Commissioning Experience of World's Largest Single-Train

2011 [47] AMMONIA TECHNICAL MANUAL

Commissioning Experience of World’s Largest

Single-Train Urea Complex

At the end of 2010, Engro Fertilizers commissioned world’s largest single-train Urea complex capable

of producing 3835 tpd prilled urea. This paper presents an overview of the project and its journey of

commissioning thru various stages. It also shares the problems encountered & key lessons during the

project phase.

Muhammad Idrees, Muhammad Azhar & Muddassar Y. Rathore

Engro Fertilizers Limited, Daharki, Pakistan

Synopsis

his paper shares Engro’s successful Com-

missioning Experience of world’s largest

single-train Urea complex of 2200 tons per

day ammonia and 3835 tons per day prilled urea. It

explains the roadmap of the project followed by

the commissioning team; starting from operator’s

team build-up, training phases including training at

Operator Training Simulator (OTS) and then the

field execution of pre-commissioning & commis-

sioning activities in 2010. It also shares the prob-

lems encountered & key lessons learned during the

project phase for future projects of this sort.

Introduction

Engro Fertilizers Limited is the second largest

manufacturer of Urea in Pakistan. Previously, En-

gro was a 75% owned affiliate of Exxon Corpora-

tion. In 1991, Exxon decided to sell its 75% equity

holding in Engro as part of a global strategy to di-

vest from the fertilizer business. Nearly 500 em-

ployees of Engro, in partnership with a group of

leading local and foreign financial institutions, ac-

quired Exxon's equity holding in Engro. The Man-

ufacturing site is located in a small town of Pakis-

tan known as Daharki, which is 600 km north of

the famous Port City of Karachi.

The original ammonia-urea plant, with self sustain-

ing utilities, was commissioned in December 1968.

The capacity was 173,000 t (metric tonne) of

prilled urea per year. This was 80% of urea market

share in the country at that time. Over the next 22

years, the plant was debottlenecked in several low

cost steps to a production capacity of 270,000 t of

urea per year.

Urea production increased from an annual capacity

of 270,000 tons in 1991 to 600,000 tons after the

startup of relocated ammonia and urea plants from

Pascagoula (USA) & Bellingham (UK) respective-

ly in 1993 and then to almost 1 million tons in

2006 after a series of revamps and energy conser-

vation projects.

T

472011 AMMONIA TECHNICAL MANUAL


After the commissioning of new plants in 2010,

annual capacity of the site has increased further to

2.3 million tons of urea. Engro has accomplished

significant progress not only in its base urea ferti-

lizer business but also in other diversified projects.

Other businesses include foods, power generation,

automation, polymer and a jetty for bulk chemical

and gas storage/shipping.

Project Overview

Pakistan is an agricultural country where the de-

mand for fertilizers has always been higher than

the in-house productions. To meet the increasing

demands of fertilizer and to use the natural gas re-

sources in an economically rational way Engro

took an initiative by developing the feasibility

analysis of ammonia-urea complex of 1.3 million t

urea production annual capacity. The feasibility

analysis was completed in 2006 and eventually gas

allocation was approved by the Government of Pa-

kistan in 1st quarter of 2007.

Plant Configuration & Process

Layout

The Ammonia plant is of Haldor Topsoe design

having a nominal capacity of 2200 t per day. In-

cluded are both front end flare, backend flare and a

CO2 removal section using BASF aMDEA solvent.

SAIPEM is the process licensor for urea technolo-

gy with capacity of 3835 t per day, including the

world’s tallest prill tower of 124 meters. The urea

plant is also equipped with continuous and discon-

tinuous flares.

Ammonia plant design is based on following Natu-

ral gas Composition.

Components Volume Percent

Methane 84.24

Ethane 1.06

Carbon dioxide 1.97

Nitrogen 12.11

Table 1. Design Composition of Natural Gas Feed

The Feed Gas contains less than 2% of Carbon

dioxide resulting in imbalance of Ammonia to

Carbon dioxide ratio for Urea Plant. In order to

compensate the above factor, the ammonia refor-

mer fluegas includes an amine based Carbon Dio-

xide Recovery unit (CDR) having the capacity of

349 t per day, based on Mitsubishi (MHI), Japan

technology.

Project Execution

Contract for license, engineering, procurement was

given to SAIPEM. Construction Contract was giv-

en to Descon Engineering Ltd (DEL), Pakistan.

Commissioning was Engro’s responsibility. This

was a unique project in comparison to other LSTK

projects, where normally a project management

consultant (PMC) is contracted by the company to

deal with EPCC contractor. Substantial utility inte-

gration was involved with the base plant, which

wouldn’t have been possible for EPC contractor to

manage. Hence, engineering and procurement of

integrated utilities and CDR unit was done by En-

gro under owner scope which makes the project

unique. The owner scope included;

• 26 MW GE frame 5 gas turbine with Heat Re-

covery Steam Generator (HRSG) cum Boiler

of 150 tons per hour, 41 Kg/cm2(g) Steam.

