swcc boiler # 1 report presentation for client presentation

Boiler # 1 Inspection and Condition Assessment

Project No. : HiTR-131-303Oracle No. : 22648

Al-Khobar Power & Desalination Plant

1

Presentation Outline

Post Outage Activity1. Boiler # 1 Risk Table2. Hi Engineering Major Recommendations3. Force Outage Rates4. Tube Failures5. Boiler Maintenance History6. Boiler Chemical Cleaning Procedure Review• Lay-up Procedures• Miscellaneous

• Objective• Boiler No.1 Particulars1. General Information2. Boiler Lay-out

• Pre Outage Inspection1. Inspection Activity2. Inspection Major Findings• Inspection during Outage1. Water Wall Tubes2. Economizer Tube3. Superheater Tubes4. Water Wall supply Headers5. Economizer Inlet Header6. Steam Drum

7. Superheater Headers8. Dead Air Space9. Burners10. Rothemuhle Air Heater11. SCAH Air Heater12. Air & Flue Gas Duct

• Inspection Plan

2Index

Objective

Index

Inspection and Condition Assessment is designed to Improve the reliability of Boiler by evaluation of present condition of boiler, Avoiding boiler failures and forced outages, Identification of risky areas, Analysis of root cause of problems and Providing technical cost effective and practical solutions .

3

Boiler No.1 Particulars

Owner or User : SWCC, Al-Khobar Power & Desalination PlantBoiler Unit : No.1Manufacturer : Babcock & WilcoxType : El Paso Type Radiant BoilerMax. Cont. Rating (MCR) : 672,200 kg/hr (1,482,000 Ib/hr)Nom. Elect. Capacity : 190 MW (150 MW+ Desal)Design Pressure : 1575 PsigOperating Temperature : 380-520 °CCommissioned Year : 1983 (30 year)Boiler Height : 38.5 m (126.5 ft.) measured from lower furnace

wall headers to steam drum

Index

1. General Information

4

Index 5

PSH-O

TSH

SSH

PSH-I

ECONOMIZER

Steam Drum

PSH I. Header

Economizer Outlet Header

Water Wall supply Headers

Air Heaters

Water Wall Tubes

Gas & Flue Gas Duct

Economizer Inlet Header

Burners(rear side)

Burners(front side)

2.Boiler Lay-out

PSH O.

TSH O.TSH I.

SSH O.SSH I.

Bottom Dead Air Space

Inspection Plan

Index

Hi Engineering Inspection Plan

The total timeframe of the inspection activity conducted by Hi Engineering to Boiler No.1 of SWCC which encompassed each course of inspection and the plan amount in each equipment.

6

7Index

Pre Outage Inspection1. Inspection Activity

List of Activity:

1. General survey for boiler outer casing temperature.

2. Insulation condition3. Boiler structure & backstay 4. Signs of flue gas & heat leakage5. Manhole & sootblower penetration6. Boiler Expansion condition

Pre Outage Inspection

Index

No. Findings Photo Action

1

Sign of overheating at TSH man hole in 6th Floor, the temperature measurements in pre-outage inspection shows more than 300°C.

Door need to be overhauled before start-up.

Boiler Walk Downs

A pre-outage unit walk-down cover the complete unit from top to bottom and all auxiliary systems.

Below is the major findings during our Pre-outage Inspection to Boiler No.1.

8

2. Inspection Major Findings

Inspection during Outage

Index

1. Water Wall Tubes & Furnace

Type of Inspection Amount of NDT Inspections

Inspection Findings

Visual Inspection 100% Welded piece attachment; lifting lug left-over; soot deposition & deteriorated refractory.

Ultrasonic Thickness Measurements

1512 Points No tubes were found below minimum wall tube wall thickness.

Penetrant Testing 16 Locations (0.5 - 1 M length)

None

Material SA 210 A1 CF SMOOTH

No of tubes Front & Rear 143 Side Walls 128

OD, mm 63. 5 63.5 75.4 75.4

Thickness, mm 5.156 6.096 5.588 5.156

9

Index


1. Water Wall Tubes & Furnace (continued)


1

Attachment of welded piece in several locations at the water wall which may lead to stress corrosion cracking then tube leak.

1- Tube sample need to be taken for at least one location.2- All attachment need to be grinded.3- PT check need to be conducted.

