Instrumentation Loop Test Loop Checking. TYPES OF LOOPS. OPEN LOOP CONTROL SYSTEM. CLOSE LOOP CONTROL SYSTEM. LOOP FOLDER CONTENTS. FLOW LOOP.
Instrumentation Loop Test Loop Checking
PURPOSE
SCOPE
INTRODUCTION (DEFINITION)
WHAT WE WILL DO IN LOOP CHECKING
TYPES OF LOOPS
RESPONSIBILITY MATRIX
GENERAL TESTING REQUIREMENT
LOOP TEST FLOW CHART
LOOP TEST DOCUMENTATION & FOLDER CONTENTS
LOOP TESTING METHODES AND PROCEDURE
LOOP TESTING FORMS
The purpose of this document is to assure that all the control loops installed by the contractors are operational and within applicable standards and manufacturer’s tolerances and that systems are installed in accordance with design specifications.
With this method cost and time will be minimized and safety integrity will be maintained.
This technical report is an informative document providing guidance on performing testing of control loops.
It covers the functionality test of digital and analog instruments and controllers used in all areas of the plant.
Inspection of all parameters and instrument response based on the checklist will depend on the approved Inspection & Test Plan (ITP) of the construction.
Loop – is defined as a combination of one or more instruments arranged to measure and / or control a process variable i.e. form the measuring device, including all components in between (electrical/pneumatic).
Loop Checking – is defined as the checking for correct operation of all instrument systems and loops and the preparation of all instrumentation for commissioning. This includes the operation of equipment by means of the plant wide Distributed Control System (DCS), ESD, FGS and correct operation of the associated graphics on the Man Machine Interface (MMI).
WHAT WE WILL DO IN LOOP CHECK
Before execution, all test equipment shall be prepared and calibrated, the necessary connector
The complete instrument loop shall be tested as one system, and when necessary adjustment shall be made
Associated alarms and trip actions of PCIMS and/or board-mounted instruments shall be checked.
Based on the sequence, each loop will be checked from field devices, through the process interface equipment and to the control room consoles via data highway
Signal will be generated from the field devices, and the test data will be filled in, then stamped on the loop wiring diagrams under the supervision of client with signature by both
The loop interfaced with packaged local panel shall be loop tested by simulating/checking signals at the interface terminal block directly.
Loop/Function test is divided by a two-group operation. One group to be in the field (Field Technician) and the other group to be positioned in the control room or front of local panel (Operator Station Technician).
Loop check also includes
– Wiring integrity check in field and at control system
– HOOK-UP verification vs installation of Instrument
– Perform analog inputs 3-point check, 0%, 50%, 100%; or more if needed
– Perform analog output 4-point check, 0%, 25%, 75%, 100%
– Perform switch contact check
After finishing loop/function test, the field instruments shall be restored immediately, especially notes:
– Connector tightly as original
– If open air supply valve during loop/function test, close it when finished
– For D/P pressure type, 3 valve manifold closed
– Lead pipe valve restored
TYPES OF LOOPS
There are two types of loops are in the field of instrumentation.
1.Open loop: It has no feed back.
2.Close loop :It has feed back.
In instrumentation a Close loop is consist of 3 basic Parts.
1.Input device (pressure ,level ,flow ,temperature transmitters)
2.Output device (Control valve)
3.Controller (DCS, PLC , etc.)
OPEN LOOP CONTROL SYSTEM
CLOSE LOOP CONTROL SYSTEM
LOOP CHECK TEAM RESPONSIBILITY MATRIX
To minimize overlaps and duplicate efforts, it is very important that the loop check team be prepared and are aware of their responsibilities
GENERAL REQUIREMENTS
Loop shall be termed ready for testing when all the construction punch list items have been satisfactory closed out.
Factory Acceptance Test (FAT) of DCS, ESD, FGS Systems and all other control panels associated with mechanical and other packages have been successfully concluded.
The appropriate pre-installation instrument calibration/testing has been completed, recorded on the Instrument Calibration Record and witnessed/accepted by Owner Representative.
All punch items are completed. All required documentation drawings are assembled within each package.
Loop checking shall be witnessed by QC Group in accordance with approved ITP.
