Civil Engineering - Water Test for Gravity Pipelines

       1.    The test pressure for gravity pipelines up to and including 750 mm nominal bore shall not be less than 1.2m head of water above the pipe soffit or ground water level, whichever is the higher at the highest point, and not greater than 6 m head at the lowest point of the section. Steeply graded pipelines shall be tested in stages in cases where the maximum head, as stated above, would be exceeded if the whole section were tested in one length.

       2. The pipeline shall be filled with water and a minimum period of 2 hours shall be allowed for absorption, after which water shall be added from a measuring vessel at intervals of 5 minutes and the quantity required to maintain the original water level noted. Unless otherwise specified, the length of pipeline shall be accepted if the quantity of water added over a 30-minute period is less than 0.5 litres per linear meter per meter of nominal bore.

    3.     For man entry Sewers special equipment is available to test joints or short section pipes insitu.

Gravity pipelines exceeding 750 mm. nominal diameter shall either have short lengths or each joint individually tested by means of an approved joint testing apparatus with a hydraulic testing which shall consist of a ring to seal internally the joint surround and enclose the joint area which shall then be tested by pumping water into the sealed space until the pressure reaches 0.1N/mm² .  A period of two hours shall be allowed for absorption. Thereafter the test pressure shall be maintained for 30 minutes, and make up water shall be pumped in at 5-minute intervals if necessary to maintain the test pressure.  The average quantity of make up water shall not exceed 0.002 liters per hour per millimetre of nominal bore of the sewer at any joint tested.

Sewer pipelines exceeding 750mm. diameter shall be visually inspected internally, before and after backfilling and any defects shall be remedied.

Where required the sewer shall be tested for obstruction by the insertion and pulling through of twin-coupled rubber plungers of the same diameter as the sewer.

All sewers, which in the opinion of the Engineer are submerged under the water  table, shall be tested for infiltration after backfilling.  All inlets to the system shall be effectively closed and the residual flow shall be deemed to be infiltration.