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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
1United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
Date of inspection:
January 6, 2003 January 10, 2003
Technical specifications:
The boiler system consists of an xxxxx Energy, Positive Pressure, Sub critical,
B & W design unit.
Introduction
The inspection was conducted by United Dynamics Corporation (UDC) boiler
inspection team consisting of Jon S. Cavote, John Linder, Dan Wyngarden, and
Marvin Bronson. This inspection effort would not have been possible without
the efforts of Lloyd Weber. UDC provided the inspection services, non
destructive testing, and overall technical support.
Inspection and planning methodology:
Standard inspection and repair guidelines were utilized by the team. These
guidelines were strictly complied with during this outage. All decisions were
data driven backed up by substantial ultrasonic thickness examinations. In
many cases data was reviewed from previous outages.
The suggested repair criteria used on pressure parts during this outage was:
0-%-65% of design minimum wall was replaced.
66%-75% of design minimum wall was pad welded.
76%-85% of design minimum wall was shielded
All repairs were ranked at the time of inspection into two categories:
Priority #1 Item that will in all probability cause a forced outage
before the next scheduled outage, cause potential hazard to humanlife, or cause a financial loss to the operation of the unit.
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
2United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
Priority #2 Item which poses a possible failure or performance
issue.
Priority #3 Item that under normal operations would not cause a
forced outage although may decrease operations to a degree but of
no significance. The item is typically planned for future work.
Summary and Analysis of Inspections and Repairs:
The process of inspection and repair interdiction is designed to statistically stack
the deck in the plants favor when it comes to availability. This process is not fool
proof although it has been proven over time to be a cost effective tool.
Conclusions and Recommendations:
Rear Screen Tubes:
The screen tube sections are noted for the front tube being a rear wall
hanger tube 2.5 x .220 MWT SA210A1. All
other screen tubes are composed of 2.0 x .220MWT SA209T1A. All items indicated in the
screen tube report are on the bottom level at the
refractory wall. All other items are indicated in
the crossover report.
Only one tube has been noted for replacement,
three tubes have been recommended for
requiring pad welds, and several have been
noted for requiring shield repairs. All shield work is due to soot blower erosion,
and pad welds are a result of gouged tubing from a mechanical source. Ensurethat all shields are installed on the trailing side of tubes and follow the pattern of
the blower across the unit. Ensure that refractory wall is repacked to design form
after all shield repairs are complete.
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
3United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
Two attachment support lugs have been noted for
requiring re-welding to the tube. Lugs being
detached will allow for tube misalignment.
KEY POINTS:
Complete all shielding work prior to
refractory wall re-construction.
Grant access to the remainder of elements at the right side of unit to
complete inspection at lower level of tubes, element #81 - #114.
Ensure that tubes are clean prior to shield installation.
Total of (4) Priority #1 items were identified.
Total of (57) Priority #2 items were identified.
Total of (1) Priority #3 items were identified.
This makes (62) total observed deficiencies.
Rear Wall Hangers:
The hangers have been noted for numerous
shield repairs on the trailing edge of tubes. Some
shields need replaced and others require re-
alignment and straps. UT verification was noted
in locations accessible, inspection report lists theseresults. Numerous shields are overheated and
fatigued, proper cooling of shield is imperative
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
4United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
requiring clean tubes and a tight fit of shields to tube surface.
KEY POINTS:
Ensure that tubes are clean and shields fit tight to tube surface prior to
shield installation.
Total of () Priority #1 items were identified.
Total of (2 records) Priority #2 items were identified.Total of (1 records) Priority #3 items were identified.
Secondary Superheat Inlet/Addendum 1:
Only the lower level of the pendant was inspected due to lack of
scaffolding access granted to upper levels. The spacer tube located on the front
side of the inlet has been previously pad welded at the element intersections dueto soot blower erosion. One 10 section of
spacer tube has been recommended for
replacement.
The tier drop wrapper tubes located at the
bottom of the pendants are being washed
from blowing soot, and several are
recommended for replacement and pad
weld installation due to UT verification.
Numerous lower pendant loops are noted for replacement and pad weld
installations on the leading edge of tubes due to soot blower erosion. The
addendum report indicates one pad weld required on the rear of pendant.
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
5United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
KEY POINTS:
Check IK1&2 soot blowing frequency and sweep, ensure that blowers
are not spraying in addition to what is required.
Grant access to the upper levels of superheater for complete inspection.
Total of (17) Priority #1 items were identified.
Total of () Priority #2 items were identified.
