report f2501

One week stay at Plant I AMMONIA II FM provided me with an opportunity to work alongside a very able and dedicated team of engineers and technicians who taught and helped me throughout while diligently working on some of the most critical jobs ever encountered at Plant I. This document highlights the various tasks I was assigned and the major jobs that I observed during my stay. The purpose was to document what I had

learnt and in a way, compile a history of major jobs conducted to assist any future maintenance jobs carried out at the same equipment’s.

TRAINING HIGHLIGHTS AMMONIA II

FM

ABSTRACT In an attempt to address the hot spots issue occurring at the furnace, when the operators at the north of the furnace observed a fire in the pigtail. On closer examination, the tube number suggested for leakage are 290-310 causing the entire assembly to slip-down. Immediately, the operation department called upon the process gas removal from the radiant tubes & steam is inserted for proper circulation & to avoid any damage. Maintenance department was called for emergency situation Through technical coordination with FFBL as well as the Enven , it was decided to replace the leaked tube along with the inspection of the other pigtails for safety aspect in future . Through the course of the job, various setbacks had to be faced-difficulties in gouging ,welding equipment , man power, identification of cracks on end of the pigtails are to name a few. Through strict compliance with the inspection indicated points, regular meeting and dedicated hard work of the team, the job was executed without a single injury. Precise root cause for the supports failure is yet to be known; however, there is high probability that the reason is either of them : material failure because of thermal shock occurring due to large number of plant loads and shut downs, extra load on the pigtail because of uneven expansion of tubes.

Prepared by: AAB Reviewed by: KMK SP

AUF ADM ZAA

AUGUST

2012 F-2501 PIGTAILS REPLACEMENT

TABLE OF CONTENTS INTRODUCTION TO FURNACE ....................................................................................................................... 1 FURNACE SECTION MODULE ........................................................................................................................ 1 HISTORY OF MATERIALS .............................................................................................................................. 2 HISTORY ....................................................................................................................................................... 2 PROBLEM DESCRIPTION ............................................................................................................................... 3 PRE-ARRANGEMENTS ................................................................................................................................... 3 JOB SCOPE .................................................................................................................................................... 3 FURNACE HANDOVER ................................................................................................................................... 3 PRE-CHECKS ................................................................................................................................................. 3 OBSERVATIONS ............................................................................................................................................ 3 INSPECTION .................................................................................................................................................. 4 INSPECTION ROOM ACTIVITIES ..................................................................................................................... 4 1ST DAY ACTIVITIES ....................................................................................................................................... 4 MEETING ...................................................................................................................................................... 5 NEAR MISS ................................................................................................................................................... 6 ACTIVITIES DURING NIGHT ........................................................................................................................... 6 2ND& 3RD DAY ACTIVITIES............................................................................................................................... 6 DEFECTS LOCATION OF LONG TUBES FROM TUBE SIDE ........................................................................... 7 WARE HOUSE ……………………………………………………………………………………………………………………………………… 12 MEETING……………………………………………………………………………………………………………………………………………… 12 PEEP HOLES ………………………………………………………………………………………………………………………………………… 12 MISCELLANEOUS JOBS……………………………………………………………………………………………………………………………… 12 TEAMS ………………………………………………………………………………………………………………………………………………… 13 SUMMARY ………………………………………………………………………………………………………………………………………………… 11 RECOMMENDATIONS………………………………………………………………………………………………………………………………….15 BENCH MARKING……………………………………………………………………………………………………………………………………….16 APPENDIX/ ATTACHEMENT…………………………………………………………………………………………………………………………17 INSPECTION RESULTS…………………………………………………………………………………………………………………………… 17 PROCESS DEPARTEMNT ANALYSIS …………………………………………………………………………………………………….... 20 FW COLD & HOT BOTTOM DESIGN ……………………………………………………………………………………………………… 21 VESSEL BOXUP ……………………………………………………………………………………………………………………………………..22 SIGNED MEMORANDUM FOR PEEP HOLES …………………………………………………………………………………………..26 STRESS COLLAR MIV ……………………………………………………………………………………………………………………………..27 TUBE REPLACEMENT CHART SHEET ……………………………………………………………………………………………………....28

