TABLE
OF CONTENTS
1. PURPOSE
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3
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2. SCOPE
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3
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3. REFERENCES
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3
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4. DEFINITIONS
AND ABBREVIATIONS
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3 - 4
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5. GENERAL
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4
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5.1.
PERSONNEL DUTIES AND
RESPONSIBILITIES
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4 - 5
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5.2.
QUALIFICATIONS AND
TRAININGS
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5
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5.3.
CALIBRATION STANDARDS AND
REFERENCE MATERIALS
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5 - 6
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5.4.
CALIBRATION WORKSHOP AND
TEST FACILITY
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6
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5.5.
PHYSICAL ENVIRONMENT OF
CALIBRATION WORKSHOP
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6
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5.6.
ENVIRONMENTAL CONDITIONS
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7
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5.7.
CALIBRATION CERTIFICATES/REPORTS
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7
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5.8.
CONTROL OF NON-CONFORMING
CALIBRATION WORK
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7
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5.9.
REFERENCE STANDARD, TEST
EQUIPMENTS AND TOOLS
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7 - 8
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5.10. RECEIPT,
HANDLING AND STORAGE
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8
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6.
SAFETY REQUIREMENTS
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8 - 9
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7. CALIBRATION
CONSIDERATIONS
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9
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8. CALIBRATION
PROCEDURE
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9
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8.1.
TRANSMITTER CALIBRATION
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9 - 10
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8.2.
TEMPERATURE CALIBRATION
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10 - 12
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8.3.
PRESSURE CALIBRATION
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13 - 15
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8.4.
LEVEL CALIBRATION
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15 - 17
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8.5.
FLOWMETER CALIBRATION
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17
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8.6.
CONTROL VALVE CALIBRATION
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17 - 18
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9. QUALITY
ASSURANCE AND TESTING
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18
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10. ATTACHMENTS
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18
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The purpose of this method statement is to
provide guideline for calibration and inspection of measuring & testing shall
be carried-out in a neat, efficient and skillful manner, assuring satisfactory
results. The work shall be in accordance with the requirements of the project
specifications, standards, and shall fulfill their true intent and meaning.
This method
statement covers the methodology for calibration and inspection of measuring
& testing in Luberef Yanbu Expansion project.
These
guidelines and information describes the calibration and inspection of
measuring & testing techniques and different requirements to be adhered
during the course of execution for calibration and inspection of measuring
& testing, to get a satisfactory result and in accordance with established
safety practices. It does not intend to cover all details and variations in calibration
and inspection of measuring & testing nor provide for every possible, available
contingency representation.
3. REFERENCES
a) Project
Scope of Works
b) Project
Technical Specification
c) Applicable Saudi
ARAMCO standards.
d) Issued for
Construction drawings
4.
DEFINITIONS AND ABBREVIATION
a) Calibration The set of operations that
establish, under specified
conditions,
the relationship between values of quantities
indicated
by a measuring instrument or measuring system
and
the corresponding values realized by standards.
b)
Accuracy The difference between a measurement reading and the
true value
of that measurement.
c) Error Offset or
deviation (either positive or negative) from the
correct
value.
d)
UUT Unit
Under Test – An instrument or equipment that shall be
calibrated
and tested to determine performance and
proficiency
of the unit i.e. instrument, equipment,
transmitter,
gauges, control valve etc.
e) Reference Standard A device or material used to calibrate UUT and provide
traceability
of measurements to international standards.
f)
TUR Test
Uncertainty Ratio – The ratio of the uncertainty of the
test
item (DUT) to that of the measurement reference
standard
used in the calibration. Commonly acceptable
TUR
in International Standards is at least 1:4 ratio.
g) Hysteresis The delay between the action and reaction of a measuring
instrument.
Hysteresis is the amount of error that results
when this
action occurs.
h) Linearity The amount of error change throughout an instrument's
measurement
range. Linearity is also the amount of
deviation
from an instrument's ideal straight-line
performance.
i) Traceability The
property of the result of a measurement or the value of
a
standard whereby it can be related to stated references,
usually
national or international standards, through an
unbroken
chain of comparisons, all having stated
uncertainties.
a)
5-point calibration In 5-point calibration , three basic steps are involved,
namely:
1) zero adjustment (LRV), 2) linearity
adjustment
(25%, 50%,
& 75%), and 3) span adjustment (URV)
b)
SAES Saudi
Aramco Engineering Standard
c)
SATIP Saudi
Aramco Technical Inspection Procedure
d)
SAIC Saudi
Aramco Inspection Checklist
e)
NEC National
Electrical Code
f)
IEC International
Electro-Technical Commission
g)
RFI Request
for Inspection
h)
MRR Material
Receiving Report
i)
ITP Inspection
and Test Plan
j)
COMPANY Luberef
or its designated Representative
k)
CONTRACTOR Samsung
Engineering Const. Ltd.
l) SUBCONTRACTOR Any Individual or Corporation under contract
to the
CONTRACTOR
who perform the entire and/or some
portion of the work or services
on a
project which the CONTRACTOR has agreed upon.
