TESTING OF PIPELINES 1 General

The Contractor shall make his own arrangements for the supply of water used for testing and cleaning of pipelines which shall be obtained from a source approved by the Engineer. All water required for testing and cleaning shall be provided by the Contractor at his cost.

SECTION 6 INSPECTION AND TESTING OF PIPELINES AND STRUCTURES

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Prior to commencement of flushing or testing, approval shall be obtained to the methods and programme for testing and to the method of disposal of all fluids used for flushing or testing purposes. Under no circumstances will permission be given for the discharge of such fluids into the existing sewerage system. If permission is given to use new or existing pipelines or culverts which are not

part of a live system, they shall be thoroughly cleaned of all silt and any resulting damage made good after use.

If lagoons for the storage of such fluids are permitted, they must be suitably protected with fencing and attended by day and night to prevent access by the general public and will not be sited adjacent to buildings. Approved means of preventing the formation of mosquito larvae on the surface of the lagoons will be employed.

Testing of pipelines shall in all cases be applied in the presence of the Engineer's Representative. The Contractor shall notify the Engineer at least 48 hours before hand of his intention to test a section of pipeline. The Contractor, at his own expense, shall provide complete plant and all struts, thrust blocks, etc., as may be necessary for effectively testing the pipelines to the specified pressures.

Pipelines shall be properly completed and supported before being put under test. No testing will be permitted until seven days after thrust blocks and other holding down works have been completed.

For both gravity and pressure pipelines only testing of new, renovated, or replaced sections of pipelines and fittings will be required under the Contract, in accordance with this Specification, unless detailed otherwise. Such testing will be carried out before making final connections to the existing network. However where tees or other fittings are inserted into existing pipelines and where lengths of pipeline are replaced no backfilling will be allowed at the tees or fittings or at the joints between new and existing pipework until the pipeline has been returned to service and a visual inspection of all such fittings and joints made at the network pressure.

Should any inspection be unsatisfactory or any test fail the Contractor shall replace defective pipes, leaking joints or otherwise re-execute defective work as instructed following which cleaning and testing will be repeated until the Engineer's Representative certifies the pipeline to be satisfactory.

6.2.2 Testing of Non-Pressure Pipelines

All non-pressure pipelines of 600 mm nominal diameter or smaller shall be given a preliminary air test when the pipeline is bedded and jointed before backfilling and a final water test after backfilling in the presence and to the satisfaction of the Engineer.

Unless otherwise instructed non-pressure pipelines shall be tested in sections between manholes.

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Preliminary and final air and water tests will not normally be applied to pipelines greater than 600 mm (nom.) internal diameter and acceptance of these pipelines will be dependent on satisfactory visual inspection of the pipes and joints.

Air Test (Preliminary Test)

After a length of pipeline is bedded and jointed, and before backfilling, it shall be given a preliminary test as detailed below:

1. The Contractor shall plug all pipe outlets with suitable plugs, and brace each plug securely where needed.

2. Air shall be pumped in slowly to the pipe until a pressure of 100 mm head of water is indicated on a manometer connected to the system.

3. After the internal pressure of 100 mm is obtained, two minutes shall be allowed for the air temperature to stabilize within the pipe.

4. Air may be added to restore the pressure to 100 mm.

5. During a further period of 5 minutes (without further pumping of air) the pressure should not fall below 75 mm.

6. Release of the air pressure shall be carried out by removal of the stopper at the end of the pipeline away from the manometer which will remain connected. Failure to carry out the air pressure release in this manner shall render the test invalid.

7. The Contractor will not be permitted to commence testing later than 4 hours after sunrise or earlier than 4 hours before sunset during the summer period unless otherwise directed by the Engineer.

Water Test (Final Test)

After backfilling the length of pipeline under test, it shall be given the following final test:

1. All branches and open ends shall be closed with suitable stoppers, secured with longitudinal braces before testing commences.

2. Water shall be filled from the lowest point and air allowed to escape. No entrapped air shall remain in the pipeline while testing.

3. An internal pressure equivalent to a head of water of depth to invert of the pipeline plus 1.25 m, or 4 m head whichever is greater shall be maintained for 30 minutes to allow for initial absorption of water.

4. After that, the test pressure shall be maintained for 60 minutes and water added shall be measured.

5. Pipeline shall be treated as passed if water consumption in 60 minutes does not exceed 7.5 litres per metre of diameter per 30 m of length of pipeline under test.