Introduction to Furnace Furnace, also known as the primary reformer, has multiple process applications i.e. heating of process air, boiler feed water, natural gas and generating KS steam. Primarily, it comprises of two sections: radiant and convection. Burners installed in the radiant section initiate cracking of feed gas in the catalyst lined tubes running vertically in the section. Convection section, on the other hand, receives hot flue gases from the radiant section and heats the process fluid travelling in horizontally running coils. The flue gases are exhausted with the aid of ID fan installed at the top of the furnace. Furnace Section Module Since the current issue of leaked pigtails has occurred at the outlet section of the radiant tubes, specifications of the same are given below: Section Coil No. E-203-1

Furnace Manufacturer/Type Foster Wheeler/ Terrace Number of casted & welded parts 6 Length of Tubes 55.625m Tube Type Staggered Inlet Temperature(oF) /Pressure (PSIG) 990/520 Outlet Temperature(oF) / Pressure (PSIG) 1438/445 Tube Material ABEX TX-63(35Ni-25Cr) Tube Max Temperature (oF) 1919 Tube O.D/I.D (mm) 4.7/ (3.7, +-0.01) Tube Weight( without Catalyst) 1320 Lbs. PIGTAIL Material/Length INCOLOY 800HT/(1112-1120mm) Stress collar Material/Type INCOLOY 800HT/Tapered Bottom/Top Blind flange Carbon steel/2.25Cr ,1Mo Lug Material SS-304

HEADER

H CASTING PIGTAIL SOCKET

RAD. TUBE CHANNEL

LUG

History of materials

Furnace part OLD MATERIAL in 2005 NEW MATERIAL (2012) Outlet header INCOLOY 800H INCOLOY 800HT Inlet header 1.25 Cr -0.5Mo SS-304H Inlet pigtail 1.25 Cr -0.5Mo SS-304H Outlet pigtail Incoly800h Incoly800ht Tube top flange 1.25Cr ,0.5Mo , 8 Bolts 2.25Cr ,1Mo, 12 Bolts Bottom top flange Carbon steel Carbon steel Top blind flange 1.25 Cr -0.5Mo 2.25Cr ,1Mo Tube Bottom flange Carbon steel Carbon steel Stress collar A297-HP40-sp cast INCOLOY 800ht HISTORY

Problem Description

Pigtail failure causing fire is the problem ever since the commissioning of the plant from 1967. All catalyst tubes & pigtail replacement along with the material brought no food but the problem continues to increase year by year till 2010 causing a huge fire in August. Continuing, the problem awakens again & again till July 2012 pretending that root cause hasn’t been called yet.

Year Problems/ works

1992 All radiant tubes + inlet & outlet pigtails + outlet header + new refractory transfer line + radiant & convection section renewed + 10 tubes in convection section added + 28 new supports addition

1995 Sealing basket angle iron change to material SS-310 + anchoring modification

1997 Hot bottom reformer Pigtail blow out resulting in fire + pressure trip 1998 20 tubes addition in convection section with 18 % increase in output + 7

% firing increase 2000 240 burners window application to improve combustion efficiency 2001 3 pigtails failure in startup , 35 thermal cycles 2002 5 pigtails failure 2005 All outlet pigtails replaced + taper stress collar addition + material

change of pigtail + counter weight increased to 105 % + outlet header support refurbished

23 august 2010

#296 pigtail failure with bulk of fire as per six thermal cycle due to the reason of the 7 day before partial failure

2011 01 tube failed in 2009 was removed from furnace 2012 July, 1tube nipped & & 42 pigtails replaced against UFD results + Jan 2

tubes nipping

Pre-Arrangements Installation of scaffolding Gouging and welding machines are brought to the west side of furnace Rods are to there as to support the bottom plates during removal

