Gas tightness testing: what IGEM/UP/1B Edition 4 changesGas tightness testing: what IGEM/UP/1B Edition 4 changes

Gas tightness testing has a new standard behind it. IGEM/UP/1B Edition 4 changes how a tightness test result is judged, and the overlap with the old edition ended on 30 September 2026. If you test small natural gas or LPG installations, this is what the update says and how to be ready for your next inspection.

What has changed

Gas Safe Register’s Industry Standard Update 133 explains that IGEM/UP/1B Edition 4 came into effect with a six-month overlap, and that Edition 3 is withdrawn on 30 September 2026. From 1 October 2026, Edition 4 is the one to work to.

The main change is how you decide whether a test has passed. The permissible pressure drop now depends on the installation volume (IV), not on meter size alone. IGEM’s questions and answers on Edition 4 add some detail:

• The permissible pressure loss is set by the standard and depends on the installation volume and the fuel gas.
• For natural gas, Table 3 of the standard gives the limit for each band of installation volume.
• You do not need to calculate the installation volume if the loss you see is below the smallest permissible limit for that gas. You do need to calculate it if the loss is higher, to find the maximum allowed.
• Any perceptible movement on the pipework alone is a failure. Where appliances are connected, isolate them and test the pipework again to find out whether the loss is in the pipework or in an appliance.

Purging is also affected. The procedure is unchanged, but IGEM says the installation volume must now be calculated for all purging, and the purge volume set at 1.5 times the installation volume.

What it means for an inspection

During the six-month overlap, Gas Safe Register said it would not defect any business that was not fully conversant with the new procedure, and that it would provide guidance where needed. That grace period is the part of the update to read carefully. The overlap has now ended, so plan on Edition 4 being the method in use for jobs done from 1 October 2026.

The standards themselves are IGEM’s, and Gas Safe Register’s updates are the authority on how it inspects. If anything here differs from them, they win.

Getting ready, job by job

The change is a technical one, but the habits around it are admin habits. A few things make the new method easier to follow on every job:

1. Agree one method across the team, and write down which edition you are working to.
2. Make sure every van has the figures the new method needs, so nobody is working them out from memory on the doorstep.
3. Record the test on the job: what was done, by whom, with timestamps, notes and any photographs.
4. Keep appliance details on the customer’s record, so the next visit starts from what you found last time.
5. Brief any subcontractors on the same method before they start a job for you.

Questions to ask your team this week

You do not need a meeting about it. Put these to each engineer on the next job and note the answers:

• Which edition of the standard are you working to on this job?
• Where do you find the permissible pressure drop for this installation?
• If a test fails, do you isolate the appliances and test the pipework again, as the standard says?
• Are you recording what you did and what you found in a place the office can see?
• Who calculates the installation volume when a job involves purging?

Gaps in the answers show you what to cover in a toolbox talk. If anything is unclear, go back to IGEM’s standard and to Gas Safe Register’s guidance, not to this article.

Where job management software fits

jobmate does not produce gas paperwork, and it is not a replacement for your Gas Safe Register obligations. What it does is hold the job around the test. A bespoke checklist on the job can prompt each step, with a timestamp and comments as it is completed, and it can be sent to the customer for confirmation. A job task can carry an asset, the customer’s record holds the job history, and every change is held in the audit log.

For firms that run several engineers, the field service and maintenance page shows how scheduling, jobs and customer history sit together.

Gas tightness testing: common questions

When did IGEM/UP/1B Edition 4 start?

According to Gas Safe Register’s update, it came into effect immediately on publication, and Edition 3 stayed usable until it was withdrawn on 30 September 2026.

What is installation volume?

It is the volume of the pipework and gas installation being tested, which IGEM’s standard uses to decide the permissible pressure loss. The standard explains how to calculate it.

Do I always have to calculate it?

Not for a tightness test where the loss is below the smallest permissible limit for the gas. For purging, IGEM says you do, in every case.

Does jobmate record a tightness test?

It can hold the job, the checklist, notes and timestamps around the test. It does not carry out the calculation or issue gas paperwork, so keep using the forms and tools your registration requires.

Next step

If you run gas and heating jobs with a team and want a job record that prompts every step, Book a demo.