The components within the loop have been installed in accordance with process piping, instrument air piping, mounting details and Instrument drawings. All cabling and wiring has been installed, tested and labeled, recorded on the Cable Test Report and witnessed/accepted by Owner Representative.
TEST EQUIPMENT AND TOOLS
Digital Multimeter
Current / Voltage Standard Source Instruments
Decade Resistor Box/Millivolt Generator
HART Communicator
Screw driver sets
Allen wrench set
Portable Pressure Calibrator
Hand Pump
Temperature Calibrator
Other Relevant Tools
Test equipments must be calibrated and performing in rated accuracy.
SAFETY AND PRECAUTIONS
All parties involved in this activity must be familiar with applicable safety practice.
Wearing appropriate PPE’s and use of proper tools in opening the instrument terminals boxes must be maintained.
Safety belts will be required in some other areas where the instruments are mounted on high elevations.
Observed proper polarity connections for electronic instruments and any other instruments requiring separate supply.
COMMUNICATION REQUIREMENTS
During early commissioning or pre commissioning activities like flushing and blowing it must be ensured that the (operational) commissioning crew is fully equipped with means of communication.
LOOP TEST DOCUMENTATION
PIPING AND INSTRUMENT DIAGRAM(P&ID)
CAUSE & EFFECT DRAWING
INSTRUMENT SPECIFICATION SHEET
INSTRUMENT HOOK-UP DIAGRAM
INSTRUMENT LOOP DIAGRAM
INSTRUMENT LOGIC DIAGRAM
INSTRUMENT LOCATION DRAWING
INSTRUMENT LOOP TESTING CHECK REPORT
INSTRUMENT LOOP AND TAG INDEX LIST
ESD BLOCK & LOGIC DIAGRAM
PUNCH LIST
LOOP FOLDER CONTENTS
TEST/COVER SHEET
Area
LOOP NUMBER
SERVICE DESCRIPTION
ASSOCIATED INSTRUMENT TAG
PRE-WITNESS LOOP CHECK TO BE SIGNED BY CONTRACTOR QA/QC
PACKAGE CHECKLIST WITH CONTRACTOR
INSTALLATIONPUNCH LIST SHEET
Record of all items found during loop physical inspection and testing
CALIBRATION RECORDS
INSTRUMENT SPECIFICATION & CALCULATION SHEETS
INSTALLATION INSPECTION RECORD
Instrument Calibration is complete and verified.
Cable continuity and meggertest complete and verified.
Instrument installation inspection record.
Impulse piping tested.
Instrument air tubing tested.
Instrument power supply inspected correctly.
Instrument direction of flow correctly.
SIMPLE ANALOG LOOP FLOW TRANSMITTER
PROCEDURE
Verify the feruling (tag) of the wiring on field device, Field junction box, Marshalling panel/rack and DCS cabinet.
Verify the Tag of Instrument on Operator Console.
Verify the Power requirement of the instrument are correctly configured for the device under test.
Verify correct cable termination at both DCS termination points and Device under test.
Verify that HOOK-UP installation has been correct.
Test the wiring termination by doing cold wire test or continuity test end to end from Field device until Marshalling Panel.
Apply Input Signal through Hand Pump to High Side of Transmitter with 0%,50% and 100% for Raising or Falling and observe reading on DCS Console.
OR
Simulate the instrument by HART to increase or decrease the simulating to 0,50,100 % of the instrument range and check on DCS console.
SIMPLE DIGITAL LOOP SWITCHES
Verify the ferruling (tag) of the wiring on field device, Field junction box, Marshalling panel/rack and DCS cabinet.
Verify the Tag of Instrument on Operator Console.
Verify the Power requirement of the instrument are correctly configured for the device under test.
Verify correct cable termination at both DCS termination points and Device under test.
Verify that HOOK-UP installation has been correct.
Test the wiring termination by doing cold wire test or continuity test end to end from Field device until Marshalling Panel.
Check Switch by simulating the signal by actuating the Switch “ON” and “OFF” by hand or put jumper at switch terminal head.
Check DCS alarms etc. Actuate the switching action and check all the related system such as alarms,trip signal, indicating lamp etc.
