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Activities of Pipeline construction
PROCEDURE Right of Way clearing and grading Delivery, Transportation, Handling, Hauling, Stringing of pipes Trenching Normal & Rock Bending Lining up and Welding Radiographic Inspection

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Activities of Pipeline construction
Application of Joint Coating Lowering & back filling Tie-ins River and Road crossings Cleanup and Restoration of ROW Air Pigging cleaning and Gauging Hydrostatic testing

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Activities of Pipeline construction
De watering cleaning and Swabbing Golden Tie ins Valve installation Caliper survey and dent repairs Line Preservation

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WORK PROCEDURE
Purpose: The purpose of work procedure is to stipulate the method that shall be used for a particular activity covering even minute steps in details.
 The work procedure is to be prepared by agency responsible for execution of work.  The work procedure is examined criticaly and approved by owner/owner representative.  No deviation from work procedure is accepted.

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NEED FOR WORK PROCEDURE
It helps:
1.In clearly defining the procedure to be adopted in execution of activity. 2.In establishing QAP a tool for inspection. 3.In developing records for future reference. 4.In case of any dispute arising at later stage.

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Document Number XX/WP/100 XX/WP/101 XX/WP/102 XX/WP/103 XX/WP/104 XX/WP/105 XX/WP/106 XX/WP/107 XX/WP/108 XX/WP/109 XX/WP/110 XX/WP/111 XX/WP/112 Trench Blasting

TITLE/Remarks Survey,Clearing & Grade

Pipe Handling And Stringing Bending Concrete coating by casting procedure Tie-in NDT Procedure for Mainline Welding Applications of Heat shrinkable sleeves Lowering in and rock shield applications Backfill Cathodic protection installation Pre testing of Pipeline crossings

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Document Number XX/WP/113 XX/WP/114 XX/WP/115 XX/WP/116 XX/WP/117

TITLE/Remarks Pipeweld numbering Casting and placing of precast weights Concrete coating of pipes impingement method handling over coated pipes at Coating yard Cased crossings

XX/WP/118
XX/WP/119 XX/WP/120 XX/WP/121

Repair of accidental arc strikes
TCP Ultrasonics DP & MPI

XX/WP/122
XX/WP/123 XX/WP/124

final cleanup and restoration
Open cut Crossings Major River crossings

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ROW Clearing and Grading
 Centre line of ROW is marked based on IP and TP fixed during detailed route survey  Wooden pegs are put on either side of the center line at a distance of 9 meters for 18 m ROW.  ROW width is kept as 6 m on left of Pipeline for storing the excavated soil and 12 m on right side for movement of equipments.

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ROW Clearing and Grading
 Dozer with flat front blade is used to clear the vegetation and trees  Prior information to land owners to clear the land of their crops before entering

PHOTO

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Transportation Handling and Stringing of the Pipes
 To prevent transit damage nylon rope rings are tied at every three meter distance  Profiled wooden supports are required to place first layer of the pipes on the trailer  To avoid damage to pipe bevel, though the bevel protectors are provided on pipe ends, crane hooks shall be provided with rubber pads for additional safety.  Careful stacking of pipes over sand bags, visual inspection of bevel ends to avoid welding defects.
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TRENCHING
 In cultivable land, to strip top soil (30 cm depth) & store separately along ROW for replacement on top of backfilled ditch.  Provide suitable crossings across open ROW for land owners/ public.  Width of trench : Pipe OD + 300 mm.  Depth of trench to be measured from original ground/ graded surface/ top of road/ bottom of rail, whichever is lower.

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TRENCHING
 Provide 300 mm additional cover where pipeline is within 15 m of private dwelling, industrial buildings or public places.  Provide temp. diversions/ bridges at road crossings to allow passage of normal traffic with min. inconvenience.  Provide warning/ traffic signs, lights, barricades, fencing, watchmen as required by local authorities.  Provide extra depth to fit min. radius of bend at crossings.

Sl. No.

