A\qerure- -T-

Numaligarh Refinery Limited

Note to: Director (Technical) June 15,2013

This has reference to our earlier submitted preliminary report dated 4tn June 2013

against your office order dated 31st May 2013 regarding enqiliry into the incident of

major fire occurred in CDUA/DU.

Final report is lrereby submitted for your perusal please

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(D Ghosh)

General Manager (Operations)

Copy to:

" Chairman, NRL. MD, NRLn All committee Members

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FINAL INVESTFGATIOI'{ REP$RT OF FrRE INCIDET,TT AT XN CDU/VDUOf NRL ON 31ST MAY 2OI3

1. f)escription of,trncident :

At around 5:24 AM of 3l't May,2a13, an incident of major fire occurred near crude boosterpumparea in cDU/vDU of Numaligarh Refinery Ltd leading to shut down of the cDtJ/vDU unit resultingin damage of equipments' piping, support & cables, etc. onsite disaster was declared at 5:57AM. Thefire was extinguished and finally all clear was declared at 9:46 AM.The exact time of various activities as recorded in the various log books are enclosed as attachment.As a precautionary measure, all process units of the refinery were taken shut down in phases" prior tothis incident, all units including CDU/VDU were running normal.

2, Appointment of committee :

To enquire into thc incident and suggest future remedial actions, a committee was constituted byDirector Technical, NRL vide office order consisting of foilowing senior officers:

a) Mr. t) Ghosh ( CiM ops), NRL

b) Mr. M Ray Baruah (GM TS & projs), NRLc) Mr. pt,N Murthy DGM {Maint), BPCL

d) Mr. pK Baruah DcM {Mp), NRL

3, Methodologyadopted:

T'he comrnittee members after initial discussion decided to adopt the following methodologies toprepare fhe report;

a) Site visit.

b) Interviews ofindividuals.

c) Iivent Logs viz. Log Books at operating areas, DCS, F& satery, power station etc.d) Team discussion and listing of probablc causes.

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Ln Yegtisa-t&.n- &epljLot-E nqum-c-qmmtt_ee lo-r N R L c D U /v D U Fi re M a v 2 0 1 3

4. Overview of CDU/VDU:

The Crude Distillation Unit (CDU) of Numaligarh Refinery Limitcd CNRL) is desigrred ro process 3.0MMTPA of Assam mix crude oil. CDU is designetl to produce Fuel gas, Liquefied petroleum gas

(LPG)' Light Naphtha, Kerosene, Light Gas Oil, Hcavy Gas Oil and l{educecl Crude oil (RCO).

vDU is of 1'26 MMTPA capacity, designed to process hot RCo frorn CDU ancl to procluce VacuumDiesel (vD), Light Vacuum Gas oil (LvGo), Medium Vacuum Gas oil (MVG9), Heavy vacuumGas oil(FIVGO) and Vacuunr Residue (VR). Design capaciry of VDU is 1.26 MMTpA. The yielil ofRCO is about 42Yo of Crude throughpur.

Products of vacuum column are LVGo, MVGO and HVGO streams which can be mixed on Iine aresenf to offsite storage after cooling down or as hot VGo transferred directly to HCU as feed.Vacuum Diesel, the top side cut of VDU can also be rnixed either with VGO or Gas Oil Stream ofcDU or with flushing oil' Slop Distillate and vacuum Residue (VR) product from vDU are mixcd online' I'his VR stream can be sent to offsite storage after cooling down or hot VR can be sent directlyto DCU as feed stock.

There are three Crude booster pumps supplying hot crude at around 1730C to the fumaces throughPre-heat train 3 & 4 and these pumps get supply from three Crude fransfer pumps located in pump

I{ouse no# I at Oflsite via pre heat train #I & Z aud Desalter.

On the day of failure two Crude Transfer pumps (A & B) and two Crude Booster pumps (A & C)were running' Except diameter of the impellers all other data for crude booster pumps and crudctrans{br pumps are similar which are nranufactured by IWS BPNC. A flow diagam of the affecte6area of CDU|/DU is enclosed as attatchment

5. Fire in CDU:

Fire I'ighting Activities

The Log books ofoperations and Firc and safety have been studiccl and sequence ofmajor events areas under-

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Invegtisatl-an Reoort of Enquiry com

a) 5.24 AM: MCP (B/CP-7) broken. The shift staff immediately isolated the critical process

systems and equipments. Finally shut down of whole unit was taken by cufting-off power

from substation. Firc Monitors & Flydrants existing around the periphery of CDU/VDUincluding i{VLRs were used for fire fighting.

5.24 AM: Major fire declared and major fire siren blown. Fire Tender reported at incidenr

site immediately.

5:21 AM: 1'otal power to cDU/vDU cut from subs station (as per cpp DCS record)

5:28 API: Crude transf'er pumps stopped

e) 5:57 AM: Onsite disaster declared.

