11stst CarbamateCarbamate Condenser, ECondenser, E--105A105A

Reliability Evaluation Reliability Evaluation Reliability Evaluation Reliability Evaluation &&&&

Replacement PlanReplacement Planpp

Case StudyCase Study

ContentsContentsE-105 A

ContentsContentsDesignDesign DataDatagg

RepairRepair // LeakageLeakage HistoryHistory

Sh tdSh td SSShutdownsShutdowns SummarySummary

ReliabilityReliability EvaluationEvaluation

SummarySummary ofof ResultsResults

O i iO i i ff C iC i E tE tOpinionOpinion ofof CorrosionCorrosion ExpertsExperts

ConclusionConclusion

Equipment Data Equipment Data

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Equipment Data Equipment Data MANUFACTURERMANUFACTURER Nuovo Pignone, ITALYNuovo Pignone, ITALYYEAR OF MANUFACTURINGYEAR OF MANUFACTURING 19791979TYPE OF EXCHANGERTYPE OF EXCHANGER KETTLE TYPE REBOILERKETTLE TYPE REBOILERTUBESTUBES MATERIAL: 25CrMATERIAL: 25Cr--22Ni22Ni--2Mo 2Mo

SIZE :3/4, THICK: 2.11 MM SIZE :3/4, THICK: 2.11 MM 288 S 288 S NUMBER: 1288 U BENDS NUMBER: 1288 U BENDS

TUBE SHEET TUBE SHEET AA--105 + W.O SS 316 Urea 105 + W.O SS 316 Urea gradegradeThick: 305 + 10 mmThick: 305 + 10 mm

CHANNEL HEADCHANNEL HEAD AA--516 GR 60 +SS 316 Ur. 516 GR 60 +SS 316 Ur. gradegradeThick: 100 + 8mm (Lining)Thick: 100 + 8mm (Lining)

Repair / Leakage HistoryRepair / Leakage History

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Repair / Leakage HistoryRepair / Leakage HistoryDATEDATE MAIN FINDINGMAIN FINDING WORK DONEWORK DONE

T/A MARCH 86T/A MARCH 86 -- 14 TUBES FOUND LEAKING IN AIR / 14 TUBES FOUND LEAKING IN AIR / HELIUM LEAK TESTHELIUM LEAK TEST

-- ALL 14 TUBES PLUGGEDALL 14 TUBES PLUGGED1

HELIUM LEAK TESTHELIUM LEAK TEST

S/D MAY 86S/D MAY 86 -- 12 OUT OF 14 PLUGS INSTALLED 12 OUT OF 14 PLUGS INSTALLED -- CORRODED PLUGS CORRODED PLUGS 2 S/D MAY 86S/D MAY 86ABOVE, FOUND BADLY ABOVE, FOUND BADLY CORRODEDCORRODED

REPLACED WITH NEW REPLACED WITH NEW ONESONES

T/A MAR 88T/A MAR 88 -- PIN HOLES IN SEAL WELDING OF PIN HOLES IN SEAL WELDING OF PLUGSPLUGS

-- SEAL WELDS OF PLUGS SEAL WELDS OF PLUGS REPAIREDREPAIRED

4 PLUGS REPLACED4 PLUGS REPLACED

3

-- ETCHING OF TUBES IN LOWER ETCHING OF TUBES IN LOWER HALFHALF

-- 4 PLUGS REPLACED4 PLUGS REPLACED

Repair / Leakage HistoryRepair / Leakage History

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Repair / Leakage HistoryRepair / Leakage HistoryDATEDATE MAIN FINDINGMAIN FINDING WORK DONEWORK DONE

S/D APRIL 89S/D APRIL 89 -- CAVITIES INSIDE 3 TUBESCAVITIES INSIDE 3 TUBESCORROSION OF TUBE SHEET INSIDE CORROSION OF TUBE SHEET INSIDE