2

Leftover of welded lifting lugs in several locations at the water wall which may lead to stress corrosion cracking then tube leak.

As per Finding No.1

10

Index


1. Water Wall Tubes & Furnace (continued)

Recommendations:

1. Two (2) Tube samples need to be taken from water to evaluate the water side condition plus requirement the boiler wall chemical cleaning.

2. Attachment of welded piece and lifting lug leftover, tube sample is required to be taken for at least two locations to assess the tube ID condition. This has to be done in the next plan outage.

11


Type of Inspection Amount of NDT Inspections Inspection Findings

Visual Inspection 100% Soot deposition;.


132 Points No tubes were found below minimum tube wall thickness.

Penetrant Testing 24 Locations (0.5 – 1 M length)

None

2. Economizer Tubes

Index

Row # 1-40

Material SA 178 C

Thickness, mm 4.57

OD, mm 50.8

12

Index


2. Economizer Tubes (continued)


1

Severe soot deposition on the tube surface at the lower bank.

Availability and Efficiency of sootblowers need to be checked.

13

Index


2. Economizer Tubes (continued)

Recommendations:

Reliability and efficiency of all Economizer sootblowers need to be checked as soon as possible.

14

Index

3. Superheater Tubes

3.1 Primary Superheater TubesNo. Section OD, mm Thickness, mm Material

1 Inlet Bank (Tube Row # 1-14) 50.8 4.57 SA 178 C

2 Outlet Bank (Tube Row # 1-3) 50.8 7.87 SA 213 T22




6 Outlet Bank (Tube Row # 16-21) 50.8 4.57 SA 209 T1 A

7 Outlet Bank (Tube Row # 22-24) 50.8 4.78 SA 209 T1 A

8 Outlet Bank (Tube Row # 25-33) 50.8 4.57 SA 178 C


15


3. Superheater Tubes (continued)

3.2 Secondary Superheater TubesNo. Section OD, mm Thickness, mm Material

1 Row # 1-15 50.8 4.57 SA 209 T1 A

2 Row # 16-20 50.8 4.57 SA 213 T2

3 Row # 21-25 50.8 5.16 SA 213 T12

4 Row # 26-30 50.8 6.48 SA 213 T12

Index

3.3 Tertiary Superheater TubesNo. Section OD, mm Thickness, mm Material

1 Row # 1-6 44.45 4.19 SA 213 T12

2 Row # 7-15 44.45 5.59 SA 213 T12

3 Row # 16-18 44.45 5.16 SA 213 T12

16

Index


Inspection Findings

Visual Inspection 100% Severe tube sagging; missing & disengaged mother lug; support lug crack, missing tube spacer; loose refractory, broken soot blower nozzle; dented tube & tube deformation.


384 Points No tubes were found below minimum tube wall thickness. (70% x t) Babcock & Wilcox – Guidelines for Tube Repair/Replacement.


A crack at the 1st row of SSH Inlet leg at the top of the Furnace.



17

Index




1

Excessive to Medium tube sagging for about 25 coils of TSH tubes which is indication of creep damage.

Tube analysis need to be done for minimum three samples of the most excessive sagged area. We suggest 3 m tubes no. 16, 22 & 26 to be sampled & no. 13, 15, 54 & 56 to be replaced.

2 Missing mother at TSH tube no. 23

Need to be repaired in the next planned outage.

18

Index


3

A total of ten (10) disengaged mother lug of SSH lower bank front side at coil no’s. 1, 3, 4, 5, 9, 10, 18, 23, 28 & 32.

All disengaged mother lug to be reengaged in the right position in the next planned outage.

4Missing sliding lug at TSH tube no. 23 & 2 front side.




19


Index



5Old repair of displaced SSH mother lug shows that the additional piece is overheated.

1- Old repair need to be removed. 2- Mother lug need to be fixed in the right position.

6A crack at the 1st row of SSH Inlet leg at the top of the Furnace.

The crack needs to be removed either by replacing the tube or grind out the crack and do repair weld.

20

Index




7Missing mother lug of TSH tube no. 23 at front wall bottom side.


8

Sign of overheating at TSH man hole in 6th Floor, the temperature measurements in pre-outage inspection shows more than 300°C.

Door need to be overhauled before start-up.