5.1.
PERSONNEL, DUTIES AND RESPONSIBILITIES
a)
Instrumentation
Manager
i) Manager will
be coordinating with concerned personnel, plan the daily work schedule and
enforce strict adherence to all project requirements.
b)
Instrument Supervisor
ii)
Supervisor is responsible and ensuring that
the works are carried out accordance to the COMPANY requirements, scope of
work, and approved Method Statement.
iii)
Monitor the progress of work in relation with
the work program and to report to the Manager.
iv)
Coordinate with Safety Officer and to ensure
that the works are carried out in safe practicing methods.
c)
Calibration Technician
i)
He shall be approved to perform calibration
by the COMPANY.
ii)
He shall demonstrate a technical competence,
education, skills, training, and practical experience. Records are to be
available in demonstrating his qualifications.
iii)
He is responsible to conduct calibration and
testing of equipment as per approved procedure and reference standard.
iv)
He shall complete required calibration and
testing in accordance with documented requirement, record and report on the
findings.
d)
Quality
Control Manager
i)
Responsible for the implementation of all
required quality control activities such as test and inspection for this
particular job and keeps record of its necessary documentation.
e)
Quality
Control Inspector
i)
Inspect the work to comply according to
Company standards.
ii)
He shall be
responsible for conducting surveillance and inspection duties during test
activities and ensuring quality compliance.
iii)
He shall review all
relevant documents and test reports.
f)
Safety
Supervisor
i)
Make sure that all safety measures are
complied before starting the work.
ii)
Provide safety instructions to the workers.
iii)
Ensure
the implementation of all the safety measures in accordance with the HSE plan
and everybody aware of it, for its proper implementation.
iv)
Ensure
all the implemented safety measures are adequate to maintain the safe working
on the site.
v)
Inspect
all the site activities and train the persons to prevent accidents and its
proper reporting to the project manager and the client.
5.2.
QUALIFICATIONS AND TRAININGS
a)
Supervisors & Inspectors must be eligible
and competent for the job.
b)
Technician must able to understand his work
and require trade certificates if necessary.
c)
Conduct trainings regularly to maintained
safety and good workmanship.
5.3.
CALIBRATION STANDARDS AND REFERENCE MATERIALS
a)
The reference standards used in calibration
workshop are to be calibrated by a calibration service provider that the
traceability of the calibration(s) is traceable to national/international
metrology institution.
b)
Equipment (Reference
standards) - Calibration
workshop must have all the calibration standards and reference materials
available for the calibrations to be performed.
c)
Calibration of Reference
Standards - The
calibration standards supporting calibration systems are to be calibrated on a
regular schedule to maintain precision and traceability as per manufacturer’s
recommendation. Records are to be available to verify the drift of reference
standards and demonstrate compliance with this requirement.
d)
The calibration certificate for reference
standards and related records must provide evidence that the calibration
service provider utilized calibration standards that are traceable to national/international
standards.
e)
The calibration standards shall be maintained
in accordance with the following:
1.
A unique identification number such as tag
number, the manufacturer’s name, an assigned identification number or model and
serial number.
2.
The manufacturer’s instructions or operating
manual.
3.
Calibration records - including adjustments
made, certificates, next calibration date and calibration dates.
4.
Calibration records and procedures shall
clearly specify when the calibration of the instrument expires.
f.
Measurement Traceability - All calibration
equipment is to be calibrated using Measurement Standards traceable to a
national metrological institute e.g. NIST or a government-sponsored / approved
national metrology institute, either directly, or through a regional group.
Calibration equipment is deemed traceable through an accredited calibration
service provider.
g.
Reference materials i.e. metric to english conversion table, RTD conversion table,
thermocouple conversion table etc. must be available at all time and easy
to locate in calibration workshop.
5.4.
CALIBRATION WORKSHOP AND TEST FACILITY
A location where the work shall be carry out, a temporary portable laboratory
facility prepared specifically for the purpose of completing calibration and
testing at project premises or site location.
