Maintain and repair instrumentation & control devices

Operation Sheet 4.2.1: Disassembly/Assembly of I & C Devices-Pressure Transmitter

• Whenever you remove the process flange or flange adapters, visually inspect the Teflon O-
rings. Replace the O-rings if they show any signs of damage, such as nicks or cuts. If they are
undamaged, you may reuse them.

The Model 3051C transmitter is attached to the process connection by four bolts and two cap
screws. Remove the four bolts and separate the transmitter from the process connection
manifold or flange. You can leave the process connection in place and ready for re-installation.
The Model 3051T is attached to the process by a single hex nut process connection. Loosen
the hex nut to separate the transmitter from the process. Do not use wrench on neck of
transmitter

2. Remove the Terminal Block
Electrical connections are located on the terminal block in the compartment labelled “FIELD
TERMINALS.”Loosen the two small screws located at the 9 o'clock and 4 o'clock positions,
and pull the entire terminal block out to remove it.

NOTE
If removing the terminal block from the housing of a previous version of the transmitter, you will
have to manually disconnect the power leads from the rear of the terminal block before
completely separating it from the housing.

3. Remove the Electronics Board
The transmitter electronics board is located in the compartment opposite the terminal side. To
remove the electronics board perform the following procedure:

1. Remove the housing cover opposite the field terminal side.

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Operation Sheet 4.2.1: Disassembly/Assembly of I & C Devices-Pressure Transmitter

2. Loosen the two captive screws that anchor the board to the
housing.The electronics board is electrostatically sensitive; observe
handling precautions for static-sensitive components.
NOTE
If you are disassembling a transmitter with a LCD display, loosen the two captive screws that
are visible on the right and left side of the meter display. The two screws anchor the LCD
display to the electronics board and the electronics board to the housing.

3. Slowly pull the electronics board out of the housing. With the two
captive screws free of the transmitter housing, only the sensor
module ribbon cable holds the board to the housing.

NOTE
Previous versions of the electronics board utilize a snap-in power plug and receptacle.
Carefully unsnap the power plug from the receptacle to free the board from the power cord.

4. Disconnect the sensor module ribbon cable to release the
electronics board from the transmitter.

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Operation Sheet 4.2.1: Disassembly/Assembly of I & C Devices-Pressure Transmitter
4. Remove the Sensor Module from the Electronics Housing

1. Carefully tuck the cable connector completely inside of the
internal shroud.

NOTE
Do not remove the housing until after you tuck the cable connector completely inside of the
internal shroud. The shroud protects the cable from damage that can occur when you rotate
the housing.

2. Loosen the housing rotation set screw with a 9/64-inch hex
wrench, and back off one full turn.

IMPORTANT
To prevent damage to the sensor module ribbon cable, disconnect it from the electronics board
before you remove the sensor module from the electrical housing.

3. Unscrew the housing from the module, making sure the shroud
and sensor cable do not catch on the housing.

IMPORTANT
Make sure the sensor ribbon cable and internal shroud remain completely free of the housing
as you rotate it. Damage can occur to the cable if the internal shroud and sensor cable
become hung up and rotate with the housing.

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Operation Sheet 4.2.1: Disassembly/Assembly of I & C Devices-Pressure Transmitter
Attach the Sensor Module to the Electronics Housing

1. Inspect all cover and housing (non-process wetted) O-rings and
replace if necessary. Lightly grease with silicone lubricant to
ensure a good seal.

2. Carefully tuck the cable connector completely inside the internal
shroud. To do so, turn the shroud and cable counterclockwise one
rotation to tighten the cable.

3. Lower the electronics housing onto the module. Guide the
internal shroud and cable through the housing and into the external
shroud.

4. Turn the housing clockwise then fasten it to the module.

IMPORTANT
To prevent damage to the cable connector, watch the cable and shroud as you attach the
housing to the module. Make sure the cable connector does not slip out of the internal shroud
and begin to rotate with the housing. Reinsert the cable connector into the shroud if it escapes
before the housing is fully fastened.

5. Thread the housing completely onto the sensor module. The
housing must be no more than one full turn from flush with the
sensor module to comply with explosionproof requirements.