21




9 Crack at the Penetration Wall of SSH Inlet Tube Leg, left side when facing the header.

Major inspection need to be done for the tube penetrations in the next planned outage.

Index 22

Index



Recommendations:

1. At Tertiary Superheater Tube, tube analysis is needed for a minimum of three tube samples of the most excessive or severe sagged area. Hi Engineering suggests 3 meters for these tubes Nos. 16, 22 & 26 to be replaced and sampled. Six (6) to seven (7) tubes of the most sagged area need to be repaired. (See attachment in Tab 4).

2. All ten (10) disengaged mother lug (Tube Nos. 1, 3, 4, 5, 9, 10, 18, 23, 28, 32) in Secondary Superheater lower bank tube front side need to be re engaged on the right position.

3. Broken Sootblower nozzle head at Primary Superheater Inlet bank need to be repaired before unit start-up.

23



Index

3. A crack at the 1st row of Secondary Superheater Inlet leg at the top of the Furnace need to be removed either by replacing the tube or grind out the crack and do repair weld. This has to be done as soon as possible.

4. Missing spacer at front side (Tube Nos. 2 & 33) and bad repair mother lugs need to be repaired in the next plan outage.

24

Index


4. Water Wall supply Headers

Material SA 106 GR C

Thickness, mm 34.925

OD, mm 241.3


Inspection Findings

Visual Inspection 100% Slight general corrosion on Header surface.


204 Points No Header were found below minimum Header wall thickness based from the original specified header wall thickness.

Penetrant Testing 15 Locations (0.5 – 1 M Length)

None

25

Index

4. Water Wall supply Headers (continued)



1 A slight corrosion of water wall supply headers at rear platen wall.

No action required in the time being. Keep monitor in the next outage.Source of corrosion need to be eliminated (wet condition).

2 A slight corrosion of feedwater pipes at front platen wall.

As per Finding No.1

26

4. Water Wall supply Headers (continued)


Index

Recommendations:

1. Borescope inspection need to be conducted within five (5) years in order to assess the header ID condition.

2. The wet conditions need to be eliminated.

27

Index


5. Econmizer Inlet Header

Material SA 106 C

Thickness, mm 34.925

OD, mm 241.3


Inspection Findings

Visual Inspection 100% Slight corrosion scale & disengaged guiding spacer



Penetrant Testing 10 Locations (0.5 – 1 M Length)

None

28

Index


5. Econmizer Inlet Header (continued)


1

Header guiding spacer at left-end was close to out of position.

Keep monitor during start up and in the next outage.(Adjustment or extension of the support may be required.)

2Flake-off scale of corrosion from Header tube stub.

Keep monitor in the next outage.Source of corrosion need to be eliminated (wet condition.)

29

Index


5. Econmizer Inlet Header (continued)

Recommendations:

1. A close to disengaged guiding spacer need to be monitored during unit start-up. The spacer should be extended if necessary.

2. The wet conditions in the header need to be eliminated in order to control the presence of corrosion. This has to be done as soon as possible.

3. Borescope inspection need to be conducted within five (5) years in order to assess the header ID condition.

30


Index

6. Steam DrumMaterial Carbon Steel (CS)

Thickness, mm 96

ID, mm 1,829


Inspection Findings

Visual Inspection 100% Slight rust deposition, foreign deposits, slight flow accelerated corrosion at Feedwater pipe spray nozzle & pinhole at drain pipe.




Deep undercut at Feedwater pipe support

31


6. Steam Drum (continued)


1

Heavy deposition at both ends of drum heads below vortex arrestor.

1. Layup procedure needs to be improved.

2. Water chemistry need to be reviewed and improved.

3. Need to be cleaned before start up.

2Feedwater pipe support at right side of Steam Drum shows deep and wide undercut and spatters.

Need repair in the next planned outage.