Unique HRSG design with Flying Takeover

system.

• 5000 tons Ammonia double-walled storage

tank

• CO2 recovery unit (CDR) from primary refor-

mer flue gas. A unit Based on MHI, Japan

technology using KS1 Solvent

• Offsite water production facility, containing 38

wells of 250 m3/hr each & a 2000 m

3/hr canal

water treatment plant.

• Onsite water treatment; containing reverse os-

mosis membranes of capacity 180 cubic meter

demineralized water (< 10 micro siemens) per

hour along-with two bed demineralization

trains of the same capacity

48 2011AMMONIA TECHNICAL MANUAL


• Instrument air system (3300 Nm3 per hour)

• Cryogenic nitrogen plant (750 Nm3 per hour)

• Natural gas receiving facility

• Plant effluent handling system and evaporation

ponds

Project Schedule

Fig. 1. Various stages of Project from Apr’07 to

Oct’10

Date Milestones / Activities

4-Apr-07 Effective Date of the Contract

Aug-08 Start of Mechanical Erection

26-Jun-09 Effluent System Commissioned

12-Nov-09 Natural Gas Receiving

Nov-09 Power available from Gas turbine

Dec-09 Steam available from HRSG

19-Dec-09 Start of Steam Blowing

25-Jan-10 Start of Air Blowing

20-Feb-10 Offsite facility Commissioned

12-Jun-10 Air Compressor Commissioned

20-Aug-10 Ammonia Storage Commissioned

12-Jul-10 Firing of Reformer for refractory

Dry-out

10-Nov-10 Firing of Reformer for startup

11-Nov-10 Feed-in to Primary Reformer

16-Nov-10 Gas to CO2 Removal & on-spec

CO2 availability

16-Nov-10 Synthesis Gas Ready

29-Nov-10 Fire at Synthesis Compressor due to

thermo-well failure

20-Dec-10 Synthesis Compressor Restart

23-Dec-10 Start of Catalyst Reduction of S-

300 Converter

26-Dec-10 Ammonia Production

29-Dec-10 Urea Production

Apr 2007

Apr 2008

Mar 2009

Oct 2008

Oct 2010



Safety Reviews

Safety reviews were conducted at SAIPEM office

in Milan, Italy during various stages of engineer-

ing. Experienced Engro personnel from various

disciplines (i.e. Safety, Technical, Operations,

Maintenance & Instrument) participated in these

reviews.

ACTIIVITY TIMEFRAME

What If 17th to 24th July, 2007

Failure Mode & Effects

Analysis (FMEA) 17th Oct to 16th Nov, 2007

P&ID Review 28th Jan to 1st Feb, 2008

HAZOP 4th Feb to 29th Feb, 2008

Table 2. Safety Reviews Timeframe

A total of 1206 recommendations were generated

during these reviews and all of them were closed

before the startup of the plant. 3D model reviews

were also conducted at different project stages

(60% & 90% - excluding small bore piping) for

checking operability, accessibility, maintenance

spaces, safety distances, emergency escape routes

etc.

Operations Team Roadmap

A roadmap was developed by operations team lea-

dership in the mid 2008, the main stages are as fol-

lows;

1. Operations Team Build-up

2. P&ID Systemization

3. Procedures Development

4. Training

5. Pre-commissioning and Commissioning

Operations Team Build-up

An organogram was developed for startup organi-

zation for defining the total operations manpower

required for pre-commissioning, commissioning &

start-up activities of the complex. The final matrix

required a total of 18 engineers and 85 operators.

Position Ammonia Urea Utilities

Unit Manager 1 1

Day Engineer 1

Shift Coordinator 5

Shift Engineer 5 5

DCS Operator 10 5 5

Field Operator 35 25 10

Table 3.Operations Team Manpower

Recruiting and gathering such a big team was a

humongous task. Some trained resources were

transferred from the already running base plant,

while most of the population was hired from other

fertilizer and oil & gas industries. The hiring

process took almost eight months from Aug 2008

till March 2009, to get the required number of re-

sources.

Formation of operations team was completed al-

most 18 months prior to the actual commissioning

& startup of world’s largest plant.

Area Champions

From the very start, distribution of responsibilities

was made using area champion concept. For ex-

ample, the ammonia plant reforming section had an

area champion, an operations engineer, leading a

team of 10 operators. Area Champions were sup-

posed to bring themselves on-board and raise their

knowledge of reforming section through study of

technical material like PFD, P&IDs, vendor ma-

nuals, HAZOP and FMEA of the respective area.