Job Scope Detection of fire from Peep holes Removal of bottom plates as numbers indicated by operation department Inspection of tubes to detect leakage Making an arrangement of appropriate fabricators, welders etc. Mechanical maintenance activities on tubes along with the inspection of weld pigtails Handover to Operation Department Startup

Furnace Handover to Ammonia-2 Field Maintenance Before handling over the furnace, it has been assured from the operation department that it has

removed any process explosive gases. While the steam flow rates as per operation department are as follows

---*LESS Than expected KSCFH = 1000 standard cubic feet per hour. SG ratio= steam to Gas ratio PSIG=pound per square inch gauge FEL= frond end load

PRE-CHECKS Explosively was checked by area operator to be zero through explosively meter and also assured by the operation.

Observations Insulation has been found in the spring supports along with the condition of mid-level reading

between cold & hot condition as temperature is still 250 degree C. After removal of the bottom plate ES-9,10,11 it is found that # 300 tube has impingement on the

tube. But as per visual view the leakage was not much obvious.

Lugs distance from the bottom channel.( PROJECT DEPARTMENT) Some of the spring support slip & load plates were found to be mis-aligned to some extent. Distance between LUGS & channel top are found as follows

DATE TIME PRC-101 PSIG

D2503 VENT

FEL FRC-101 (KSCFH)

FRC 104 KPPH STM/HR

FRC-105 STM/HR

SG RATIO

01/08/12 00:00N 466.3 569.9 140.6 2088.1 108 108 2.53 08:00 465.9 571.3 10.7 2089.5 109 109 2.54

02/08/12 16:00 467.7 571.3 142.8 2091.1 109.1 109 2.52 00:00 487.0 578.2 142.1 2120.7 111.8 111.8 2.53 08:00 471.7 576.7 140.9 2110.7 112.2 112.2 2.56

03/08/12 16:00 467.6 574.9 141.9 2092.7 109.9 109.9 2.53 00:00 468.0 574.7 141.6 2102.0 110 110 0.24 08:00 491.9 510.9 74.3 1102.6 91 90.6 ---*

04/08/12 16:00 521.1 232.2 1.0 14.2 19.4 13.2 ---* 00:00 524.9 1.5 0.4 5.5 13.5 7.0 ---* 08:00 524.2 3.7 0.4 6.0 12.6 6.9 ---*

Inspection After proper temperature maintenance of around 100 degree C, UFD was initiated. After inspection & controlling the flow-rate of steam leakage was clear This tube was handed over to the maintenance department & other bottom plate tubes of

named ES-6,7,8,9,12,13,14 is inspected with UFD. Recommendation from the inspection section came for replacement of 7 pigtails while the

work on the leaked tube is under process by maintenance.

Inspection Room Activities The following tubes of last shut-down was brought back & UFD test were done for to replace #300 tube in RT room & following tubes were accepted after UFD.

* Visual inspection of unknown tube number has resulted in hindrance to use.

#225 tube is machined to the required length of 45 inch minimum

Also the tube implementation sides are reversed to even the stresses in working.

1st Day Activities The gouging operation were started 10:30 A.M The following characteristics of gouging machines were used. Two machines

Of 250 Ampere Of 300 Ampere

were used to reach the current capacity to 500 AMPERE. 12-14 inch long carbon electrode with carbon coating and usage mark indicated.

S. No Tube number UFD Fretting check 1 335 Rejected Not performed 2 93 Rejected Not performed 3 214 Rejected Not performed 4 228 Rejected Not performed 5 225 OK 14 % 6 UNKNOWN* OK 14%

UFD Testing fretting Testing Visual inspection defects

Tube side indication marked

Upto 5000 degree C was the temperature limit Gouging was done from bottom to top

After removal of tube the crack found as follows

Then the tube #225 (from old shut-down) was brought from workshop after cutting down the proper length & welding work was initiated.

For For we l

for welding GTAW welding was used which have the following specifications

Inconel-182 bare wire Gas type Cylinder pressure(PSIG) Torch pressure(PSIG) Oxygen gas 1450 60 Argon gas 195 10

During implementation of the pigtail there was a proper distance between the socket head & tube end of 1/8 inch.