Index 32


Index

6. Steam Drum (continued)

Recommendations:

1. Lay-up procedure and water chemistry need to be reviewed and improved. This has to be done as soon as possible.

2. Welding defects at non-pressure parts of the Steam Drum need to be repaired in the next plan outage.

33


Index

7. Superheater Headers

No. Component OD, mm Thickness, mm Material

1 PSH Outlet Header 425.45 41.275 SA 335 P11

2 TSH Outlet Header 533.4 60.325 SA 335 P22

3 TSH Inlet Header 355.6 34.925 SA 335 P11

4 SSH Outlet Header 431.8 44.45 SA 335 P11

5 SSH Inlet Header 425.45 34.925 SA 335 P11

34

Executive Summary

Index

7. Superheater Headers (continued)


Inspection Findings

Visual Inspection 100% Slight deterioration of wall & ceiling; sign of water leakage

Remote Visual Inspection 20% Two (2) broken Attemperators spray nozzle head at TSH Inlet Header; slight accumulation of water at TSH Outlet Header

Replica 10 Locations No evidence of creep related damage


280 Points No Headers were found below minimum header wall thickness based from specified original wall thickness.

Ultrasonic Testing (Shear wave)

3 Joints No Headers were found any indication of discontinuities.


None

35

Executive Summary

Index


1

Two (2) broken Attemperators spray nozzle head was found inside the TSH Inlet Header.

Attemperators need to be repaired and broken parts to be removed before boiler start-up.

2 Slight accumulation of water at TSH Outlet Header internal.

Required for total drain of the header in order to eliminate the water inside. And review the storage procedure.


36


Index


Recommendations:

1. Two (2) broken Attemperator spray nozzle head need to be repaired before unit start-up.

2. SSH inlet header and its attemperator need to be inspected for the same finding before unit start-up.

3. Boiler need to be drained totally during shutdown period. 4. Lay-up procedure needs to be reviewed and improved as soon as

possible.5. Major inspection need to be done for the tube penetrations in the next

plan outage.

37


Index

8. Bottom Dead Air Space


Inspection Findings

Visual Inspection 100% One (1) tube leak at tube no.19 Platen Wall; slight tube corrosion; loose nut of boiler structural support; tube deformation; moderate corrosion on structural support; bottom & wall deformation.


None

38


Index


1

Tube leak from rear platen wall tube No. 19 at the penetration area between furnace and dead air space.

Tube need to be repaired before unit start-up.

2 Slight corrosion at rear platen water wall tube.

The wet conditions need to be eliminated in order to control the corrosion.

8. Bottom Dead Air Space (continued)

39


Index

8. Bottom Dead Air Space (continued)

Recommendations:

1. Tube leak from rear Platen Water Wall at tube no.19 need to be repaired before unit start-up.

2. Bottom and wall deformation need to be inspected in the next plan outage.

40


Index

9. BurnersOil Burner Gas Burner

Design Data Design Data

Oil Pressure 16.4 Kpa (238 Psi) Throat Diameter 813 mm (32”)

Atomizing Steam/Burner

76.2 Kg/hr @ 10.3 Bar Impeller Diameter 304.8 mm (12”)

Throat Diameter 812.8 mm (32”) No. of Gas Spuds 8

Impeller Diameter 304.8 mm (12”) Flame Retainer Diameter

114.3 mm (4.5”)

Type of Inspection Amount of NDT Inspections Inspection Findings

Visual Inspection 100% Six (6) broken support at windbox side; support lug was tilting; slight corrosion at structural support.

Penetrant Testing 4 Locations (0.5 – 1 M length) None

41


Index

9. Burners (continued)


1A general photo of PT check at Burner Swirler shows weld in good condition.

No action is required.

2 A general photo of the Igniter shows in condition.

No action is required.

42


Index

9. Burners (continued)

Recommendations:

1. Bad welding quality at non-pressure parts of the burner windbox side need to be repaired in the next plan outage.

2. Support lug tilting downward need to be fixed in the next plan outage.

43


Index

10. Air Heater - Rothemuhle

Manufacturer Hitachi Zosen – Rothemuhle

Design Pressure 889 mmWG

Design Temperature 370 °C

Heating Surface 10608 m²

Type Vu 6.7/0.0675+0.675+0.3C

Serial No. 1604/1605


Inspection Findings

Visual Inspection 100% Broken & deformed expansion joints; slight rust in the unit surface.

44


Index

10. Air Heater – Rothemuhle (continued)


1

A minor cut in the AH expansion joint at No.2 unit.

1-Need to study the root cause of failures of the expansion joints.2-It needs to be repaired in the next planned outage.

2Moderate deformation of AH Expansion joint at No.1 unit.

As per Findings No.1

45


Index

10. Air Heater – Rothemuhle (continued)

Recommendations:

1. Defective expansion joints need to be repaired in the next outage.2. Need to study the root cause of failures of the defective expansion joints

in order to eliminate recurrence.

