Gas Pipework

Are you replacing your gas appliances or installing new appliances into a new property? Do you know the up-to-date regulations? Does the existing pipework comply with the latest directives, are they the correct size and is the correct gas meter is installed?

You may be surprised that a significant number of existing gas supply systems are installed with undersized gas meters and pipework. This may be due to the pipework and meter were not correctly sized in the first place or additional equipment have been added over time. Nearly all new appliances require the correct volume of gas at the designed pressure to operate correctly, so under sizing the gas meter or gas pipework can cause significant problems in their operation and reliable operation

For existing systems that are being upgraded the meter and pipework must be fully inspected, not just for size but the length of the pipe run and the number and types of fittings.

Do all the fittings meet the current regulations, is it threaded, flanged, copper etc?

What will be the pressure drop over the system including the gas meter, is it under the required 1mbar?

Is the pipework correctly marked?

Is there a solenoid valve correctly installed just inside the plantroom?

Is there a schematic of the gas pipe system in the gas meter room and the plantroom?

Does the gas pipe run through void spaces, is the spaces correctly ventilated?

Are all the pipework correctly sleeved as it passes through walls and floors?

We are here to inspect the system to ensure that the gas pipework and gas meter is suitable for the new appliances and that the supply pressure is adequate for all the appliances connected running to the system running at 100% output

All gas meters will have a maximum flow rating, but it is important to check the pressure drop at the required maximum gas flow rate. Most domestic and small commercial properties that require gas meters up to 100m³/h are fitted with diaphragm meters, these will have an inherent pressure drop depending with flow. The pressure drop can be between 2 and 4mbars when the gas meter is operating at 100% flow rate. For these gas meters it is prudent to match the maximum gas requirement to about 70% of the gas meter rating, this is likely to ensure the pressure drop over the gas meter to below 1 mbar.   

For all gas pipes 75mm and over must now be welded and connected with flanged joint, in the past it was common to thread pipework up to systems as large as 150mm, and on LPG all pipework 50mm and over must be welded, will again be welded with flanged joints

All pipework and fittings used must be suitable for transporting natural gas or LPG and correctly painted or marked clearly.

We carry out design, installation and commissioning of large domestic and all commercial gas pipework for both natural gas and LPG. The installations will comply with all relevant regulations including the Institute of Gas Engineers UP2 Edition 3, BS6644:2011, Safety in the installation and use of gas systems and appliances Gas Safety (Installation and Use) Regulations 1998 as amended Edition 5 (2018) and the Health and Safety document; L56 (Fifth edition) Published 2018. Other regulations that may cover Gas Supplies passing through communal areas or other properties are covered in the British Standard BS6891-1, IGEM/UP/7 Edition 2 and, where necessary, manufacturer’s installation instructions. Guidance for gas in flats and other multi-occupancy dwelling buildings can be found in 
IGEM/G/5(3). 

Before any commercial (and large domestic) gas pipework is taken out of service or put into service the pipework must correctly purged by a suitable qualified engineer. This may be using nitrogen as an innate gas to ensure that there is never an explosive air/gas mix in the pipeline, and the procedure is set down in IGE/UP/1 (or1A)

Just a look at all the commercial gas regulations

In England, gas pipework and fittings in commercial buildings, flats, hospitals, and schools must comply with several laws, regulations, British Standards, and guidance documents. Here’s a comprehensive overview:

 Primary Regulations for Gas Pipework & Fittings in England

 Gas Safety (Installation and Use) Regulations 1998 (GSIUR)

 Legal requirement for all gas work in domestic and non-domestic premises.

  • Covers installation, maintenance, safety of appliances, pipework, and flues.

  • Employers must ensure gas work is done by Gas Safe-registered engineers.

  • Key clauses:

    • Regulation 3: Competence of persons.

    • Regulation 26: Safe installation and maintenance.

    • Regulation 27: Tightness testing and purging.

    • Regulation 35: Installation pipework should not be dangerous.

 Building Regulations 2010 (Approved Document J – Combustion appliances and fuel storage)

 

  • Applicable to flues, ventilation, and chimney systems, but also references gas safety.

  • Applies to buildings undergoing construction or major alterations.

 Health and Safety at Work etc. Act 1974 (HSWA)

 

  • Employers must ensure safety of employees and others.

  • Applies to gas safety in workplaces (schools, hospitals, commercial kitchens, etc.).

 Workplace (Health, Safety and Welfare) Regulations 1992

 

  • Covers ventilation, maintenance, and safety of services.