From these, they developed the pre-commissioning

& commissioning procedures, and then prepared

training material and conducted training sessions in

classroom trainings to bring the knowledge of rest

of the population at par. In this way, the ammonia

plant, which also included ammonia storage area,



was distributed to five area champions, similarly

the urea plant was divided into four sections, and

each section was looked after by a separate area

champion. Utilities were distributed to two area

champions. By following this methodology, the

management of activities became very effective

and efficient as each area champion was responsi-

ble for achieving the time-line and schedule of his

own area.

P&ID Systemization

The P&ID Systemization is the separation of the

plant into smaller and manageable packages called

systems & subsystems to support the mechanical

construction as per commissioning requirements.

In this way, pre-commissioning of certain systems

was started even before 100% construction was

complete. Similarly commissioning of certain early

needed systems (mostly utilities) was completed

even before the completion of pre-commissioning

activities at site. As a result of following a syste-

mized approach, there was the benefit of time sav-

ing. This prioritization was applied once 70% con-

struction scope was completed. The process of

systemization followed, consisted of the following

steps;

1. Defining systems & subsystems

2. Assigning specific color to each sub system

3. Marking on the P&IDs (using software)

4. Tracing each sub-system on P&ID and not-

ing down all the pipeline numbers, instru-

ments, vessel, control valves, safety valves,

ESD interlocking etc in a tabular form.

5. Interlinking for total system (Ammonia,

Urea & Utilities) and developing the com-

missioning requirements for each system

6. Assigning priority number to each sub-

system and handover of the final document

to construction shop to put focus on high

priority items accordingly.

7. Development of comprehensive barcharts

& Start-up Control Diagrams based on the

priorities defined in P&ID Systemization.

Procedure Development

After a lot of thought process, discussion and deli-

beration a procedure template was developed, it in-

cluded the following contents;

1. Circuit Information & acceptance criteria

2. Arrangements/Preparations to be made by

Instrument & mechanical teams

3. Personal protective equipment required

4. Hazards & consequences

5. Pre-checks

6. Field Execution checklists

7. Circuit/ Loop clearance certificate

8. Checklist for Reinstatement

9. Marked up P&IDs

More than 530 procedures for carrying out various

pre-commissioning and commissioning activities

were developed based on the above template. Ex-

amples include air blowing, steam blowing, chemi-

cal cleaning, lube oil circuits flushing, commis-

sioning and startup of machinery equipment,

refractory dry-outs, alkali boil-out, alkali washing,

over-speed trip (OST) testing of turbines etc. The

lists of preparatory items for each activity were

handed over to the mechanical pre-commissioning

group at an early stage. Each procedure was pre-

sented in class-room trainings, where it was re-

viewed by the trainee population and corrections

were incorporated. Furthermore, document ap-

proval protocol was developed for proper review

and approval of each procedure from the relevant

and knowledgeable authorities.

Training

Training is the key element, especially when it

comes to the startup of the Ammonia-Urea com-

plex, an intricate mixture of hazard and vulnerabil-



ity. An elaborate training syllabus was prepared

covering all facets of operations: PFD, P&ID,

HAZOP, FMEA, pre-commissioning, commission-

ing, startup, shutdown, normal operation and

emergency handling etc. More than 40,000 man-

hours were spent on training with an average of

around 400 man-hours per person. The whole

training program had a complete methodology be-

hind it and that was a series of layers concept,

which clearly illustrated the connection between

one layer and the other.

In-house Classroom Training (Apr-Jun

2009)

The first layer was the in-house classroom training

which started in April 2009 when the hiring

process had been completed. Respective Area

champions were nominated for In-house Trainings

with an objective to develop area-wise trainings &

then share these with whole group. Extensive In-

house training sessions were conducted to develop

knowledge & base of individuals for upcoming

practical trainings. Contents of each area training

were;

• Process description

• PFD / P&IDs

• Control Systems / ESD logic

• Standard Operating Conditions (SOC)

• Safety Reviews (FMEA / HAZOP)

• Pre Commissioning & Commissioning

procedures

• Startup / Shutdown / Emergency Handling

Procedures

Dedicated sessions on site safety systems (work

permit protocol, process safety management etc)

were also delivered to individuals hired from other

industries. Written tests were also conducted at the

end of each session to evaluate knowledge retained

by individuals and it was made a pre-requisite for

each individual to pass the written evaluation be-

fore getting skill certified at that area.

Training at Similar Technology (Jul-Oct

2009)

Second layer illustrated the importance of practical

exposure where, special groups of people were sent

to similar technology plants i.e. Fauji Fertilizer

(FFC) for seven weeks & then to Oman India Ferti-

lizer Company (OMIFCO) for two weeks to get

hands-on to Topsoe & SAIPEM technologies. Tai-

lor-made training programs were developed which

covered the following training aspects;

• Startup / Shutdown Discussions

• Emergency Handling Procedures

• DCS orientation

• Field Orientation

• Experience Sharing of Pre-commissioning

/ commissioning

• Problems Encountered during commission-

ing

Training by Technology Licensors (Oct -

Nov 2009)

The representatives of SAIPEM / Haldor Topsoe

delivered lectures on design and operating philoso-

phies of urea / ammonia plants, however, till that

time, operations team had been so well-prepared

after going through series of trainings that repre-

sentatives appreciated the team by calling it ‘a very

well prepared team, ready for start-up’. Extensive

discussions were carried out in these sessions on

Pre-commissioning, Commissioning, Startup,

Shutdown, Emergency Handling and Trouble

Shooting.

