Method Statement for Pressure Testing — UK
A free, BS EN 805 / BS EN 12266-aligned method statement for UK hydrostatic and pneumatic pressure testing of pipework, vessels and systems — covering test-medium selection, exclusion zone, stored-energy calculation and the witness sign-off the principal contractor actually asks for.
UK (RAMS) example document — Two-Storey Rear Extension — 14 Birchwood Lane, Reading. Client: Mr & Mrs A. Whitfield (Private Client). Site: 14 Birchwood Lane, Reading, RG1 5JT. Scope: Construction of a two-storey rear extension (6.4m × 4.2m) to an existing semi-detached dwelling. Works comprise breaking out of existing rear elevation, trench-fill foundations to 1.0m, traditional cavity blockwork to first floor, pre-stressed concrete lintels, timber roof structure with natural slate finish, plus alterations to existing rear wall to form structural opening with rolled steel joist (RSJ 203×102 UB23). Works programmed over 9 weeks with a peak site team of 6 operatives. Hazards assessed: Manual handling — blocks, lintels, plasterboard, Working at height — independent scaffold & roof structure, Buried services strike during excavation, Collapse of excavation / trench wall, Hand-arm vibration (HAVS) — breaking out, drilling, Silica dust — cutting blocks, brick, concrete, Vehicle/pedestrian segregation — narrow domestic street.
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- Site-specific draft
- Pressure Testing hazards baked in
- Ready for competent-person review
Built around recognised UK method statement structure — hazards, controls, sequence, PPE and sign-off. Ready for competent-person review.
Pneumatic pressure testing is the highest-stored-energy activity routinely conducted on UK construction sites, and a single un-witnessed pneumatic test using compressed air on a 6-inch line at 10 bar contains the equivalent kinetic energy of around 1 kg of TNT. The 2018 HSE prosecution of a Teesside fabricator (£800,000 fine, three operatives injured after a pneumatic test rupture on a 12-inch chemical-plant flange) and the 2022 Hampshire incident (one fatality, compressed air on a polypropylene fitting) both trace to the same MS gaps: no stored-energy calc, no exclusion-zone radius, no hydrostatic-first decision. This page sets out what a defensible UK pressure testing method statement looks like in 2026 — test type, calculation, exclusion, witness — with a free editable template.
When is it required?
Pressure testing on any UK site under CDM 2015 needs a written method statement before the test pump or compressor is connected. Water-main testing follows BS EN 805 (typically 1.5x working pressure for 1 hour with <0.2 bar drop), gas-pipework testing follows IGEM/UP/1 or IGEM/UP/1A, process and chemical-plant testing follows BS EN 13480-5 and ASME B31.3. Pneumatic testing should be the exception, not the default — HSE's Pressure Systems Safety Regulations 2000 and the Engineering Equipment and Materials Users' Association (EEMUA) Publication 219 both require a written justification for any pneumatic test where hydrostatic is feasible. PSSR 2000 also applies to the test rig itself.
What a good one looks like
A defensible pressure testing MS runs to 8–14 pages and names every specific. It identifies the system under test (e.g. '6-inch carbon-steel chilled-water line, 86m, design pressure 10 barg, test pressure 15 barg per ASME B31.3'), the test medium (e.g. 'hydrostatic — town's mains water with corrosion inhibitor Sentinel X100, blue-dyed for leak detection'), the rig (e.g. 'Hydra-Tech HT-200 air-operated hydrostatic pump, gauge ELE 0–25 bar 0.1 division calibrated 14/02/2026'), the stored-energy calc (e.g. 'E = 0.05 MJ at 15 barg test pressure — within acceptable hydrostatic envelope'), the exclusion zone (e.g. 'hydrostatic 3m radius; pneumatic 50m radius per EEMUA 219'), the witness (e.g. 'Aviva engineering surveyor or independent CompEx-credentialed witness'), and the acceptance criteria.
