SUBJECT : THE INTERNAL PRESSURE TESTS ON GRE COMPOSITE PIPE -175 PSI & ACCESSORIES BY HYDROSCAN TESTER:
- STD ASTM D 2992: LONG-TERM HYDROSTATIC PRESSURE (LTHP) – PROCEDURE B
- STD ASTM D 1599: SHORT-TERM TEST (WEEPING UNDER STATIC PRESSURE)
- STD ASTM D 2143: SHORT-TERM CYCLIC PRESSURE FOR 750 CYCLES
PRINCIPLE OF THE TESTS
(1) ASTM D 2992 PROCEDURE B:
TESTED BY EQUIPMENT IN LAB ACCORDING TO THE STD TEST METHOD, IT EXTRAPOLATES THE FAILURE POINTS OF STRESS VALUES AT LEAST 10,000 HRS WHICH MEANS AROUND 420 DAYS FOR THIS TEST, AFTER APPLICATION OF A SAETY FACTOR OF 3 OR TEST AT 525 PSI (APPROX 36 KG/CM2).
WE WLD REDUCE THE TESTING HRS BY CONDITION ACCLERATION SUCH AS INCREASE THE PRESSURE VALUE AND THEREAFTER USE THE LEAST SQUARES CALCULATION METHOD TO FIND OUT THE LTHP OF MATERIALS.
A DESIGN SERVICE LIFE OF 50 YRS OR 438,000 HRS HAS BEEN ASSUMED N THEN PLOTS THE LINEAR REGRESSION GRAPH.
THE ESTMATED LTHP CALCULATED BY THE FLWG LINEAR FUNTONAL RELATIONSHIP:
Y = A + BX
Y = 1ST VARAIBLE, X = 2ND VARIABLE, B = SLOPE OF THE LINE, A = INTERCEPT ON THE Y AXIS
(2) ASTM D 1599:
ACCORDING TO THE SPECIFICATION, THE FORMULA CALCULATED AS FLWS FOR THE REFERENCES:
T (WALL THICKNESS) = 0.02 D (INNER DIAMETER)
S = P (D – T) / 2T
S = P X 25
HOOP STRESS OF GRP PIPE (S) = 2,700 KG/CM2
P (INTERNAL PRESSURE) = AT LEAST 108 KG/CM2
THE TEST EQUIPMENT COULD PROVIDE AT LEAST 6 TIMES OF THE DESIGN PRESSURE (175 PSI) OR THE “MAXIMUM SERVICE PRESSURE”.
IN THIS CASE, THE TEST PRESSURE VALUE = MAX. SERVICE PRESSURE X SAFETY FACTOR OF 3
MAX. SERVICE PRESSURE = 175 X 6 X 3 = 3,150 PSI (APPROX. 217 KG/CM2)
(3) ASTM D 2143:
APPLIED THE CYCLIC INTERNAL PRESSURES AT SERVERAL DIFFERENT PRESSURE LEVELS N MEASURING THE CYCLES BY TESTED FOR 750 CYCLES AT CYCLING RATE TO AT LEAST 25 + 2 CYCLES/MIN.
TESTING PROCEDURE
STEP (1) : PREPARED THE TEST SPECIMENS
STEP (2) : MOUNTED THE BOTH HOSE ENDS OF TEST PIECE INTO THE CLAMPING HEADS OF TESTER
STEP (3) : INSTALLED THE SPECIMEN ON HYDROSCAN TESTER
STEP (4) : SET THE PRESSURE N CLOSED THE TEST CHAMBER WHILE APPLYING TEST PRESSURE
STEP (5) OPENNED THE CHAMBER AFTER THE TEST N DRAINED THE TEST FLUID FROM TEST PIECE
TEST RESULT
DATE OF TEST : TIME : 8:00 – 17:00 HRS. PLACE :
TEST OPERATOR : AUTHORIZED WITNESSES : ASSIGNED BY :
TESTER : MICROPROCCESSOR-CONTROLED P 200 UNIMATICONTROL-E SYSTEM , S/N 3PEN AC 400V, P/N 80, MFG 03/00, I 0.9 A, P 0.4 KW, 50 HZ
TEST SUBJECT : INTERNAL PRESSURE TESTS OF COMPOSITE TUBES & ACCESSARIES FOR OIL&GAS FIELD APPLICATION
SPECIMEN (1) : 45O ELBOW LONG REDIUS W/ CLOSED END HOSES MOUNTING, SIZE 100 MM., GRE COMPOSITE PIPE -175 PSI
ONE OF THE CLOSED END LIDS LEAKED AT 2 BAR (29 PSI) PRESSURE DURING THE TEST OPERATION, WE HV TO DO THE SUPPORT OR FIXTURE ON ELBOW SPECIMEN.
SPECIMEN (2) : 90O ELBOW LONG REDIUS W/ CLOSED END HOSES MOUNTING, SIZE 100 MM., GRE COMPOSITE PIPE -175 PSI
WE HV NOT TESTED YET BECAUSE OF FAILURE ON THE LAST CLOSED END LIDS ON 45O ELBOW, WE HV TO DO THE SUPPORT OR FIXTURE ON ELBOW SPECIMEN.
SPECIMEN (3) : 0.85 M. LENGTH SHORT STRAIGHT PIPE W/ 4 X STUD-BOLTS SUPPORT ON AXIAL DIRECTION + CLOSED END HOSES MOUNTING, SIZE 100 MM., GRE COMPOSITE PIPE -175 PSI
DUE TO THE SPECIMEN CONSUMES A LARGE VOLUME OF TEST FLUID THEN THE PRESSURE LINE N HIGH PRESSURE PUMP UNIT IN OUR HYDROSCAN TESTER HD THE LEAKAGE N OVERHEAT PROBLEMS. WE THEN DECIDED TO TERMINATE THE TEST PROCESS TEMPORARILY, OTHERWISE OUR TESTER WLD BE MORE DAMAGED N OUT OF ORDER.
WE WL CONTINUE THE APPROVAL TEST SOON AFTER OUR TESTER WS CHECKED N REPAIRED.
CONCLUSIONS
1) ELBOWS N ACCESSARIES :
WE HV TO IMPROVE THE CLOSED ENDS OF ELBOW SPECIMEN BY USING ANY SUPPORT OR FIXTURE ON THE CIRCUMFERENTIAL OR AXIAL DIRECTION.
2) STRAIGHT TUBES OR PIPES :
WE HV TO REVISE THE TEST PROCEDURE N SPECIMEN SIZE IN ORDER TO CONSUME LESS TIME N THE VOLUME OF TEST FLUID, OTHERWISE OUR HYDROSCAN TESTER WL BE SPOILED.
OVERVIEWS: –
THE APPROVAL TESTS FAILED DUE TO THE LEAKAGE OF PRESSURE LINE N OVERHEAT PROBLEMS; WE TEMPORARILY TERMINATE THE TEST BY OUR HYDROSCAN TESTER FIRST BECAUSE WE R AFRAID OF THE TESTER IS DAMAGED. WE HV TO MAINTAIN N REPAIRS OUR TESTER TO CONTINUE THE APPROVAL TESTS.
REMAINING AT YR DISPOSAL FOR ANY CLARIFICATION.IF U HV ANY QUERIES, PLS DON’T HESITATE TO CONTACT US.
THANKS FOR YOUR KIND CORPORATION.
B.RGDS,
SUPPAWIT H.