Operator Training Simulator (OTS)

The final and most important layer was the imple-

mentation of the Operator Training Simulator, the

phases are explained as follows.

Development

Justification of OTS implementation for the am-

monia plant had been approved on the basis of cost



saving during the commissioning. Engro’s team

remained involved right from the start of the

project. To harmonize the architecture and ergo-

nomics, the same vendor (Honeywell) was selected

for both DCS & OTS. In addition, the training hall

structure & layout were developed in a manner that

the operator had the feeling of sitting inside the ac-

tual control room (Fig. 2 & 3).

In Jan 2009, a team comprising of Engro opera-

tions and process engineers was sent to Honeywell

Singapore for kick off meeting. In that meeting,

scope of work was finalized and P& ID markup

was done to build a Unisim model for the ammonia

plant OTS. Later in May 2009, in the presence of

Engro engineers, Model Acceptance Test (MAT)

was conducted in Singapore. The completed model

was tested for initial conditions and startup as per

SOP. It took around ten days to do the start-up as

at that time no DCS schematic was linked to the

model. This start-up test was done on the model in-

terface which made for quite a chaotic activity.

Subsequently plant shutdown was also tested and a

detailed punch list was made for the corrections. In

August 2009, all the logics & schematics database

of Integrated Control System (ICS) including DCS

and Emergency Shut Down (ESD) were sent to the

vendor to do complete linking of ICS with the

ammonia plant model.

The Factory Acceptance Test (FAT) was carried

out in Dec 2009.

Fig 2. Operators training in OTS hall

Following sequence was followed;

• MAT punch list killing and Steady state

verifications as per PFD

• Initial conditions verification

• Plant Startup

• Plant Steady state conditions verification as

per PFD

• Plant Shutdown

• Malfunctions Testing

During these activities, the following observations

were recorded;

1. During startup, shutdown and malfunctions

execution, a number of needed changes

were identified to make model operation

more close to actual plant operation.

2. Several points on schematics for which in-

dications were not appearing because of

having no link between model and sche-

matics were identified.

3. DCS related logics and complex control

loops testing was carried to see model be-

havior. A few logics were found incorrectly

built-in in the database and were sent back

technology licensor for corrections.

4. All ESD logics were tested. Anomalies

were identified in some of the logics which

needed correction by technology licensor.

Fig 3. Operators sitting at DCS inside control room



On completion of the FAT activity, two days of in-

structor training was conducted in Singapore to

train the Engro team instructors about different

features of OTS and trainee evaluations by induc-

ing the malfunctions.

Training on OTS

Effective utilization of OTS played a vital role in

safe and trouble-free commissioning of the plant

and resulted in cost saving during commissioning

phase of the plant through upfront identification of

problems, controllers tuning, troubleshooting,

smooth start-up, emergency handling and above all

due to ZERO tripping on operator error.

The OTS arrived at site four months prior to actual

commissioning. A well structured training program

had developed for round the clock training of oper-

ators and shift engineers in day and night shifts.

Skill certification of DCS operators was done on

the basis of their scores in various exercises at

OTS. A sense of competition among different op-

erators was developed while completing the scena-

rios with quick and correct actions.

Benefits

A number of potential shutdowns were saved by

the OTS trained operators during actual startup of

the plant. Frontend was normalized in record time

of five days from Feed-in till methanator outlet.

Following are the benefits that Engro team ex-

tracted out of OTS training.

1. Testing & validation of Operating Proce-

dures.

2. Based on experience from OTS, controller

tuning parameter adjustments were made

on DCS prior to startup. Process & steam

vents were tuned to act very fast while lev-

el controller were tuned to act relatively

slower. Tuning parameters of all the con-

trollers in OTS were simply replicated in

DCS and they worked well.

3. Cascade controllers / split range controller

mistakes were identified in the OTS and

corrected in DCS. For example, the 3-

element controller algorithm for steam

drum level had problems, so this was cor-

rected and then incorporated in DCS pro-

gramming.

4. Mistakes in interlocks were identified and

then these were corrected in the ESD e.g.

protection steam to air coil is established

when air to secondary reformer is cut but in

the interlock, it was mandatory to keep 60

tph of protection steam flow through air

coil to prevent the reformer trip.

5. Delay time and set points of the protection

securities were adjusted on the basis of ex-

perience e.g. 110 Kg/cm2(g) steam (KS)

coil outlet temperatures rose sharply when-

ever there was a tripping of any major con-

sumer of KS i.e. synthesis or CO2 com-

pressor. After discussion with technology

licensor; high temperature trip set point

was slightly increased and a delay time was

added.