Where in the opinion of the Engineer's Representative the above test is not sufficiently indicative of water tightness by reason of high ground water levels the test will not be applied. Acceptance of the pipelines will then depend on satisfactory inspection or testing for infiltration as referred to below, and air test of the pipeline in manhole lengths.

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The Engineer may require any length of pipe suspected of being damaged to be retested by the water test at any time during the contract period.

Infiltration Test

After completion of backfilling and restoration of normal subsoil conditions, all gravity pipelines and manholes shall be examined for infiltration as follows: 1. All inlets to the system shall be closed to prevent the entrance of water. 2. Pumping of groundwater shall be discontinued for at least 3 days prior to

the test for infiltration.

3. The section of the pipeline under test, including manholes, shall be accepted as satisfactory if the infiltration does not exceed 1.00 litre per hour per metre of pipe line per metre of nominal internal diameter.

Notwithstanding the satisfactory completion of the infiltration test, if there is any discernible flow of water entering the pipeline at a point which can be located either by visual or closed circuit television inspection, appropriate measures shall be taken to stop such infiltration.

6.2.3 Testing of Pressure Pipelines

All pressure pipelines of 675 mm or more internal diameter shall have each joint individually tested by means of an approved joint testing apparatus. Pipelines of less than 675mm shall be subjected to a preliminary air test as

soon as a length of pipe has been laid and before backfilling. Pressure pipelines shall then be given a final test using water after they have been backfilled, cleaned and inspected.

Preliminary pressure testing of pipelines may be carried out if so required by the Engineer with partial backfill only and exposed joints, but the stability and safety of the Works must be ensured at all times.

Each test shall be restricted to pipes of one class. Pipelines shall be tested in sections not exceeding 500m or between valve positions. In addition the whole pipeline shall be tested upon completion. Particular care must be taken to isolate air valves, etc., not to apply higher pressure than specified at any point on the pipelines and to ensure that the pipelines are adequately anchored before any test is carried out.

Gauges used for testing pressure pipelines shall be capable of reading increments of 0.1m head. Before any pressure gauge is used, the Contractor shall arrange for it to be checked independently and a dated certificate of its accuracy shall be provided to the Engineer. Calibration of pressure gauges shall be carried out at regular intervals as required by the Engineer

SECTION 6 INSPECTION AND TESTING OF PIPELINES AND STRUCTURES

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As soon as a length of pressure pipe has been laid and before backfilling, when applicable and when ordered it shall be subjected to the following preliminary test:

1. The Contractor shall plug all pipe outlets with suitable plugs, and brace each plug securely where needed.

2. Air shall be pumped in slowly to the pipe until a pressure of 300 mm head of water is indicated on a manometer connected to the system.

3. After the internal pressure of 300 mm is obtained, two minutes shall be allowed for the air temperature to stabilize within the pipe.

4. Air may be added to restore the pressure to 300 mm.

5. The test will not be satisfactory if the air pressure falls to less than 275 mm during a period of 5 minutes without further pumping of air.

Water Test (Final Test)

Pressure pipelines shall be given the following final test using water after they have been backfilled, cleaned and inspected:

1. All the joints of the pipeline shall be left open for the purpose of inspection for leakage if any, where practicable or instructed by the Engineer.

2. Pipe ends shall be closed with suitable stoppers, secured with longitudinal braces/thrust block, before testing commences.

3. Water shall be filled slowly (to prevent possible water hammer) from the lowest points and air allowed to escape through an air vent fixed for the purpose at the highest points of the pipeline section under test. No entrapped air shall remain in the pipeline while testing.

4. Pressure in the pipeline shall then be raised steadily upto and maintained at the rated pressure for a period of 30 minutes to allow for absorption and achieve conditions as stable as possible for testing.

5. If no leakage has been observed, pumping shall then be resumed and the pressure slowly raised to the specified test pressure.

6. Unless specified elsewhere or directed otherwise by the Engineer, the test pressure shall be 900 KN per square metre (91.8 m head of water).

7. Test pressure shall be continuously maintained by the use of the pump for a period of 60 minutes and the amount of makeup water required to maintain the pressure shall be accurately measured (to the nearest 1/8 litre).

8. Pipeline shall be deemed to have passed the test if all the following conditions are satisfied:

i. No water is visible coming out of the pipe or joints at any point; ii. Amount of make-up water required does not exceed 1 litre per hour

per 100 mm diameter per kilometer of pipeline under test;

iii. The loss of the pressure during the test period does not exceed 70KN per square metre.