-- PLUGS OF ABOVEPLUGS OF ABOVE

14 TUBES REPLACED14 TUBES REPLACED4

-- CORROSION OF TUBE SHEET INSIDE CORROSION OF TUBE SHEET INSIDE HOLE UP TO 100 MM LENGTHHOLE UP TO 100 MM LENGTH

14 TUBES REPLACED14 TUBES REPLACED

-- 3 NEW TUBES PLUGGED3 NEW TUBES PLUGGED

T/A SEP 89T/A SEP 89 -- PLUGS REMOVED & EDDY PLUGS REMOVED & EDDY CURRENT INSPECTION CARRIED CURRENT INSPECTION CARRIED

-- 24 NEW TUBES PLUGGED IN 24 NEW TUBES PLUGGED IN THE VICINITY OF THE VICINITY OF

5

OUT. TUBE SHEET FOUND OUT. TUBE SHEET FOUND DAMAGED IN UPPER HALF OF DAMAGED IN UPPER HALF OF PLUGGED TUBES UP TO 90MM PLUGGED TUBES UP TO 90MM

PREVIOUSLY PLUGGED PREVIOUSLY PLUGGED TUBES DUE TO DEFECT IN TUBES DUE TO DEFECT IN SEAL WELDINGSEAL WELDING

LENGTH LENGTH

Repair / Leakage HistoryRepair / Leakage History

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Repair / Leakage HistoryRepair / Leakage HistoryDATEDATE MAIN FINDINGMAIN FINDING WORK DONEWORK DONE

T/A FEB 91T/A FEB 91 -- MINIMUM TUBE THICKNESS OF MINIMUM TUBE THICKNESS OF 1.3MM OBSERVED JUST AFTER TUBE 1.3MM OBSERVED JUST AFTER TUBE

-- 25 NEW TUBES WERE 25 NEW TUBES WERE PLUGGED BASED ON PLUGGED BASED ON

6

SHEET IN EDDY CURRENT TESTINGSHEET IN EDDY CURRENT TESTING SPS RECOMMEND.SPS RECOMMEND.

T/A FEB 92T/A FEB 92T/A FEB 92T/A FEB 92 -- LEAKAGE FROM PREVIOUSLY PLUGGED LEAKAGE FROM PREVIOUSLY PLUGGED TUBES & TUBE TO TUBE SHEET SEAL TUBES & TUBE TO TUBE SHEET SEAL WELDSWELDS

-- SEAL WELDS WERE SEAL WELDS WERE WELD REPAIREDWELD REPAIRED

-- FLOW INVERTEDFLOW INVERTED

7

S/D OCT 93S/D OCT 93 -- LIGAMENT FOUND CRACKED B/W TUBE LIGAMENT FOUND CRACKED B/W TUBE # 7 & 8 (2# 7 & 8 (2NDND ROW OF RIGHT LOWER ROW OF RIGHT LOWER

-- LIGAMENT AREA WAS LIGAMENT AREA WAS GROUND & WELD GROUND & WELD

8

# 7 & 8 (2# 7 & 8 (2 ROW OF RIGHT LOWER ROW OF RIGHT LOWER SIDE)SIDE)

GROUND & WELD GROUND & WELD REPAIREDREPAIRED

Repair / Leakage HistoryRepair / Leakage History

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Repair / Leakage HistoryRepair / Leakage HistoryDATEDATE MAIN FINDINGMAIN FINDING WORK DONEWORK DONE

T/A OCT 94T/A OCT 94 -- PIN HOLES IN SEAL WELDING OF PIN HOLES IN SEAL WELDING OF PLUGS (25 TUBES)PLUGS (25 TUBES)

-- SEAL WELDING OF PLUGS SEAL WELDING OF PLUGS & TUBE TO TUBE SHEET & TUBE TO TUBE SHEET

9

PLUGS (25 TUBES)PLUGS (25 TUBES)-- CAVITIES IN SEAL WELDING OF CAVITIES IN SEAL WELDING OF

TUBESTUBES--

& TUBE TO TUBE SHEET & TUBE TO TUBE SHEET SEAL WELDS REPAIREDSEAL WELDS REPAIRED

T/A JULY 96T/A JULY 96 -- ETCHING OF OUTLET TUBE ENDSETCHING OF OUTLET TUBE ENDS -- DEFECTIVE WELDS WERE DEFECTIVE WELDS WERE REPAIREDREPAIRED