6. Because of repeated exercises on OTS, op-

erator familiarization of the screens made

the transition to the DCS easier.

7. On the basis of training exercises, Emer-

gency handling groups were developed.

Thus controllers to be operated in a par-

ticularly emergency were kept in the same

group.

8. Identification of problematic areas prior to

the actual startup was another operator

benefit. As an example, BFW coil tempera-

tures remained close to the upper limit at

lower load especially before air introduc-

tion due to low steam generation during

start-up exercises. The same phenomenon

was also experienced during actual start-

up, however, operators were prepared for

that and drain at the coil outlet was opened

to control the temperatures.

9. Emergency handling skills developed

through various OTS exercises later

averted plant shutdowns.



Skill Qualification Protocol

The operations team goal was safe and flawless

pre-commissioning, commissioning and start up of

Ammonia, Urea and Utilities. Through a well ma-

naged skill qualification program, better trained

and skilled operating personnel can be developed

and contribute towards safe and timely start-up of

the complex. This protocol provided for the skill

qualification of operations personnel for the pre-

commissioning, commissioning and startup activi-

ties of respective areas. Skill Qualification was

made mandatory for everyone before taking the in-

dependent duty. Skill qualification process in-

cluded the initiation, preliminary evaluation, final

evaluation and certification process. Skill qualifi-

cation process was applied to:

• Field Operators

• DCS Operators (Boardmen)

• Shift Engineer

• Shift Coordinators

For each individual, two bodies were involved in

the process;

• Mentoring body (Level-II); responsible for

the initial training & evaluation. This was

comprised of Shift Supervisor and Shift

Coordinator.

• Reviewing Body (Level-I); responsible for

the final evaluation of the skill forwarded

by mentoring body. It was comprised of a

board who reviewed the skill and know-

ledge of the individual. For DCS Opera-

tors, the board was comprised of one shift

coordinator, 02 unit managers, Operations

and Startup manager and SAIPEM com-

missioning manager.

The skill qualification process started with the is-

suance of training plan to the individuals and then

the self training on technical literature was carried

out by the individual. Help and guidance was pro-

vided by respective mentoring bodies, which also

conducted routine reviews to monitor the progress

of the individual. Then the individuals went

through the in-house training for the assigned area.

It was mandatory for the individual to clear the

Process Safety Management tests and the in-house

evaluation before skill certification is initiated and

forwarded to the reviewing body. An oral and prac-

tical review was conducted by the review board

and results were recorded on the review sheet. If

knowledge and skill of the candidate was found sa-

tisfactory, the candidate was skill certified for in-

dependent duty at his respective area. If the candi-

date failed to satisfy the board, his skill

qualification process was halted and his mentoring

body was informed regarding the areas of im-

provement. The candidate would be called for re-

evaluation after an interval set by the reviewing

body. Anyone, who failed to get skill certification,

was not allowed to work in the field.

Pre-commissioning

Pre-commissioning of the project, a gigantic task

was initially the contractor's responsibility, but

looking at the tight deadlines, this task was taken

over by the operations team, which started with

development of pre-commissioning procedures in

line with DuPont Process Safety Risk Management

(PSRM) guidelines. It was well understood right

from the beginning that success of project would

lie with a ‘once through’ approach for pre-

commissioning and saving of two hours by skip-

ping any step can cost you days during commis-

sioning. Pre-commissioning execution was done

with high quality and there was no problem of sys-

tem cleaning. During commissioning phase, none

of the control valves had problems getting sticky.

The thoroughness of steam blowing and lines

flushing resulted into smooth startups of all steam

driven turbo-trains. Maximum steam consumption

of 100 to 120 tph was recorded from HRSG for

blowing for large bore pipes like steam line to syn-

thesis compressor turbine.

Respective area champions carried out regular list-

ing of deficiencies in the form of punch & butt lists

as the construction progressed. This provided con-

tinuous feedback to the construction group for cor-

recting deficiencies as soon as they happened. This



also resulted in a significant time savings and mi-

nimized rework.

Proper cleaning of aMDEA system is very impor-

tant as it is sensitive to any foreign material. Con-

sidering that fact, extra focus was put for cleaning

of packing and the circulation established with sa-

crificial strainers of fine meshes for almost double

the duration than recommended. Antifoam dosing

was continued right from the start as per licensors

recommendation. After LTS line-up, gas was

vented for six hours at 80% equivalent load before

gas introduction to aMDEA section which also

helped in avoiding catalyst dust carry-over the

clean system. As a result, the commissioning of

CO2 removal system was very smooth.

High pressure test of synthesis loop was carried out

at 200 Kg/cm2(g) by an outsourced company. More

than 25 leakage points were identified and at-

tended.

Audits before Feed-in The following audits were carried out in the field

prior to feed-in, to ensure that area is free of ha-

zard.