5.5.
PHYSICAL ENVIRONMENT OF CALIBRATION WORKSHOP
a)
Calibration workshop must maintain appropriate
environmental conditions as specified by documented calibration procedures or
methods being applied to assure the correct performance of calibrations. This
requirement includes control and monitoring of parameters that may affect the
quality of calibrations including humidity, temperature, vibration, etc.
b)
Other relevant conditions that may be a
source of error such as dust, electromagnetic disturbances, radiation,
electrical supply, sound and vibration levels are to be controlled and
monitored as appropriate to the technical activities concerned. Calibrations
are to be halted when the environmental conditions may jeopardize the results
of the calibrations. Corrective action is to be taken before proceeding with
calibrations.
c) There shall
be effective separation between neighboring areas in which there are
incompatible activities. e.g. Construction
works, Vibration from heavy equipment that may affect a calibration process.
Distance or appropriate barriers must separate these calibration activities.
5.6.
ENVIRONMENTAL CONDITIONS
25 °C ±3 °C, 40%
to 50% RH
5.7.
CALIBRATION
CERTIFICATES/REPORTS
Calibration
certificates and/or reports provided by calibration workshop shall contain the
following information:
a) Company logo of Luberef, Samsung and
SUBCONTRACTOR.
b) Location where the calibrations were
carried-out.
c) Unique identification of the calibration
certificate. Each page of supporting
data requires an identification to ensure that the page is recognized as a part
of the calibration certificate package.
d)
An unambiguous identification of the item(s)
tested or calibrated e.i. Tag Number,
Nameplate Data (Manufacturer, Model Number, Serial Number etc).
e) Reference to the sampling plan and
procedures used by the workshop or other bodies if these are relevant to the
validity or application of the results;
f)
Reference Standards data e.i. Tag Number, Nameplate data, Calibration due date etc
g)
Calibration Range and Calibration Tolerance
h) The calibration results (as-found and
as-left data) with the units of measurement, where appropriate,
i)
Calibration date and Due date
j)
The
name(s), functions(s) and signature(s) or equivalent identification of
person(s) authorizing the calibration certificate;
k) The conditions (e.i. environmental
temperature and humidity) under which the calibrations were made that have an
influence on the measurement results;
l)
Evidence
that the measurements are traceable (to national standards)
m) Comments
5.8.
CONTROL OF NON-CONFORMING CALIBRATION WORK
a)
Records to be maintain of every event where
non-conforming calibration work is found.
b)
Where non-conforming conditions occur, Calibration
personnel is to determine if there are defects in the processes used or data
developed.
c)
If the cause of the non-conforming work is
found to affect calibration or testing data. CONTRACTOR shall be informed for
immediate resolution if the “as-found” data was not within the acceptable
tolerance.
5.9.
REFERENCE STANDARD, TEST EQUIPMENTS AND TOOLS
a)
Pressure source of pressure such as a hand
pump or regulated pressure source (Compressor-oil free type), Nitrogen Gas
b)
Precision gauge or digital test standard
c)
Comparator
d)
Manometer or dead weight tester
e)
Temperature dry-well calibrator
f)
Thermometer Simulator
g)
Decade Resistance Box
h)
Temperature reference standard
i)
6.5 Digital Multimeter
j)
Handheld Multimeter (Digital and Analog type)
k)
HART Communicator
l)
Milli-Ampere Simulator
m)
Automatic Voltage Regulator
n)
DC Power Supply
o)
Calculator
p)
Hand Tools
a)
Other appropriate
standard equipment required to be used during calibration
q)
Appropriate safety equipment
5.10.
RECEIPT, HANDLING
AND STORAGE
a)
After receiving the UUT. It shall be
calibrated and inspected to ensure
that it functions
correctly, establish the reliability of the UUT and is in fit condition to be
installed in projects site. All calibrated instrument must be signed off by
concerned parties.
b)
All UUT for calibration & testing shall
be checked on receipt for damage and deficiency, any item found to be defective
or incomplete at this stage, or during subsequent calibration, or testing shall
be reported to the CONTRACTOR and their disposition agreed before any further
action.
c)
All UUT calibration certified or tested
condition must be handled with care and protected from any impact, vibration or
any magnetic disturbance, dust free environment, away from direct sunlight and
sudden change in temperature that could adversely affect the accuracy of the
instrument.
a) Conformity
and execution in accordance with field Safety Management Plan.