6. Tighten the housing rotation set screw using a 9/64-inch
hex wrench.

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Operation Sheet 4.2.1: Disassembly/Assembly of I & C Devices-Pressure Transmitter
Attach the Electronics Board
1. Remove the cable connector from its position inside of the
internal shroud and attach it to the electronics board.
2. Insert the electronics board into the housing, making sure that
the posts from the electronics housing properly engage the
receptacles on the electronics board.

3. Tighten the captive mounting screws.

4. Replace the electronics housing cover. The transmitter covers
must be engaged metal-to-metal to ensure a proper seal and to
meet explosion proof requirements.

Reassemble the Process Connection to the Sensor Module

1. Visually inspect the Teflon (PTFE) sensor module O-rings. If the O-rings are undamaged,
you may reuse them. If the O-rings show signs of damage, such as nicks or cuts, or if there is
any doubt about their ability to seal properly, replace them with new O-rings.

NOTE
If you are replacing the O-rings, be careful not to scratch the O-ring grooves or the surface of
the isolating diaphragm when removing the damaged O-rings.

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Operation Sheet 4.2.1: Disassembly/Assembly of I & C Devices-Pressure Transmitter

2. Install the process flange on the sensor module. To hold the process flange in place, install
the two hex head alignment screws. These screws are not pressure retaining and need only be
finger tight. Do not overtighten; this will affect the module/flange alignment.
3. Install the appropriate flange bolts.
a. IF the installation requires a 1/4–18 NPT mounting, THEN use four 1.75-inch flange bolts.
Go to Step f.
b. IF the installation requires a 1/2–14 NPT mounting, THEN use four 2.88-inch process
flange/adapter bolts. EXCEPTION: For gage pressure configurations, use two 2.88-inch bolts
and two 1.75-inch bolts. Go to Step d.
c. IF the installation uses a three-valve manifold (differential pressure applications only), THEN
use four 2.25-inch manifold flange bolts. Go to Step e.
d. Hold the flange adapters and adapter O-rings in place while finger-tightening the bolts. Go to
Step g.
e. Align the process flange with the three-valve manifold.
f. Finger tighten the bolts.
g. Tighten the bolts to the inital torque value using a crossed pattern. See Table 4-1 for
appropriate torque values.
h. Tighten the bolts to the final torque value using a crossed pattern. See Table 4-1 for
appropriate torque values. When fully tightened, the bolts should extend through the top of the
module housing.
i. If the installation uses a three-valve manifold, then install flange adapters on the process end
of the manifold using the
1.75-inch flange bolts supplied with the transmitter.

Bolt Material Initial Torque Value Final Torque Value
300 in.-lb (34 N-m) 650 in.-lb (73 N-m)
CS-ASTM-A449 Standard 150 in.-lb (17 N-m) 300 in.-lb (34 N-m)
316 SST—Option L4 300 in.-lb (34 N-m) 650 in.-lb (73 N-m)
ASTM-A-193-B7M—Option L5 300 in.-lb (34 N-m) 650 in.-lb (73 N-m)
Monel—Option L6

4. IF you replaced the Teflon sensor module O-rings, THEN re-torque the flange bolts after
installation to compensate for cold flow.
5. Install the drain/vent valve.

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Operation Sheet 4.2.1: Disassembly/Assembly of I & C Devices-Pressure Transmitter

a. Apply sealing tape to the threads on the seat. Starting at the base of the valve with the
threaded end pointing toward the installer, apply two clockwise turns of the sealing tape.
b. Take care to place the vent opening on the valve so that process fluid will drain toward the
ground and away from personnel when the valve is opened.
c. Tighten the drain/vent valve to 250 in.-lb (28.25 N-m).

NOTE
After replacing O-rings on Range 1 transmitters and re-installing the process flange, expose
the transmitter to a temperature of 185 °F (85 °C) for two hours. Then re-tighten the flange
bolts in a cross pattern, and again expose the transmitter to a temperature of 185 °F (85 °C)
for two hours before calibration.