1. System-wise requirements audit before

feed-in.

2. Pre-startup PHA recommendations closure

3. Pre-startup Safety Reviews (PSSR) rec-

ommendations closure

4. Temporary gaskets audit

5. Piping conformity audit by SAIPEM for

frontend

6. Instrument air leakages audit

7. Flow meters audit

8. Sample coolers audit

9. Audit for completion of permissive for

feed-in

10. Housekeeping & unnecessary material

(scaffolding, cabling etc) audits

Commissioning and Startup

Unlike the conventional EPCC (Turn Key) projects

where contractor provides a complete team for

commissioning & startup, Engro decided

to keep this responsibility with the operations

team, showing confidence on the in-house opera-

tional expertise and training systems. The team

measured up to the mark and saved millions of dol-

lars which are normally paid to the contractor for

commissioning services.

The team endured all external pressures & chal-

lenges (like gas limitations, abstruse steam bal-

ances, steam drum level fluctuations, BFW leakag-

es, synthesis gas fire, unreliable flow indications).

Barring the time lost due to gas limitations and

synthesis compressor outage Engro started the

world’s largest fertilizer complex in 12 days. Front

end was normalized in a record time of five days

from feed-in to reformer. On-spec production of

urea was also registered within 48 hours of the

urea plant startup.

Fig 4. Energy & Gas Consumptions during Project

Because of the advance training and preparation,

many start-up emergencies were well handled by

operations team making swift and correct deci-

sions. The team proved its competence to counter-

act those emergencies, which could have delayed

the production for an indefinite period of time. As

shown in figure 4, the total energy consumed dur-



ing pre-commissioning and commissioning phase

was 1,200,000 Giga Calories.

Important Numbers During the Project

Energy for Pre-commissioning 550,000 G cal

Energy for Commissioning & star-

tup

650,000 G cal

Total Energy Consumption 1,200,000 G cal

Frontend Startup & Normalization

from Feed-in

05 Days

Backend Startup & Production 07 Days

Effective Ammonia Plant startup

time barring the gas outages & syn

comp incident

12 Days

Total waste water generated 26,000 K Gal

Construction Completion Time

from Effective date of Contract

43 months 22 days

Table 4. Important numbers during the project

Problems Encountered

The cooperative efforts by the construction, in-

strument and electrical teams resolved each prob-

lem diligently and patiently. Even though some

disturbances did occur during the construction

phase (like man-power unrest and extended rainy

season) and then during the initial startup, first

product was obtained in 45 months from the effec-

tive date of the contract.

The following summaries provide the details of

some major problems encountered during commis-

sioning and startup.

1. Syn Gas Fire

On Nov 29th, 2010, fire occurred due to dislodging

of a thermo-well from recycle suction line of syn-

thesis gas compressor. The machine was imme-

diately shutdown by using field manual switch and

vents were accordingly opened to depressurize the

system. The fire was extinguished immediately by

operating deluge system (water sprinkler).

Incident background

Synthesis compressor was started around 2330 hrs

for surge mapping and ramped to minimum gover-

nor (7227 rpm). In order to draw the surge curve

the anti-surge valve was closed very slowly till it

was 35% closed and the final discharge pressure

was 157 kg/cm2(g). At that moment, when the re-

cycle stage suction pressure was 139 kg/cm2g, a

thermo-well (11-TW-5053), installed at recycle

suction dislodged resulting in synthesis gas leakage

and explosion. Flames from the fire hit the instru-

ment cable tray beneath the air compressor turbine

resulting in air compressor tripping as its ESD

cables got damaged. The synthesis compressor was

tripped using manual trip switch, and the compres-

sor inter stage was depressurized immediately. The

deluge system was operated resulting in the forma-

tion of water curtain around the machine and fire

was extinguished in five minutes of occurrence.

Key Findings

The root cause of the incident was the faulty instal-

lation of threadolet on synthesis gas recycle stage

suction. This did not allow the thermo-well to be

fully tightened.

Fig 5. Inadequate height of thread (courtesy SAFR)

At various instances the construction team encoun-

tered a problem during installation of thermo-wells

not properly screwing inside threadolet. This was

primarily due to issues with fabrication and weld-

ing of the threadolet installed on piping at con-

struction contractor’s fabrication shop. These holes



had been made with gas cutting set which is not a

standard practice especially where instrumentation

is involved. In some cases, excessive root penetra-

tion was also found hindering thermo-well inser-

tion (Fig 6).

Fig. 6. Excessive root penetration hindering insertion

Recommendations

1. Carry out mechanical and quality assurance

checks of all thermo-wells, instrument hook-

ups and small bore piping on all critical / ha-

zardous systems.

2. Install all thermo-wells as per standard practice

given in ANSI Standard on NPT threads.

