NTPC |
Centre For Power Efficiency And Environmental |
Procedure Number: |
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Protection, NOIDA |
CENPEEP / EFF/ TP/ 306 |
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TITLE |
Rev. |
1 /EMS |
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Routine Condenser Air – In – Leakage |
Issue Date: 20/04/2000 |
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CENPEEP |
Detection Test |
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3 OF |
15 |
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A small portion of the gaseous mixture is drawn into the probe and to the detection system. The system analyses the concentration of the helium and is displayed on the instrument and recorded in the strip chart (as applicable). The engineer operating and monitoring the instrument observes the display and relates the result to the person disbursing helium.
The gaseous tracer leak detection is a widely accepted technique for the identification of condenser airin - leakage. Helium leak detectors have provided a very sensitive and practical means of locating leakages.
4.0 Objective (1) Determine if Corrective Action is required (2) Identify Problem Areas and (3) Assist in Optimization of Operation.
STATION: ------------ |
UNIT No.: ----------- |
START (Date/Time): ------------ |
FINISH (Date/Time): ----------- |
TEST ENGINEER (TE):----------------------------------------- |
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INSTRUCTIONS: |
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Steps should be performed in the sequence given. Document the completion of each step by placing “check” in the “OK” column. Document missed Targets in the “Comments” column. Take corrective action on missed Targets.
NO. |
WHO |
WHAT |
HOW |
TARGET |
COMM. |
OK |
01 |
TE |
Familiarize |
Review Annexure-B |
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Yourself with Test |
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02 |
TE |
Schedule |
Review Annexure-C |
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Condenser Air |
prerequisites |
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Inleakage Test |
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03 |
TE |
Schedule |
Notify the Shift Incharge |
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Condenser Air |
that a Condenser Air |
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Inleakage Test |
Inleakage test is to be |
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performed on the |
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affected unit |
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Notify the appropriate |
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Unit Incharge that a |
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Condenser Air Inleakage |
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test is being performed |
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on his unit |
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NTPC |
Centre For Power Efficiency And Environmental |
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Procedure Number: |
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Protection , NOIDA |
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CENPEEP / EFF/ TP/ 306 |
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TITLE |
Routine Condenser Air – In – Leakage |
Rev. |
1 /EMS |
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Issue Date: 20/04/2000 |
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CENPEEP |
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Detection Test |
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NO. |
WHO |
WHAT |
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HOW |
TARGET |
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COMM. |
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OK |
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Note: Sampling of the air removed from the non-condensable gases for helium should be conducted in such a manner as to
prevent spraying the sample tube with helium either directly or indirectly. This is |
accomplished by inserting the sample |
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tube up into the exhaust pipe of the steam ejector or vacuum pump |
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04 |
TE |
Ensure that |
Issue a walkie-talkie to |
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adequate |
the test crew. |
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communication |
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facility is available |
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for the Test crew |
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05 |
TE |
Verify all |
Walk - down and |
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instrumentation |
visually verify that all |
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required for this |
required instruments are |
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test have been |
properly installed and |
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installed and are |
operating properly. |
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operating properly |
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06 |
TE |
Note down Control |
Refer Annexure-D |
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Room / Unit data |
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Verify that the leak |
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Low voltage may |
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detector has at least a 15 |
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scramble |
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Amp supply circuit. |
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electronics |
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07 |
TE |
Conduct any |
Walk-Thru a practice test |
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training necessary |
run, instructing |
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for Assistant(s) to |
Assistants as necessary. |
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successfully |
The test set up to be |
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perform their tasks. |
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developed as shown in |
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Annexure –A .The list of |
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Instruments & |
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Accessories required for |
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test set up and testing are |
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given in Annexure-E. |
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08 |
TE |
Warm up complete |
Warm up time as |
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recommended by the |
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instrument manufacturer. |
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NOTE: There are two reasons for conducting routine periodic test shots. The first is to confirm that the leak detector is or remains sensitive to leaks. Therefore we conduct a test shot at the start of testing and again about four hours later or at the end of testing, whichever comes first. The second reason is to establish an approximate relationship between a known leak and the response seen at the leak detector.
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NTPC |
Centre For Power Efficiency And Environmental |
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Procedure Number: |
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Protection, NOIDA |
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CENPEEP / EFF/ TP/ 306 |
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TITLE |
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Rev. |
1 /EMS |
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Routine Condenser Air – In – Leakage |
Issue Date: 20/04/2000 |
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CENPEEP |
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Detection Test |
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Page: |
5 Of |
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NO. |
WHO |
WHAT |
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HOW |
TARGET |
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COMM. |
OK |
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09 |
TE |
Conduct a Test |
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Point found where a |
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Shot at the |
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controlled amount of air |
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Identified Point |
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can be admitted to the |
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condenser. |
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CAUTION: Plant personnel should confirm that the test shot point does not connect to any sensing line of a unit instrument with output to a trip circuit.
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Point located above the |
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09.01 |
condenser. (Usually the |
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Condenser Back pressure |
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test point) |
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NOTE: The person spraying notifies the person at the leak detector when he starts and stops spraying. The person at the leak detector will record the response time and total duration for the spray indication appearing on the instrument. Please refer typical chart of response time given at Annexure-F.
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Spray a 2-3 second burst |
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09.02 |
of at the test shot point. |
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When the spraying |
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begins the person at the |
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09.03 |
leak detector begins a |
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stopwatch. |
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As soon as the leak |
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detector starts showing a |
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response to the |
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helium gas, the person |
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records the time from the |
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09.04 |
stopwatch. |
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When the response of the |
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detector reaches its peak |
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the person records the |
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magnitude of the peak |
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and the time from the |
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stopwatch. |
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When the response of the |
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detector drops back to |
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09.05 |
approximately its |
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original value, the person |
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stops the stopwatch and |
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records the final time. |
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NTPC |
Centre For Power Efficiency And Environmental |
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Procedure Number: |
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Protection, NOIDA |
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CENPEEP / EFF/ TP/ 306 |
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TITLE |
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Rev. |
1 /EMS |
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Routine Condenser Air – In – Leakage |
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Issue Date: 20/04/2000 |
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CENPEEP |
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Detection Test |
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Page: |
6 Of |
15 |
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NO. |
WHO |
WHAT |
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HOW |
TARGET |
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COMM. |
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OK |
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10 |
TE |
Begin Air |
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Start spraying areas |
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Inleakage |
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identified as per sample |
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Detection Test |
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check list in Annexure- |
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G. |
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10.01 |
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Allow helium from |
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previous leak to clear out |
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before spraying again. |
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10.02 |
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Spray from top to bottom |
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On turbine flanges, spray |
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10.03 |
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bolt heads and flange |
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seams separately. |
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11 |
TE |
Initiate Corrective |
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Regular Maintenance |
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Action for any |
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leaks, which were |
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not repaired during |
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the test. |
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12 |
TE |
Issue Report |
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Narrative describing any |
Issued<7 Days. |
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unusual findings. |
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Copy of Plots (as |
Issued<7 Days. |
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12.01 |
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applicable) |
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NTPC |
Centre For Power Efficiency And Environmental |
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Procedure Number: |
||
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Protection, NOIDA |
CENPEEP / EFF/ TP/ 306 |
|||
|
|
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|
|
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TITLE |
Rev. |
1 /EMS |
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Routine Condenser Air – In – Leakage |
Issue Date: 20/04/2000 |
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CENPEEP |
Detection Test |
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Page: |
7 |
Of |
15 |
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Annexure - A
Schematic Diagram of Helium Sampling system for
HELIUM LEAK DETECTOR