Location

Min. Cover (m)

1
2

Industrial, Commercial, Residential Areas (Normal Terrain)
Uncased/ Cased Road Crossings & Cart-Track Crossings

1.25
1.25

3
4 5

Railway Crossings
Normal Terrain / Drainage ditches at Railways, Highways etc. Minor Water Course Crossings

1.70
1.20 1.50

6
7 8

Marshy Areas/ Water reservoir Areas/ Ponds
Submerged River Crossings Rocky Areas

1.50
2.50 1.00

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BENDING

Cold field bends for change of vertical & horizontal alignment by using bending machine & mandrel. Bends to be made without causing wrinkles, buckles, stretching & damage to pipe coating. Bending procedure to be established including step length & max. degree per pull per foot (0.9550 for 18” OD pipes). Over bends to be made to clear high points of the trench bottom.

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BENDING
  
 

Sag bends to fit the bottom of the trench. Side bends to leave min. clearance to trench wall. Radius of curvature > 40 D upto 18” OD & > 60 D for above 18” OD pipes. End of bend should not be closer than 2 m from girth weld or pipe end. Bends to be installed by positioning longitudinal welds in upper quadrant.

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BENDING
 Ovality of bent pipe < 2.5 % of nominal dia. at any point; to be checked by passing a gauge consisting of two discs of 95% nominal pipe internal dia. To layout pipes in such a way that Nos. of pieces cut off less than 2 m are held min. No Mitre bends are permitted. Hot pulled bends may be used in unavoidable circumstances.

  

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MAINLINE WELDING
    STANDARDS/CODES. WELDING TECHNIQUES. WELDING PROCEDURES. WELDER’S QUALIFICATION TEST.

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STANDARDS/CODES
FOLLOWING STANDARDS/CODES ARE REFFERED IN INSPECTION & TESTING OF WELD.
 API 1104, Welding of pipelines and related facilities.  ASME Sec IX, Boiler & Pressure vessel Code.

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Destructive Test
A) Tensile strength test

B) Nick break test
C) Root, face and side bend test

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Radiography
Scope of work includes 100% Radiographic inspection of all joints for the initial 1 Km of the pipeline in each spread. For balance portion of the pipeline ,20% of all joints shall be radio-graphically inspected except for specific crossings and tie-ins which need 100% radio-graphic inspection

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JOINT COATING
 COATING CLEARANCE IS AVAILABLE FROM RADIOGRAPHY CREW.  HUMIDITY <85%, IF BETWEEN 75% TO 85% PREHEAT BEFORE BLASTING.  CLEANING OF JOINT AREA AND ADJACENT COATING DONE UPTO 100MM ON CTE COATING ON BOTH PIPES  CHAMPER THE PIPE COATING TO AN ANGLE<30  PREHEAT THE WELDED JOINT AREA TO 60-80 C

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JOINT COATING

 SANDBLASTING IS DONE UPTO 100 MM ON CTE COATING ON BOTH PIPES  ENTIRE SAND BLAST SURFACE IS FREE FROM MOISTURE.  THE ROUGHNESS OF SAND BLASTED SURFACES IS BETWEEN 50-70 MICRON AS MEASURED BY PRESS-O-FILM/ELCOMETER.  PART A(60+10ml)PRIMER & PART B(30+10ml) EPOXY IS MIXED FOR MIN 30 SEC  PREHEATING OF PIPE TO A TEMPERATURE OF 6080o C DONE.

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JOINT COATING

 THE OVERLAP POSITION OF THE SLEEVE IS AT 2 OR 10 ‘O’ CLOCK.  WET FILM THICKNESS OF PRIMER IS BETWEEN 5070 MICRONS.  SIDE OF OVERLAP PORTION HEATED & PRESSED WITH SILICON ROLLERS.  THE CLOSURE PATCH IS HEATED, PRESSED & SEALED ON THE SLEEVE.  DIRECTION OF FLAME IS CIRCULAR & FROM ONE END TO OTHER END.  THE SLEEVE IS COMPLETELY SHRUNK AND CONFORMS TO PIPE

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JOINT COATING
 SLEEVE IS FREE FROM WRINKLES, COLD SPOTS, ENTRAPPED AIR IS EXPELLED BY HEATING & PRESSING WITH ROLLER OR BY HAND.  THICKNES OF SLEEVE ON WELD SEEM IS MIN 1.7MM AND ON PARENT METAL IS MIN 2MM.  PEEL TEST DONE ONE IN EVERY 100 JOINTS OR DAY’S PRODUCTION WHICHEVER IS LOWER ON SUBSEQUENT MORNING.

