ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
SAMPLE BOILER REPORT
RFET INSPECTION OF AUXILIARY BOILER
AT ANY PLANT
DATE OF TEST : 2
ND
OCTOBER 2001
REPORT REF. : KESB/AB/FR/01
TH
REPORT DATE : 6 OCTOBER 2001
REPORT PREPARED AND REVIEWED BY :
………………………..
XXXXXXXXXXX
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
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ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
TABLE OF CONTENTS
S.No.
Title
1
Introduction
2
Unit / Inspection Details
3
Inspection Results Summary
4
Sample Waveforms
App-A
RFET Inspection Principle
App-B
Equipment Description
App-C
Calibration Details
App-D
Preliminary Report
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
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ESCON
1.0
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
INTRODUCTION
Kejuruteraan Escon Sdn. Bhd., was contracted by ANY COMPANY., to inspect an Auxiliary Boiler.
The aim of the inspection was to assess if there was any wall thinning in the boiler tubes adjacent to the leaking
tube ( shown below).
The Inspection was carried out using the Testex developed Eagle 2000C system based on the Remote Field
Electromagnetic Technique (RFET) on the 2 nd October 2001.
Remote Field's limitations in the detection of tiny isolated pits and tight flaws especially in the bend region were
explained prior to inspection commencement and this report outlines the findings of the inspection along with
brief descriptions of the unit details, sample waveforms, inspection principle and equipment description.
LEAKING TUBE
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
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ESCON
2.0
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
UNIT / INSPECTION DETAILS
Plant
:
ANY PLANT
Location
:
ANY WHERE
Unit
:
Auxiliary Boiler
Orientation
:
Vertical
Tube Length
:
2.58 meters
Tube Material
:
Carbon Steel
Tube Details
:
50.8 mm OD and 2.9 mm Thickness
Total Tubes Inspected
:
100% except the super heater tubes
Inspection Period
:
2nd October 2001
Drawing Reference
:
As provided by CLIENT
Inspection Technique
:
Remote Field Electromagnetic Method
Equipment
:
TesTex Eagle 2000-C series equipment
S.No. :970544
Probe
:
1.2 inch diameter probe was used.
Refer to Figure 1 & 2 for tube numbering and RFET Inspection details.
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
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ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
Figure 1 : Auxiliary Boiler with shaded region indicating coverage
of Tube length by RFET
S
C
A
N
N
I
N
G
Inspected
region from
bend near
mud drum to
the steam
drum end
D
I
R
E
C
T
I
O
N
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
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ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
Figure 2 : Auxiliary Boiler - Tube Numbering details as viewed from Manhole
end at the Southern side of Steam drum
E
A
S
T
S
E
A
S
I
D
E
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
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ESCON
3.0
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
INSPECTION RESULTS
All the tubes in the Boiler except for the Super Heater tubes were inspected.
1. No wall thinning near the leaking tube was found. Visual inspection revealed the leak to be close to the
bend area and adjacent to a welded region. ( Refer Photos on Page ii). This was not picked up by RFET
as explained earlier due to the nature of wall loss and its location.
2. Wall thinning was found on all the tubes previously reported and was found to be the same i.e. no further
deterioration was seen. Please refer Table-1 for inspection findings including a comparison of results
between the previous and current inspection.
3. The wall thinning was as high as 40-45% on Tube 2 in Row 2. This was confirmed with UT Thickness
measurements which recorded remaining wall thickness values between 1.6-1.8 mm compared to an
original thickness of 2.9 mm
4. Tube 7 on Row 1 was blocked with a loose nut inside.
5. The results seem to confirm the wall thinning to be a localized phenomenon in the first few rows of the
boiler. The leak seems to be a localized case and not due to thinning.
6. The details of wall loss in the various tubes inspected is depicted in the Tube layout in page viii of this
report while Table-1 provides a list of tubes with wall thinning.
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
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ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
T
U
B
E
N
U
M
B
E
R
I
N
G
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
Page viii
ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
TABLE -1 SUMMARY OF FINDINGS
ROW
TUBE
% WALL LOSS
PREVIOUS INSP.
No.
No.
(%WL)
(%WL)
Oct. 2001
Apr. 2000
3
Plugged
15-20
7
Blocked
Blocked
2
40-45
40-45
3
20-25
20-25
5
25-30
25-30
8
20-25
20-25
1
25-30
25-30
2
30-35
15-20
3
20-25
15-20
4
20-25
20-25
5
25-30
25 - 30
6
30-35
25-30
5
6
20-25
<15%
10
3
20-25
20-25
C2
1
1
2
3
Not Inspected
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
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ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
4.0 SELECTED WAVEFORMS
Tube 2 - 2
Wall Thinning of 40-45%. UT
indicated remaining wall
thickness as 1.6-1.8mm
compared to nominal wall
thickness of 2.9mm.