46


Index

11. Air Heater - SCAH

Design Pressure 14.8 BARg (200 Psig)

Design Temperature 171 °F

Approx. Weight/Element 816 Kg (1800 Ibs)

Approx. Size/Element 228 mm (9”)w x 1.8 m (6’)h x 3.66 m (12’)L


Inspection Findings

Visual Inspection 100% Twenty-eight (28) defected tubes

47


Index

11. Air Heater – SCAH (continued)No. Findings Photo Action

1

Old repair by tube plugging of SCAH at Unit No.1, right side.

SWCC has already set a major repair in this equipment and plan for a major replacement to be done during the outage and Hi Engineering support this action.

2 Defective tube at Unit No.1, left side

As per Findings No.1

48


Index

11. Air Heater – SCAH (continued)

Recommendations:

1. SWCC has already set a major repair in this equipment and plan for a major replacement to be done during the outage and Hi Engineering support this action.

49


Index

12. Air & Flue Gas Duct


Inspection Findings

Visual Inspection 100% Broken pressure measurement tube; excessive loose of insulation; debris deposition


None

50


Index

12. Air & Flue Gas Duct continued


1

Broken pressure measurement tube at the left side of the flue gas duct

Shall be replaced with new spare before start-up.

2

Excessive loose of insulation at 1st expansion joint top center wall - left side of the flue gas duct.

Shall be repaired as soon as possible.

51


Index

12. Air & Flue Gas Duct (continued)

Recommendations:

1. Defective pressure instrument tubes need to be repaired before unit start-up.

52

Post Outage Activity1. Boiler # 1 Risk Table

Index

No. Section Risk Risk Source Action to Reduce Risk Time

1 PSH Tubes M Broken soot blower Sootblower need to be repaired

Before start-up

2 SSH Tubes

H Crack at tube support Crack need to be repaired

Before start-up

M

1. 10 numbers of mother lug disengaged

2. 2 numbers of tube spacer missing

3. Bad Repair mother lug

All lugs need to be repaired

Next Outage

L Anti-vibration ties overheating

Anti-vibration need to be replaced

5 years

H Manhole overheating Manhole need to be repaired

Before start-up

53

Post Outage Activity

Index

1. Boiler # 1 Risk Table (continued)


3 TSH Tubes

H Severe tube sagging

Three (3) tube samples is required to assess the life (Tubes No’s. 16, 22 & 56) and6-7 (Tube No’s. 13, 16, 18, 22, 26, 54 & 56) tube need to be replaced.

ASAP

MH Missing mother lug Missing lug need to be repaired

ASAP

4 TSH Inlet Header

MH Water accumulation

1. Boiler need to be drained totally during shutdown

2. Layup procedure need to be improved

ASAP

54


Index



TSH Inlet Header

H Two (2) broken Attemperator

Attemperator need to be repaired

Before start-up

5 TSH Outlet Header

MH Water accumulation

1. Boiler need to be drained totally during shutdown


ASAP

6 SSH Inlet Header

MH Unknown condition for tube penetration

Major inspection need to be done for the tube penetrations

Next Outage

7 SSH Outlet Header

MH Unknown condition for tube penetration

Major inspection need to be done for the tube penetrations

Next Outage

55

Index




8 Water Wall Tube

MH Unknown condition of tube ID

Tube sample is required to assess the tube ID condition

ASAP

MH Leftover welded pieceLeftover lifting lugs


Next Outage

M Slight soot deposition

Boiler tuning is required to improve the firing condition

ASAP

9 Economizer Tube

M Severe soot deposition

Sootblower need to be paired

Next Outage

MUnknown condition of tube ID


Next Outage

56

Index

Post Outage Activity1. Boiler # 1 Risk Table (continued)


