MEP · 10 checks

Gas Installation
QA inspection checklist

Gas installation quality audit.

Every check below carries what good looks like, when it passes, the standard it comes from and the defects that usually fail it. That guidance is what turns a tick-box into an inspection.

Pipework & Installation

  1. 1.
    Pipe material and size correct
    What to look forPipe material per design and gas family — copper to BS EN 1057 R250, steel to BS EN 10255, MDPE to BS EN 1555 below ground. Pipe diameters sized via IGEM/UP/2 for the design load with pressure drop ≤ 1 mbar (natural gas) or ≤ 2.5 mbar (LPG) under maximum simultaneous use.
    Acceptable whenPipe sized per IGEM/UP/2 and verified against connected appliance kW load and length of run. Material per location — copper indoors, steel for risers, yellow MDPE buried with marker tape. Identification per BS 1710 (yellow ochre).
    StandardIGEM/UP/2 Edition 3 — Installation pipework on industrial and commercial premises. BS 6891 (domestic) / BS 6400 (meters). BS EN 1057, BS EN 10255, BS EN 1555. Gas Safety (Installation and Use) Regulations 1998.
    Common defectsPipe undersized — appliance starved, soot/COWrong material below ground (copper instead of MDPE)No yellow identification — confusion with other servicesMDPE used inside building (combustible, prohibited)Joint type not approved for the family (compression on natural gas indoors > 28 mm)
  2. 2.
    Joints tested and accessible
    What to look forSoldered, brazed, compression, or welded joints per design. Mechanical joints accessible — not buried in walls or above closed ceilings. Joints inspected before any concealment. Each joint visible during tightness test.
    Acceptable whenPer IGEM/UP/2 and BS 6891: only welded, brazed, or capillary-soldered joints concealed. Compression joints must remain accessible. Buried pipework typically electrofusion-welded MDPE. Joints sleeved through walls — sleeve sealed at one end only.
    StandardIGEM/UP/2. BS 6891:2015+A1:2019 — Domestic gas pipework. BS 6400-1/2/3. Gas Safety (Installation and Use) Regulations 1998.
    Common defectsCompression fittings buried in plaster — illegal, undetectable leaksJoints behind permanent boxing without access panelBrazed joint not penetrated — surface bond onlyPipe sleeved both ends — water/condensate trapped, corrosionNo witness of joint test before concealment
  3. 3.
    Isolation valves accessible and labelled
    What to look forEmergency Control Valve (ECV) at meter position, accessible without keys/tools. Each appliance has its own isolation valve within 600 mm of appliance. Valves labelled with appliance served. Lever orientation indicates open/closed at a glance.
    Acceptable whenPer IGEM/UP/2 and BS 6891: ECV maximum 1.5 m above floor, accessible (within 1.0 m horizontal of meter). Appliance isolation within 600 mm. Tags or engraved labels per BS 1710 / 1192. AECV (Additional ECV) at zone boundaries in commercial.
    StandardIGEM/UP/2. BS 6891. BS 1710:2014 (pipe identification). Gas Safety (Installation and Use) Regulations 1998 reg 8.
    Common defectsECV behind cupboards or built-in furniture — emergency access blockedNo label — wrong valve closed in emergencyValve too high — cannot be reached without ladderCombined isolation valve serves multiple appliances — cannot isolate oneValve handle removed for "tidy" appearance
  4. 4.
    Ventilation requirements met
    What to look forOpen-flue and flueless appliances have permanent low-level air supply per BS 5440-2. Boiler rooms with heat input > 70 kW have high and low ventilation. Air vents not obstructed by furniture or external grilles. Combustion air calculation cross-checked against appliance net heat input.
    Acceptable whenPer BS 5440-2:2009 — flueless: 100 cm² per kW (with 5 cm² minimum); open-flue: 5 cm² per kW > 7 kW; room-sealed: nil (sealed unit). Plant rooms per IGEM/UP/10: high vent ≥ 50% of low vent area. Vents rodent and weather protected.
    StandardBS 5440-2:2009 — Ventilation for gas appliances. IGEM/UP/10 Edition 3 — Installation of flued gas appliances. Gas Safety (Installation and Use) Regulations 1998.
    Common defectsVent blocked by external cladding or insulationVent cross-sectional area undersized — incomplete combustion, COHigh-level vent missing in plant room — heat build-upFree-area calculation ignored grille obstructionInternal vent door fitted with grille that closes
  5. 5.
    Gas meter and regulator installed correctly
    What to look forMeter installed in approved location — outside in meter box, or internal location with approval. Meter on adequate bracket, level, with manufacturer's clearances around it. Regulator vent piped to safe outside position. ECV upstream of meter.
    Acceptable whenPer BS 6400-1 (≤ U6 domestic) / BS 6400-2 (commercial). Meter height typically 0.6-1.8 m. Installation by gas transporter or competent person registered for meter work. Meter box BS EN 1555-7. Regulator vent ≥ 25 mm pipe to outside, screened.
    StandardBS 6400-1:2016 — Domestic meters ≤ 6 m³/h. BS 6400-2:2010+A1:2017 — Commercial meters. IGEM/GM/8 — Meters and metering installations.
    Common defectsRegulator vent terminated indoors — gas release into building if regulator failsMeter at wrong height — unreadable, unstableNo bracket — meter hanging on pipework, stress on jointsMeter inside under stair without ventilation — confined space riskWrong meter capacity for design load (U6 supplying > 6 m³/h)