Total of (1) Priority #3 items were identified.
This makes (18) total observed deficiencies.
Reheat Inlet:
The front of the inlet pendants has been noted for numerous shields
requiring replacement due to overheat and fatigue, first and second tube in from
the front. There is no scallop bar located on the lugs in front of pendant, however
misalignment is not a problem.
The problem area of the pendant is located
on the trailing side in the IK 25/26 path. Soot
blower erosion is the most common form of
damage found on boiler pressure part
components and can be easily overlooked if
erosion is smooth across the entire surface of
tube. The trailing reheat tubes have shielding
on several elements however erosion is
pushing off the bottoms of the existing
shields causing wash on the outer radius bends of lower loops, others have noshielding at all. Numerous replacements, pad welds, and shields are
recommended in this area.
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
6United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
The second tube in from the rear is showing significant signs of erosion however
tubes are composed of .220 MWT. No
repairs have been noted during this
overhaul, however if soot blowing
continues at the same rate, this will
become a high priority area during future
overhauls.
Shield work on the back of this pendant
will include lower radius bends of tubes,
as well as 3 straight sections.
One bulged tube was found on the back side of this component and will need to
be monitored during future overhauls.
KEY POINTS:
Check blower frequency and pressure, do not run blower more than
necessary.
Grant access to elements #91 all the way to the right wall. It is
imperative that the remainder of these elements be inspected and
repairs are made accordingly. PSH work is in progress preventing
further inspection at this time.
Grant access to the upper elevation on the rear of pendant for
inspection during a future overhaul.
All front upper level repairs are indicated in the crossover report.
Ensure that tubes are clean and shields fit tight to tube surface prior to
shield installation.
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
7United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
Total of (26) Priority #1 items were identified.
Total of (4 Records) Priority #2 items were identified.
Total of (3 Records) Priority #3 items were identified.
Reheat Outlet:
Please note that all repair identified in the upper rear levels will be
indicated in the crossover report.
Two tubes have been noted for replacement onthe back side of the pendant, and two tubes
have been noted for requiring pad welds in the
IK33 path.
Numerous handcuff supports have been noted
for re-welding the end weld due to cracking.
Numerous shields have been recommended
for installation as well, due to overheating of existing shields, Ensure that tubesare clean prior to new shield installation.
Several support lugs have been found to be broken and elements misaligned.
Ensure that pendants are re-aligned and new support lugs are installed. Broken
lugs are found on the lower level as well as the upper level of pendants. The
upper support/alignment lugs will require re-attachment because not only do
they align the pendants, they provide structural support. The top portion of the
pendants will sag forward causing the bottoms of pendants to kick back if upper
support is lost.
Elements 48 68 are showing moderate signs of overheating, no significant sign
of exfoliation or creep is evident. It has been concluded that the tubes are
suffering from long term overheat, not abnormal for a component of this vintage.
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
8United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
After discussions with plant personnel it has been concluded that tube surface
temperature in the reheat crossover is running around 1,100 degrees F. This is an
average tube surface temperature for this component, and would not expect that
this would cause any short term overheat issues. It has also been noted that this
component is run in excess of 1150+ degrees, this is the leading contributor to
signs of long term overheat. Other factors can come into play to cause short term
overheat in this component:
1. Plugging patterns (will increase gas velocity and temperaturethrough open areas
2. ID blockage (if reheat has had a water filled static test, ensurethat lower loops are cleared prior to unit returning to service.Tube surface temperature will reach excessive temperature before
reheat loops clear enough to allow steam to circulate. This can
cause excessive spaghetti like bowing as well as creep and
exfoliation.)
3. Crushed tubes (flow restriction is the quickest way to overheat atube in a short period of time.)
4.
Sudden increases in steam temperature and surface temperaturedue to excessive slagging in the fire box (The more slagging and
insulators on the water walls will increase the superheat and
reheat temperatures due to less heat transfer in the fire box)
KEY POINTS:
Grant access from elements 72 113 on the rear of pendant to
complete inspection in the lower level.
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
9United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
To Reduce Superheat and Reheat temperatures
(The removal of refractory that covers studded tubes in the
fire box will decrease Superheat and Reheat temperature due to
more heat transfer in the fire box. Too much heat transfer is also
bad, not allowing superheats and reheats
to reach necessary temperature. UDC
recommends that if this process is to take
action, that only 10% of the refractory is
removed from the top of stud section.
Ensure that exposed studs are removed
from tubes to prevent heat absorption on
tubes.)
Total of (5) Priority #1 items were identified.