10Water Wall supply Headers

MH General corrosion Tube leak need to be repaired Before start-up

M Unknown condition of Header inside

Borescope need to be conducted

5 Years

11Economizer Header

MH Close to disengaged guiding spacer

1. Monitor during start-up2. Extend the spacer ASAP

MH Corrosion under insulation

Eliminate the wet condition ASAP

12 Steam Drum

M Deposit accumulation


2. Water chemistry need to be reviewed and improved

ASAP

57

Index



Steam Drum

M Bad quality of non-pressure parts welds

Welding defects need to be repaired

Next Outage

13 Bottom Dead Air Space

MH General corrosion

1. Tube leak need o be repaired

2. Wet condition need to be eliminated

Before start-up

M Support loose nut Need to be fastened ASAP

L Bottom & wall deformation

Need to be inspected Next Outage

14 Burners M

1. Bad quality of non-pressure parts welds

2. Support lug3. Support lug

tilting

Welding defects need to be repaired

Next Outage

58

Index



15 Air Heater Rothemuhle

M

1. Defective expansion joints

2. Expansion joints deformation

Expansion joints need to be replaced

Next Outage

16 Air Heater - SCAH

H 28 number of defective tubes

SWCC already plan to replace the equipment

Next Outage

17 Air & Flue Gas Duct

M Defective pressure instrument tube

Pressure instrument tube need to be repaired

Before start-up

Abbreviations:

H : HighMH : Medium to HighM : MediumL : Low

59

Index

2. Hi Engineering Major Recommendations


The following is the summary of the Hi Engineering recommendations for boiler No. 1 which need to be done to increase the Boiler reliability and availability.

1. Regarding the TSH tube sagging at Material SA 213 T11, The seven most excessive sagged tube (Tube Nos. 13, 16, 18, 22, 26, 54, 56) need to be replaced and three (3) tube need to be sent for analysis to evaluate the material creep and the signs of aging. When the study show this section need to be replaced we suggest to replace SA 213-T11 with SA 213-T22.

2. Two (2) Tube samples need to be taken from water to evaluate the water side condition and the requirement of boiler wall chemical cleaning.

3. Attachment of welded piece and lifting lug leftover, tube sample is required to be taken for at least one (1) location to assess the tube ID condition. This has to be done in the next plan outage.

4. When boiler shut down for maintenance, the Boiler should be in dry for two reasons, first to allow maintenance group to do their activity. Second it will be healthier for boiler compare than wet condition with boiler partially filled with the absence of pressurized Nitrogen blanket.

60


Index

3. Force Outage Rates

Forced Outage Rates covered the date from January 1, 2008 until September 14, 2013.

Defined as,FOR = B A – C

Where:FOR = Force Outage Rate, in %A = Total no. of hrs from 1-1-2008 to 14-9-2013 = 50,016 hrsB = Total no. of hrs S/D, Overhaul due to tube failures = 782.74 hrsC = Total no. of hrs S/D, Trip & Overhaul due to non-tube failures = 10,239.7 hrs

Thus,FOR = 782.74 50,016 – 10, 239.7

X 100%

X 100%

61

= 1.97


Index

4. Tube Failures

Below is the Summary of Tube Failures History of Boiler No.1 since commissioned time until September 14, 2013.

Table 3Tube Failures History

No. Date Findings

1 December 1995 Economizer Inlet Header tube stub joint failure.

2 December 1998 Economizer bottom bank tube welded joint has leak and caused another leak from adjacent tube.

3 February 2001 Division wall tube failure at Economizer area.

4 July 2008 Every shutdown Tertiary Superheater Outlet Bank tubes found serious sagging, bowing and displaced from the row.

5 July 2008 Primary Superheater Outlet Header handhole end cap welding has cracked.

6 January 2013 Shutdown due to eighteen (18) Header leaks.

62


Index

5. Boiler Maintenance History

Below is the Summary of Boiler No.1 Maintenance History covered the date from January 1, 2008 until September 14, 2013.

Table 4Boiler Maintenance History

No. StatusDate

Total Hours ActivityFrom To

1 Overhaul 09-07-08 03-11-08 2,799.53 Shutdown for major Overhaul.

2 S/D 18-03-09 25-03-09 184.12 To install strainer 1RA20/300N001.

3 S/D 19-12-09 26-12-09 157.85

Shutdown for stopping all equipment for trfs 01AT01/BT01 isolation for Generator protection panel replacement.