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JOINT COATING
 PEEL TEST PROCEDURE PEEL SIZED 1” BY 8” PEEL CUT UPTO BARE PIPE

ANY LOCATION- AT WELDED SEAM, ON PIPE AND ON CTE COATING
FAILS IF PEEL OF FORCE IS LESS AT OBSERVED TEMP. OR ADHESIVE LAYER OF SLEEVE IS PEELED OFF FROM PIPE. PEEL TESTED PORTION IS REPAIRED.

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PIPELINE LOWERING IN TRENCH
Before lowering of pipeline in the trench,  To clear the trench of all debris, stones, pipe cut pieces, welding rods, hard clods, skids etc. before lowering of pipeline.  To drain out water from the trench (if any) to avoid floatation.  To carry out complete check by full circle holiday detector.

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PIPELINE LOWERING IN TRENCH
Before lowering of pipeline in the trench,  To repair all coating damages.  To provide sand padding (150 mm thick) free from gravel/ pebbles in rocky areas.
 Pipeline to be lifted & laid by using nonabrasive material (Teflon) coated hooks.

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PIPELINE LOWERING IN TRENCH
Before lowering of pipeline in the trench,
  No sling to be put around field joint coating. Adequate Nos. of side booms to be used for holding the pipeline in gentle S-curve maintaining elastic bend radius. Pipeline not to be laid in tension. Trench to be rectified (if required) so that the pipeline fits the excavation and rests on the trench bed. To avoid movement of pipeline in the trench.

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PIPELINE LOWERING IN TRENCH
 BACKFILLING OF PREVIOUS SECTION HAS BEEN COMPLETED.  LOWERING CLEARANCE FROM JOINT COATING SITE IS AVAILABLE.  RADIOGRAPHY CLEARANCE FOR LEFT OUT JOINTS IS AVAILABLE.  COATING CHECKED VISUALLY FOR DEFECTS AND REPAIRS DONE, IF REQUIRED.  HOLIDAY DONE AT 15 KV  DEPTH AT 4 LOCATIONS IS CHECKED AND FOUND .1.5 M

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PIPELINE LOWERING IN TRENCH
 WIDTH CHECKED AT BOTTOM OF TRENCH AT 4 LOCATIONS AND FOUND . 1.2 m  TRENCH BOTTOM IS FREE FROM ROCKY STRATA  SOFT PADDING ON THE BOTTOM OF TRENCH DONE  NIGHT CAPS ARE PROVIDED ON OPEN ENDS OF PIPE SECTION.  SLING OF SIDE BOOM IS NOT BE ON FIELD JOINT COATING.  PIPE IS LOWERED IN THE RIGHT SIDE OF THE TRENCH.  DISTANCE OF HDPE PIPE FROM MAIN PIPE IS 400MM.

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PIPELINE LOWERING IN TRENCH
 SPIKES PROVIDED AT 10 M INTERVAL ALONG THE ROUTE OF HDPE PIPE.  SPIKE REMOVED AFTER PADING.  WARNING TAPE IS LAID AT 400 MM ABOVE HDPE PIPE

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Tie- Ins
The gaps which are left out during mainline welding due to road/railway crossing, canal/river crossings etc are connected in the form of Tie-in joints

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TYPES OF CROSSINGS
1. Cased crossings for Railways & Highways (NH/ SH)  Casing pipe: 24” OD x 0.281” WT API 5L Gr. B  Carrier Pipe: 18” OD x 0.250” WT API 5L X65 2. Uncased crossings (open cut) for minor roads/ cart – tracks using heavy wall pipe (18” OD x 0.281” WT API 5L X65). 3. Minor water course crossings (open cut) using normal pipe (18” OD x 0.250” WT API 5L X65)

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TYPES OF CROSSINGS
4. Submerged river crossings (open cut) using heavier wall pipe (18” OD x 0. 375” WT API 5L X65) with concrete coating/ HDD XING 5. Crossings for existing underground facilities like pipelines, cables using normal pipe (18” OD x 0.250” WT API 5L X65) with min. clearance of 500 mm. Crossings at Sl. No. 2, 3 & 5 above are part of mainline item. Cased and submerged river crossings are separate items.

