1 PURPOSE
2 SCOPE
3 REFERENCE, CODE &
STANDARD
4 DEFINITIONS
5 RESPONSIBILITY
AND AUTHORITY
6 WORK PROCEDURE
7 SAFETY
8
QUALITY
CONTROL
1 PURPOSE
The
purpose of this procedure is to specify responsibilities and describe the
2 SCOPE
This method statement (M/S)
shall be applied to Instrument Loop Check / testing work.
3 REFERENCE, CODE & STANDARD
3.1
Subcontractor document
3.2 Work index, symbol and detailed drawing
3.3
Process Control and Automation Engineering Standard Specification.
European (IEC and EN) standards shall be
adopted throughout,
4 DEFINITIONS
4.1 Within this document
following definitions shall apply.
OWNER / COMPANY
CONTRACTOR SUBCONTRACTOR
PROJECT
5 RESPONSIBILITY
AND AUTHORITY
5.1 Site Manager
5.1.1 Site manager bears the responsibility and
authority on work and quality related to this method statement.
51.2 Site manager approves work plans.
5.2 Construction Superintendent
5.2.1 A construction Superintendent bears the
responsibility and authority to train their staff and subcontractor’s after
preparing work plan according to this method statement.
5.2.2 A construction team manager takes the
responsibility of all Instrument Loop check /testing work execution and
preparation.
5.3 Construction
Supervisor
5.3.1 Construction Supervisor shall execute
inspections and tests to secure quality materials, take adequate measures,
manage results as quality records, and utilize checklist.
5.3.2 Construction
supervisor bears the responsibility of Instrument Loop check
/testing according to the dimensions specified in specifications or
drawings,
5.4 Quality Manager
5.4.1 Site Quality Manager is responsible for
management and supervision of implementing inspection work as specified in this
method statement.
5.4.2 Inspection request to QC when portions of
the work are ready for inspection, as depicted in the ITP’s.
5.4.3 Responsible for preservation and
maintenance of equipment at site.
6.0 INSTRUMENT LOOP-CHECK / TESTING PROCEDURE
6.1 General Requirements
6.1.1 All instruments in a loop are calibrated,
installed and inspected prior to commencing loop check in accordance with the
applicable procedures and specifications.
6.1.2 The loop testing shall be witnessed by QC
group in accordance with approved ITP.
6.1.3 Documents compiled for loop checking (loop
folder) should contain but not be limited to the following:
-
Piping & Instrument Diagram
-
Instrument Data Sheet
-
Instrument Installation Acceptance Checklist
-
Instrument Loop Acceptance Certificate
-
Instrument Calibration Record
-
Instrument Piping / Tubing Test Record
-
Instrument Cable Test Record
-
Instrument Hook-up Drawing
6.2 Procedure
6.2.1 Pressure testing of signal or process piping
is to be completed, witnessed and signed-off by the responsible authorities
prior to the commencement of loop checking.
6.2.2 Prior to loop testing, instrument cable
shall be checked for continuity & insulation resistance test.
6.2.3 Prior to loop testing, check all components
for correct zeroing and adjust if necessary except for those indicated in
calibration procedure to be zeroed during commissioning.
6.2.4 Completed loops are to be tagged in
accordance with approved ITP on pre-loop and final-loop check.
6.2.5 All wires are checked for correct tagging
and termination. Any wires disconnected for purposes of the loop check are to
be reconnected to the proper terminals upon completion of activities.
6.2.6 Instrument tubing disconnected for loop
check will be covered with protective tape / plugs at the ends to prevent entry
of foreign materials.
6.2.7 Instrument tubing disconnected during the
loop check is to be re-inspected to ensure proper reconnection as per
instrument drawing.
6.2.8 The completed instrument loop shall be
tested as one system and adjustment shall be made to ensure that the loop is
fully operational as a system and is correctly calibrated. Associated alarms
shall be checked during loop testing.
6.2.9 Loop testing of remote control loops is a
two groups operation, one in the field and one in the
control room. They must be provided with adequate means of remote Two-way RADIO
communication system suitable for the area classification of the site of work.
