Section 13 Testing

13.1.1 The pipeline system is to be hydrostatically tested after installation. Hydrostatic testing procedures are to comply with IP6 — Institute of Petroleum, Model Code of Safe Practice in the Petroleum Industry — Petroleum Pipelines. The required minimum test pressure is to be 150 per cent of the maximum allowable operating pressure, or a pressure that will result in a hoop stress (based on specified minimum wall thickness) equal to 90 per cent of the specified minimum yield strength of the pipe material at any point in the line, whichever is less. This pressure is for strength testing. By holding this pressure for 24 hours and accounting for all pressure losses, the tightness of the line is also to be demonstrated. A written procedure is to be developed before hydrostatic testing commences. The acceptance criteria are to be agreed.

13.1.2 The recorded pressure is to be equal to or greater than the maximum test pressure minus the static head between the lowest pipeline elevation and the elevation of the recorder, provided this pressure is not less than 125 per cent of the maximum working pressure.

13.1.3 Under the terms of IP6 Code — Petroleum Pipelines, it is permissible to have pressure variations during a hydrostatic test provided they can be explained in terms of temperature changes.

13.1.4 In order to calculate the effect of temperature on pressure, It is essential that the temperature of the fluid in the pipe is measured and recorded at the same time as each pressure measurement is made and recorded. Ambient air or sea water temperature are not relevant.

13.1.5 As a minimum, the temperature is to be measured near each end of the pipeline; preferably at least one transducer on the seabed part of the pipeline should also be provided.

13.1.6 Temperature sensors attached to the outside of the steel wall of the pipe and insulated from the thermal effects of the sea are acceptable provided the test medium has been in the pipeline for at least 24 hours before the test is started, in order to allow the temperature of the fluid and steel to stabilise.

13.1.7 When conducting a hydrostatic test of a steel pipeline or riser, the following requirements are to be complied with:

1. The pressure (and temperature if applicable) is to be continuously recorded for the duration of the test on a chart recorder.

2. The chart is to be signed by the Surveyor at the beginning and end of the test.

3. Pressure (and temperature if applicable) readings are to be made at intervals not greater than 30 minutes and tabulated.

4. Where temperature readings are to be taken the line is to be filled at least 24 hours before the test to enable the temperature to stabilize.

5. The results of a hydrostatic test are to be recorded by a dossier containing:

   • copies of all charts made during the test;
   • copies of all tables of pressure readings (and temperature readings where applicable) made during the test;
   • copies of calibration certificates for the pressure recorders used;
   • calculations demonstrating temperature correction to pressure change where applicable.

13.1.8 The sections of pipeline are to be hydrostatically tested at the pipe mill in accordance with Ch 6 Steel Pipes and Tubes of LR's Rules for the Manufacture Testing and Certification of Materials or the relevant national standard.

13.1.9 Before a consent to start up a pipeline can be given, evidence of a satisfactory hydrostatic test is to be provided. The evidence is to relate to a test completed during the 12 months prior to the date of application for the consent to start up, providing that the pipeline has been left pressurized during the intervening period.

13.2.1 Adequate examination of the pipeline is to be carried out to determine that the completed pipeline is free from buckles, dents or similar damage.

13.2.2 Buckle detection may be carried out using a calmer pig and is to be arranged after final back-filling or covering of the pipeline.

13.3.1 All sacrificial anodes are to be examined to ensure that securing arrangements are efficient.

13.3.2 Measurements of potential are to be taken and any deficiencies corrected by the addition of extra sacrificial anodes.

13.3.3 Measurements are to be taken to ensure that there is no over-protection.

13.4.1 Communication systems, remote and automatic controls, emergency shutdown systems and other safety devices are to be tested in accordance with the approved test schedules required by Ch 1, 5.3 Plans and data to be submitted 5.3.1.