b) Safety
management during work (Worker Personnel Protective Equipment and temporary
safety structure establishment / operation).
c) Regarding to
safety all relevant JHA (Job Hazard Analysis) will be submitted separately.
d) Toolbox talk
shall be conducted daily prior to work start Permit to Work (PTW) must be
obtained and available at the work location.
e) Safety Supervisor
/ Officer to ensure working area shall be safe and in good condition.
f) Safety Supervisor
/ Officer shall carry out the safety site inspections to ensure that safety
requirements laid in the safe work plan are being followed during and after the
work.
g) CONTRACTOR/SUBCONTRACTOR
shall provide safety equipments as necessary according to an evaluation of
expected needs during the work. This applies to temporary fire extinguishers
first aid equipments, stretcher, etc.
h) Authorized
personnel shall inspect all equipments and electrical tools prior to commence
any Work and shall be inspected & tag by safety personnel to ensure their
safe worthiness at work. The inspection reports shall be kept for record.
i) Hazardous
substance likely to be used during the work e.g. Paint, Lubricant, etc. shall
be used per established safety work practice and in accordance with the
information from a Material Safety Data Sheet (MSDS).
j) Calibration
personnel shall ensure that before leaving their working places, it must be
clean, tidy and free from rubbish.
7. CALIBRATION CONSIDERATIONS
a)
Correct reference standard equipment used during
calibration and shall meet the required criteria of TUR per available national/international
standards.
b)
Before any UUT is calibrated, the UUT must
stabilize (warm-up) according to manufacturer’s instructions.
c)
Bench test for calibration is performed at
the workshop.
d)
Since precise test for the instrument or equipment
has been performed at the manufacturing shop, the bench test inspects more on the
zero point calibration and span rather than precise calibration.
e)
Check the air (with clean air without oil)
and power utilities for use before testing.
f)
Transmitter (UUT) shall be checked both the
milli-ampere value and specified process variable.
g)
Tolerance shall be checked as per Datasheet
of the instrument, gauges, control valve etc.
h)
For UUT that has completed testing shall be
clean by blowing with clean air without oil, and seal the joints and equipment
inlets to prevent moisture and dust from entering.
i)
Install the testing instrument on rigid
points free from vibrations.
j)
If necessary, UUT power source shall be
provided if separate power source is required. Make sure that the method of
wiring connection is correct before proceeding the calibration to avoid before
instrument or equipment damages.
k)
Calibration label shall be affixed in every UUT to identify a successful
calibration, it specified
the tag number, date of calibration, and initial/sign of calibration
technician.
l)
All calibrated UUT shall be sealed with
tamper-resistant seals to preclude any tampering with calibration controls or
adjustments.
8.
CALIBRATION
PROCEDURE
8.1.
TRANSMITTER
CALIBRATION
8.1.1.
HART
FUNCTION
1.
The standard test equipment used is a Communicator
(HART).
2.
Hook-up the transmitter (UUT) to reference standard
(communicator).
3.
Simulate milli-ampere signal that corresponds
to 0%, 25%, 50%, 75% and 100% (5-point test) of the UUT measurement range and record the
“as-found” value. Check the UUT ranges both the upscale and downscale
directions.
Note: For UUT
with square root capability make sure to simulate a correct required current
value.
4.
Record the “as-found” value of reference standard
and UUT.
5.
Evaluate the error against the acceptable
tolerance to determine if adjustment is required.
6.
If adjustment is required, perform zero and
span adjustment per the manufacturer’s procedures.
7.
Or use the general instructions of Zero and
Span point adjustment, as follows:
a.
Using the Zero-and-Span adjustment screw
b.
Pressing the Zero and Span push button
adjustment
c.
Others require the use of handheld interface
or communicator to convey specific information to the UUT.
8.
Because some zero and span adjustment
interact, it is important to recheck the zero and span until no further
adjustment is required.
9.
Once no further adjustment is required,
repeat the 5-point test, verify that it is within tolerance over the defining
specification and record “as-left” values.
8.1.2.
FIELDBUS
FUNCTION
1.
Normally, workshop calibration for
Fieldbus function is not essential but data record is required.
2.
Ensure that the UUT and its
accessories are in good conditions and no physical damage on the body.
3.
Record data such Tag number,
Maker, model number, etc on the calibration data sheet.
4.
The UUT shall be tested as part of loop test.
5.
Lest that the calibration of
Fieldbus function is recommended by COMPANY. Make sure that the change of
device parameters during calibration shall be put the control loop in
Manual/Out of Service before applying any changes. Verify the output and device
parameters are correct during the normalization state of the transmitter.