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 Execute crossing work as per concerned Statutory Authority permission conditions.  Highways, main roads, rail roads & their verges and banks of water courses not to be used for loading, unloading or stacking of materials or equipment.  Roads or water courses not to be closed or diverted without prior permission of concerned Statutory Authority.  Before execution of cased and submerged river crossings, detailed methodology to be submitted by contractor containing:  Time schedule,  Working method,  Equipment to be deployed  Test procedure  Manning  Soil Investigations.

CROSSINGS

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CASED CROSSINGS
 To be executed by horizontal boring technique.  Casing pipe to be 6” larger in dia. than carrier pipe.  Carrier pipes to be 3 LPE coated. No coating of casing pipes.  Ground water table (if encountered) over length of boring to be lowered up to at least 0.5 m below bottom of the pipeline.

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CASED CROSSINGS
 For boring pits in unstable soils, closed sheet piling to be used.  Boring/ exit pit bottom to be graded for min. 12 m at the approach to each end of casing.  Backfill in boring/ exit pits to be compacted in 15 cm layers to 90% proctor density by mech. compactor after dewatering.

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CASED CROSSINGS
 Dia. of bored hole to be almost same as casing pipe OD.  Vent pipes to be provided on both ends of casing in such a way that there is no contact with carrier pipe.  100% radiographic inspection of weld joints of carrier pipes.

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CASED CROSSINGS
 Prior to installation, hydrostatic pre-testing of the carrier pipeline section to be carried out at a pressure corresponding to 95% SMYS of pipe material (120.62 kg/cm2 for SSPL) . Test pressure to be maintained for min. 4 hrs.  Insulators to be securely fastened to carrier pipes @ 1 m c/c.

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CASED CROSSINGS
 At both ends of casing, double set of insulators to be installed.  Carrier pipe to be pulled/ pushed into casing in such a way that insulators are not disturbed.  Annular space between casing and carrier pipes at both ends to be packed tightly with jute and bitumen before fixing end seals in order to prevent ingress of moisture/ water.

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CASED CROSSINGS
 After installation, electrical test to be conducted to determine resistance between carrier pipe & casing pipe or carrier pipe & soil, which should be min. 1 mega ohm.  The earth to be properly compacted up to a distance of 3 m from end of casing pipe on both sides to avoid uneven settlement of carrier pipe.

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TYPICAL CASED RAILWAY CROSSING
HDPE Insulators @ 1 m c/c Vent Pipe (80mm dia. MS pipe)
GL

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HDPE End Seal

Railway
1.25 m
GL

1.7 m Min.
0.3 m.

1.0 m Min.

1.0 m Min.

0.5 m

18 OD x 0.250” WT API 5L-X65 Grade Carrier Pipe 24 OD x 0..312” WT API 5L Grade B Casing Pipe

Boring Pit

Exit Pit

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Clean-Up and Restoration
 Clear the site by removing all rubbish,broken skids, empty canes,pieces of electrodes and other construction material  Restore ROW to the satisfaction of farmers and obtain NOC from them

 Restore cut roads, canals, river banks etc and obtain NOC from concerned Government Department
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Air pigging cleaning and Gauging
 Cleaning with compressed air with the help of series of brush pigs  Gauge plate of softer metal like Al of 95% of ID of highest wall thickness pipe is fastened to pig  Retrieved gauge plate is analyzed and preserved
PIG

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Hydrostatic Testing
 MECHANICAL CLEARANCE IS AVAILABLE. (Pipe book completed)  INSTRUMENTS AND EQUIPMENT TO BE USED ARE WITH VALID CALIBRATION AND OF REQUIRED RATING.  WATER TESTING CERTIFICATE AND CORROSION INHIBITOR DOSAGE RECOMMENDATION AVAILABLE.

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Hydrostatic Testing
 GAUGE PLATE OF 95% ID AND 10 MM THICKNESS SHALL BE PASSED THROUGH THE SECTION AFTER CLEANING OF THE PIPE.  GAUGE PLATE WITH < 2 MM SCRATCH ON SIDE WALL AND WITH NO DENT IS ACCEPTABLE.  CHECKING THE CONDITION AND SEQUENCE OF PIGS IN THE HYDROSTATIC HEADER.

