1. GENERAL
This specification defines minimum quality and technical
standards governing materials and equipment used for cleaning, gauging and
hydrotesting the export system pipelines and infield system flowlines. This specification is to be used in
conjunction with the following documents:
·
Basis of Design 84506-60-00-2L-060
·
General Specification
84506-60-00-2L-000 - Definitions and Specification Directory
·
General Specification
84506-60-00-2L-010 - Quality Assurance / Quality Control
·
General Specification
84506-60-00-2L-020 - General Offshore Specification
·
DNV OS-F101 Submarine Pipeline Systems
2000.
·
ASME B31.8 Gas Transmission and
Distribution Piping System.
2. PROCEDURES
·
Water winning, treatment and disposal
·
Filling, cleaning and gauging
·
Pig tracking
·
Hydrotest
·
Contingency procedures
·
Defect identification procedures
·
Testing parameters
·
Certification of handover for
installation completion of documentation and certification of all pipelines
requiring testing
2.2 In addition to normal safety procedures,
CONTRACTOR shall institute and enforce safety measures appropriate to the
degree of hazard existing along the pipeline during the cleaning and
gauging. Only personnel necessary for
cleaning and gauging operations shall be present during this work.
2.3 CONTRACTOR shall be responsible for any
delays in the event of a pig becoming stuck in the pipeline and its subsequent
release.
2.4
The Export pipeline shall be
hydrotested in accordance with the minimum requirements of DNV OS-F101. Infield flowlines shall be hydrotested in
accordance with ASME 31.8. For details
of hydrostatic test pressures refer to Basis of Design, 84506-60-00-2L-060.
2.5
Treated hydrotest fluid and indication
dye shall be acceptable to authorities for release into the sea in order to
ensure environmental compliance.
3. PIG DESIGN
3.1 The design of pipeline pigs for flooding,
cleaning and gauging of the pipelines shall be the responsibility of the
CONTRACTOR taking into account specific COMPANY requirements. CONTRACTOR will be required as part of the
detailed procedure to demonstrate to the satisfaction of COMPANY the suitability
of any pig design and its safe operation.
3.2 The design of pig trains for flooding,
cleaning and gauging of the pipelines is the responsibility of the
CONTRACTOR. CONTRACTOR shall as part of
the detailed procedure, demonstrate to the satisfaction of COMPANY the
suitability of any pig train design and associated operational safety.
3.3 All pigs shall be capable of negotiating
all ball valves, and other valves, fittings and bends as indicated in the work
scope.
3.4 COMPANY acceptance of any design or
procedure will not absolve CONTRACTOR of his responsibility to complete the
work in as diligent and as timely a manner as is practically possible.
3.5 Each pig train will include at least two
(2) pigs fitted with a ‘Helle’ pinger or COMPANY-approved equal. These pigs will be located at each end of the
train. For trains comprising five or
more pigs a third pinger shall be fitted to the pig closest to the center of
the train. The pinger shall be capable
of continuous operation for not less than 30 days.
3.6 Gauging plates shall be made of aluminum
and shall have the following dimensions:
·
Thickness of plate shall be 6 mm
·
Diameter of plate shall be 95% of
nominal ID
The
leading edge shall be chamfered to 45o for half the plate thickness.
3.7 All pigs shall be permanently marked with
a unique number that shall be clearly visible.
A photographic record shall kept of all pigs and gauging plates before
and after each run.
3.8 Pigs containing gauge plates shall only
be installed and removed from the launcher /receiver in COMPANY presence. Pig removal shall be such that the gauge
plate is not damaged during the operation.
4. PIGGING OPERATIONS
4.1 The pigging sequence shall be repeated
such that each individual piping section will be cleaned and gauged. The pigging sequence shall be:
a) Run
one (1) cleaning pig.
b) Retrieve
and inspect the cleaning pig from the piping.
c) If
the piping has not been adequately cleaned by the first cleaning pig run, in
COMPANY’S opinion, CONTRACTOR shall make a second cleaning pig run at no extra
cost to COMPANY.
d) Run
the gauging pig through the piping.
e) Inspect
plate wear.
