Air testing is used to verify the integrity of gravity drainage systems before they are buried and backfilled. The test involves sealing the pipeline and pressurising it with air to detect leaks at joints and connections. Although the pressures are relatively low, trapped energy in sealed pipework can cause plugs to blow out violently. This talk covers the safe procedures for air testing drainage on UK construction sites.
Key Hazards
Plug blowout from air pressure launching the stopper at high velocity
Workers struck by displaced inflatable bags or mechanical stoppers
Pipeline movement from trapped air pressure in unsecured pipe sections
Ear injuries from sudden pressure release creating a loud noise
Control Measures
Use only test plugs rated for the pipe diameter and the required test pressure.
Restrain test plugs securely to prevent blowout using struts, chains, or purpose-built frames.
Establish an exclusion zone at both ends of the test section and at all access points.
Pressurise the section gradually and monitor the gauge continuously during the hold period.
Never exceed the maximum test pressure specified in the testing standard or plug rating.
Ensure the pipeline is adequately restrained and bedded before applying air pressure.
Bleed air pressure completely through the test valve before removing any plug.
Brief all nearby workers on the test schedule, exclusion zones, and the plug blowout risk.
Record all test results including pressure, hold time, and ambient temperature on the test certificate.
Remember
Restrain all test plugs securely to prevent them from blowing out under pressure
Establish exclusion zones at both ends of the test section during pressurisation
Never exceed the maximum test pressure specified in the standard or the plug rating
Bleed all air pressure completely before attempting to remove any test plug
Record test results including pressure, duration, and temperature on the certificate
Applicable Legislation: CDM 2015 · Pressure Systems Safety Regulations 2000 · BS EN 1610 (Drain and Sewer Construction Testing) · Building Regulations Approved Document H