PROCEDURE FOR HYDRO TESTING.pdf PDF

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PROCEDURE FOR HYDRO TESTING CONTRACTOR : TECHNO FIRE CONTROLS PVT.LTD CLIENT : AMPTPL NAME OF THE WORK : Fire fighting system CONTRACT NO & DATE : PO. 4500055135 DTD 25TH NOV 2011 rd Document Ref No, : MS/AMPTPL-Techno/FF/05 dated 03 Sep 2012 Pressure Test Test Preparation a. If lines to be insu...

Description

PROCEDURE FOR HYDRO TESTING

CONTRACTOR

: TECHNO FIRE CONTROLS PVT.LTD

CLIENT

: AMPTPL

NAME OF THE WORK

: Fire fighting system

CONTRACT NO & DATE

: PO. 4500055135 DTD 25TH NOV 2011

Document Ref No,

rd

: MS/AMPTPL-Techno/FF/05 dated 03 Sep 2012

Pressure Test Test Preparation a. If lines to be insulated or painted before the test, appropriate measures shall be taken to ensure that flanged couplings, intersections & welds, which were not previously tested are neither insulated nor painted so that leaks may be easily detected. b. The time during which the lines keep under pressure for detecting leaks shall be intimated through inspection notice. c. Piping designs for vapour or gas shall be provided with additional temporary supports, only in consultation with M/s AMPTPL. d. An appropriate vent or drain point shall be provided in case of piping system subject to pressure test do not include a suitable vent or drain point to allow complete venting or air. e. Temporary blind flanges and test blind used to isolate a test system shall be adequate thickness to withstand the test pressure. Selection of blinds shall be as per table-1 attached. f. Temporary blind flanges and test blinds shall be adequately gasket to prevent damage of flange faces. g. Valves shall not to be used to isolate a test system except for lines not pressurized in service (e.g. flare line, gravity drain lines, black and grey sewage system etc.) h. Expansion joints shall be fitted with temporary studs that can withstand the internal test pressure. i. Expansion joints shall be tested without temporary restraint if test pressure is below 1.5x of its designed pressure. j. To isolate a system from equipment, a blind or valve may be used, provided the rating of valve selected shall be suitable to withstand the test pressure. A safety valve shall be provided in the test fluid discharge line of the pump. k. Unless otherwise indicated, the safety valve shall be set at 105% of the pressure planned. l. All instruments such as safety valves, thermo wells, rupture disc, orifice plates, level indicators and controllers etc. Shall be dismantled before the test or shall be isolated from the pipe to be tested by means of blind flanges, in order to avoid the impact of test medium or foreign matter during the flushing or purging process may damage them. m. All piping components that may damage during the test shall be removed from piping system prior to hydro test.

n. The item removed from the lines shall be properly labelled or tagged in order to ensure the correct replacement of components after the test. o. As a rule these items include, orifice plates, flow limiting device, differential pressure measuring device, turbine and magnetic meters, rota meters, flow indicators, venturimeter, filter etc. p. Check valves shall have their internal removed or securely blocked in a manner acceptable to the AMPTPL. q. All valves except as excluded specifically herein, shall be included in the pressure test, ball valves shall be in the half open position and all other valves fully open. However, where the test pressure to be applied to the lines is greater than the maximum allowable test pressure specified for the valves, the valve shall be blinded on the test side or replaced with a temporary spool. r. All temporary supports, spring supports restrains, temporary spools, blinds and plugs etc. , shall be prominently plugged or painted bright orange or red to ensure their removal following the test. s. Before testing begins, the test package has been declared ready for testing and the system requires to be cleaned, the system shall be flushed with the test medium to remove all dirt and foreign matter. t. Strainers shall be included in the piping system and care shall be taken to ensure that dirt and debris cannot be forced into instrument branches or pocket in lines. Once the line is ready for pressure test, mechanical and line clearance for testing shall be taken in prescribed format from AMPTPL QC Engineer. It must be ensured that before start of Hydro test. All NDT work, repair & re-NDT have been completed & duly documented. u. Flushing shall proceed in an intermittent manner allowing time between flushes for debris to be cleaned from the line. Flushing shall continue for sufficient time to ensure that the line cleaned to AMPTPL satisfaction. Liquid flushing shall not be employed on system required pneumatic test. v. The test pressure gauge shall be located at the high point of the system. w. A check gauge shall, in addition be located at the low point of the system if significant vertical legs could cause the static head pressure to over pressure part of the system. Preparation of test circuit documents: Contractor shall provide the marked up.