  • Gas services must be safely installed and maintained.

 

Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR)

 

  • Addresses risks of gas leaks and explosions.

  • Risk assessments must include pipework and fittings in plant rooms or kitchens.

 

The Pressure Systems Safety Regulations 2000 (PSSR)

 

  • Applies to pipework under pressure (e.g. LPG systems, high-pressure mains).

 

Key British Standards and Industry Specifications

 

General Pipework Standards

 

  • BS 6891: Low pressure gas pipework up to 35mm in domestic and small commercial premises (≤0.035 m³/h flow).

  • IGEM/UP/2: Installation pipework for natural gas & LPG in industrial and commercial premises.

  • IGEM/UP/1 & UP/1A: Strength testing, tightness testing, and purging of pipework.

  • IGEM/UP/6: Gas installations in educational establishments.

  • IGEM/UP/10: Gas installations in multi-occupancy buildings.

 

Specialist Standards

 

  • HTM 02-01: Medical gas pipeline systems in hospitals.

  • HTM 04-01: Water safety, relevant where water pipes are in proximity to gas installations.

 

Guidance and Industry Publications

 

Institution of Gas Engineers and Managers (IGEM) Guides

 

These are essential for non-domestic gas work:

 

  • IGEM/UP/1: Strength testing and purging of pipework >28mm.

  • IGEM/UP/2: Design and installation of gas pipework in industrial and commercial settings.

  • IGEM/UP/6: Gas safety in schools.

  • IGEM/UP/10: Multi-occupancy buildings – covers meter locations and riser installations.

  • IGEM/G/5: Gas in multi-dwelling buildings (including laterals and risers).

  • IGEM/G/11: Gas supplies to mobile dwellings and outdoor events.

 

Gas Safe Register Guidance

 

  • Covers acceptable practice and qualifications needed.

  • Free downloads and bulletins for registered engineers.

 

HSE (Health & Safety Executive) Guidance

 

  • INDG238: Gas safety in catering establishments.

  • HSE L56: Approved Code of Practice and guidance to the GSIUR (very authoritative).

  • HSE PM5: Guidance for gas plant safety, especially older installations.

 

Design and Installation Considerations

 

When working on commercial and public buildings, consider:

 

  • Material: Steel (BS EN 10255), copper (BS EN 1057), or MDPE for external buried pipes.

  • Testing: Strength and tightness testing per IGEM/UP/1 or UP/1A.

  • Purging: To avoid air/gas mix that could be explosive.

  • Ventilation: Sizing and location in line with GSIUR and IGEM guidance.

  • Accessibility: Riser cupboards, ceiling voids, or plantrooms.

  • Labelling and identification: BS 1710 for pipe marking.

  • Emergency isolation: Essential in schools and kitchens – key part of IGEM/UP/2 and GSIUR.

 

 

Specific Building Types – Notes

 

Schools

 

  • Must follow IGEM/UP/6.

  • Mandatory emergency shut-off valves in classrooms.

  • Timers and key-operated valves to prevent misuse.

 

Hospitals

 

  • Must also comply with HTM 02-01 for medical gases.

  • Natural gas installations still follow GSIUR and IGEM/UP/2.

 

Flats & Multi-Dwelling Buildings

 

  • Follow IGEM/UP/10 and IGEM/G/5.

  • Pay special attention to meter locations, risers, fire separation, and ventilation.

 

Commercial Kitchens

 

  • Must comply with:

    • IGEM/UP/19: Ventilation and interlocks in catering appliances.

    • GSIUR Reg 27 (tightness) and Reg 35 (safe condition).

    • Emergency cut-off valve with clearly marked location.

 

 

Summary Checklist

 

Requirement Reg or Guide

  Competent person (Gas Safe) GSIUR Reg 3

Pipe sizing/design IGEM/UP/2

Testing/purging under 28mm IGEM/UP/1

Testing/purging over 28mm IGEM/UP/1A

Ventilation GSIUR, IGEM/UP/10 Edition 4, BS6644:2011, BS5544, IGEM/UP/19 (kitchens)

Emergency shut-off

IGEM/UP/6 (schools), IGEM/UP/2

Pipework material standard

BS EN 10255 (steel), EN 1057 (copper)

Multi-occupancy buildings

IGEM/UP/10, IGEM/G/5

Fire safety in risers

Building Regs Part B, UP/10

Catering kitchens

IGEM/UP/19, HSE INDG238

Hospitals

HTM 02-01, IGEM/UP/2