1、大型LNG液貨罐的水壓和氣密試驗要求Hydrostatic Test and Leakage Test of Cargo Tank1 PURPOSEThe hydraulic and leak test shall be conducted for Cargo Tanks according todrawing and design requirements to inspect the integral mechanicalproperty and tightness property and verify that the safety properties of theCargo Tan

2、ks conform to requirements.2 RULES FOR THE HYDRAULIC AND LEAK TESTGL rules shall be followed, the rules of GB 150-, Chapter 10.9 may beconsidered.During the test and inspection additional safety regulations have to beobserved.3 SUPPORTS3.1 Temporary supportsDuring hydrostatic test the bullets may be

3、 supported by temporary supports.Number and design of the temporary supports shall consider the maximumload requirements of the soil.Drawings of the temporary supports and of their arrangement under theTank shall be submitted to SMC for approval.In order to avoid surface damages of the tanks, the to

4、p surface of thetemporary supports shall be equipped with a layer of softwood.3.2 SettlementTheodolites shall be used for measuring the foundation settlement. Thereshall be one monitoring point on each side of the tank above the supports. Atthe start of the test procedure, all monitoring points shal

5、l be in one line withthe accompanying theodolite.The total number of monitoring points shall be not less than 6.The settlements shall be recordedbefore start of water fillingat 1/3 water fillingat 2/3 water fillingat complete water fillingduring complete water filling every 10 minutes.The water fill

6、ing shall be interrupted if the settlement of one monitoring pointis found to exceed 10 mm or if the differential setting of two neighbouredmonitoring points exceeds 5 mm.4 HYDROSTATIC TEST AND LEAK TEST4.1 The area for testThe area for hydrostatic test and leak test will be the final assembly site

7、ofcargo tanks. The area shall be symbolized with safety protection and safetyidentification, and inspected and approved by chief engineer and safetymanager.During the complete test procedure, only authorized personnel related to thetests shall be allowed to stay near the tanks.4.2 Test water4.2.1 Wa

8、ter qualityTest water shall have at least industrial water quality. The chloride contentshall not exceed 25 ppm. In case that harbour water will be used, high pressure fresh water washingof all tank internals and surfaces shall be carried out straight after the tankshave been discharged from the tes

9、t water.Afterwards the tank shall be airdried completely.4.2.2 Water temperatureThe temperature of the water used for the test shall be at least 1C5 duringthe whole test procedure until all water is drained off.4.2.3 Ambient conditionsThe hydrostatic test shall take place in dry weather condition.Fo

10、r ambient temperatures below 0 C it must be ensured that neither thewater inside the vessel, nor manometers and filling lines can freeze. It isrecommended to carry out the hydrostatic test procedure at an ambienttemperature above +5C.It is recommended to carry out the hydrostatic test (test pressure

11、) at daytime.If the natural lighting conditions are not sufficient, extra lighting facilitiesmust be provided to ensure that coming-out water can be detectedimmediately and that all readings can be done correctly.4.3 Test equipment4.3.1 PumpsFilling water pumps shall have appropriate capacities in o

12、rder to fill the tankwithin the shortest possible time. The soil conditions and the symmetricalsettlement of all supports shall limit the filling rate.The pressurizing pump shall have a minimum capacity of 20 m/3h at 3.0Pa(g) with appropriate and safe hose connections. The pump must beable to mainta

13、in the test pressure at Zero flow rate.4.3.2 Safety valveOn one of the tank nozzles a safety relief valve shall be installed with a setpressure of 1.2 MPa(g). The size of the safety valve shall be sufficient tolead off the flow of the pressurizing pump.4.3.3 Temporary blind flangesNozzles which are

14、not equipped with their original blind flanges at the time ofthe hydrostatic test shall be closed with temporary blind flanges. Thetemporary blind flanges shall be provided by manufacturer.4.3.4 Temporary gasketsFlanged connections which are not equipped with their original gaskets atthe time of the

15、 hydrostatic test shall be closed with suitable temporarygaskets. The temporary gaskets shall be provided by manufacturer4.3.5 Shut-off valvesAll butt-welded nozzles shall be equipped with the original shut-off valves inorder to avoid welding after hydrostatic test.4.3.6 Local pressure gaugeThree ca

16、librated and certified local pressure gauges of the same measuringrange shall be placed on different nozzles:Measuring range: approx. 6.5 Bar (g) (min. 4.875 Bar(g), max. 13 Bar(g)Accuracy: 60 kPa over the full rangeMinimum dial diameter: 100 mm4.3.7 Remote controlled pressure indication and recorde