2. Leakage at Ammonia Export Line

On Sep 30, 2010, an ammonia leakage occurred

during the commissioning of ammonia export line

from ammonia storage facility to existing base

ammonia plant. One of the transfer line drain

bleeders failed at the pipe rack.

Background:

Prior to the introduction of ammonia, a survey of

the entire transfer line was carried out and all the

bleeders were found closed and capped. Further to

ensure the tightness of the flanges, a soap test of all

the flanges on the line was carried out and the ni-

trogen pressure of 7 kg/cm2g was held in the line

for three hours which hardly dropped to 6.85

Kg/cm2(g). Ammonia vapors were then introduced

from the existing base ammonia plant in the trans-

fer line to carry out gassing up and controlled cool-

ing of the line. After ensuring the displacement of

the nitrogen with ammonia vapors, the jump-over

valve towards the tank was opened to avoid over

pressurization of the line.

After two hours, leakage at one drain bleeder on

the line at pipe rack top was reported. The line was

isolated immediately and depressurized through

the jump-over line going back to the tank. Water

curtains were developed immediately to avoid the

impact of ammonia to the surroundings.

Key Findings

1. An audit of the bleeders and drains found that

the bleeder at which leakage occurred might

have been choked by some rust/dust in slightly

open position and on exposure to the low tem-

perature liquid ammonia might get released.

2. The high cooling rate of the line might have

caused a sudden contraction of the line. The

earlier survey showed that all the bleeders were

capped; however, the leaking point cap might

not be completely tightened and the sudden

contraction might have caused the bleeder cap

to displace.

Recommendations

1. A lock-out & tag-out strategy was developed

for bleeders and drain points provided on the

ammonia service lines.

2. To ensure all the bleeders are being mentioned

and isolated, the procedure and checklist was

updated by carrying out the field audit using

isometric drawings.

3. BFW leakage at Valve Gland

Pusher

On Dec 02, 2010, the isolation valve of a BFW

control valve at the back-end BFW preheater began

to leak excessively. Plant shutdown seemed immi-



nent but the plant parameters were adjusted in a

way that BFW consumption reduced to minimum

decreasing the BFW header pressure and helped in

leakage rectification.

Background

Just after the introduction of air to secondary re-

former, at about 2330 hrs, a heavy BFW leakage

started from the isolating valve of BFW control

valve to Back-end BFW heater (see fig 7). The

valve was in closed position and its gland pusher

was found cracked from middle. Attempt was

made to open the valve for back-seating but the

moment valve was opened, the extent of leakage

further increased. Decision was made to go for

normal shutdown of the plant and if leakage further

increased, total trip (I-1) to be activated to avoid

WHB dry-out condition.

In parallel, the following strategy was developed to

avoid complete shutdown,

• Process air to the secondary reformer was

stopped which reduced the BFW consump-

tion.

• Furnace firing was reduced by lowering the

fuel pressure and extinguishing some burn-

ers in the top row.

• Front end load and steam drum pressure

was reduced and BFW header pressure was

also reduced by reducing the speed of tur-

bine driven BFW pump.

• BFW main isolation valve (Butterfly type)

towards steam drum through LTS and con-

verter preheater was closed and all BFW

flow to Steam drum was directed through

BFW convection coil.

• The level of Steam drum was put on ma-

nual and board man was advised to actuate

I-1 if in any case level drops. The area op-

erator was also deputed at local glass level

guage of the steam drum to observe any

unusual level variation.

• Partial gas vent was started at HTS inlet to

reduce heat load in the LTS upstream BFW

heater.

By taking the above actions, leakage at the valve

reduced to almost 50%. So the valve was opened

for back-seating using necessary personal protec-

tive equpiment (PPE), and the leakage initially in-

creased a bit but after 60% valve opening the lea-

kage trend started to reduce. On 100% opening of

the valve (back-seating), the leakage from gland

reduced to minimum - sufficient for repacking of

the valve and a new gland pusher, fabricated in two

pieces, was welded & tightened.

It was found, that the original gland pusher was of

low strength due to hollow configuration. That re-

sulted in a crack in the middle of gland pusher

leading to the BFW valve leakage.

Fig.7. BFW leakage at Valve Gland Pusher

4. Unreliable Flow Transmitters

Flow meters are very important for the uniform

and normal operation of the plant as they are the

direct indication of the system behavior. Flow

transmitters remained problematic especially for

the case of steam flows to compressor turbines

which caused tremendous problems in steam calcu-

lations and understanding the behavior of turbine

drivers. On tripping of synthesis or CO2 compres-

sors, problematic flow transmitters resulted in dis-

turbance of entire steam system. Steam consump-

tion signals continuously go to KS-HS letdown

station (PRDS) and on tripping of any of the com-

pressor PRDS opens to let down the additional

steam. Since the flow meters were not showing the



correct indications of steam consumption so a ma-

nual value of steam consumption, based on steam

balance was input to PRDS.

