Pressure testing suction pipes

In my company we commonly pressure test pipes to the following standards:

Pressure pipelines

• Buried pipes except PE - BS EN 805
• Buried PE - WIS-4-01-03
• Above ground pipes - WIMES 8.08

Gravity sewers/drains

• Code for adoption sections E7.4 and E7.5
• BS EN 1610

But none of the above standards address how to pressure test suction mains.

From a little reading around the subject I tentatively suggest the following approach.

The main issue with suction mains is to ensure air isn't drawn in through any leaky joints. It takes approximately 3 - 5 times less differential air pressure than water pressure for air to leak see link.

So I suggest selecting a water test pressure above atmospheric pressure of 5 times the anticipated negative suction. So for instance if anticipated minimum pressure is -0.2 barg

Test pressure \(= |-0.2| \times 5\) = 1 barg

If the suction line remains above atmospheric then I'd suggest just doing a water test.