Failure to do so may result on device damage.
6.
Calibration of Fieldbus devices is similar
with calibration of HART function.
7.
Follow the calibration procedure of HART function.
8.2.
TEMPERATURE
CALIBRATION
a)
CALIBRATION
OF A DIAL THERMOMETER
1.
The standard test equipment use is a
temperature dry-well calibrator, and temperature reference standard.
2.
Set the temperature of dry-well calibrator
and wait that the temperature value to stabilize.
3.
The dial thermometer (UUT) sensor and
reference standard thermometer shall be immersed in the temperature dry-well
calibrator. Consider to correctly depth the immersion length of each
thermometer.
4.
Simulate temperature signal that corresponds
to 0%, 25%, 50%, 75% and 100% (5-point test) of the UUT measurement range and record the
“as-found” value. Check the UUT ranges both the upscale and downscale
directions.
5.
Record the temperature “as-found” value of
Reference Standard and UUT.
6.
Evaluate the error against the acceptable
tolerance to determine if adjustment is required.
7.
Some thermometer (UUT) are not adjustable, in
which case the UUT status shall be informed to CONTRACTOR for immediate
resolution if the “as-found” data was not within the acceptable tolerance.
8.
In case the UUT can be adjusted, adjust the UUT
based on the average error such that all readings are as close as possible.
9.
Once no further adjustment is required,
repeat the 5-point test, verify that it is within tolerance over the defining
specification and record “as-left” values.
b)
CALIBRATION
OF TEMPERATURE SENSOR (RTD AND TC TYPE)
1.
The standard test equipment use is
temperature dry-well calibrator, and temperature indicator reference standard.
2.
Set the temperature of dry-well calibrator
and wait that the temperature value to stabilize.
3.
Hook-up the temperature sensor (UUT) in
temperature indicator reference standard. Make sure that the temperature type
is matching with type settings of reference standard.
4.
Immersed the UUT in the temperature dry-well
calibrator. Consider to correctly depth the immersion length of sensor.
5.
Simulate temperature signal that corresponds
to 0%, 25%, 50%, 75% and 100% (5-point test) of the UUT measurement range and record the
“as-found” value. Check the UUT ranges in upscale directions (linearity
check).
6.
Evaluate the error against the acceptable
tolerance to verify that it is within tolerance over the defining specification
of the UUT
7.
Temperature sensors (UUT) are not adjustable,
in which case the UUT status shall be informed to CONTRACTOR for immediate
resolution if the “as-found” data was not within the acceptable tolerance.
8.
This will complete the calibration of
temperature sensor.
c)
CALIBRATION
OF RTD TYPE TEMPERATURE TRANSMITTER
1.
The standard test equipment use is a decade
box or Resistance Temperature Detector (RTD) simulator.
2.
Commonly used RTD type temperature sensor in
industrial-grade RTD is PT100, which is a 100 ohm at 0°C, platinum,
with coefficient values of 0.00385 ohm/ohm/°C
alpha.
3.
Hook-up the RTD type temperature transmitter
(UUT) to reference standard test equipment (Decade box or RTD simulator).
Note: When using
Decade Resistance Box as standard it will introduce error to wiring connection.
Make sure that the test lead used of 3-wire system is the same size and length.
For 2-wire system, make sure to eliminate error associated to the test lead
resistance.
4.
Simulate temperature/resistance signal that
corresponds to 0%, 25%, 50%, 75% and 100% (5-point test) of the UUT measurement
range and record the “as-found” value. Check the UUT ranges both the upscale
and downscale directions.
5.
In case, a decade box has been-used as
standard equipment. Record the resistance and temperature “as-found” values and
check the correct corresponding temperature values per Temperature conversion
table of RTD -PT100 type temperature.
6.
Evaluate the error against the acceptable
tolerance to determine if adjustment is required.
7.
If adjustment is required, perform zero and
span adjustment per the manufacturer’s procedures.
8.
Or use the general instructions of Zero and
Span point adjustment, as follows:
a.
Using the Zero-and-Span adjustment screw
b.
Pressing the Zero and Span push button
adjustment
c.
Others require the use of handheld interface
or communicator to convey specific information to the UUT.
9.
Because some zero and span adjustment
interact, it is important to recheck the zero and span until no further
adjustment is required.
10.