Total of (7 Records) Priority #2 items were identified.
Total of (4 Records) Priority #3 items were identified.
Furnace Floor:
The furnace floor has been noted for
impact gouging requiring pad weld repairs.
Refractory and other has been removed for re-
studding and inspection, pad welds are to be
completed before re-studding and refractoryare re-installed.
The rear bends are planned for replacement
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
10United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
over the next several overhauls. No repair items have been noted
for that location.
Total of (12) Priority #1 items were identified.
Total of ( Records) Priority #2 items were identified.
Total of (1 Records) Priority #3 items were identified.
Econ Gas outlet:
The ductwork was noted for numerous casing cracks that will require seal
welding, and the removal of ash and debris throughout the ducts.
Total of () Priority #1 items were identified.
Total of ( Records) Priority #2 items were identified.
Total of (5 Records) Priority #3 items were identified.
Upper dead air space:
Upper dead air space was noted for casing cracks requiring seal welding.Upper casing at the upper slope has been removed for reheat components
replacements. Ensure that this casing is replaced after slope tubes are replaced.
Total of (1) Priority #1 items were identified.
Total of ( Records) Priority #2 items were identified.
Total of (2 Records) Priority #3 items were identified.
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
11United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
Steam Drum:
Steam drum was noted for requiring the removal of debris including
excessive amounts of magnetite and remains of doors gaskets.
The drum shell was found to be in good condition as found. No stress cracking
in shell and corrosion was found at a minimum.
KEY POINTS:
Removal of debris is imperative due to the affects it can have on
the blocking lower inlet header orifices. Over time, debris that isrun down the down comers will accumulate in the lower inlet
headers and block orifices. If possible, UDC recommends that a
lower inlet header inspection be performed by means of Bore
Scope for debris accumulation.
Total of (1) Priority #1 items were identified.
Total of ( Records) Priority #2 items were identified.
Total of (7 Records) Priority #3 items were identified.
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
12United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
Secondary Air duct:
No action items have been found.
Total of () Priority #1 items were identified.
Total of ( Records) Priority #2 items were identified.
Total of ( Records) Priority #3 items were identified.
Air Heater Gas Outlet:
No action items have been found.
Total of () Priority #1 items were identified.
Total of ( Records) Priority #2 items were identified.
Total of ( Records) Priority #3 items were identified.
Air Heater Gas Inlet:
The right rear corner was noted for an expansion joint replacement.
Expansion joint in the right front corner will need to be patched due to open
holes.
Remove ash from expansion joint flex points , to allow for proper expansion.
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
13United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
Turning vane support struts are noted for repair as well.
Total of () Priority #1 items were identified.
Total of (2 Records) Priority #2 items were identified.
Total of (4 Records) Priority #3 items were identified.
Reheat Crossovers:
The crossover section is the highest priority pressure part area of this
overhaul. Numerous tubes have been noted for replacement, pad welding, andshielding. These repairs include the front
side of the inlet, back side of the outlet, the
crossovers themselves, and the rear screen
tubes that intersect the crossovers.
IK 23/24 is severely eroding reheat outlet
tubes with a rough eroding surface. It
appears that the steam is not completely
superheated, saturated steam will erodesharp jagged edges and can cause tubes to
reach quick failure. Numerous tubes have
been previously pad welded and are now eroded through the pad weld and back
into the tube.
Screen tubes have been noted for shield, and pad weld repairs from blower wash
and detached welds. 7 tube U straps at the upper level have been marked for
replacement due to overheat and failure, install new strap 6 above or below
previous strap to help prevent welding on the same heat effected zone.
Numerous outlet tubes have been noted for existing horizontal weave pad welds,
we need to plan to have these tubes replaced. During this overhaul, the thin
tubes are a much higher priority to replace.
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
14United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
KEY POINTS:
Prevent Saturated Steam:
1. Ensure that blower lance has
weep holes located in the
bottom of lance, and that lance
is rested in its proper position.
2. Ensure that all steam piping is
insulated properly to
minimize condensation.
3. Ensure that all steam piping isat least at a 30 degree pitch to help drain access moisture.
Check soot blowing frequency (Only blow when necessary)
If any of the replacement recommendations are not completed
during this overhaul, ensure that they are completed during the
next scheduled overhaul.
Total of (52) Priority #1 items were identified.
Total of (14 Records) Priority #2 items were identified.
Total of (8 Records) Priority #3 items were identified.