TESTING: The following activities shall be carried out before introducing the test fluid: i. ii.

For every test circuit, two calibrated pressure gauges shall be used. Capacity of pressure gauges shall be 1.5 times to 4 times of test pressure. As a rule, one of these shall be fixed on the lowest point of circuit and the second on shall be fixed at the high point.

iii. iv.

Pressure gauge calibration certificate shall be submitted to AMPTPL before start of testing per review. Minimum two no’s of pressure gauges shall be used for pressure test.

 Blind flanges shall be used when indicated in the circuit to isolate the following: 1. Safety valves. 2. Control valves. 3. Instruments in general. 4. Equipments 5. Machinery. 6. Pressure & thermal relief valve. 7. Rupture disc. Stud bolts required for the joints shall not be tightened until the fluid is purged. Hydro test shall be performed in specified loops.

Type of test fluid: i.

Water shall be used as general test fluid. The minimum water temperature during the hydraulic testing shall be ambient temperature. Portable fresh water shall be used as test medium. Length of loop line shall be such that, after carrying out test, the loop should be easy to handle to avoid any permanent deformation in the line or crack in joints. All field joints must be kept open for underground line during test for leak detection.

Introduction to test fluid and purging: 1. Once testing activities have been carried out, test fluid shall be introduced in the pipes to be tested and shall purge the maximum possible quantity of fluid from all drains, vents and flanged couplings. 2. As soon as the contractor M/S AMPTPL is satisfied that the fluid purged from the various points is clean, all the flanged joints shall be tightened without removing the shut-off blind flanges.

3. Application of pressure. 4. As soon as all connection are closed, AMPTPL shall put the circuit or line to be tested under pressure by venting, in the case of hydrostatic test any air which may still be present in the circuit by using relief and \ or vent valves if approved or by partly disconnecting connections in the tope part of the circuit (if there are no relief and \or vent valves). 5. It must be remembered that the test pressure shall only be reached by the pressure gauge in the lowest part of the circuit or line, whereas the pressure gauge in the highest part shall record in the case of hydrostatic testing a value equal to the test pressure less the pressure head. 6. The hydrostatic test shall be carried out with 1.5 times of design pressure holding up to 03Hrs for all above and underground lines. 7. Piping system designed for vacuum conditions shall be internally tested at 3.5 bars unless the design limits the allowable test pressure to a lower figure. The minimum internal test pressure for vacuum system shall be 1.0 bar. Testing and Associated Checks: After witnessing a test, the contractor’s representative shall check the following: a. Test pressure value (which shall be kept constant throughout the test either by pumping or by venting the pump safety valve). b. Leaks from flanged connection. If leak is found and cannot be eliminated by tightening the connections, the flange seal surface shall be checked are repaired, gasket replaced and the system hydro test repeated when seal checks shall be performed. No additional test shall be carried out on the line, either by AMPTPL or subcontractor, until pre-commissioning, when seal checks shall be performed. c. Spatter and tack welds resulting from connecting temporary tests supports have been removed. d. It will be contractor’s /QC Engineer responsibility to check for any leak, constant pressure valve and any seepage on pipes and same shall be jointly witnessed by AMPTPL rep/QC Engineer.

e. In case of leak is defected from weld joint same shall be rectified by draining the fluid completely from system and weld repair to be done. After repair test to be repeated with same procedure. f. Valves installed in the circuit or line being tested shall be kept in the open position. g. Whenever a test circuit shall terminate at valves with a normal diameter of 2” and larger, a blind flange shall be installed to maintain the pressure. h. Once the above checks have been carried out and if there was no leakage found, the test can be considered completed. i. After test results found satisfactory should be documented as per approved format by AMPTPL. j. After completion of hydro test all vents and drains shall be kept open till lines are fully drained after that system lines shall be drained by air. k. All piping shall be completely drained of all testing fluid. Special precaution should be taken to ensure the drained of all pockets where tested fluid may be entrapped. l. Following acceptance of successful test, the system shall be immediately de pressurised and vented in gradual manner. Prior to draining out the test medium all valve is partially open position shall be fully opened after dropping pressure to system. m. All items removed for test shall be replaced and all test blinds temporary supports etc., shall be removed....