Once no further adjustment is required,
repeat the 5-point test, verify that it is within tolerance over the defining
specification and record “as-left” values.
d)
CALIBRATION
OF THERMOCOUPLE (TC) TYPE TEMPERATURE TRANSMITTER
1.
The standard test equipment use is a
thermocouple simulator of correct type.
2.
Connect the TC type temperature transmitter
(UUT) to reference standard test equipment. Make sure that the UUT typesetting is
matching with reference standard thermocouple simulator.
3.
Simulate temperature signal that corresponds
to 0%, 25%, 50%, 75% and 100% (5-point test) of the UUT measurement range and
record the “as-found” value. Check the UUT range in both the upscale and
downscale directions.
4.
Repeat procedure for remaining temperature
type of the UUT.
5.
Once the “as-found” data has been recorded
evaluate the error against the acceptable tolerance to determine if adjustment
is required.
6.
If adjustment is required, perform zero and
span adjustment per the manufacturer’s procedures.
7.
Or use the general instructions of Zero and
Span point adjustment, as follows:
a.
Using the Zero-and-Span adjustment screw
b.
Pressing the Zero and Span push button
adjustment
c.
Others require the use of handheld interface
or communicator to convey specific information to the UUT.
8.
Because some zero and span adjustment
interact, it is important to recheck the zero and span until no further
adjustment is required.
9.
Once no further adjustment is required,
repeat the 5-point test, verify that it is within tolerance over the defining
specification and record “as-left” values.
8.3.
PRESSURE
CALIBRATION
a)
CALIBRATION
OF PRESSURE GAUGES
1.
Pressure gauges (UUT) shall be calibrated
using a source of pressure such as a hand pump or regulated pressure source,
precision gauge or digital test standard with the correct module, Comparator, manometer
or dead weight tester
2.
Use a Tee to connect the input reference
standard to the pressure source and the UUT. Mounting of UUT during calibration
to be followed as per site installation. In case, you are unsure for mounting
direction, vertical position is the prepared method.
3.
Simulate a 50% pressure and locked-in signal
pressure-check system for leaks, then reset to zero.
4.
For any mechanical instrument, it is
important to determine whether hysteresis error is present in the UUT. This
means you will begin your upscale check from 0% and approach the first test
point, 10% from below. Approach each increasing test point from below and do
not overshoot.
5.
Similarly, start the downscale check by
increasing the input to 100%, then approach 90% from above.
6.
Once the “as-found” data has been recorded
evaluate the error against the acceptable tolerance to determine if adjustment
is required.
7.
If the result is outside the allowable
tolerance, determine the type of error present (linearity, zero, span, and
hysteresis), and adjust per the manufacturer’s instructions or use the general
instructions, as applicable, that follow.
a.
For motion balance instruments, linearity adjustment
shall be done first. The movement of the elastic element in a pressure gauge
causes a proportional movement in the linkage.
b.
On a properly calibrated gauge, the linkage
angle will be exactly 90 degree when the input to the gauge is 50% of total
range. Therefore, apply 50% input and use
a template to check the 90 degree angle.
c.
With linearity adjusted, position the pointer
so the gauge reads mid-scale. You may need to remove the pointer and reposition
it on the shaft. If removing the pointer is necessary, be sure to use the
proper tool. Adjust the pressure input to 10% and adjust the zero so the gauge
reading equals the applied input.
d.
Now correct the span error. Increase the
input pressure to 90% and adjust the gauge to read the input value. For span
adjustment, loosen the crews and rotate the entire adjustment mechanism.
e.
Repeat the zero and span adjustment until the
reading of 10% and 90% are accurate. Zero and span interact in the mechanical
device, so rechecking them is necessary. When zero and span require no further
adjustments, recheck the linearity to make sure it is still properly adjusted.
f.
There is no adjustment for hysteresis.
8.
After adjusting linearity, zero and span,
perform another full scale check, verify that it is within tolerance over the
defining specification and record “as-left” values.
b)
CALIBRATION
OF PRESSURE TRANSMITTER
1.
Connect the pressure transmitter (UUT) to
applicable standards.
2.
Simulate pressure signal that corresponds to 0%,
25%, 50%, 75% and 100% (5-point test) of the UUT measurement range and record
the “as-found” value. Check the UUT ranges both
the upscale and downscale directions.
3.
Evaluate the error against the acceptable
tolerance to determine if adjustment is required.
4.
If adjustment is required, perform zero and
span adjustment per the manufacturer’s procedures.
5.
Or use the general instructions of Zero and
Span point adjustment, as follows:
a.