6.2.10 Loop testing shall not be carried out on
electronic equipment until an adequate warm up period has elapsed. Where
possible instruments shall be energized for at least 24 hours prior to testing
or as recommended by the manufacturer.
6.2.11 On completion of loop testing, all
controllers shall be left with correct action and with 100% proportional band
setting. Derivative & Integral function shall be set at minimum time value (Set by DCS Vendor).
6.2.12 Inspect the loop setting air / electrical
supplies where appropriate. Check in particular the control valve air supply
pressure at site in accordance with the specification.
6.2.13 For electronic loops, check the polarities
to be correct at field instrument.
6.2.14 Each loop must be tested from the field
signal input through to the receiving instrument and in the case of
controllers; the output of controller shall be checked through to the final
control element operation. During a loop test all ancillary items in the loop
ex. signal converters, alarms, switches, etc. shall be tested.
6.2.15 Each loop will be checked as per the
following documents :
a) Instrument
Data Base (IDB) printout (range, configuration, etc.)
b)
Graphic display (the point shall appear in the designated Graphics)
c)
Alarm summary.
6.2.16 Signals shall be generated equivalent to 0, 25, 50 and 100% of the instrument range and the
loop function checked for correct operation at each point in both rising and
falling modes. Any adjustments found
necessary shall be carried out during loop check in accordance with approved calibration
procedure and manufacturer’s instruction and using approved
and certified field calibrators .
6.2.17 For controller applications the following
test also apply :
a) Switch
the controller to manual mode and by applying the appropriate signal, ensure
that the control valve or valves stroke
correctly. Valve positioner gauges also be checked during this stage.
b) Apply
an actuating signal to the controller equivalent to 50% of the instrument range
c) Check
alarm by varying the actuating signals and adjust as necessary.
d) After
each loop is satisfactory tested the controller shall be switched to manual and
identified.
e) For
three and four wire resistance detector installations, care must be taken to
ensure the correct connections. Trips and
alarms e.g. initiating devices which stop / start pumps etc. shall be checked.
f) All
system shall be checked for fail / safe operation which will include the
checking of
“ burn
out “ features on thermocouple installations .
6.2.18 For gas alarm system:
a) Sensors
shall be tested in accordance with the manufacturer’s instruction.
b) Where
voting logic is involved then each combination of the activities inputs shall
be
NOTE : The testing of field
audible and visual alarms shall be carried out on an
6.3.1 Loop Test Methods
6.3.2 Flow Loop
Simulate
appropriate input signal as follows :
Transmitter Type Input
Source
Differential Pressure Type FF/Hart Communicator
Vortex Flow meter
Ultrasonic Flow Meter
Mass
Flow Meter
a)
FF/Hart
Communicator will be used to simulate signals. In case FF/Hart Communicator
b)
Simulate signal 0%, 50% and 100% of full
scale & check indication of local indicator
c)
If the flow loop includes consist with
control output, manually output 0%, 25%, 50%,
75% and100% of valve operating signal and
check valve stroke. Check tight closing of control valve if necessary.
6.3.3
Pressure Loop
Simulate appropriate input signal as follows
:
Transmitter
Type Input Source
Pressure FF/Hart Communicator
Differential
Pressure
a)
FF/Hart
Communicator will be used to simulate signals.
b)
Simulate signal 0%, 50%, 75% and 100% of
full scale & check indication of local indicator and DCS indicator.
c)
If the pressure loop includes control
output, manually output 0%, 25%, 50%, 75% and 100% of valve operating signal
and check valve stroke. Check tight closing of control valve if necessary.
6.3.4
Level Loop
Simulate appropriate input signal as
follows:
Transmitter Type Input
Source
Differential
Pressure Type FF/Hart
Communicator
a)
FF/Hart
Communicator will be used to simulate signals. In case FF/Hart Communicator is not applicable,
portable millampere simulator will be applied.
b)
Simulate signal 0%, 50% and 100% of full
scale & check indication of local indicator and DCS indicator.
c)
If the level loop is consist with control
output manually output 0%, 25%, 50%, 75% and 100% of valve operating signal and
check valve stroke. Check tight closing
of control valve if necessary.
6.3.5
Temperature Loop
Simulate
appropriate input signal as follows:
Measuring
Element Type Input Source
Thermocouple Type
Accurate Millivolt Generator
RTD Type
Decade Resistance Box
a.