10

-- PIN HOLES IN SEAL WELDING OF PIN HOLES IN SEAL WELDING OF PLUGS & TUBE TO TUBE SHEET PLUGS & TUBE TO TUBE SHEET WELDINGWELDING

REPAIREDREPAIRED

Repair / Leakage HistoryRepair / Leakage History

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Repair / Leakage HistoryRepair / Leakage HistoryDATEDATE MAIN FINDINGMAIN FINDING WORK DONEWORK DONE

T/A APR 99T/A APR 99 -- ETCHING OF TUBE ENDS IN UPPER ETCHING OF TUBE ENDS IN UPPER HALFHALF

-- SURFACESURFACE DEFECTSDEFECTS ININ SEALSEAL

-- LINING WELDS LINING WELDS REPAIREDREPAIRED

-- SEAL WELDS REPAIREDSEAL WELDS REPAIRED

11

-- SURFACESURFACE DEFECTSDEFECTS ININ SEALSEALWELDINGWELDING OFOF PLUGSPLUGS

-- -- TIETIE RODSRODS && SPACERSSPACERS FOUNDFOUNDCORRODEDCORRODED

-- SEAL WELDS REPAIREDSEAL WELDS REPAIRED

S/D FEB 2000S/D FEB 2000 -- TUBE TO TUBE SHEET SEAL TUBE TO TUBE SHEET SEAL WELDS TOE DETACHMENT & WELDS TOE DETACHMENT &

-- REPLUGGING OF REPLUGGING OF EXTREME TWO ROWSEXTREME TWO ROWS

12

PIN HOLES PIN HOLES -- PINPIN HOLESHOLES ININ SEALSEAL WELDINGWELDING

OFOF PLUGSPLUGS-- PIN HOLES IN WELD OVERLAY PIN HOLES IN WELD OVERLAY

-- REPAIRREPAIR OFOF PINPIN HOLESHOLES ININSEALSEAL WELDSWELDS && TUBETUBESHEETSHEET OVERLAYOVERLAY

ON TUBE SHEETON TUBE SHEET

Repair / Leakage HistoryRepair / Leakage History

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Repair / Leakage HistoryRepair / Leakage HistoryDATEDATE MAIN FINDINGMAIN FINDING WORK DONEWORK DONE

S/D OCT 2000S/D OCT 2000 PINPIN HOLESHOLES ININSEALSEAL WELDWELD OFOF PLUGGSPLUGGS

-- PINPIN HOLESHOLES GROUNDGROUND OFFOFFUPUP TOTO SOUNDSOUND METALMETAL &&

13

SEALSEAL WELDWELD OFOF PLUGGSPLUGGSSEALSEAL WELDWELD OFOF TUBESTUBESTUBETUBE SHEETSHEET WELDWELD OVERLAYOVERLAY

UPUP TOTO SOUNDSOUND METALMETAL &&REWELDEDREWELDED

T/A MAR 2001T/A MAR 2001 -- SHARPSHARP PINPIN HOLESHOLES ININ WELDWELD --WELDINGWELDING DEFECTSDEFECTS14OVERLAYOVERLAY OFOF TUBETUBE SHEETSHEET

-- PINPIN HOLESHOLES ININ TUBETUBE TOTO TUBETUBE--SHEETSHEET SEALSEAL WELDINGWELDING &&

GROUNDGROUND UPUP TOTO SOUNDSOUNDMETALMETAL && REPAIREDREPAIRED

WELDINGWELDING OFOF PLUGSPLUGS

Repair / Leakage HistoryRepair / Leakage History

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Repair / Leakage HistoryRepair / Leakage HistoryDATEDATE MAIN FINDINGMAIN FINDING WORK DONEWORK DONE