In the welding process, a weld mark of 2.5mm on #301 tube happened which was later weld buildup.

Meeting Meeting of executives was called & decided to get tubes for pigtails from FFBL.so proper arrangement was done & FFBL deported the tubes from KARACHI at evening hrs. On 3/8/2012. These tubes reached in E-FERT around early morning

#300 tube crack

Length measurement Length reduction Beveling of end for welding

Operations on #300

Weld mark

Near-Miss During welding process at about 00:30 Afternoon, due to the leakage from the plant an 990 PPM AMMONIA puff comes along with the steam that causes the fire. so proper arrangements are done to avoid any mishap.

Activities during night Inspection team demanded more bottom plate’s removal & Following 7 tubes are successfully gouged + welded with DPT test clearance

2ND & 3rd DAY ACTIVITIES On 4/8/2012, inspection team further show 21 more tubes for the replacement point of view. Out of which 9 were long tubes while other were short which all were from bottom of furnace East cell. In order to fasten the work, Morning MEETING decided to remove these pigtails & get more welding equipment & Man power from contractor. so following was the list along with other discussion.

The long tubes have to be shortened to 1115-1120 mm for the use along with the clearance from the inspection. Here is the list of tubes +inspection results. The reason of rejection of tubes were described below

288 290 292 302 304 306 318

Tube type Tube numbers Long Tubes 273,281,321, 323, 325, 351,353, 359,363, Short Tubes 272,274,280,330,340,344,346,348,352,354,360,362

Equipment /man power Quantity Welding machine 6 Argon set 4 Welding leads 12 Fabricator 3

Tube type Defected Available pigtails To be plugged Long tubes 9 2 7 Short tubes 12 1 6

Tube number DPT TEST DIMENSIONAL CHECK UFD 325 OK 42.1 ~42.3 OK 359 OK 42.1 ~42.3 OK 353 OK 42.2 ~42.3 OK 363 OK 42.2 ~42.3 OK 351 Not performed Not performed Not performed 323 Not performed Not performed Not performed 321 Not performed Not performed Not performed 273 Not performed Not performed Not performed 281 Not performed Not performed Not performed

TUBE NUMBER REASON OF REJECTION 323 rejected after visual inspection DUE TO ARC STRIKE 321 rejected after visual inspection DUE TO ARC STRIKE 273 rejected after visual inspection DUE TO ARC STRIKE 281 rejected after visual inspection DUE TO ARC STRIKE 351 rejected after visual inspection DUE TO PIN HOLE

Pin hole of #351

Defects (arc strike & pin-hole) of tubes

WAREHOUSE ISSUEANCE

MEETING

Meanwhile in MEETING at afternoon decided to use the ENVEN PLANT FURNCAE pigtails which have a less I.D than the F-2501. Here was provided the list of diameter comparison for tube vendors

Also analysis was carried out by process department Which results in the following results, With outlet pigtail of reduced ID

Process flow will decrease by 1 % TMT of tubes shall increase by ~ 10 degree F avg.

Within the tolerable limits till the T/A, it were suggested to implement that Enven tubes. Also the west side tubes(w-8 , w-9) are removed & inspected & no flaw in indicated by UFD machine. PEEP HOLES ADDITION: The arrangement was performed at each cell for 2 more peep holes but only 1 peep hole were implemented during that duration. SUB HSE were also performed Now the quantity of peep hole were as follows

N= NORTH S= SOUTH

Miscellaneous Jobs All preparations were done to get the Box up certification All plates were placed on their cell location with the insulation entangling in the plate Box up signed from inspection , process departments Insulation were removed from the spring supports Proper oiling were done of the SS spring Housekeeping at the furnace basement were properly conducted

Material Order number Reservation number Stress collar 410000001703 643427

Tube vendor Outer diameter(mm) Internal diameter(mm) Old tube 42.6 32.5 FFBL 42.6 30 Enven plant 42.6 26

Cell Peep holes quantity (old) Peep holes quantity (new) East 1 N , I S 1N, 2S West 1 N , 1S 2N,1S

