PACKAGE : I Bid Document VOLUME : II - Public Health Engineering

2. Protective devices, such as relief valves, surge or break pressure stations, may be
provided to ensure that the internal pressure at any point in the pipe line does not
exceed the design pressure.
3. Pressure indicating and flow recording instruments and burst alarms may be provided
at suitable places.
18.10 Testing of pipe line.
Before putting it into commission, the welded pipe line shall be tested both for its
strength and leakage.
Procedure for test – Each valved selection of the pipe shall be slowly fitted with
clean water and all air shall be expelled from the pipe line through hydrants, air
valves and blow-offs fixed on the pipe line. Before starting the pressure test, the
expansion joints should be tightened.
(a) Pressure test : The field test pressure to be imposed should be not less than the greatest
of the following:
1½ times the maximum sustained operating pressure,
1½ times the maximum pipe line static pressure, and
Sum of the maximum static pressure and surge pressure subject to the test pressure.
Where the field test pressure is less than two thirds the test pressure, the period of
test should be at least 24 hours. The test pressure shall be gradually raised at the rate
of nearly 0.1 N/mm² per minute.
If the test pressure measurements are not made at the lowest point of the section, an
allowance should be made for the static head between the lowest point and the point
of measurement to ensure that the maximum pressure is not exceeded at the lowest
point. If a drop in pressure occurs, the quantity of water added in order to reestablish
the test pressure should be carefully measured. This should not exceed 0.1
litres per mm of pipe dia per km of pipeline per day for each 30m head of pressure
applied.
Where the pipe line is tested in sections, two or more welded joints at each gap may
not get tested under pressure. Special care should be taken in making these welds
and these joints should be kept under observation during the commissioning of the
system.
DTS : Detailed Tender Specification. Page 175