4.2 Gauging or cleaning pigs shall be driven at
a speed of 0.5 meters/second. Driving
pressure shall be recorded on a recording pressure chart with a minimum range
of 2068 kPa (300 psig), and a minimum chart size of 254 mm (10 inches). Chart time shall correspond to actual
time. Charts and other data relating to
cleaning and gauging shall be turned over to COMPANY at the completion of each
run.
4.3 Pumps
shall be capable of driving pigs at the above speed and pressure range, and
pumping pressure.
4.4 Should a pig become stuck, CONTRACTOR
shall cease operations and immediately inform COMPANY. CONTRACTOR shall retrieve all stuck pigs in
accordance with COMPANY-approved procedures.
5. STANDARDS OF ACCEPTABILITY FOR GAUGING
5.1 Piping sections shall not be accepted if
the gauging plate suffers deformation.
When such defects are indicated, the piping section containing the
defect shall be located, cut out and replaced, and the piping gauged again at
no additional cost to COMPANY. Repair of
damaged pipe shall be performed based on a procedure prepared by CONTRACTOR and
approved by COMPANY. All gauging plates
shall become property of COMPANY.
6. HYDROTEST EQUIPMENT
6.1 Test Head - all hydrostatic test heads shall
have fittings for attachment of a relief valve, vent valve and pressure
gauge. Relief valves, if required, shall
be set at 1.1 times the specified maximum test pressure and ‘POP’ tested prior
to use in accordance with statutory requirements. Relief valve exhaust port shall have piping,
which directs any discharge to a safe location.
Fittings
for all instrumentation shall have a double block valve that can be used to
isolate the instrument at any time. Test
heads shall have provisions for mounting instrumentation to record the test
medium temperature and the test head on the pressurising end of the flowline
shall have a double isolation valve at the connection to the pump which will be
‘Locked Off’ during the test, COMPANY shall witness.
Test
heads shall be pre-tested prior to offshore operations to ensure that they are
fit for intended service.
6.2 Filling Pump
and Tanks
- For line filling operations, seawater intakes, suction pumps, manifolds,
break tanks, hoses, filters and flowline filling pumps shall be provided where
required. The filling pump(s) shall be
capable of a volume flow rate that can push the pigs between a minimum 0.5
m/sec and a maximum 1.0 m/sec, while overcoming the maximum head loss generated
by the flowline and testing system. The
filling pump shall not allow entry of air into the flowline.
6.3 Pressurising
Pump and Tank
- a variable speed, positive displacement pump(s), equipped with a stroke
counter shall be provided. The
pressurising pump(s) shall be capable of providing a pressure at least 1.4 MPa
above the specified test pressure. The
pressurising pump shall take its suction from a suitably sized tank.
6.4 Chemical
Injection Equipment - Chemical injection equipment shall be capable of
injecting chemicals into the filtered water, during each operation, at the
rates and location specified by the chemical manufacturers. The chemical injection pump(s) shall be a
variable speed, positive displacement pump(s), equipped with a stroke counter.
6.5 Temperature
Measuring Instruments - CONTRACTOR shall supply temperature monitoring and
recording equipment that shall be used for continuously recording the flowline
temperature, ambient air temperature, seawater and seabed temperature.
Temperature measuring
instruments and recorders
shall be calibrated and accurate
to ± 1.0°C, and a sensitivity better than ± 0.1 degree C.
Recorders
shall be capable of recording for 24 continuous hours. The operating temperature range of the
measuring equipment shall be suitable for the project location and season.
6.6 Test Pressure
Measuring Instruments - CONTRACTOR shall provide a dead weight tester with an
accuracy better than ± 0.1 bar and a sensitivity better than
0.05 bar. The range of the dead weight tester shall be a minimum of 1.25 times
the specified maximum test pressure. The
dead weight tester shall have been certified in accordance with the relevant
statutory authorities within 30 days of its use.