Initially, fire seemed to be at the ground level which lur". ,p."ud to the over heatl pipe rake area

and was further aggravated due to failure of fcw pipes holding highly volatile products.

Fire tenders from State Fire services also joined in fire fighting.

6. Information to External agencies :

All concemed Govt' and statutory and other related organizations were informed about the incident.

OISD and CCOE <leputed their officials to coliect inputs for making independent assessment of the

incidcnt. Meanwhilc Chief Inspector of Factories has advised us to submit some data related to the

Incident.

7. Observations by Comrnittee IVIembers

a) Huge fireball upto the second tier pipe rack was observed.

b) All fire monitors from all directions were put in use to cool the nearby equipment.

c) The fire was contained within I hour and fire was put off at 9;30 AMd) Initially CISF personnel and contract workers also helped operations and F&S in

firefighting,

e) Disaster declared at 5:57 AM.

0 Spillage of crude was extensive.

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JLn_v_cstioation Report of

'n-,J..

13 g) Cable tray damage was observed to be more at top end.

h) Surface cracks observed in Concrete beams.-] i) As the plaster of the concrete beam got loosens cable tray supports have fallen and hence;9+ cables fell on the ground.

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"-a Damages were caused to pumps, motors, steel and RCC structur'es, pipiqg, instrumentatiqn an4

3 elechical cables. A provisional estimate of damage has been made at around Rs 14 crs apart from loss

a of oroduction. Details enclosed as Annexure-l . Sketch showing affected area along with equipmentsJis enclosed as attachment.

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) 8- Attachrnent (Event rogs & Departmental reports) :

) a. Summary of event logs from DCS from 5:20 ta 5:45 cnclose d as Attachment-I

) b. Control Room Shift iu charge log book (Attuchment-2).

3 r. Refinery Shiff Supervisor log book {Attachment_3).

d. CDUA/DU Field Operarors four nos Log. Book{Auachmew_4).

l e. CDU/VDU trenct (Attachment-S).

i f. OMS Control Room Shift in charge Log book. (Attachment-6).

3 8- Power & Utility Control Room in charge Log book (Attachment-7)

I h. OMS Field Opcrators Log book. (Attachment-g).

i. Fire & Safery Shift in charge Log Book {Attachment_9).j. Fire & Safcty ControlRoom Log Book Q4ttachment-L0).

k. Fire & Safety Fire Call Registrar Log Book (Attachment.ll).

l. Report of Inspection department (Attachment-12).

m. Report from rotary group (Attachment-13).

n. Sub Station log Book (Attachment -14).

o. DCS Alarm history (Attachment -IS).

p. DCS Historian (Exaquanrum) data (Attachme nt _161.

9" Other important / relevant data

a. History data of crude booster pumps (,4ftachment-lT).

b. History data of orude transfer pump (Aaachment-tg).

c. Inspcction rcport of all the 9 failed pipes (,4ttachment_19).

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Inve$jqation_&ep_ort qfjjrqujry_Eoxnm!-ttesforj$r_-_CD!/VD_U. Jjre_ Ma:y_Zgl--

d. Simplificd flow diagram of the affected section of CDU/VDU (Attachmernt-20).

E. Flow diagram of aflected area of CDU/VDrJ (Attachnrcnh2l).

f. Sketch showing affectcd ar:ea (Attschment-22).

g. Localion of Hydrant & monitor around CDU/VDU (Auachment_23).

h. cMG (condition Monitoring Group) vibration data (Attachment-24).

i. Process Data sheet of CDU booster pump (01-PA-0IA/B/C) & OM&S crude transfer

pump (40-PA-l0l A/B/C) (Attrchment-Z|).

j. Sketch showing affected area(Ailachment-26).

i0. Fhotographs of fire affected Areas/Equiprnents:

Photographs of ire affected areas, crude booster pumps enclosed as Attachment-27.

11. Persons lnterviewed:

'l'he committee interviewed following persons who were associated with the job during the fire

incident. They are:

Devraj Talukdar Process Operator

Abdul Mukib Choudhury

Gaurang Mishra

Arnab Ratan Mitra

Panel Officer, CDU

Itupeswar Saikia

Manager (NSU, H2U)

BipulKalita Manager (CDU, DCll)

H. K. Nath CM, MechanicalMaint.

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Investioation. Reoort of Fnauiry committee for NRL_cp_u*twD.l,l F_ire tl_a.y 21013

'I ') Dipak Kumar Saikia SIC, Fire & Safety

l3 Surdeep Bordoloi Manager, lnspection

t4 Divyajyoti Saikia Sr. Manager, Inspection

I5 Iftikher Zahan Dy Managcr, Rotary (Workshop)

The interview proceedings are attached herewith as Attochment-2g.