S/D OCT 2001S/D OCT 2001 SHARP PIN HOLES IN: SHARP PIN HOLES IN: -- TUBE SHEET WELD OVERLAY TUBE SHEET WELD OVERLAY

TUBE TO TUBE SHEET SEAL TUBE TO TUBE SHEET SEAL

-- SEAL WELDSGROUND SEAL WELDSGROUND UP TO SOUND METAL UP TO SOUND METAL & WELD REPAIRED& WELD REPAIRED

15

-- TUBE TO TUBE SHEET SEAL TUBE TO TUBE SHEET SEAL WELDS WELDS

-- WELDING OF PLUGSWELDING OF PLUGS-- SEVERE CORROSION INSIDE TUBE SEVERE CORROSION INSIDE TUBE

-- TUBE SHEET HOLE TUBE SHEET HOLE SHOWING DAMAGE SHOWING DAMAGE WAS REPLUGGEDWAS REPLUGGED

SHEET HOLE IN CARBON STEEL SHEET HOLE IN CARBON STEEL PORTIONPORTION

T/A 2004T/A 2004 -- HEAVY CORROSION ON WELD HEAVY CORROSION ON WELD OVERLAY & PINOVERLAY & PIN HOLES AT NEW HOLES AT NEW -- DEFECTS IN WELDING DEFECTS IN WELDING

16OVERLAY & PINOVERLAY & PIN--HOLES AT NEW HOLES AT NEW LOCATIONSLOCATIONS

-- WELD CRATER DEFECTS & KNIFE WELD CRATER DEFECTS & KNIFE LINE CORROSION ATTACK ON LINE CORROSION ATTACK ON SEAL WELDING OF TUBES & SEAL WELDING OF TUBES &

DEFECTS IN WELDING DEFECTS IN WELDING WERE GROUND UP TO WERE GROUND UP TO SOUND METAL & SOUND METAL & WELD REPAIREDWELD REPAIRED

SEAL WELDING OF TUBES & SEAL WELDING OF TUBES & PLUGSPLUGS

-- ETCHING OF TUBESETCHING OF TUBES

Shutdown Summary due to Tube Shutdown Summary due to Tube

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Shutdown Summary due to Tube Shutdown Summary due to Tube LeakagesLeakages

26TH MAY 8626TH MAY 86 : 3 DAYS 23 HRS : 3 DAYS 23 HRS 28 8928 89 6 S S6 S S28TH APRIL 8928TH APRIL 89 :: 6 DAYS 7 HRS6 DAYS 7 HRS07TH FEB 200007TH FEB 2000 :: 6 DAYS 14 HRS6 DAYS 14 HRS15TH OCT 200115TH OCT 2001 : 5 DAYS 3 HRS: 5 DAYS 3 HRS

Reliability EvaluationReliability EvaluationE-105 A

Reliability EvaluationReliability EvaluationTUBESTUBES

TOTALTOTAL 132132 UU--ENDSENDS ((55%%)) AREARE PLUGGEDPLUGGEDTUBETUBE PROTRUSIONSPROTRUSIONS AREARE ETCHEDETCHED ANDAND THINNEDTHINNED OUTOUTDEEPDEEP PITSPITS ANDAND CAVITIESCAVITIES OBSERVEDOBSERVED ATAT INNNERINNNER SIDESIDE OFOFTUBESTUBES

SEAL WELDSSEAL WELDSTUBE TO TUBE SHEET SEAL WELDS ARE UNDER SEVERE KNIFE LINE TUBE TO TUBE SHEET SEAL WELDS ARE UNDER SEVERE KNIFE LINE CORROSION ATTACKCORROSION ATTACKSHARP AND DEEP PIN HOLES OBSERVED AT SEAL WELDS OF MOST SHARP AND DEEP PIN HOLES OBSERVED AT SEAL WELDS OF MOST OF THE TUBES AND PLUGSOF THE TUBES AND PLUGS

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Reliability EvaluationReliability EvaluationTUBE SHEETTUBE SHEET

EXCESSIVE CORROSION ON TUBE SHEET WELD OVERLAY EXCESSIVE CORROSION ON TUBE SHEET WELD OVERLAY

Reliability EvaluationReliability Evaluation

EXCESSIVE CORROSION ON TUBE SHEET WELD OVERLAY EXCESSIVE CORROSION ON TUBE SHEET WELD OVERLAY SHARP AND DEEP PIN HOLES ARE PRESENT IN LIGAMENT AREA ALL SHARP AND DEEP PIN HOLES ARE PRESENT IN LIGAMENT AREA ALL OVER THE TUBE SHEETOVER THE TUBE SHEET