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Operation Sheet 4.3.1 : Troubleshooting -Pressure Transmitter

Learning outcomes:
4 Repair I & C Devices
Learning Activity:
4.3 Diagnose Fault, Repair and/or replace I & C devices

Troubleshooting Chart-Pressure Transmitter

Symptoms Corrective Actions
Milliamp Reading is Zero
• Check if Power Polarity is Reversed
Transmitter is not • Verify Voltage Across Terminals (should be 10 to 55 V
Communicating
with Communicator dc)
• Check for Bad Diode in Terminal Block
Milliamp Reading is Low or • Replace Transmitter Terminal Block
High
• Check Power Supply Voltage at Transmitter (Minimum
No Response to
Changes in Applied Pressure 10.5 V)
• Check Load Resistance (250 V minimum)
Pressure Variable • Check if Unit is Addressed Properly
Reading is Low or High • Replace Electronics Board

Pressure Variable • Check Pressure Variable Reading for Saturation
Reading is Erratic • Check if Output is in Alarm Condition
• Perform 4–20 mA Output Trim
• Replace Electronics Board

• Check Test Equipment
• Check Impulse Piping for Blockage
• Check for Disabled Span Adjustment
• Check Transmitter Security Jumper
• Verify Calibration Settings (4 and 20 mA Points)
• Replace Sensor Module

• Check Impulse Piping for Blockage
• Check Test Equipment
• Perform Full Sensor Trim
• Replace Sensor Module

• Check Impulse Piping for Blockage
• Check Damping
• Check for EMF Interference
• Replace Sensor Module

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Job Sheet 4.3.2 : Troubleshooting -Field Transmitter

Learning outcomes:
4 Repair I & C Devices
Learning Activity:
4.3 Diagnose Fault, Repair and/or replace I & C devices

Purpose and scope

This Job Sheet covers the Troubleshooting of Pressure Transmitter and the confirmation
that they are functioning in accordance with the design.
References

 Pressure Transmitter Operation/Maintenance Manual/Datasheet
Materials and Equipment

Test Equipment to be used includes:
Digital or Analog Multimeter
Pressure Calibrator
SFC/HART Communicator

Standard hand tools:
 Screw drivers
 Precision Screw Drivers
 Wrench
 Portable Compressor
 Air Filter/Regulator

Work Instructions/Activity

1. Check if the following symptoms occur in the Pressure Transmitter and do the necessary
corrective actions needed.

Symptoms Corrective Actions

Milliamp Reading is Zero • Check if Power Polarity is Reversed
• Verify Voltage Across Terminals (should be 10 to 55 V

dc)
• Check for Bad Diode in Terminal Block
• Replace Transmitter Terminal Block

Transmitter is not • Check Power Supply Voltage at Transmitter (Minimum
Communicating
10.5 V)
• Check Load Resistance (250 V minimum)

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Job Sheet 4.3.2 : Troubleshooting -Field Transmitter

with Communicator • Check if Unit is Addressed Properly
Milliamp Reading is Low or • Replace Electronics Board
High
• Check Pressure Variable Reading for Saturation
No Response to • Check if Output is in Alarm Condition
Changes in Applied Pressure • Perform 4–20 mA Output Trim
• Replace Electronics Board
Pressure Variable
Reading is Low or High • Check Test Equipment
• Check Impulse Piping for Blockage
Pressure Variable • Check for Disabled Span Adjustment
Reading is Erratic • Check Transmitter Security Jumper
• Verify Calibration Settings (4 and 20 mA Points)
• Replace Sensor Module

• Check Impulse Piping for Blockage
• Check Test Equipment
• Perform Full Sensor Trim
• Replace Sensor Module

• Check Impulse Piping for Blockage
• Check Damping
• Check for EMF Interference
• Replace Sensor Module

2. Record any problem found and all the remarks and corrections done at the instrument.
3. Ensure that the work site is left tidy.