Inject input signal 0%, 50% and 100% of full
scale and check the DCS indication and indication of transmitter. If there will
be system equipment with burn out function, check it by opening the temperature
element circuit while observing the output.
b.
If the temperature loop includes control
output, manually output 0%, 25%, 50%, 75% and 100% of valve operating
signal and check valve stroke. Check tight closing of control valve, if
necessary.
c.
Reassemble the temperature element to the
original condition.
6.3.6
Switching Loop
Simulate appropriate input signal as follows:
Using
a wire jumper, short out the input terminals or disconnect wire
termination to simulate
Switching
Type Input Source
Level Switch Wire jumper
Miscellaneous Type Level Switch Disconnect wire termination
Miscellaneous Type
Valve having limit
switch for Open/Close condition .
Check DCS graphic, alarm etc. Actuate
switching action and check all related system such as
6.3.7 Integrated Control System
a) The
Programmable Logic Controller (PLC), H I M and associated peripheral equipment
are generally completely configured and tested in the supplier’s factory
includes complete
b)
After installation of
equipment in the control room, the system is checked for grounding plan,
c) The system is loaded and
checked for required displays and operation of auxiliary devices by the supplier’s
representative with direct manpower assistance. System alarms, operation of
redundant modules, and back-up power supplies are checked at this time.
d) During loop check , the
input /output display is checked for correct engineering units, control
e) Alarm set Report print
outs and auxiliary recorders or other devices are checked for correctness. the
loop check document shall be filled out for control loop .
f) After the tests have been
completed, the instrumentation shall be identified with a colour sticker.
g) Results will be filed and
recorded on applicable test form per approved ITP.
6.3.8 Analyzer
and Miscellaneous Loop
The
Analyzer and miscellaneous loop shall be checked as per Vendor’s instruction
If
special techniques required checking out the specific instrumentation,
6.4 FUNCTIONAL
TEST
6.4.1 Function test will be carried out after completion
of loop test.
6.4.2 The field Instrument can be simulated from field
through HART/ FF communicator.
6.4.3 Pump
operation interlock check will be carried out based on HIM, function test will
be
6.4.4
Documents compiled
for function check should contain to the following:
a)
Piping & Instrument Diagram.
b) Instrument Specification
Data Sheet.
c)
Instrument Loop Acceptance Test Record.
d) Loop Test
Sing-Off From Sheet.
e)
Instrument Index..
7 SAFETY
7.1.1 To
ensure best practice HSE control is being implemented throughout all Instrument
Loop check work, Contractor Instrument Supervisors and HSE Supervisor with Sub
contractors Instrument Supervisors and HSE Supervisor shall carry out
inspections prior to Work commencing and at regular intervals during the
activities.
7.1.2 Persons
working at height (above 1.8 meters) shall be protected from falling by the
installation of safe access/ egress and working platforms.
7.1.3 Persons involved
in Instrument Loop check work shall be provided with and use the necessary PPE
and as a standard each person shall wear a Safety Helmet and Safety footwear.
The requirement for additional PPE shall be identified in the Risk Assessment
and may include the use of the following:
7.1.4 Eye
protection.
7.1.5 Hand
Protection.
7.1.6 Dust masks.
7.1.7 Reflective
jackets if working in the vicinity of moving traffic.
7.1.8 Any other
necessary PPE
Note: - The issue and use of PPE is the final step
in protecting people and must not be see as the only safety control method.
Risks must be reduced to the smallest amount possible and the PPE is the ‘back up’ equipment.
8 QUALITY CONTROL
8.1 ITP is a document
submitted to the owner or owner’s representative formulated in an orderly
manner by the construction supervisor or site quality manager to record main
working processes for tests and quality inspections, and to enable the owner or
owner’s representative to assign inspection points.
8.2
Witness Point
8.2.1 Point where permission to the
next level is granted without Owner’s agreement.
8.3 Hold Point
8.3.1 Point
where further progress is not allowed without Owner’s written permission
8.4 Inspector
8.4.1 Person
that inspects whether processes quality of materials or specifications are
consistent with prescribed or desired requisites.
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