Commercial Gas Testing & Purging

Testing and purging is the part of commercial gas work where most installations are won or lost. A new installation cannot be put into service until it has been strength tested (where required), tightness tested and purged, and an existing installation cannot be safely worked on or decommissioned without the same discipline.

These guides explain how the procedures in IGEM/UP/1 and IGEM/UP/1A work in practice: how installation volume is calculated, how test pressures and durations are chosen, when direct purging is acceptable and when nitrogen is needed, and what records should be produced at the end.

Guides in this section

• What Is IGEM/UP/1? Commercial Gas Testing & Purging Standard

  IGEM/UP/1 explained: scope, when it applies instead of UP/1A, and the strength, tightness and purging procedures it sets out.

• What Is IGEM/UP/1A? Small Commercial Gas Installations

  IGEM/UP/1A explained: the limits that decide whether you can use it, and how its tightness test and purge procedure differs from IGEM/UP/1.

• Commercial Gas Tightness Testing Procedure, Step by Step

  The full commercial gas tightness test procedure: volume calculation, gauge selection, let-by test, stabilisation, test period and pass criteria.

• Strength Test vs Tightness Test: What Is the Difference?

  Why new commercial gas pipework needs a strength test before a tightness test, how the pressures differ, and when a strength test is not required.

• Commercial Gas Purging Explained

  What gas purging is, why it is needed on commercial pipework, how purge volume and velocity are calculated and how a purge is proven complete.

• Direct Purging vs Indirect Purging

  The difference between direct purging with fuel gas or air and indirect purging with nitrogen, and how to decide which a commercial installation needs.

• Purging Into Service: Commissioning Commercial Gas Pipework

  How commercial gas pipework is purged into service after testing, including purge points, venting, monitoring and appliance purging.

• Purging Out of Service: Decommissioning Commercial Gas Pipework

  How commercial gas pipework is safely purged out of service before alteration, removal or hot work.

• Calculating Gas Installation Volume

  How to calculate the internal volume of a commercial gas installation for tightness testing and purging, with worked examples.

• Commercial Gas Pipework Commissioning: The Full Sequence

  The commissioning sequence for new commercial gas pipework, from visual inspection and strength test to purging, appliance commissioning and handover.

• When Is Nitrogen Purging Required?

  The situations where commercial gas pipework should be purged with nitrogen rather than directly with gas or air.

• Testing Large Commercial Gas Installations

  How large commercial and industrial gas installations are tightness tested: sectioning, long durations, temperature effects and electronic gauges.

• Gas Tightness Testing: What Happens and How Long It Takes

  How commercial gas tightness testing works under IGEM/UP/1 and UP/1A, when it is needed and how long it takes on site.