When pressure testing is performed
from a vessel, test pressures shall be measured using a high accuracy pressure
transducer and a high accuracy pressure gauge, in accordance with DNV OS-F101
Section 9 O 500.
A
minimum of one pressure recorder, calibrated using the dead weight tester
described above, one calibrated direct reading pressure gauge and one
calibrated barometer for measuring atmospheric pressure shall be provided by
the CONTRACTOR.
The
pressure recorder shall use a recording cylinder permitting a continuous,
24-hour record. It shall be checked
using the dead weight tester before each hydrotest. The pressure recorder shall have a certified
accuracy of 0.05 MPa. The pressure gauge
shall be selected such that the specified test pressure is between 50% and 90%
of the scale range.
6.7 Flow Meters - Water turbine flowmeter(s), shall be
provided by the CONTRACTOR to record flowrates during flooding, cleaning and
gauging operations.
CONTRACTOR
shall provide volumetric meter(s) to measure the volume of pressurisation water
injected into the flowlines.
Flowmeters
shall show both instantaneous and cumulative flowrates and shall have a
certified accuracy of ± 1 % over the full scale deflection
(FSD). The maximum expected flowrate
shall be within 50% to 90% of the meter flow range.
The
meters shall have been certified within 30 days of use.
6.8 Pumps, pressure gauges, temperature
gauges, deadweight load tester and pressure transducers, shall be provided by
the CONTRACTOR with signed and correctly dated test certification in accordance
with manufactures recommendations and in accordance with DNV OS-F101 and ASME
B31.8 as applicable to relevant pipeline system.
7. PIPELINE FILLING
7.1 Pipeline
filling shall not commence until written approval has been provided by
COMPANY.
7.2 Fill
water shall be free of substances which can settle in the pipeline, or coat the
interior of the pipeline, cause corrosion of or be harmful to the pipeline,
valves, meters, pump impellers and seals or other such equipment used in the
pipeline or pumping facilities. Water
suitability shall be established and approved by COMPANY prior to start of work
to ensure environmental acceptability in the event of subsea leakage.
7.3 Fill
water shall be filtered, chemically treated seawater, or fresh water, free from
suspended matter. Suspended matter shall
be removed before injection into the pipeline by a filter capable of removing
ninety-nine percent (99%) of all particles 50 microns in diameter and larger. Filters will be placed in parallel to ensure
they can be cleaned or changed without interrupting operations. If harmful material is pumped into the
pipeline because of faulty equipment or careless workmanship, CONTRACTOR shall
flush the pipeline with clean water.
7.4 Fill
water shall be within a range of pH 7 to pH 8.
CONTRACTOR will be responsible for developing a chemical cocktail
comprising corrosion inhibitor, bactericide and oxygen scavenger to mitigate
against deterioration of the pipeline between cleaning and commissioning, and
dye to enable flange leak checks during the leak test. CONTRACTOR shall minimize environmental
hazards and ensure during disposal that all procedures for disposal are in
accordance with requirements of DNV OS-F101 and statutory requirements of
Indonesian/Malaysian authorities.
7.5 A
flow meter of sufficient size and accuracy shall be used to measure the
quantity of water injected into the test section. CONTRACTOR detailed filling procedures shall
include methods and equipment used to measure and monitor injection rates.
7.6 Concentrations
of chemicals, manufacturer’s recommended dosage rate and material certificates
for each chemical shall be submitted to COMPANY for approval 30 days prior to
the start of all filling activities.
Chemical injection rates shall be monitored to ensure the correct
concentrations are being created.
7.7 If
in COMPANY opinion cleaning pigs have not adequately cleaned the pipeline, the
pig sequence shall be repeated until results obtained are satisfactory to
COMPANY.