4 S/D 01-05-11 03-05-11 54.62 230 KV Breaker protection upgrade.

5 S/D 11-04-12 26-04-11 364.34Unit Transformer AT/BT01 Oil Filtration job.

63


Index

5. Boiler Maintenance History (continued)

No. StatusDate

Total Hours ActivityFrom To

6 S/D 22-05-12 23-05-12 16.93Shutdown due to replace Drum level control valve gland packing.

7 Overhaul 21-04-13 14-09-13 3509 Shutdown for major Overhaul.

Table 4Boiler Maintenance History

64

Index

Post Outage Activity6. Boiler Chemical Cleaning Procedure Review

Hi Engineering did not receive any Boiler Chemical Cleaning Procedure from SWCC plus no record of Boiler Chemical Cleaning history.

We suggest SWCC to have a written Chemical Cleaning Procedure for Boiler which includes the requirement criteria of the Chemical Cleaning & Chemical Cleaning Procedure.

65

Index

Best Lay-up Procedure

Best lay-up practices and Boiler Storage during outages

In order to maintain high plant availability, it is essential to use good storage techniques during off-load periods. Improper storage practice has a major contributor to boiler tube in power plants and a major cause of reduced plant reliability and availability. Hi Engineering tries to identify the best practices and the practical methods to protect boiler during outages that will aid plant operators in achieving successful boiler storage.

.The primary purpose of the shutdown and storage practice should be to preserve those protective oxide surfaces and prevent damaging corrosion.

66


Storage Methods: Wet and Dry

Wet Storage permits chemically treated and deaerated water to remain in the Boiler, deaerator, condenser, and all associated piping. The goal is to provide proper chemical treatment and prevent air from entering any wet area in the cycle where pitting and corrosion can occur.

Dry Storage is an effective method when equipment must be periodically opened and inspected. Two options can be used for dry storage: nitrogen gas blanketing and dry air.

Index 67

Index

Storage Methods: Wet and Dry (continued)

1. Dry air offers additional advantages to nitrogen gas. The dry condition can be maintained even while equipment is opened for routine inspections. Dehumidified air systems are also less costly to maintain over the long term.


68

Index


For a particular plant, the final choice of storage procedure will require a balance of the following requirements, some of which may conflict with each other:

1. Duration of the Outage2. How fast the unit need to be return in service3. Purpose of the Outage4. Availability of specialized storage equipment

Storage Methods: Wet and Dry (continued)

69

Index


Duration of the Outage

How fast plant personnel need to return a unit to service, can place constraints on how it is shutdown or on the procedures and practices used for storage.

• Short-Period Shutdown

Involves periods extending overnight or through a weekend. This shutdown period is typical of cycling operation and utilizes a wet storage or hot standby approach.

70

Index

Duration of the Outage (continued)


• Long-Period shutdown

Is one extending from a few weeks to six months. Such outages can involve major equipment repair, a planned outage, or a long-term storage due to system load requirements. Both wet and dry approaches can be applied, but if return-to-service timing is not an issue, totally dry storage is preferred for extended outages.

71

Index


Purpose of the Outage

A prime factor affecting the choice of a storage procedure is the type or purpose of the Outage: Economic operation, Forced outage, or Scheduled outage for maintenance.

72

Index


Item Type of Outage Duration Boiler Deaerator Condenser

1Forced Outage for Boiler Tube Failure

Less than 24 hours

Dry storage drained for repairs

Wet storage Wet storage residual heat of turbine should mitigate damage

2Short Scheduled Outage

8 to 24 hours

Wet storage w/ Nitrogen, if pressure decays

Wet storage w/ Nitrogen, if pressure decays

Maintain steam seals and vacuum on condenser

3Scheduled Outage with uncertain Return to Service

Uncertain return to service quickly

Wet storage w/ Nitrogen

Wet storage w/ Nitrogen

Dry storage w/ dehumidified air or wet storage w/ Nitrogen

4Maintenance or Seasonal Outage

More than two weeks

Dry storage w/ dehumidified air



Purpose of the Outage (continued)

73

Index


Three key points should be emphasized:

1. Keep water and moisture out of steam-touched components and any water-touched surface to be maintained dry during the shutdown period.

2. Partial storage of the system, or storage of only some of the equipment (boiler), will not produce the desired results or protect against corrosion. The simultaneous presence of moisture and oxygen should be avoided.

3. Quickly and completely draining all water-containing equipment while it is hot at the start of overhauls, utilizing residual heat to facilitate drying.

74

Index

Miscellaneous

1. Numbering Procedure

2. Illustrations, Records & Measurements during Inspections

75

Thank you

Index 76

swcc boiler # 1 report presentation for client presentation

Documents