F-2501 operation were Handed over to the operation & process department at 10:00 A.M on 5/8/2012

Teams Team Lead: ADM/ZAA Morning Shift Supervisor: KMK Tech: Imran khan, M.ALI, SAHID NADEEM, AMJAD RASOOL, SHAMSHIR Welders: M.ATTAR, NAZIR Night Shift Supervisor: SP Tech: UZAIR, KHADIM, RAFIQ BHUTTO, IMRAN MANZOOR Welders: MUNAWAR, ANJUM

SUMMARY

After applying all the activities of welding and Inspection, here is the list of the tube numbers & vendors.

D = Day N= Night

S. No. Tube No. Tube vendor Final DPT Test Clearance

1 272 Enven plant 4/8/12 N 2 273 Enven plant 4/8/12 N 3 274 Enven plant 4/8/12 N 4 280 Enven plant 4/8/12 N 5 281 Enven plant 4/8/12 N 6 288 FFBL 3/8/12 N 7 290 FFBL 3/8/12 N 8 292 FFBL 3/8/12 N 9 300 Old tube 3/8/12 D 10 302 FFBL 3/8/12 N 11 304 FFBL 3/8/12 N 12 306 FFBL 3/8/12 N 13 318 FFBL 3/8/12 N 14 321 Enven plant 4/8/12 N 15 323 Enven plant 4/8/12 N 16 325 Enven plant 4/8/12 N 17 330 Enven plant 4/8/12 N 18 340 Enven plant 5/8/12 D 29 344 Enven plant 5/8/12 D 20 346 Enven plant 5/8/12 D 21 348 Enven plant 5/8/12 D 22 351 Enven plant 4/8/12 N 23 352 Enven plant 4/8/12 N 24 353 Enven plant 4/8/12 N 25 354 Enven plant 4/8/12 N 26 359 FFBL 4/8/12 N 27 360 Enven plant 3/8/12 D 28 362 Enven plant 3/8/12 D 29 363 FFBL 4/8/12 N

Tube No. Operation Done 294 Nipped tube was plugged at inlet and outlet headers 301 Grinding mark of 2.5 mm depth was weld buildup

TUBE VENDOR NUMBER OF TUBES Enven 19 FFBL 9 E-FERT plant 1 1

Root cause analysis & Recommendation:

If we ponder upon the history we will find out that major failures are associated with the pigtails occurred in the failure causing fire. Upon my root cause analysis i went through the history which recommends that the outlet pigtail should be looped to compensate the expansion & make it flexible to bear stresses. So ICI Methanol based suggestion is installed but not successful as it burst out also The major difference is that Engro has implemented although hot bottom design as following the ICI Methanol but the major difference are that

The failure is basically due to the circumferential stress or longitudinal. As per the results of analysis it is indicated that

Failure is basically due to the stress cycle related rather than temperature driven Failure start from the taper stress collar design (highest stress area)

Conclusion: So we can say that the given stress collar design is inherently wrong as it doesn’t remove stresses but in fact shift it from tube collar end to the stress collar taper end & any concentration of stress at that point causes to propagate it to other parts & finally causing the failure of the outlet pigtail .Also local high temperature concentration at that taper collar causes the oxidation of the surface of pigtail along with the nitride formation. It appears that the fundamental pigtail design continues to be the root cause of the cracking problems. It can be seen that in the past that there have been a number of attempts to fix that problem, but no significant design change to eradicate it. The fundamental issue is the lack of flexibility in the pigtails amplified by the reformer staggered tube row induced distortion & the high reliance on the correct & functional reformer tube.

In order to make it flexible, the tube arrangement has to be changed with single rows making the outlet pigtails more flexible (may with hot bottom design)

Welded parts should be thin enough so that, upon cooling, the metal dissipates heat too quickly for chromium carbide to precipitate.

The carbide formation at the grain boundaries of the chromium as per the research papers causes to initiate the crack then it further propagates

Leaching is the standard reason for the carbide formation. Also oxidation at the surface is major reason as it goes deeper into the surface.