7.8 Flooding,
gauging or cleaning pigs shall be driven at a maximum speed of 0.5
meters/second. Driving pressure shall be
recorded on a recording pressure chart with a minimum range of 2,068 kPa (300
psig), and a minimum chart size of 254 mm (10 inches). Chart time shall correspond to actual
time. Charts and other data relating to
cleaning and gauging shall be submitted to COMPANY at the completion of each
run.
7.9 Pumps
shall be capable of driving pigs at the above speed and pressure range, and
pumping pressure, volume and temperature shall be recorded.
7.10 Should
a pig become stuck in the pipeline, all operations shall be shut down. The pig shall be located and removed and the
pipeline shall be repaired as necessary.
Repaired pipelines shall then be re-cleaned and re-gauged and re-hydrotested.
7.11 Pigs
used during filling, cleaning and gauging and subsequent commissioning
activities shall be launched from and received in temporary traps furnished and
installed by CONTRACTOR.
7.12 CONTRACTOR
shall provide procedures for safe delivery of the pig at the receiver end of
all operations.
8. PRESSURIZATION PROCEDURE
8.1 High-pressure
pumps shall be equipped with a digital counter, that shall be zeroed before
starting. During pressurizing operations
the counter reading and gauge pressure shall be recorded, with time of day, at
15-minute intervals. Mean pipeline
temperature and test water temperature shall be recorded at the beginning and
end of the test and at two (2) hour intervals.
CONTRACTOR shall submit pressurization charts prepared for the test to
COMPANY for approval before commencing the test.
8.2 Both
pressure recording instruments and temperature recorders, equipped with 24-hour
recording charts, shall be used to record time, pressure, ambient and test
water temperatures during pressuring and testing operations. Pressure recorders shall have an accuracy and
repeatability of zero point one percent (+/- 0.1%). Temperature recorders shall be accurate to 0.1oC. Possible effect of temperature on pressure
shall be evaluated and taken into account in determining the correct pressure.
8.3 Pressure-recording instruments shall be tested
and calibrated with a deadweight tester before the pressure test begins. Deadweight testers shall be capable of
measuring in increments of 10.0 kPa.
8.4 Pressure recorder, pressure gauge,
deadweight gauge (or tester) and pressure transducers, shall be installed in
parallel on a manifold, with individual instrument valves and vents. CONTRACTOR shall provide to COMPANY
calibration certificates from an independent laboratory for the chart recorders
and deadweight gauges, showing they have been calibrated within thirty (30)
days prior to use.
8.5 Pressurizing
pumps shall be installed with the suction port flooded at all times and shall
have a minimum suction head of 1.5 m.
The discharge shall be connected to the system through a check valve and
leakproof injection block valve. Pump
discharge shall be easily separable from the system to be tested.
8.6 During
pressurisation, the pressure shall be increased at a maximum rate of 1 bar per
minute up to 95% of the test pressure. The last 5% up to the test pressure
shall be by a linear diminishing rate down to 0.1 bar per minute.
8.7 During
pressurisation CONTRACTOR shall maintain a pressure / volume plot (in accordance
with the requirements of Section 4.0 of this Specification) by taking regular
readings from the dead-weight pressure tester or the alternative testing
equipment, if testing is done from a vessel, and from the pump stroke counter.
The regularity of readings and the plot obtained shall be to the satisfaction
of COMPANY. CONTRACTOR shall complete a pipeline filling and pressurisation
log.
8.8 At
35% of the test pressure, the volume of air within the test section shall be
estimated.
The air volume shall be estimated by
constructing the pressure / volume plot from static head pressure to the full
hydrostatic test pressure and extrapolating the linear section of the plot back
to the volume axis, in accordance with an approved procedure conforming to
standard industry practice.
The air volume estimated shall not be
more than 0.2% of the calculated total volume of the pipeline under test. If
the air volume exceeds 0.2% the test will be aborted and actions taken to
reduce the air content.
8.9 Once
the test pressure has been reached, it shall be held until the pressure has
stabilsed and topped up, if necessary, recording the volume added. The
pressurising hose shall then be disconnected. All connections shall be
inspected for leaks, and thereafter the hold period shall begin. Variations due
to temperature shall be observed. Any drop shall be compensated prior to start
of the hold period.