Testing & Certification

  1. 6.
    Tightness test passed
    Record: Test pressure (mbar)
    What to look forTightness test (TPR) carried out per IGEM/UP/1 (commercial) or IGE/UP/1B (domestic) using calibrated water gauge / digital manometer. Pressure rise/drop within allowable. ECV closed during test. Test recorded with date, engineer, pressure and result.
    Acceptable whenPer IGE/UP/1B (domestic ≤ 35 mbar): test at 20 mbar, no drop in 2 minutes after 1-minute stabilisation (allowing thermal correction). IGEM/UP/1 (commercial): test pressure and duration per pipe size, allowable drop calculated from pipe volume.
    StandardIGE/UP/1B Edition 3:2021 — Tightness testing of small low pressure systems. IGEM/UP/1 Edition 2 — Commercial tightness testing. BS 6891.
    Common defectsPressure drop > permitted — leak somewhere, must be locatedTest cut short before 2-minute holdNo thermal correction — false drop on cooling pipeworkTest gauge uncalibrated — invalid resultNo record kept — no proof of competent commissioning
  2. 7.
    Let-by test completed
    What to look forLet-by test on ECV before tightness test — confirms ECV holding without leak. Pressure raised on downstream side of closed ECV; no upstream pressure transmission. Test result recorded.
    Acceptable whenPer IGE/UP/1B: at 7 mbar test pressure, no rise on gauge in 1 minute. If pressure rises, ECV is letting by — installation cannot be commissioned until ECV replaced or repaired by transporter.
    StandardIGE/UP/1B Edition 3:2021. IGEM/UP/1.
    Common defectsLet-by test skipped — defective ECV not detectedECV passing but engineer continues anywayTest run with downstream open — no isolation, false passNo record — disputes if ECV replaced later
  3. 8.
    Purge completed safely
    What to look forPurge of installation pipework after tightness test using gas — air vented to safe outside location. Purge volume calculated. Purge complete when 100% gas detected at terminal point (gas detector). No-smoking exclusion zone maintained. Adjacent works stopped.
    Acceptable whenPer IGE/UP/1A — purge volume ≥ 5 × pipe internal volume. Vent to outside ≥ 600 mm from openings. Gas detector or smell test confirms purge. Purge supervised by competent gas engineer.
    StandardIGE/UP/1A Edition 2 — Strength testing, tightness testing and direct purging. Gas Safe Technical Bulletin 001 (Purging).
    Common defectsPurge into building space — gas release indoorsPurge volume underdone — air pocket in pipe, ignition failNo exclusion zone — ignition source nearbyPurge run through appliance — appliance gas valve riskMultiple purges combined incorrectly
  4. 9.
    Gas Safe certificate issued
    What to look forGas Safety (Installation and Use) certificate issued by Gas Safe registered engineer to client and held on file. Includes installation details, test results, appliance specifics, and engineer registration number. Defect-free certificate not issued if any "At Risk" or "Immediately Dangerous" findings.
    Acceptable whenPer Gas Safe Register / Gas Industry Unsafe Situations Procedure (GIUSP): only safe-to-use appliances commissioned. Annual landlord gas safety record (CP12) where applicable. CP1 (commercial) or CP4 (purge & test) as appropriate.
    StandardGas Safe Register requirements. Gas Industry Unsafe Situations Procedure (GIUSP). Gas Safety (Installation and Use) Regulations 1998 reg 36.
    Common defectsCertificate not issued — non-compliance with regulationsCertificate issued by non-Gas-Safe engineerDefects noted but not communicated to clientCertificate covers wrong property/installationNo copy held by installer — disputes about scope
  5. 10.
    Engineer Gas Safe registered — card verified
    What to look forEngineer holds current Gas Safe ID card with photo. Card lists the specific competencies (CCN1, CENWAT, MET1, etc.) covering the work. Card verified online via Gas Safe Register or QR code. Expiry date in date.
    Acceptable whenPer Gas Safe Register: engineer must hold competency for the gas family (Natural Gas, LPG), pressure tier, appliance type, and pipework class. Verification via gassaferegister.co.uk. Working under supervision allowed only with apprenticeship documentation.
    StandardGas Safety (Installation and Use) Regulations 1998 reg 3. Gas Safe Register Operating Manual.
    Common defectsCard expired — engineer no longer registeredWrong competencies — engineer not qualified for commercial tierPhoto on card does not match personApprentice working unsupervised — illegalEngineer on someone else's registration ("ghost" working)

Questions people ask

What is a gas installation QA inspection for?

To record that the work was checked against the specification before it was covered up or handed over: a pass or fail against each item, a measurement where one matters, and a photo where it failed. It is the evidence a client's quantity surveyor or clerk of works asks for, and the thing that settles the argument at final account.

What standards does this checklist check against?

Each item names its reference. On this checklist that includes IGEM/UP/2 Edition 3, IGEM/UP/2. BS 6891:2015+A1:2019, IGEM/UP/2. BS 6891. BS 1710:2014 (pipe identification). Gas Safety (Installation and Use) Regulations 1998 reg 8., BS 5440-2:2009, BS 6400-1:2016, IGE/UP/1B Edition 3:2021. The contract specification and the approved drawings always take precedence over a general standard; where they say something stricter, inspect to that.

Who signs a QA inspection off?

The person who carried out the check, named and dated, and where the contract calls for it the client's representative as a witness. The signature records that the check was done and what was found. It is not a warranty of the work.

How many items are on it, and do I have to use them all?

10 checks across 2 sections. Delete what does not apply to the job and add anything the specification asks for that is not here. A checklist that has plainly been thought about carries more weight than a long one nobody read.

Is this useful for a subcontractor as well as a main contractor?

More so. The subcontractor is the one who gets asked to come back and open something up. A signed inspection sheet with photos at the time is the cheapest insurance on a construction site.

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