SIMPLE LOOP
FLOW LOOP
Verify the ferruling (tag) of the wiring on field device, Field junction box, Marshalling panel/rack and DCS cabinet.
Verify the Tag of Instrument on Operator Console.
Verify the Power requirement of the instrument are correctly configured for the device under test.
Verify correct cable termination at both DCS termination points and Device under test.
Verify that HOOK-UP installation has been correct.
Test the wiring termination by doing cold wire test or continuity test end to end from Field device until Marshalling Panel.
Apply Input Signal through Hand Pump to High Side of Transmitter with 0%,50% and 100% for Raising or Falling and observe reading on DCS Console.
Perform simulation using 0%,50%,and 100% of full scale and verify the indication on the DCS Console and local indicator if provided.
In case of flow loop is having control output element, manually set the output to 0%, 25%,75% and 100% of the operating signal in the HMI. Check for the valve stroke and tight closing of control valve. Check the fail-safe position of the valve after completing the test by removing the air supply to the valve.
PRESSURE LOOP
Verify the ferruling (tag) of the wiring on field device, Field junction box, Marshalling panel/rack and DCS cabinet.
Verify the Tag of Instrument on Operator Console.
Verify the Power requirement of the instrument are correctly configured for the device under test.
Verify correct cable termination at both DCS termination points and Device under test.
Verify that HOOK-UP installation has been correct.
Test the wiring termination by doing cold wire test or continuity test end to end from Field device until Marshalling Panel.
Apply Input Signal through Hand Pump to High Side of Transmitter with 0%,50% and 100% for Raising or Falling and observe reading on DCS Console.
Perform simulation using 0%, 50%, and 100% of full scale and verify the indication on the DCS Console and local indicator if provided.
In case of flow loop is having control output element, manually set the output to 0%, 25%, 75% and 100% of the operating signal in the HMI. Check for the valve stroke and tight closing of control valve. Check the fail-safe position of the valve after completing the test by removing the air supply to the valve.
LEVEL LOOP
Verify the ferruling (tag) of the wiring on field device, Field junction box, Marshalling panel/rack and DCS cabinet.
Verify the Tag of Instrument on Operator Console.
Verify the Power requirement of the instrument are correctly configured for the device under test.
Verify correct cable termination at both DCS termination points and Device under test.
Verify that HOOK-UP installation has been correct.
Test the wiring termination by doing cold wire test or continuity test end to end from Field device until Marshalling Panel.
Apply Input Signal through Hand Pump to High Side of Transmitter with 0%,50% and 100% for Raising or Falling and observe reading on DCS Console.
Perform simulation using 0%, 50%, and 100% of full scale and verify the indication on the DCS Console and local indicator if provided.
In case of flow loop is having control output element, manually set the output to 0%, 25%, 75% and 100% of the operating signal in the HMI. Check for the valve stroke and tight closing of control valve. Check the fail-safe position of the valve after completing the test by removing the air supply to the valve.
TEMPERATURE LOOP
Verify the ferruling (tag) of the wiring on field device, Field junction box, Marshalling panel/rack and DCS cabinet.
Verify the Tag of Instrument on Operator Console.
Verify the Power requirement of the instrument are correctly configured for the device under test.
Verify correct cable termination at both DCS termination points and Device under test.
Verify that HOOK-UP installation has been correct.
Test the wiring termination by doing cold wire test or continuity test end to end from Field device until Marshalling Panel.
For thermocouple input, use a voltage source and deliver input signals corresponding to 0%, 50%, and 100% of the input span of temperature transmitter according to the standard table. While in RTD input, connect the decade resistor box in place of RTD and obtain the resistance values corresponding to 0%, 25%, 50%, 75% and 100% of the span and use the obtained resistance as the input value.
Verify the indication in the DCS indicator and local indicator if provided.
In case of temperature loop is having control output element, manually set the output to 0%, 25%, 75% and 100% of the operating signal in the HMI. Check for the valve stroke and tight closing of control valve. Check the fail-safe position of the valve after completing the test by removing the air supply to the valve.
Reassemble the temperature element to the original position