The stabilisation period shall only be
completed on approval of COMPANY representative. COMPANY representative shall
approve and witness on the pressure chart, in writing, the start of the hold
period (this will be completed after the test has been successfully completed).
In addition, representatives of CERTIFYING AUTHORITIES may witness and approve
tests and records.
During the pressure stabilition and the
hold period, readings of time, gauge pressure, recorder pressure, barometric
pressure, dead-weight pressure, air temperature, test head water pressure and
tide level shall be taken and recorded as follows :
·
Every 15 minutes for the stabilisation
and first two hours of the hold period.
·
Every half – hour thereafter
When final test pressure is reached, all parties shall be
informed. Any subsequent operations on the line are to be reported immediately
to all parties.
The commencement of the hold period shall only be identified
retrospectively on completion of a satisfactory test internal, if a period of
stabilisation cannot be clearly identified by COMPANY, CLIENT and CERTIFYING
AUTHORITY.
The reading for each pipeline shall be recorded on the
Hydrostatic Pressure Testing Log (Time plots of these readings shall be made
during the test period).
All pressure, volume bled-off and temperature records,
charts and graphs shall be witnessed by both CONTRACTOR and COMPANY
representatives and CERTIFYING AUTHORITY and shall be included in the final
pigging and hydrotesting report. The pressure and temperature records, graphs
and charts shall be annotated with the times of major events and brief comments
describing the test and any discrepancies. The chart originals shall become the
property of COMPANY.
8.10 If
any water is required to be bled off during the holding period CONTRACTOR shall
obtain COMPANY approval and shall compare the volume of water bled-off with the
theoretical volume (V) calculated from:
DV
= V0 DP
[ 2 r (1 - n2) + 1 ] + V0 B DT
E
t K
Where :
DP = pressure
difference between start and finish of “bleeding-off”
r = internal
radius of pipeline
t = pipe
wall thickness
K = bulk
modulus of water
B = thermal
expansion coefficient for water
T = temperature
rise from start temperature
V0 = internal volume of pipeline
n = Poison’s ratio for steel
Before any water is bled off CONTRACTOR shall determine and
demonstrate to COMPANY, CLIENT and CERTIFYING AUTHORITY that the temperature
rise has caused and increase in test pressure in excess of the safe test
limits.
The discrepancy between the theoretical bleed volume
calculated and the measured volume bled-off shall not be more than 0.1% of the
internal volume of the pipe.
8.11 If
leaks are found during the test, the leaked volume shall be collected (if
possible) and may be used to justify the pressure drop, with prior agreement of
COMPANY, CLIENT and CERTIFYING AUTHORITY.
If the pressure drop exceeds two bar due to leakage then the
test shall be aborted, the leak fixed and the test re-started.
9. HYDROSTATIC PRESSURE TEST
9.1 Hydrotest
pressure shall be held without additional pumping, for a minimum period of
twenty-four (24) hours. During this
time, pressure shall remain constant. No
pressure decrease shall be accepted unless demonstrated to be due to a fall in
temperature, or test water removal that was documented by CONTRACTOR and
verified by COMPANY.
9.2 Chart
records shall be substantiated by deadweight pressure gauge readings and test
water temperature readings as follows:
·
One made at the start of the test
period
·
One every half-hour for the full test
period
·
One at the end of the test period
All charts shall be signed ‘ON’ and ‘OFF’ test by the
COMPANY and CONTRACTOR representative.
9.3 Time,
test water temperature and deadweight pressure gauge readings made during the
hydrotest period shall be recorded in tabular form and approved as true
readings by the COMPANY.
9.4 Any
known causes of pressure/temperature changes occurring during the hold period
shall be noted. A pressure increase due
to temperature increase during the hold period shall be limited to the maximum
permissible test pressure stated in Section 2.4, by a slow bleed-off as
detailed in section 8.10.