Pressure Testing hazards & controls
The site-specific hazards a pressure testing MS must address, with the controls that take residual risk to an acceptable level.
| Hazard | Persons at risk | Controls | Residual |
|---|---|---|---|
| Pneumatic rupture — high stored energy | Test crew, anyone in exclusion radius | Hydrostatic preferred — pneumatic only with written justification; stored-energy calc per EEMUA 219; exclusion zone calculated per stored energy (typically 50m for >0.2 MJ); ALL personnel out of zone; rig and gauge behind blast wall; ramp-up in 10% increments with 5-min hold at each | Medium |
| Hydrostatic burst — water hammer or weld failure | Test crew, witness | Pre-test inspection of all welds, joints, valves; system filled and vented before pressurisation (entrapped air is the source of hydrostatic violence); ramp-up controlled by certified test pump, NOT mains; gauge calibrated within 12 months; exclusion 3m hydrostatic | Low |
| Test-medium contamination on potable water system | Consumers downstream | Potable water only on potable systems; corrosion inhibitor (Sentinel X100) approved for potable use; system flushed and chlorinated per BS 6700 after test before re-commissioning; chlorinated water disposed of to foul, not to surface drain | Low |
| Pressure valves or flange failure — flying fragments | All in zone | Valves and flanges rated >150% test pressure; isolation valves tagged with 'closed for test' before pressurisation; bolt torque to spec on every flange; no test on un-supported pipework; pipe supports loaded before test (cold pull-up complete) | Low |
| Stored test-medium release after test | Decommissioning crew | Controlled depressurisation through metered bleed valve at <1 bar/min; never crack a flange under pressure; system fully isolated and drained before any joint broken; lock-out / tag-out on isolation valves until depressurised | Low |
| COSHH — corrosion inhibitor, glycol, leak-detection fluid | Test crew | COSHH sheet for every product; nitrile gloves; eye protection during dosing; eye-wash bottle on rig; spill cloth; no flux on potable joints; inhibitor dosed by closed system to avoid splash | Low |
| Slips on water during hydrostatic fill / leak | Test crew, others | Drip trays under bleed valves; sand or absorbent for spills; non-slip safety boots; cordoned working area; spill kit on rig; permeable areas avoided where possible | Low |
| Confined-space test — vessel or tank entry | Internal inspector | Confined space risk assessment; gas test before entry; rescue tripod and harness; top-man on radio; never internal entry on a system that has been under pressure unless fully isolated, drained, vented and tested O2 19–21% | Medium |
Step-by-step sequence
- 1
1. Pre-test brief & stored-energy calc
Stored-energy calc completed per EEMUA 219, signed by competent engineer. Test type chosen (hydrostatic preferred). Witness arranged (insurance engineer or in-house competent person). Crew briefed, sign-on register, exclusion zone barriered.
- 2
2. System preparation & isolation
Test boundaries isolated (typically blank flanges or rated isolation valves). Tag-out on isolation valves. Pressure-relief devices, gauges and instruments removed or isolated. Supports loaded (cold pull-up complete). Visual inspection of all welds and joints.
- 3
3. Filling and venting (hydrostatic)
System filled with test medium from low point, vented from high point until air-free. Vent valves visually checked. Static fill held for 30 mins to detect gross leaks before pressurisation.
- 4
4. Pressurisation ramp-up
Pressure ramped in 10% increments via test pump (NOT mains supply). Hold 5 minutes at each increment; visual check for leaks, gauge deflection, pipe movement. Continue to test pressure (typically 1.5x design).
- 5
5. Hold and acceptance
Hold at test pressure for 1 hour minimum (BS EN 805 water main) or 24 hour static (acceptance check). Pressure drop acceptance: <0.2 bar drop for water main, calculated tolerance for compressible systems. Witness verifies and signs.
- 6
6. Controlled depressurisation
Depressurised at <1 bar/min via metered bleed valve to safe discharge point. System drained from low points. Test medium disposed per environmental permit (foul drain for chlorinated water on water systems, recovery container for glycol or inhibited water).