Mud drum
Scanning direction
Steam drum
Bend signal
Steam drum
Row 2 Tube 2 - It exhibits gradual wall thinning to the order of 40-45% of the original
wall thickness of 2.9 mm in an area near to the steam drum bend as shown above.
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
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ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
4.0 SELECTED WAVEFORMS
Section C1-Tube 26
Mud drum
Scanning direction
Steam drum
Tube 26 in Section C1 – This is a good tube with no significant wall loss
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
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ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
4.0 SELECTED WAVEFORMS
Possible Leak
Location near a
welded area
Section C2 -Tube 1 ( Leaking Tube)
Tube Bend Signals
Mud drum
Scanning direction
Steam drum
Tube 1 –in Section C2 is the leaking tube. The leak is close to the weld as shown above
and cannot be detected by RFET. No significant wall loss was noted in the tube except
some permeability changes which was more predominant near the Mud-Drum.
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
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ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
APPENDIX-A
RFET ISNPECTION PRINCIPLE
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
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ESCON
KEJURUTERAAN ESCON SDN. BHD.
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APPENDIX- A
RFET INSPECTION PRINCIPLE
The RFET technique differs from conventional eddy-current inspection techniques as it uses two coils for the
generation and receiving of Ele ctromagnetic signals. Two signals, a Direct signal and a Remote Field signal
arrive at the receiver/ pick up coil. By suitably adjusting the distance between the two coils i.e. the driver and
the pick-up, the Direct signal can be eliminated. The useful Remote-Field signals penetrate through the walls of
the tube being inspected. Changes in the Phase ( Ø ) and Natural Log of Amplitude ( A ) of the Remote field
signals are measured. A change in the phase is related to depth changes in the tube while amplitude is more
sensitive to volumetric changes in the tube. A basic block diagram explaining the principle of RFET inspection
is shown in figure 1A.
Inspection involves calibration of the system on a tube sample similar to the one being inspected. This helps in
obtaining the necessary information that serves as a comparator / baseline for quantifying flaws on the actual
tubes being inspected. This involves the preparation of a calibration chart for inspection which is explained in
Appendix-C.
Phase and Amplitude changes measured during the actual inspection are compared with values in the
calibration chart and defects are thus quantified.
Fig. 1A Principle of RFET inspection
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
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ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
APPENDIX-B
EQUIPMENT DESCRIPTION
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
Page xv
ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
APPENDIX-B
EQUIPMENT DESCRIPTION
The following are the list of equipment available for the RFET of Heat-Exchanger tubes of which serial
number 2 was used for the boiler.
1. Eagle 2000C - most commonly used Eagle, frequency ranges 20 to 9900 Hertz.
2. Eagle 2000C/4 - divides set frequency by a factor of 4. Used for better penetration on thick
and/or high permeability material. At the low frequencies, slow pull rate must be maintained to
eliminate pull noise.
3. Eagle 2000C x 2 - multiplies set frequency by a factor of 2. Used mostly for austenitic materials
(i.e. stainless steel, nickel). Frequency ranges
40 to 19800 Hertz.
4. Eagle Plus - is a multi-channel system which allows up to 8 channels of data acquisition and is
used to characterise and size small flaws like Pitting, Cracks etc..
System Description :
Electronics:
The digital system consists of the following :
• Function Generators, Power Amplifiers, Difference Amplifiers, Phase Rotators, Auto-Zero phase
shifters, A-to-D converters, Digital controllers.
One of the key design objectives is to achieve as low a noise as possible. Phase changes to an
accuracy of 1/10 of a degree and amplitude signals of a fraction of a microvolt are detected.
The EAGLE 2000 digital system ( fig. 1B ) contains all the electronics and software for data
acquisition. It contains an internal A-to-D converter which connects to the PC through a serial port.
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
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ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
Block diagram of the Eagle 2000 series RFET inspection system
Fig. 1B
Software:
It consists of two modules.
A)
Data Acquisition Module
This module collects the tube data at a given sample rate. The menu driven, user-oriented
program provides for real-time display of phase, amplitude, and probe position in the tube. The row
and column of the tube, probe speed, and other bookkeeping details are also handled by the data
acquisition module.
B)
Data Analysis & Display module
The data analysis and display module contains the calibration curves for wall thinning, volume
losses, pits, vibration/fret wear, and correlates the calibration standard information with the actual plant
data for flaw sizing and evaluation. It has routines for digital filtering, averaging techniques, background
evaluation, curve fitting, and other useful signal processing techniques. Up to three waveforms can be
displayed simultaneously on the screen and the “zooming algorithm” enables the user to easily examine
small segments of the waveform.