Using the Zero-and-Span adjustment screw
b.
Pressing the Zero and Span push button
adjustment
c.
Others require the use of handheld interface
or communicator to convey specific information to the UUT.
6.
Because some zero and span adjustment
interact, it is important to recheck the zero and span until no further
adjustment is required.
7.
Once no further adjustment is required,
repeat the 5-point test, verify that it is within tolerance over the defining
specification and record “as-left” values.
c)
PRESSURE
SWITCHES CALIBRATION
1.
A pressure switch (UUT) is a device that
senses pressure and changes state at the programmed or adjusted set-point.
2.
Connect variable pressure source to reference
test gauge and Hi-side pressure switch (UUT) port.
3.
Connect a Multimeter set to continuity range
across Common “C” and Normally Open “NO” switching element contacts. The meter
should read an open circuit.
4.
Increase the pressure to the set-point of the
pressure switch (UUT) until the contacts change over. The meter should read
“short circuit”. Record the “as-found” pressure value for a rising pressure.
5.
Increase the pressure to the switch maximum
rating. Slowly reduce the pressure to the UUT until the switch changes over
from closed to normally open position. Record the “as-found” pressure value for
a falling pressure.
6.
From the two readings been taken, the
pressure difference between the rising and falling pressure settings. This is
called “dead-band” of the switch.
7.
Evaluate the error against the acceptable
tolerance to determine if adjustment is required.
8.
If adjustment is required, follow the
manufacturer’s procedures for adjustment of set-point.
9.
Once no further adjustment is required,
repeat the procedure, verify that it is within tolerance over the defining
specification and record “as-left” values.
d)
PRESSURE
METERS
(Displacement
type Pressure meter)
1.
Workshop calibration is not
essential but data record is required.
2.
Ensure that the UUT and its
accessories are in good conditions and no physical damage on the body.
3.
Record data such Tag number,
Maker, model number, etc on the calibration data sheet.
4.
The UUT shall be tested as part of loop test.
8.4.
LEVEL
CALIBRATION
8.4.1.
SPECIAL
CONSIDERATIONS WITH LEVEL CALIBRATION
a)
SUPPRESSED/ELEVATED
ZERO
1.
If the D/P cell is not located at an
elevation that corresponds to 0% level in the tank, it must be calibrated to
account for the difference in elevation. This calibration adjustment is called
zero elevation when the cell is located above the lower tap; it is called zero
suppression when the cell is located below lower tap.
2.
To calculate the amount of elevation or
suppression, the distance between the zero reference level and the high
pressure port of the D/P cell must be accurately measured.
b)
SPECIFIC
GRAVITY
1.
During calibration of DP level devices, it is
important to consider the specific gravity of the process material to avoid
error during the calibration.
2.
To calibrate a D/P transmitter for a sensor
monitoring. The nominal test point for input pressure must be multiplied with
equivalent process fluid specific gravity
c)
DRY AND WET
LEGS
1.
For differential pressure measurements, the
pressure of the vapor in pressurized vessels is connected to the low pressure
side of the D/P cell. When process vapor are non-condensing, non-corrosive,
non-plugging, the leg external to the vessel that is connected to the D/P cell
is a dry leg. If any condensate accumulates in the leg, significant error would
result in the level indication. This would reduce the D/P sensed and result in
a level indication or output that is lower than the actual level. If the
process vapors condense, the reference leg can be filled to form a wet leg. The
specific gravity and height of the reference column must be accurately
determined and accounted for in any calibration of the D/P cell.
8.4.2.
LEVEL CALIBRATION
a)
CALIBRATION
OF DIFFERENTIAL PRESSURE (D/P) LEVEL TRANSMITTER
1.
Connect the D/P Transmitter (UUT) to
applicable standards.
2.
Calibration of UUT is similar to calibrating
a pressure transmitter.
3.
Measured pressure is applied to the high
pressure port of the D/P cell, and low pressure side is vented to atmosphere.
4.
Be sure to remove any caps, and the low
pressure side is vented to atmosphere. Be sure to remove any caps, cleanliness
plugs, or obstructions from the low pressure port.
5.
Simulate pressure signal that corresponds to 0%,
25%, 50%, 75% and 100% (5-point test) of the UUT measurement
range and record the “as-found” value. Check the UUT ranges both the
upscale and downscale directions.
6.
Evaluate the error against the acceptable
tolerance to determine if adjustment is required.
7.
If adjustment is required, perform zero and
span adjustment per the manufacturer’s procedures.
