5.2 Construction Schedule
East-west Gas Pipeline Project Construction Procedure for Cleaning, Gauging And Hydro testing of Pipelines Rev.: A1 China Petroleum Pipeline Bureau（CPP） Document No.: EWPL00-COS-PR-0014 For detailed information about the construction schedule, please refer to Construction Execution Plan
6.0 PIPELINE SECTION CLEANING AND GAUGING
6.1 General
Pipeline section cleaning and gauging activities are carried out after pipeline welding and backfilling and before hydrostatic testing. Pipeline cleaning is provided to remove any large debris left inside the pipeline after the welding, while gauging inspection is conducted to identify the extent of any out-of roundness, buckles, dents or other deformation in the pipelines.
The length of cleaning/gauging section basically will be the distance between two line valve stations or a line valve station and the nearby pig trap station. Compressed air will be used as propelling medium for pipeline pigging and gauging.
6.2 Preparations for Cleaning and Gauging 6.2.1 Site Layout
Layout of the Construction Site
The arrangement of the main equipment and devices involved in the operations of section cleaning and gauging is shown in Sketch-1 below.
Main equipment and devices for pigging:
? The Capacity of Compressed Air: 160 m/min.
? Temporary pig traps: launchers and receivers for the pipeline of 48”
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East-west Gas Pipeline Project Construction Procedure for Cleaning, Gauging And Hydro testing of Pipelines Rev.: A1 China Petroleum Pipeline Bureau（CPP） Document No.: EWPL00-COS-PR-0014
Before section cleaning operation pits shall be excavated at the both ends of the pipeline section for the installation of temporary launcher and receiver traps, and for the pig launching and receiving. 6.2.2 Cleaning pig
The pig shown as below will be used for pipeline sections for cleaning. Cleaning pigs will be equipped with 4 urethane cups, 2 nylon wire brushes and 4 spacers.
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East-west Gas Pipeline Project Construction Procedure for Cleaning, Gauging And Hydro testing of Pipelines Rev.: A1 China Petroleum Pipeline Bureau（CPP） Document No.: EWPL00-COS-PR-0014
Figure-2
6.2.3 Gauging pig
The sketch shown as below is the pig used for pipeline sections gauging inspection. Gauging pigs will be equipped with 4 urethane cups, 4 spacers and an aluminum gauging disc.
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East-west Gas Pipeline Project Construction Procedure for Cleaning, Gauging And Hydro testing of Pipelines Rev.: A1 China Petroleum Pipeline Bureau（CPP） Document No.: EWPL00-COS-PR-0014
Figure-3
The diameter of the gauging disk is 95% of the minimum internal diameter of the pipeline section. The thickness of the disks is10mm and the disk shall be made with radial incision at interval of 45°.
Before sending the gauging pigs, Reference marks shall be made to them witnessed by both the Engineer-in-Charge and CONTRACTOR?s test engineer. Reference marks as
Diameter of the Disc: ____ Date & Time: ____ Engineer-in-Charge: ____ CONTRACTOR’s Test Engineer: ____
shall be made by water-resistant paint.
6.2.4 Installation of the equipment and devices for cleaning & gauging pigging Main equipment and devices for pigging:
? ?
The capacity of supply compressed air: 90 m/min~ 160m/min. Temporary pig traps: launchers and receivers for the pipeline of 48”.
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