FLOW REVERSALFLOW REVERSALFLOW REVERSAL CARRIED OUT IN 1992 TO ADDRESS TUBE ENDS FLOW REVERSAL CARRIED OUT IN 1992 TO ADDRESS TUBE ENDS CORROSION, AND BOTTOM TWO ROWS WERE PLUGGEDCORROSION, AND BOTTOM TWO ROWS WERE PLUGGEDAFTER FLOW REVERSAL, AFTER FLOW REVERSAL, NO NEW TUBENO NEW TUBE WAS PLUGGEDWAS PLUGGED

02 SHUTDOWNS OCCURRED DUE TO LEAKAGE THRU PLUG WELDS02 SHUTDOWNS OCCURRED DUE TO LEAKAGE THRU PLUG WELDS02 SHUTDOWNS OCCURRED DUE TO LEAKAGE THRU PLUG WELDS02 SHUTDOWNS OCCURRED DUE TO LEAKAGE THRU PLUG WELDS

PRODUCTION LOSSPRODUCTION LOSSCUMMULATIVE PRODUCTION LOSS DUE TO TUBE LEAKAGES IS CUMMULATIVE PRODUCTION LOSS DUE TO TUBE LEAKAGES IS 527527 HRSHRS

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PLUGGED TUBES

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Porous / etched tube-ends

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Deep pits and annular cavities inside the tubes

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Weld toe-detachment due to knife-line-corrosion attack at outer perimeter of tube-sheet

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Pinhole in seal weld of tube

Deep pinholes in plugs seal weld

Condition of tube ends after

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Condition of tube ends after weld repair in ligament area

Sharp pinhole in ligament areaTUBE SHEET CORROSION

Summary of ResultsSummary of ResultsE-105 A

Summary of ResultsSummary of ResultsNDTNDT isis notnot capablecapable enoughenough toto quantifyquantify defectsdefects

severityseverity

ProlongedProlonged serviceservice hashas severelyseverely affectedaffected thethe healthhealth ofof

basebase--metalmetal duedue toto continuouscontinuous corrosioncorrosionbasebase--metalmetal duedue toto continuouscontinuous corrosioncorrosion

DefectsDefects areare locatedlocated inin completecomplete tubetube--sheetsheet areaarea

RepairRepair intricacyintricacy isis limitinglimiting futurefuture maintenancemaintenance ofof

equipmentequipment

Summary of ResultsSummary of ResultsE-105 A

Summary of ResultsSummary of ResultsAtAt times,times, repairrepair ofof defectsdefects furtherfurther deteriorateddeteriorated thethe

situationsituation

PotentialPotential ofof leakageleakage duedue toto plugplug toto tubestubes sealseal weldswelds isis

alwaysalways onon higherhigher sideside duedue toto NDTNDT inadequacyinadequacyalwaysalways onon higherhigher sideside duedue toto NDTNDT inadequacyinadequacy

ETET performedperformed byby NCNDTNCNDT revealedrevealed pinholepinhole atat outerouter

surfacesurface ofof tubestubes

Opinion of Corrosion ExpertsOpinion of Corrosion ExpertsE-105 A

Opinion of Corrosion ExpertsOpinion of Corrosion Experts

SPSP CorrosionCorrosion expertexpert && MrMr MiolaMiolaSPSP CorrosionCorrosion expertexpert && MrMr.. MiolaMiola

InspectedInspected thethe 11stst CarbamateCarbamate CondenserCondenserInspectedInspected thethe 11stst CarbamateCarbamate CondenserCondenser

inin TATA--20042004 andand recommendedrecommended totoinin TATA--20042004 andand recommendedrecommended toto

replacereplace thethe samesame inin nextnext turnaroundturnaroundreplacereplace thethe samesame inin nextnext turnaroundturnaround

ConclusionConclusionE-105 A

ConclusionConclusion

R li bilitR li bilit ff 11STST C b tC b tReliabilityReliability ofof 11STST CarbamateCarbamate

CondenserCondenser waswas uncertainuncertainCondenserCondenser waswas uncertainuncertain

ReplacementReplacement waswas performedperformed ininReplacementReplacement waswas performedperformed inin

turnaroundturnaround 20062006