8.
Or use the general instructions of Zero and
Span point adjustment, as follows:
a.
Using the Zero-and-Span adjustment screw
b.
Pressing the Zero and Span push button
adjustment
c.
Others require the use of handheld interface
or communicator to convey specific information to the UUT.
9.
Because some zero and span adjustment
interact, it is important to recheck the zero and span until no further
adjustment is required.
10.
Once no further adjustments are required,
repeat the 5-point test and verify that it is within specification over the
defined operating range. Record “as-left” values in calibration data sheet.
b)
CALIBRATION
OF DISPLACEMENT TYPE LEVEL GAUGE
1.
Establish an independent method for determining
the actual level in the tank
2.
Fill the level gauge chamber (UUT) with clean
water using plastic tubes at the bottom of the drain, similar to the gauge
glass.
3.
Simulate level that corresponds to 0%, 25%,
50%, 75% and 100% (5-point test) of the UUT measurement
range and record the readings “as-found” at each test point.
4.
Evaluate the error against the acceptable
tolerance to determine if adjustment is required.
5.
Some level gauge are not adjustable, in which
case the gauge status shall be informed to CONTRACTOR for immediate resolution
if the “as-found” data was not within the acceptable tolerance.
6.
In case the UUT can be adjusted, adjust the UUT
as per manufacturer’s recommendation.
7.
Once no further adjustments are required,
repeat the 5-point test and record “as-left” values.
c)
LIQUID LEVEL
METERS
(Displacement,
Ultrasonic, Capacitance and Diaphragm type Level meter)
5.
Workshop calibration is not
essential but data record is required.
6.
Ensure that the UUT and its
accessories are in good conditions and no physical damage on the body.
7.
Record data such Tag number,
Maker, model number, etc on the calibration data sheet.
8.
The UUT shall be tested as part of loop test.
8.5.
FLOWMETER
CALIBRATION
a)
DIFFERENTIAL
PRESSURE FLOWMETERS
1.
Calibration of D/P Flowmeter is similar with
a D/P pressure transmitter.
2.
Follow the calibration procedure of D/P
pressure transmitter.
b)
FLOWMETER
(Turbine
and Static Capacity, Ultrasonic, Magnetic, Vortex Shedding, Rotameter, Coriolis
and Diaphragm type Flow meter)
1.
Workshop calibration is not
essential but data record is required.
2.
Ensure that the UUT and its
accessories are in good conditions and no physical damage on the body.
3.
Record data such Tag number,
Maker, model number, etc on the calibration data sheet.
4.
The UUT shall be tested as part of loop test.
8.6.
CONTROL
VALVE (FINAL CONTROL DEVICE) CALIBRATION
1.
The control valve (UUT) is set with chain
Block or Pulley, to the identical condition or actual installation.
2.
Control valves (UUT) operated by diaphragm or
piston are operated with air (oil free) or using a nitrogen by using pressure
regulator, test gauge, and direct current supply device, milli-ampere
simulator.
3.
Inspect accessory material operations such as
hand wheel, amplifier, relay, and lockup valve.
4.
Set-up the UUT and makes sure that it is secure.
5.
Simulate signal that corresponds to 0%, 25%,
50%, 75% and 100% (5-point test) of the UUT
measurement range and record the “as-found” value. Check the UUT range
in both the upscale and downscale directions.
6.
Test the following performance of control valve
(UUT) as follows:
a.
Valve action
b.
Air and power supply fail action
c.
Stroke Test
d.
Stroking time
e.
Limit Switch function
f.
Other function test that is required for
specific control valve.
7.
Evaluate the error against the acceptable
tolerance to determine if adjustment is required.
8.
If necessary, adjust the UUT in accordance
with the manufacturer’s instruction.
9.
Once no further adjustments are required,
repeat the 5-point test and record “as-left” values.
9. QUALITY ASSURANCE AND TESTING
a) A Quality
Assurance System shall be operated conforming to related Standards,
Specifications and Procedures.
b) Controls and
checks shall be established and documented Manufacturer’s recommendation for
products and materials that used needs special attention.
c) Quality
Control, Inspection and Testing are covered under the Quality Control
Procedure.
d) Inspections
and tests shall be carried out in accordance with the approved ITP and
procedures and in accordance with the project specification.
e) Request for
Inspection (RFI) and material testing to be raised as per procedures.
f) The
inspection result shall be documented on the related reports/checklist.
10. ATTACHMENTS
a) Job Safety
Analysis (JSA)
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