas fitters should consider whether proposed live work is truly essential or whether planned shutdown is feasible with appropriate client coordination, scheduling during low-demand periods, or providing temporary alternative gas supply during shutdown for critical applications.

Australian Standard AS/NZS 5601 Gas installations provides comprehensive requirements for gas pipe materials, installation methods, support, protection, testing, and commissioning that collectively ensure safe, compliant gas systems. For pipe materials, AS/NZS 5601 specifies approved materials including black steel pipe (AS 1074) for exposed installations in all applications, steel pipe with approved coatings or wrappings for underground installations protecting against corrosion, polyethylene pipe (PE) meeting AS/NZS 4130 for underground natural gas installations up to specified pressures, copper tube (AS 1432 or AS 1571) for specific applications including meter connections and certain appliance connections, and corrugated stainless steel tubing (CSST) for specific applications per manufacturer approvals. Material selection depends on gas type—natural gas may use black steel, coated steel, PE, or copper; LPG requires more corrosion-resistant materials with certain limitations on copper use due to LPG corrosive characteristics. Operating pressure determines material requirements with higher-pressure systems requiring thicker-wall pipes or specific materials capable of safely containing higher pressures. For pipe jointing, AS/NZS 5601 specifies methods appropriate to pipe materials including threaded connections for black steel pipe using approved thread sealants or PTFE tape (not plumbing thread tape which is too thin), welded connections for steel pipe following welding standards and procedures, fusion welding for PE pipe creating homogeneous joints with full pipe strength, and compression fittings or soldered joints for copper following approved procedures. Installation requirements include pipe sizing using specified calculation methods ensuring adequate flow capacity and acceptable pressure drops, pipe support at maximum spacings preventing sagging and stress on joints, clearances from electrical services (minimum 150mm separation) and other utilities, protection from damage including impact protection in traffic areas and burial depth requirements for underground pipes (typically minimum 450mm cover), corrosion protection for buried steel pipes through coatings, wrappings, or cathodic protection systems, and fire protection for pipes penetrating fire-rated walls and floors. Pressure testing requirements vary by gas type and operating pressure, typically specifying test pressure 1.5 to 2.0 times operating pressure, test duration 30-60 minutes depending on system size and complexity, test medium (air, inert gas, or actual gas), and allowable pressure drop limits indicating leak-free installation (typically zero pressure drop for small installations, minimal calculated leakage for large systems). Leak detection is required before commissioning using approved methods including soap solution, electronic gas detectors, or pressure monitoring verifying no leaks exist at joints, connections, or penetrations. Purging procedures must follow AS/NZS 5601 methods ensuring complete air removal before energisation, preventing flammable mixture creation during purging, and venting purge gas to safe exterior locations. Ventilation requirements for appliance locations are specified based on appliance type and input rate, with detailed calculation methods for combustion air supply and combustion product dilution. Flue system requirements cover materials, sizing, installation, clearances, and termination locations ensuring safe combustion product exhaust. Compliance certification requires Certificate of Compliance issued by licensed gas fitter to gas supply utility, building owner, and regulatory authority documenting installation complies with AS/NZS 5601, has been pressure tested and leak tested, and is safe for operation. Installers should maintain current AS/NZS 5601 standard and reference it throughout gas fitting work as it is the definitive technical standard for all gas installation requirements in Australia.