17、rA remote controlled pressure transmitter may be placed on one tank nozzle:Indicator: DigitalAccuracy: Class 0.14.3.8 Temperature indicationThe temperature inside and outside the tank shall be measured andrecorded during the hydrostatictest:One local thermometer inside the storage tank, using the th

18、ermowell, for themeasurement of the water temperature at the bottom of the bulletOne outside thermometer for the measurement of the ambient temperatureAccuracy of all thermometers used: Class 0.6Temperatures shall be recorded manually or automatically before start oftest and during holding time4.3.9

19、 Compressed air supplyFor emptying and drying of the storage tank after the hydrostatic test,oil-free compressed air at approx. 0.6 MPa(g) with appropriate and safehoses and connections shall be provided. The maximum relative humidity ofthe drying air shall be 30 % at +15 C. In order to accelerate t

20、he dryingprocess, the air may be heated by appropriate means.4.4 Test procedurePreparation, realization and finishing of the hydrostatic test shall follow thebelow listed procedure:1. Verify bullet position on the saddles.2. Record tank and saddle position on lower tank shell with respect to laterse

21、ttlements. Mark the reference level on the tank.3. Function test of all instrumentation and equipment required for thehydrostatic test.4. Fill in water up to approx.1/3 level with all flanged nozzles and weldedshut-off devices open for venting.5. Take measurements of tank / soil setting. The maximum

22、 settingdifference between two saddles shall not exceed 5 mm.6. Fill in water to 2/3 level, take measurements acc. to 5.7. Fill in water to full level, take measurements acc. to 5.8. The outer surface of the vessel must be kept dry during the whole testingprocedure.9. Continue water filling with a s

23、mall flow rate (overfill) in order to releasethe air out of pipe systems, pockets etc.10. Release air bubbles by leaving open all nozzles for about 3 to 6 hours.After this, overfill with a small flow rate.11. Close all nozzles with blind flanges and temporary (rubber) gaskets.12. Close all shut-off

24、devices welded to pipes involved in the pressure testafter they are overfilled.13. Pressurize tank by water pump up to test pressure 6.5 bar(g) accordingto paragraph 98 of the “ Supervision Regulations on Safety Technologyfor Pressure Vessels”14. Record pressure and settlements continuously.15. Test

25、 pressure shall be held for minimum 30 minutes.16. Release pressure to 80 % of test pressure (6.5 bar(g). During holdingtime, all welding seams shall be inspected visually for tightnessconsidering that the outer tank shell is dry (free from wetness,condensate etc.)17. Lower the internal pressure to

26、atmospheric pressure. Open at least oneman hole and then lower the water level to approx. 100 mm below thetop of the cylindrical shell.18. Leak test: Close all openings again and pressurize the remaining spaceto 0.05 MPa(g) by pressurized air. Use soap film test to verify tightnessof all nozzles, pi

27、pes and flange welds.19. Lower the internal pressure to atmospheric pressure. Open all nozzlesand manholes and afterwards empty the tank completely via nozzle B1.For speeding up the emptying process, compressed air acc. to 5.9 maybe used.20. Dry the tank completely using dry air. Dry air shall have

28、a maximumrelative humidity of 30 %HSE Measures?The policy of“ safety first, precaution primarywtihllebaewaalwreanyessksethpat,t safety forat + 15 C.21. If a leak occurs at any point of the testing procedure, it shall be repairedand the complete testing procedure shall be repeated. The repairingproce

29、dure shall be laid down by manufacturer and it shall be approvedby TGE.22. Perform leak test for the saddle reinforcing plates23. Record all test data and results.4.5 Drying and Anti-rusting ProcedureManufacturer / designer shall prepare specifications for the dryingprocedure and for the anti-rustin

30、g procedure after hydro test. Thesedocuments shall be approved by SMC.4.6 Notice1) Before hydraulic test be carried out, the tightening bolts for all the jointsof the tank shall be complete fixed, and the tightening bolts or pressureparts shall not be pressed by external pressure during hydraulic te

31、stbeing carried out.2) No welding shall be carried out after hydrostatic test, otherwisehydrostatic test shall be carried out again.3) When hydrostatic test is carried out, inspector from SMC, Third partysurveyor and SGCS shall be present, and confirm the test result.4) After qualified pressure test, hydrostatic test report