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
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ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
Probe Details :
1. Probe types - Probes used for boilers are the flexible probes. The probes have one receiver in
the Single-channel probe ( used with Eagle 2000 series) and 6-8 receivers in the Multi-channel
probes ( used with Eagle Plus).
2. Probe-size - Fill factor is not a criteria in remote field, but sizing the probe is important..
For rigid probes only and assuming the tubes are reasonably clean maintaining a fill factor
of 60% or better will usually serve as a quick method of optimising, however, cleanliness and
inserts will always factor in. It is important to know if there are any tube inserts, sleeves or
ferrules in use and the thickness of these restrictions.
Inspection Accuracy
The TesTex, Inc. developed lock-in amplifier is capable of measuring very low level signals in the
microvolt range and can measure small phase angle changes of a fraction of a degree, even in the
presence of a considerable amount of noise. This system, when used in conjunction with the calibration
standards: partial and through-wall pitting, gradual wall loss, vibration/fret wear, etc. and their
respective calibration curves, allo ws us to measure small gradual wall losses on the order of 10%, pits
of diameter 0.09" (1.57mm), and vibration/fret wear of five-volume percent. The System has however,
limitations to the detection and sizing of solitary pitting and other tight flaws especially at the bends.
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
Page xviii
ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
APPENDIX-C
CALIBRATION DETAILS
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
Page xix
ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
APPENDIX-C
CALIBRATION
Selection / Preparation Of A Calibration Standard
The selection of the calibration standard plays a crucial role in the inspection to be performed. The
calibration sample must be of the same specification i.e. it must be of the same material, diameter,
thickness and permeability as the tube to be inspected.
Artificial flaws are generated in it at suitable distances from one another. Calibration tubes will normally
have machined flaws for wall loss and pitting, fret wear etc.
•
Separate standards were made for 360 ° and 180 ° wall loss.
•
For general wall loss calibration wall loss in various percentage combinations like 30 & 60 % or 40
& 80 % are introduced in the calibration tubes.
•
Pitting standards were made for 2 and 3 mm diameter holes and wall losses of 50 and 100% were
introduced to make the calibration curves.
The following page gives the curve generated for general wall thinning.
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
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ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
CALIBRATION CHART FOR TUBE : 50.08 MM O.D / 2.9 MM THICKNESS
360 degree Calibration chart 50.8 mm OD and 2.9 mm thickness CS tube
PROBE# 1.2" OAV=152/146
% WL 1 = 29.00 , PHASE 1 = 44.55 , AMP 1 =
% WL 2 = 62.10 , PHASE 2 = 106.02 , AMP 2 =
% WL 3 = 0.00 , PHASE 3 =
0.00 , AMP 3 =
% WALL LOSS
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
55.0
60.0
65.0
70.0
DELTA PHASE
7.06
14.38
21.96
29.80
37.89
46.24
54.85
63.72
72.85
82.24
91.88
101.79
111.95
122.37
DELTA LNA
1.52
3.02
4.51
5.97
7.41
8.84
10.24
11.62
12.99
14.34
15.66
16.97
18.26
19.52
180 degree Calibration chart 50.8
PROBE# 1.2" OAV=152/146
% WL 1 = 35.70 , PHASE 1 = 23.60
% WL 2 = 59.20 , PHASE 2 = 55.98
% WL 3 = 0.00 , PHASE 3 =
0.00
% WALL LOSS
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
55.0
60.0
65.0
70.0
DELTA PHASE
1.45
3.50
6.16
9.42
13.29
17.76
22.84
28.53
34.82
41.71
49.21
57.32
66.03
75.35
8.55 | *
17.51 | *
0.00 | [QUADRATIC FIT]
WALL REMAINING
2.755
2.610
2.465
2.320
2.175
2.030
1.885
1.740
1.595
1.450
1.305
1.160
1.015
0.870
mm OD and 2.9 mm thickness CS tube
, AMP 1 =
, AMP 2 =
, AMP 3 =
DELTA LNA
0.35
0.73
1.13
1.57
2.04
2.53
3.06
3.61
4.19
4.81
5.45
6.12
6.82
7.55
3.13 | *
6.01 | *
0.00 | [QUADRATIC FIT]
WALL REMAINING
2.755
2.610
2.465
2.320
2.175
2.030
1.885
1.740
1.595
1.450
1.305
1.160
1.015
0.870
Sample-Report- Auxiliary Boiler – October 2001- RFET Inspection - Final Report
Page xxi
ESCON
KEJURUTERAAN ESCON SDN. BHD.
(222506-M)
APPENDIX-D
PRELIMINARY REPORT
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Page xxii