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Hydrostatic Testing
 ONLY QUALIFIED WELDER IS ALLOWED TO PERFORM WELDING OF HEADER.  CHECK RATING AND CONDITION OF HEADER FITTINGS.  USE THE FILLING WATER FROM TESTED WATER SOURCE ONLY.  FILL 500 MTRS. OF WATER BEFORE FIRST PIG AND 1000 MTR WATER BETWEEN FIRST AND SECOND PIG.  FINAL FILLING SHALL BE DONE WITH FILL RATE OF 2 KM/HRS.

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Hydrostatic Testing
 AFTER RECEIPT OF PIGS AT RECIVER MINIMUM 2 HRS. WATER FLUSHING SHALL BE ENSURED.  TURBINE METER READING RECORDING SHALL BE PRESERVED.  THERMAL STABILIZATION FOR 24 HRS. SHALL BE DONE AND SECTION IS SAID TO BE THERMALLY STABILIZED IF DIFFERENCE NOT HIGHER THAN 1 DEGREE IS ATTAINED BETWEEN THE AVERAGE VALUE OF SOIL TEMPERATURE READINGS

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Hydrostatic Testing
 PRESSURISE THE SECTION NOT MORE THAN 2 BAR/MIN RATE.
 FOLLOWING THE SEQUENCE MENTIONED BELOW:a) PRESSURE THE PIPE SECTION TO 50%HOLD FOR I HR.

b) DROP 0.5 BAR DO AIR VOLUME CALCULATION. c) DROP PRESSURE TO STATIC +1 BAR. d) FOLLOW B & C FOR 75% PRESSURISATION. e) IF AIR VOLUME CALCULATION VALUE IS BETWEEN 1 TO 1.06, THEN FILLING IS ACCEPTED.

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Hydrostatic Testing
 PRESSURE THE PIPE TO 125.18 TO 118.55 KG/CM2 (DEPENDING UPON PIPE SECTION PROFILE) AND HOLD IT FOR 24 HRS.  USE DWT AND RECORDING SYSTEM DURING TESTING.  THE TEST IS CONSIDERED ACCEPTABLE IF DIFFERENCE IS LESS OR EQUAL TO 0.3 BAR IN CASE OF DOUBT TESTING PERIOD SHALL BE EXTENDED.

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Cleaning and Gauging Operation
 Need of cleaning and gauging  Cleaning with compressed air with the help of series of brush pigs  Gauge plate of softer metal like Al of 95% of ID of highest wall thickness pipe is fastened to pig  Retrieved gauge plate is analyzed and preserved

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Markers and Valve Installation
 Boundary Pillars ( A set at every 250 m)  Kilometer post  Turning Point marker  Direction Marker( Before and after a TP 200m)  Warning Sign Valve Installation: Pre tested valves are installed at designated locations after completion of hydrotest

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Caliper Survey
 To establish a benchmark of internal conditions of pipeline viz dents,ovalities for future references and surveys  Dewatering by foam pigging  Cleaning by brush pigging  Magnetic pigging  Programmed caliper pigging PHOTO  Downloading and interpretation
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Line Preservation
 To preserve the line from internal corrosion for a prescribed period due to noncommissioning  Pressurize pipe with inhibited water  Dosage of inhibitor depending on duration of preservation monthly, half yearly,yearly etc and Quality of water to be filled  Keep line in air tight condition by monitoring pressure
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TYPICAL HEAVY WALL PIPE ROAD CROSSINGS
GL ROAD TOP GL
DRAINAGE DITCH

1.25 M min. cover 1.0 M min. cover

δ

PIPELINE

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ROW
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HDPE PIPE
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AIR-VOLUME CALCULATION AIR-VOLUME RATIO=Vi/Vp (Acceptable limit is 1.06 at 75%of test pressure cycle) Vi=Actual volume of water drained to drop pressure by 0.05 Kg/Cm2 Vp=(0.884 ri / ti+A)X10-6 X Vt X PXK Vp=Computed water amount required to raise by P the pressure in the section to be tested (M3) Vt=Geomatrical volume of the section (M3) ri=Nominal inner radius of the pipe (mm)(Average) ti=Nominal wall thickness of the pipe (mm)(Average) A=Isothermal compressibility value for water at the pressurization tempreture in the P range (bar-1)x106. Ref graph. P=Pressure Raise (bar) K=A dimensionless coefficient that is equal to 1.02 for longitudinally welded pipe.