Short answer
IGEM/UP/1 is the Institution of Gas Engineers and Managers standard for strength testing, tightness testing and direct purging of industrial and commercial gas installations. It applies to installations of any size up to a maximum operating pressure of 16 bar, and is the standard to use whenever an installation falls outside the limits of IGEM/UP/1A.
What the standard covers
UP/1 covers natural gas and LPG installation pipework downstream of the emergency control valve (ECV) or the outlet of the primary meter installation. It sets out how to calculate installation volume, how to choose test pressures and test durations, how to calculate the maximum permitted leak rate (MPLR), how to carry out let-by tests on valves, and how to plan and execute direct purges.
It also covers the risk assessment and written procedure expected before a test or purge, the competence of the people carrying it out, and the documentation that must be produced afterwards.
UP/1 versus UP/1A
IGEM/UP/1A is a simplified procedure for smaller natural gas installations. Broadly, UP/1A can be used where the installation volume is no more than 1 m³, the maximum operating pressure at the outlet of the ECV is no more than 40 mbar, and pipe diameters do not exceed 150 mm. Anything larger, at higher pressure, or using LPG beyond the UP/1A scope, falls under UP/1.
In practice, a single restaurant kitchen is usually a UP/1A job; an office block, hospital, school campus or large plant room is usually UP/1.
Key concepts in UP/1
Strength test pressure (STP) and tightness test pressure (TTP) are derived from the maximum operating pressure (MOP) of each section. Test duration depends on installation volume, gauge readable movement (GRM) and the MPLR, which in turn depends on whether the pipework runs through inadequately ventilated or occupied areas.
Purging requires a calculated purge volume, a minimum purge velocity to avoid stratification, controlled venting to a safe location and continuous monitoring with a suitable gas detector until the purge is proven complete.
Records
Every test and purge should be recorded: the section tested, volume, test medium, pressures, durations, gauge used, result and the engineer's details. On non-domestic work this is commonly recorded on a CP16 or an equivalent test and purge certificate.
Figures are typical for UK natural gas. The current edition of the relevant IGEM standard and the manufacturer's instructions always take precedence on site.
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