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
15United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
Furnace Tube Sample:
One tube in the fire box was pulled for metallurgical analysis per plant
personnel request. Right sidewall tube #70, elevation 658.
Total of () Priority #1 items were identified.
Total of ( Records) Priority #2 items were identified.
Total of ( Records) Priority #3 items were identified.
PSH Bank 1, 2, 3:
The primaries are noted for elements falling off of their saddle lugs at the
front of the banks.
The right half of the primaries are being replaced during this overhaul, and the
left half of the primaries have been replaced
last year.
Debris has been noted for accumulation at the
front of the bank from deteriorated refractory
wall and slag. This will need to be cleaned out
to prevent eddying channels for fly ash to
erode, as well as allowing gas velocity to pass
through component at an even pattern with no
restrictions.
A few scallop bar support have been noted for repair. Bank 3 was noted forrepairing two support guides on the rear wall, and for the removal of loose
debris.
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
16United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
UT verification surveys have been performed at the base of the riser tube sections
to help project tube wastage rates during future overhaul. UT survey has also
been performed on the dogleg sections between banks.
KEY POINTS:
Review weld X-rays for a percentage (of plants request) of butt
welds made on new PSH bank tubes (If greater than 10% of x-
rays reviewed fail, UDC recommends that a minimum of 50% of
all welds be X-rayed and approved by contractor QC and an
Alliant CWI.
Air Heater Gas Outlet:
No action item have been found.
Total of () Priority #1 items were identified.
Total of ( Records) Priority #2 items were identified.
Total of ( Records) Priority #3 items were identified.
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
17United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
SSH Outlet:
This component was noted for three pad welds on the front of the pendant
on the spacer tube due to soot blower erosion.
A 100% visual was not possible due to the excessive amount of slag build up on
the tube surface.
KEY POINTS:
Grant access to the upper levels of pendants for inspection.
Total of (1) Priority #1 items were identified.
Total of ( Records) Priority #2 items were identified.
Total of (2 Records) Priority #3 items were identified.
Furnace Grinds:
The furnace was laid out with 6 bans for grinding to record accurate 3-
point UT verification. Discussions with plant personnel indicate that the unit
may run with low oxygen if not negative in the fire box. No exact numbers or
facts have been concluded as to stokemetric measures at and or below burner
elevation.
For a 100% water wall inspection, it is recommended to pressure wash or sand
blast the water walls.
Total of () Priority #1 items were identified.
Total of ( Records) Priority #2 items were identified.
Total of ( Records) Priority #3 items were identified.
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
18United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
Penthouse:
The penthouse was noted for numerous floor casing cracks, as well as
holes in the side casings. Due to excessive cracking in the floor casing, there is
approximately 8of ash build up on the floor. Ash build is a result of gases
passing through the cracks and entering into the penthouse. Gases from the
boiler below will elevate the penthouse temperatures which are not designed to
exceed limits of structural steel integrity.
SSH headers are noted for missing insulation; this will also elevate temperature
and potentially affect carbon steel supports in the general vicinity of headers.
KEY POINTS:
Excessive temperatures in the penthouse can contribute to
structural degradation of support rods and other carbon steel
structures.
If interlocking tiles are used for isomembrane installation
(Ensure that roof tube below are properly supported by means of
support clips that should be connected to the collector barsrunning left to right at the front and rear of high crown seal
boxes. Improperly supported roof tubes can sag at a greater rate
due to additional tile weight.)
If roof tubes are not supported properly (Install 8 fire
blanketing in place of the interlocking tiles to reduce weight. Fire
blanketing is effective however, is more of a short term fix than a
permanent fix. Plan on additional repairs in less than 10 years if
fire blanketing is used.)
Total of (0) Priority #1 items were identified.
Total of (3 Records) Priority #2 items were identified.
Total of (8 Records) Priority #3 items were identified.
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xxxxxx unit #4 January 2003Planned OutageExecutive Summary
19United Dynamics Corporation
1345 Old Preston Hwy. N. Louisville, Ky 40229voice 502.957.7525 fax: 502.957.5441 www.udc.net
Economizer:
The economizer banks were in good condition as found.
Retractable blower lances have been noted for minor abrasion, no action is
required.
Total of () Priority #1 items were identified.
Total of ( Records) Priority #2 items were identified.
Total of (2 Records) Priority #3 items were identified.
Items not inspected:
DA Tank
De-Superheat sprays
Reheat De-superheat sprays
Reheat Pendant (Upper level rear of inlet)
Superheat Pendant (Upper levels)
Fire Box (UT survey only)
Cyclone Burners