!2. Probable cause(s) of incident:

Two probable causes were shortlisted at the time of submission of preliminary report cletailed analysisof which is as under.

l2.l: Booster Pump failure:

Af l the three booster pumps removed from site post the fire incident on i 1 't May 2013 and brought toworkshop for repair. observation on major components all the three pumps after dismantling are as

under' A sketch showing important dimension of the booster pump with a write up is enclosecl as

Annetture-II.

Fump A:

o Suction side casing thinned down circumferentially. At the point of failure rhickness is

observed to be almost I mm against original 30 mm measured on the spare casing.

' Failure of shaft at threaded portion used for locking of the impeller.o Suction side of impeller thimred down by around 4 mm.

c Suction wearing ring got stuck to the impeller

Pump B:

o d groove is observed in the suction casing of the pump. (Failure of shaft at threadedportion used for locking of the impeller observed twice since Dec 2010. Broken nut having.dimensiou of approx 4i x 41 mm may also cause damage as it will be floating in thesuction side of the pump till the pump is stopped. on previous two occasions the pumpswere reported as seal failure, but on dismantling it was found the nuts in broken condition.

s No other damage observed.

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.ILvestiaation Reoot of

Fump C

o No danrage observed.

A few salient points from history record of booster pumps around past few years are as follows:Pump A

o No casing changed since inception.

r Last replacement of shaft done on 9s May 2013.

" High vibration & failure of sears and bearings high Vibration

Fump B

o No casing changed since inception.

o Failure of shaft at threaded portion observed twice irr pump B since 2010 Decernber.

Such incident was not observed in other two pumps.

' High vibration & failure of seals and bearings high Vibration,

o Intermiftent reportiug of loss of suction.

Pump C

o No major failure except occasional high viblation arrd failure of seals etc.

Though actual cause leading to failure of pump can be ascertained only after detailed analysis of failedcomponenls, a school of thought have emerged that some abrasive material got carried with cru4e,probably from crude tanks via crude transfer pumps and De Salter and series ofheat exchanges.

L2.2 FSV Failure:

I3eing PSV discharge line connected to flare this is a no flow line. But this line is connected with theflare header within CDU /DU having pressure of around 0.2KglCn2gthe flare gas out of CDU,{/DUis normally consisting of components viz Cl, C2, C,l|, C4, etc. Though two holes observed on this lingInspection deparlment observed that it is due to molten material falling on tlre highly oxidizer] line,

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Investioation Report of Ensuirv Committee for NRL CDU/VDU Fire Mav 2013

From the logs, reports and the interviews taken, the committee observes that the probably the

incident ofrtre was cqused by hot ignition saurce to the good quantity of crude which spilled

out of the failed casing of crude booster pump A.

However. reason for failure of pump can be ascertained anly after detailed analysis af failed

components of pumps, pipelines, etc in a reputed material testing lab through EIL, the

licensor cttm EPCM consultant for CDU/VDU unit. In addition, observations noted in

Annexure-Ill may also be taken into consideration while concluding the root cause of Fire.

13. Recommendations:

i. Pipe stress as observed by CMG group to be addresserl befbre start up.

ii. Loss of suction for crude booster pumps to be addressed by controlling slop processing

rate.

iii. On line vibration monitoring for these pumps to be implemented at the earliest to monitor

the health of this critical equipment.

iv. Fire proofing of structures, cable ducts around the booster pump may be implemented

immediately, The same can be extended to other areas/ units in consultation with expert

agencies.

v. Inclividual booster pump discharge pressure indication to be. provided at the DCS to

ascertain abnormalities of the individual pump with an alarm.

vi, Emergency shutdown switch for Crude booster/ transfer pumps at DCS panel to be

provided after Hazop study.

vii. HC gas detector may be provided near booster pumps.

viii. Booster pump data sheet may be reviewed to explore possibility of replacing the pump

with new spccifications.

ix. SOP for existing power cut off practice from substation during emergency may be

discussed in the wake of the fire incident.

r--N-q-L--gD u /V D U- F.r-e-l!o-v 20-13

X.Sprinklersystemoverboosterpumpstobcprovided.Theexisting}tVLRstobe'replaced

by recentlY Procured HVLRs'

xi. Installation of CCTV with recording facility covering critical areas inside the plant may

be considered-

xii. Audibility of sircns at all parts of the township to be measured periodically'

xiii. walk way to be provided in the pipe rack area with approaches from all technological

structure.

xiv. Inspection pockets for the insulated line/vessels to be made aud records of the same to be

maintaincd.

xv. Inspection of all IIC vapor lines to be done during all opporfunity shut downs and records

to be maintained.

xvi. Provision of motor current display for critical pumps in DC$'

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)\PLN Murthy

DGM(Maint) BPCL, Mumbai

W,*SM Ray Baruah

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GM(IS & Projects) I

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-r%il,?D Ghosh

GM(Ops) NRL

Ilaruah I