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Operation Sheet 5.1.2: Testing I & C Devices- Instrument Pressure Test

Learning outcomes:
5 Test I & C Devices
Learning Activity:
5.1 Conduct Tests and Inspection of I & C devices

I. Impulse Piping/Tubing

1. General
All the pressure/vacuum lead piping (impulse piping/tubing) which connect a instrument to
process should be pneumatically tested for tightness. The test fluid should be clean air or
nitrogen gas.
2. Testing Pressure
Impulse piping/tubing shall be tested at 110% of the design pressure.
3. Test Preparations

3.1 Before commencing the pressure test for the differential pressure instruments,
close block valves at the process and open the bypass valve and block valves at the
instrument.
3.2 Close block valve at the process for pressure instruments.
3.3 If the differential type level instrument is not equipped with bypass line, close block
valves at the vessel and add temporary bypass line between the high pressure and low
pressure sides to prevent excess differential pressure at the instrument.
3.4 All joint, including welds, are to be left uninsulated and exposed for examination
during the test.
3.5 Vacuum service lines shall be tested at minimum pressure of 20 PSIG unless
limited.
3.6 Analyzer unit shall be disconnected before pressure testing of sampling lines.
4. Testing Sequence
Step 1 : Prepare piping to be tested as indicated in chapter 4.2.1(3), test preparation.
Step 2 : Connect the test assembly to the impulse piping/tubing.
Step 3 : Inject preliminary test pressure upto 20 PSIG.
Step 4 : Locate major leaks and correct them.
Step 5 : Increase testing pressure gradually in steps with providing sufficient time to allow
the piping equalize the strains during test.

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Operation Sheet 5.1.2: Testing I & C Devices- Instrument Pressure Test

Step 6 : The pressure is to be reached the testing pressure which was discussed earlier (110%
of the design pressure)
Step 7 : The test pressure shall be maintained for a sufficient time to determine if there are any
leaks, but not less than 10 minutes.
Step 8 : Accurate records shall be maintained for all the lines tested on the form provided.

II. Signal Transmission Tubing

1. General
All of the control and signal transmission tubings shall be tested pneumatically prior to final
loop check. Testing medium shall be instrument air or nitrogen gas.
2. Testing Pressure
The signal transmission tubing shall be tested at maximum pressure of the signal range, i.e.,
15 PSIG for 3 to 15 PSIG signal range.
3. Test Preparations

3.1 Establish the identity of each component of a given control loop and its conformance
to design specification.
3.2 Blow air lines clean.
3.3 Identify positively the air circuit from air supply valve through instrument to air-
operated element by setting instrument to deliver air and observing air leakage at the
disconnected air line at the air-operated element.
3.4 Before any test of pneumatic line, instruments which would consume air from the
line must be disconnected and the line be blocked at the point of disconnection.
4. Testing Sequence
Step 1 : Disconnect air consuming pilots from
the section of tubing to be tested.
Step 2 : Connect the bubbler unit to the open
end of the line to be tested. (Refer to
Fig.5.1.1)

Figure 5.1.1 Bubble Test pot

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Operation Sheet 5.1.2: Testing I & C Devices- Instrument Pressure Test

Step 3 : Close all three valves - A,B and C.
Step 4 : Open the air supply valve and adjust regulator so that the pressure reach to testing
pressure.
Step 5 : Open the valve A and allow the line to be fully pressurized.
Step 6 : Close valve A and open valve B and C.
Step 7 : Observe the bubbler unit. A leak on the line will cause bubbles to appear in the unit.
Step 8 : Determine the source of the leak and correct it.
Step 9 : The line shall be considered acceptable when the bubbles are slowed to a rate
of no more than three per minute.
Step 10 : It must be stressed that air supply pressure to the bubble unit must be stable.
Step 11 : Accurate records shall be maintained for all the lines tested on the from provided.

III. Air Supply Piping
1. General
All instrument air subheaders and branch systems shall be subject to leak and pressure
testing. Main instrument air piping shall be pressure-tested by piping group. The test medium
for these tests shall be clean, oil free air. A portable compressor may be used with dry alumina
filter for this purpose; however, main instrument air compressor shall be used if it is available.
2. Testing Procedure
Step 1 : Operate the system instrument air compressor.
Step 2 : Put drain traps and air dryer into operation, and check quality of instrument air at
the down-stream of air dryers.
Step 3 : Test pressure shall be the maximum operation pressure of the instrument air supply
piping system.
Step 4 : Open the end of air supply pipe at the nearest union or coupling from the instruments
and blow air pipes clean removing all the foreign object and drain trapped inside pipes.
Step 5 : After blowing is finished, reconnect all the supply piping to the instruments.
Step 6 : Apply soap solution around all the possible source of leaks (union, coupling, etc.).
Step 7 : Check for leaks observing bubbles.
Step 8 : Mark on the leak points and depressurized the leaking section of the air supply
piping for maintenance.
Step 9 : Repeat above steps throughout the piping system.
Step 10 : Accurate records shall be maintained for all the line tested on the form provided.