The stress pattern may be due to

The improper functioning of the supports, Possible support maintenance issues Fabrication & variation during firing,

Specification ICI Methanol FW reformer Engro FW reformer Original construction year 1971 1967 Reformer tube arrangement

Single tube row Staggered tube rows

Reformer tube bottom Converted from cold bottom design to hot bottom design

Original cold bottom pigtail

Reformer tube counter weight

Each counter weight supports 4 tubes

Combination of load supporting

Reformer tube pusher bars Yes Yes Outlet pigtail type Horizontal pigtail with

complete loop Horizontal straight pigtail

Introduction of stresses at the start & shut down The proper maintenance plan has to be conducted as recommended by HASEEB & BILAL AWAN.

If we ponder upon the TUBE REPLACEMENT CHART SHEET (in hard form), we will find out that the EAST cell is continuously getting worse with time although the pigtails are replaced with the new ones in July then the again problem occurs in the EAST CELL with some other tube replacement, this shows that EASE cell is not properly maintained as well as PM plans has to be properly worked upon. We replaced the pigtails of number majorly 197-250 majorly. Then in AUGUST it is shifted to 270+ tubes means this is a precaution for us to have an eye on 320+ tubes numbers

Best recommendation is the comparison of the west & east cells all values.

Bench marking

Bench marking has to be done with the ENVEN Plant for pigtail designing.

APPENDIX

INSPECTION RESULTS

S.No TUBE No.

UFD Grade REMARKS

1 90 Y C Changed D-C 2 91 Y D 3 92 Y D 4 93 Y D 5 94 Y C 6 95 Y C 7 96 Y C 8 97 Y C 9 98 Y C

10 99 Y C Changed D-C

11 101 Y C Changed D-C 12 102 Y D 13 103 Y C Changed D-C 14 104 Y C Changed D-C 15 105 Y C 16 106 Y C 17 107 Y C Changed D-C 18 272 Y B Tube Replaced with new one from Plant-2

19 273 Y C Tube Replaced with new one from Plant-2

20 274 Y B Tube Replaced with new one from Plant-2

21 275 Y C

22 276 Y C

23 277 Y C

24 278 Y D

25 279 Y C



28 282 Y C

29 283 Y C

30 284 Y D

31 285 Y C

32 286 Y D

33 287 Y D

34 288 Y A Tube Replaced with new one from FFBL

35 289 Y C


37 291 N/A


39 293 Y C

40 294 N N/A Nipped tube was plugged at inlet and outlet headers

41 295 Y C

42 296 Y D

43 297 Y D

44 298 Y D

45 299 Y D

46 300 Y A Leaking Pigtail/ Tube replaced with OLD tube

47 301 Y D

48 302 Y B Tube Replaced with new one from FFBL

49 303 Y C


51 305 Y D


53 307 Y C

54 308 Y D

55 309 Y C

56 310 Y D

57 311 Y C

58 312 Y D

59 313 Y D

60 314 Y D

61 315 Y D

62 316 Y D

63 317 Y D


65 320 Y C


67 322 Y D

68 323 Y C Tube Replaced with new one from Plant-2

69 324 Y D


71 326 Y C

72 327 Y C

73 328 Y C

74 329 Y C

75 330 Y A Tube Replaced with new one from Plant-2

76 333 Y D

77 334 Y D

78 335 Y D

79 336 Y C

80 337 Y C

81 338 Y C

82 339 Y C


84 341 Y C

85 342 Y C

86 343 Y C


88 345 Y C


90 347 Y D


92 349 Y C

93 350 Y D





98 355 Y C

99 356 Y C

100 357 Y C

101 358 Y C



104 361 Y C



107 364 Y C

108 365 Y C

109 366 Y C

Summary:

UFD Done : 108 at 100% (29 Tubes replaced 01 plugged .) Found Defective / Deseased : 29 out of 108 @ 27%

report f2501

Documents

arc strike

hot bottom

visual inspection

ffbl tube

peep holes

process department

nipped tube

basically