9.5 Following
completion of the test period, the pressure/volume relationship shall be
re-evaluated in the following manner:
·
If pressure is within the test range,
volume shall be reduced in 40 liter or less increments, not to exceed 70 kPa
(10 psi) pressure change for 5 intervals.
Time of day, pressure after volume removal and volume removed for each
interval and five (5) data points of time, pressure, and volume shall be
established.
·
If pressure is below the test range,
the pump counter shall be reset to zero.
Pressure shall be raised back to minimum allowable test pressure and
stopped. Time of day, pressure and
counter number shall be recorded at 70 kPa (10 psi) intervals, or at least
every five (5) minutes during the repressurizing period.
9.6 Following
the hydrotest, the pump counter shall be reset to zero and a calibrated vessel
shall be filled to recheck the counter for pump volume output at atmospheric
pressure. The final counter figure and
volume output shall be recorded.
9.7 Completed
records shall be turned over to COMPANY following the post-hydrotest pressure
volume recording.
9.8 If
there is a pressure loss after the twenty-four (24) hour test period,
CONTRACTOR shall evaluate how much pressure loss can be attributed to
temperature change and to free air dissolving in the water only. The test shall only be excepted if such
pressure drop can be explained to complete satisfaction of COMPANY.
Calculations of factors required to evaluate pressure change, shall be included
in the testing procedure.
9.9 If
CONTRACTOR explanation for pressure drop during the twenty-four (24) hour
period is not accepted by COMPANY, CONTRACTOR shall extend the hydrotest period
beyond twenty-four (24) hours, until a completely satisfactory hydrotest is
obtained.
9.10 If
any leaks are identified CONTRACTOR shall be responsible for locating and
rectifying the leaks, and retesting the system in accordance with this
specification.
9.11 Hydrotest
results shall be witnessed and certified by COMPANY and CONTRACTOR as a
condition of hydrotest acceptance.
Immediately after COMPANY accepts each successful hydrotest, CONTRACTOR
shall relieve pressure on the completed section.
9.12 After
the test has been completed, CONTRACTOR shall depressurise the system at a rate
that shall not exceed 1.0 bar per minute.
10. REPAIR OF TEST LEAKS AND FAILURES
10.1 CONTRACTOR
shall promptly tighten any mechanical fittings and / or repair or replace any
materials that have caused a leak in the pipeline system.
10.2 Failures
shall be located and a detailed program developed and approved by COMPANY for
field repairs. Such repair programs
shall include methods and procedures for depressurizing, removing and disposing
of test water, repairing the pipeline, refilling with test water, venting and
repressurizing.
10.3 Complete
records of failures occurring during the hydrotest shall be maintained. Records shall include the exact location,
type and cause of failure, method of repair, etc. Pipe, fittings, or valves that fail and are
replaced shall have the location and pressure at which they failed
recorded. Such materials shall be tagged
and delivered to COMPANY designated locations.
11. RECORDS
11.1 CONTRACTOR
shall submit for COMPANY approval as agreed in the contract procedure but not
limited to the following:
·
Chemical certificates
·
Equipment calibration certificates
·
Time/pressure plots
·
Temperature plots
·
Tabulated records
·
All calculations and explanations of
test pressure changes
11.2.1
Original records, data, and charts
shall be clearly marked with the following information and shall be furnished
to COMPANY in accordance with CONTRACTORS approved procedures and requirement
of DNV-OS-F101 and ASME B31.8:
·
COMPANY and COMPANY representative
names
·
CONTRACTOR and CONTRACTOR
representative names
·
Description of facilities tested
·
Date and time of test (start and
completion)
·
Test pressure and duration
·
Description of test medium used
·
Total volume of chemical additives and
water injected
·
Explanation of any pressure
discontinuities that appear on any chart
·
A full explanation of any failures
during the hydrotest
·
COMPANY representative and testing
CONTRACTOR representative signatures
11.3 All records
shall be submitted in both hard copy and electronic format.