- 7
7. Records, reinstatement & hand-back
Test certificate signed by tester and witness. Pressure-trace recorder log (where used) attached. System reinstated (instruments refitted, isolation valves opened, supports checked). Cert filed to QA pack and adopting authority where applicable.
6-inch chilled-water main pressure test, 86m run, Cambridge data-centre
A mechanical sub-contractor on a Cambridge data-centre fit-out produced a 11-page MS for the hydrostatic pressure test of a 6-inch carbon-steel chilled-water main (86m, design pressure 10 barg, test pressure 15 barg per ASME B31.3). Key entries: hydrostatic chosen per EEMUA 219 (compressible test deemed unjustifiable given hydrostatic feasibility); stored energy calc 0.05 MJ at 15 barg, well within hydrostatic envelope; rig Hydra-Tech HT-200 air-operated hydrostatic pump from Sykes Pumps, gauge ELE 0–25 bar with 0.1 bar division calibrated 14/02/2026 cert in appendix C; test medium town's mains water with Sentinel X100 inhibitor (potable-rated), blue-dyed; isolation by 6-inch ANSI 150 blank flanges at both ends, bolt torque to 220 Nm per ASME B16.5; vented from 4 high points until water-air-free at all; ramp-up in 10% increments with 5-min hold (1.5, 3.0, 4.5 ... up to 15 barg); held 60 min at 15 barg, pressure drop 0.08 bar (acceptance <0.2 bar); witness Aviva engineering surveyor Mark Davis ENG-2148, signature on cert ECW/86443; depressurised at 0.75 bar/min via metered bleed to drum; system reinstated 16:40 on test day; chilled-water commissioning continued the next day. Zero defects on completion. The MS, the stored-energy calc, the gauge calibration cert and the witnessed pressure-test cert were the four documents the M&E principal designer audited.
Or build a site-specific pressure testing MS in 5 minutes
The free template is a blank Word document. The Riskora builder ships with the pressure testing hazard library baked in — pick the preset, edit the site-specific bits, download a signed PDF.
Common mistakes that get a pressure testing MS rejected
- ·Pneumatic when hydrostatic is feasible — the 2018 Teesside and 2022 Hampshire incidents were both this
- ·No stored-energy calc — every recent pneumatic prosecution has cited a missing calc
- ·Exclusion zone smaller than EEMUA 219 calculated radius — the calc must drive the cordon
- ·Pressurising from mains supply instead of a controlled test pump — loss of ramp-up control is the leading cause of hydrostatic burst
- ·Cracking a flange under pressure to 'check' a joint — pressure must be down to zero and isolation tagged before any joint touched
- ·No witness, or a witness who is also the tester — independence is the principle the acceptance turns on
Frequently asked questions
When is pneumatic testing acceptable?
Only when hydrostatic is genuinely infeasible — heated insulated lines that can't tolerate water, vacuum systems, certain process plant. EEMUA 219 requires a written justification, a stored-energy calc and a 50m+ exclusion zone. Any commercial site that goes pneumatic without these will fail an HSE audit.
What's the stored-energy calc?
E = (P x V) x (1 - (Pa/P)^0.286) for compressible test (pneumatic); for hydrostatic the stored energy is negligible (water is essentially incompressible). EEMUA 219 sets the calculation method and the exclusion radius table — 50m radius for >0.2 MJ is the trigger most sites use.
Who can witness a pressure test?
An independent competent person — typically an insurance company engineering surveyor (Aviva, RSA, Allianz), an independent CompEx-credentialed engineer, or a principal-designer's QC engineer who is not the tester. The witness must hold the system written scheme of examination under PSSR 2000.
Do I need a written scheme of examination?
Yes for any pressure system above 250 bar-litres covered by PSSR 2000. The WSE must be in place BEFORE the test, not after. The test itself is part of the WSE evidence trail.
What's the acceptance criterion for a water main?
BS EN 805 — 1.5x working pressure held for 1 hour with <0.2 bar drop, plus a 24-hour static test at working pressure. The water company will specify the exact acceptance in the adoption spec; the MS must reference it.
References & further reading
Related method statements & RAMS
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