Use this planning template to assemble a site-specific procedure for testing and purging natural gas
pipework in accordance with IGEM/UP/1. Complete each section, capture risk controls, and export the
finished document for review and approval.
1. Project and Personnel Details
2. Pipework Overview
Pipe, meter and purge volume estimator
Build the IGEM/UP/1 Table 3 and Table 4 volumes directly in the browser. Add every pipe segment that forms part of the
test, including purge hoses listed alongside the pipe sizes, and select the installed diaphragm or rotary meters to
replicate the worksheet logic. Pipe purge volumes use the same multiplier defined in IGEM/UP/1 Sheet 1.
Pipe size (DN)
Length (m)
Installation volume (m³)
Purge volume (m³)
Actions
Purge hose size
Length (m)
Purge volume (m³)
Diaphragm meter
Installation allowance (m³)
Purge allowance (m³)
Rotary meter
Installation allowance (m³)
Purge allowance (m³)
Add at least one pipe segment to calculate installation and purge volumes.
Table 12 – Maximum purge flow reference
Pipe diameter to be purged
Maximum purge flow rate (m³/h)
Purge time at maximum flow (seconds)
Table 6 – Gauge selection
Gauge choice
Gauge range (mbar)
Gauge reading multiplier (GRM)
TTD max (minutes)
Fuel type factors – F₁ reference
Fuel type
Gas factor F₁ (gas purge)
Gas factor F₁ (nitrogen purge)
Fuel type factors – f₃ reference
Fuel type
Operating factor f₃ (gas service)
Operating factor f₃ (nitrogen purge)
IGEM/UP/1 requirements, alongside the HSE gas safety guidance and National Gas emergency procedures, expect the
testing plan to document the reference data that underpins TTD decisions. The tables below capture the gauge
limits and F₁/f₃ factors so the procedure records the published allowances feeding into the plan.
Time to discard (TTD) estimates
Combine the total installation volume from Step 5 with the gauge choice and gas factors to estimate TTD for
different system categories. Enter the room volume to complete the in-place Type A calculation.
Scenario
TTD using gas (mins)
TTD using N₂ (mins)
TTD new/existing Type A
Existing Type C & D
Existing in Type A
MPLR estimates
MPLR gas
MPLR N₂
Breakdown
Installation build-up
Step
Volume (m³)
Purge build-up
Step
Volume (m³)
TTD calculation steps
Step
Gas (mins)
N₂ (mins)
Cross-check these totals with the latest IGEM/UP/1 publication on the IGEM technical services site and guidance in
Section 8 to confirm that the chosen approach still reflects the published standard before issuing the procedure.
3. Strength & Tightness Testing Plan
Reminder: Document instrument calibration dates and verify leak detection fluid compatibility with pipe materials.
4. Purging Plan
5. Risk Controls & Permits
6. Acceptance Criteria & Sign-off
Store the final signed procedure within project QA documentation and retain for traceability in accordance with IGEM/UP/1 clause 10.