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Operation Sheet 5.1.2: Differential Pressure/Pressure Transmitter Calibration
Learning outcomes:
5 Test I & C Devices
Learning Activity:
5.1 Conduct Tests and Inspection of I & C devices

Differential Pressure Transmitter/Pressure Transmitter Calibration

Step 1 : Hook up testing equipments as per Fig. 5.1.1 Below

Figure 5.1.1

Step 2: Vent low side.
Step 3: When no pressure is applied to the high side, the transmitter output should be 0% of

output range. If it is not, adjust zero adjustment until the output indicates 0%
Step 4: Increase input signal to full range (100%) as shown in the specification sheet.

The transmitter output should be 100% of its range. If not, adjust span adjustment.
Step 5: Recheck zero after span adjustment. Repeat until both are correct.
Step 6: Check output for 0, 25, 75 and 100% of range with signal rising and falling.
Step 7: Every output reading shall be within error limit. If not, adjust linearity adjustment and

repeat step 3 to 7 until every output reading corresponds with input signal within
acceptable error limit.
Step 8: If the instrument equipped with high/low range limit mechanism, adjust it to meet
proper requirement.

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Job Sheet 5.1.3 : Differential Pressure/Pressure Transmitter Calibration

Learning outcomes:
5 Test I & C Devices
Learning Activity:
5.1 Conduct Tests and Inspection of I & C devices

Purpose and scope
This Job Sheet covers the Calibration of Differential Pressure/Pressure Transmitter and
the confirmation that they are functioning in accordance with the design.

References
 Differential Pressure/Pressure Transmitter Operation/Maintenance
Manual/Datasheet

Materials and Equipment
Test Equipment to be used includes:
Digital or Analog Multimeter
Pressure Calibrator/Pneumatic Calibrator
Power Supply 24 Vdc

Standard hand tools:
 Screw drivers
 Precision Screw Drivers
 Wrench
 Portable Compressor
 Air Filter/Regulator

Work Instructions/Activity

Step 1 : Hook up testing equipments as per Fig. 5.1.1 Below

Figure 5.1.1

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Job Sheet 5.1.3 : Differential Pressure/Pressure Transmitter Calibration

Step 2: Vent low side.
Step 3: When no pressure is applied to the high side, the transmitter output should be 0% of

output range. If it is not, adjust zero adjustment until the output indicates 0%
Step 4: Increase input signal to full range (100%) as shown in the specification sheet.

The transmitter output should be 100% of its range. If not, adjust span adjustment.
Step 5: Recheck zero after span adjustment. Repeat until both are correct.
Step 6: Check output for 0, 25, 75 and 100% of range with signal rising and falling.
Step 7: Every output reading shall be within error limit. If not, adjust linearity adjustment and

repeat step 3 to 7 until every output reading corresponds with input signal within
acceptable error limit.
Step 8: If the instrument equipped with high/low range limit mechanism, adjust it to meet
proper requirement.
Step 9: Record any problem found and all the remarks and corrections done at the instrument
in the Calibration form provided.
Step 10:. Ensure that the work site is left tidy.

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Information Sheet 5.2.1 : Testing and Function Check Sheets

Learning outcomes:
5 Test I & C Devices
Learning Activity:
5.2 Fill-up Maintenance Checklist/Report.

1. Instrument Loop Check Sheet

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Information Sheet 5.2.1 : Testing and Function Check Sheets
2. Instrument Pressure Test Sheet

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Information Sheet 5.2.1 : Testing and Function Check Sheets
3. Instrument Calibration Report

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010

Information Sheet 5.2.1 : Testing and Function Check Sheets

Code No. Maintain and Repair Instrumentation and Date: Developed Date: Revised Page #
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Control Devices July 07, 2010