Due to unreliable behavior of the flow transmitters

during steam introduction, feed-in and process air

line-up, flows were controlled by manipulating the

opening of control valves through valve Cv calcu-

lations.

The operation remained smooth even with unrelia-

ble flow indications of plant’s most critical para-

meters. This was due to the Abnormal Situation

Management Skills that the team had developed

over the period.

5. Delay in Air Introduction to Sec Refor-

mer

On Nov-26, 2010, at about 20:15 hrs air introduc-

tion to Secondary reformer failed twice due to

stuck check valve but was successfully lined up in

the third attempt. The activity delayed the startup

activities for about six hours.

Background:

Air introduction to the secondary reformer failed in

the first attempt and it was concluded that the air

pressure (35 Kg/cm2g) might be slightly lower than

the required driving force as reformer pressure was

around 25 kg/cm2g. During the second attempt the

air compressor discharge pressure was increased

till 38 kg/cm2g and valve was opened till 35 % to

allow significant flow but still no indication of

temperature rise in secondary reformer was ob-

served.

The startup activity was delayed for about six

hours for inspecting all the flanges for any blind

left in place, however no such blind was observed.

It was decided to increase the air compressor dis-

charge pressure to 40 kg/cm2 and the opening of

valve to 50 % to allow maximum flow. An abnor-

mal sound was observed from the 2nd air coil inlet

check valve resulting in the establishment of air to

secondary reformer.

Fig 8. Process air to secondary reformer

6. Syn Machine faulty RPM Indications

During startup of synthesis compressor, it was ob-

served that the governor speed indicator was show-

ing more RPM than the actual - the prime reason

for unpredictable behavior of the compressor. Dis-

charge pressure and steam consumption was not up

to the marked value. After getting RPM confirmed

by the portable tachometer the indication got cor-

rected. The activity delayed startup for about six

hours.

Background:

On Nov 26 at about 0900 hrs, synthesis gas com-

pressor was started and ramped to minimum gov-

ernor but the behavior of the turbine was quite un-

predictable as the machine reached at min governor

(7227 RPM). It was consuming only 30 tph of the

steam and the discharge pressure was about 56

kg/cm2 instead of 90 kg/cm

2 at min governor.

When the speed of the machine was checked by us-

ing portable tachometer it showed that the actual

RPM were 2/3rd of the RPM indication at gover-

nor. After that the governor speed indication was

checked and rectified.

Key Findings

On checking the speed indication calculation chart

following observations were made.



1. Total no of teeth at the turbine are 30 per

revolution.

2. The value of no. of teeth placed in speed

calculation formula was 20 teeth per revo-

lution.

This was a clear indication of the unpredictable

behavior of the turbine as in actual the RPM of the

machine was quite lower than the governor speed

indicator. The speed calculation formula was cor-

rected and activity was resumed.

7. Surging of CO2 Compressor Low Pres-

sure Case

Surging was observed in low pressure stage of the

compressor during the surge mapping of CO2

compressor.

Background:

The inter stage schematic of Compressor is shown

below,

Fig 9. CO2 Compressor interstage schematic.

On 20th December 2010, surge mapping activity of

CO2 compressor was started at 6476 rpm. Dis-

charge pressure was being increased slowly to ob-

serve any signs of "incipient surge" but nothing

appeared. Suddenly at pressure of 168 kg/cm2(g),

the machine went into active surge. Abnormal

sounds were heard in field and machine was

tripped manually. It was found that the machine

2nd stage was surging first and as flow measure-

ment was at 3rd stage, incipient surge couldn’t be

detected. Also machine discharge pressure safety

valve (PSV) and high pressure trip was configured

at170 kg/cm2(g) so surge map could not be drawn

for speeds higher than 6476 rpm. Therefore, it was

decided to obtain two points lower than 6476 but

above 5693 rpm (min governor speed).

The exercise again started on the night of 21st De-

cember 2010. Machine speed was increased to

6084 rpm, and valve HV-1803 was being closed

slowly to increase the pressure of the machine so

that the test could be started. On closing HV-1803

to 40 %, surge was observed in the field, but valve

also HV-1803 also opened suddenly and it was as-

sumed that there was some loose connection from

Woodward governor system. But on investigation,

it was found that HV-1803 is interlocked to open

with min governor speed and tripping of machine.

Since in the entire test, the variation in speed was

observed and speed reduced to min speed resulting

in opening of HV-1803.

Key Findings:

It was clear from the above tests that the inter stage

valve cannot be closed at speed of 6048 rpm

(which was above min governor ie 5693 but lower

than 6476 rpm, this was not the case at 6476 rpm).

Doing so caused the 2nd stage of the compressor to

go into active surge causing whole train to surge.

So after discussion with the vendor it was con-

cluded that the minimum governor speed (5693)

given by vendor is wrong, as the machine goes into

surge if an attempt is made to close the inter stage

valve so the minimum governor speed of the ma-

chine was changed to 6476 rpm.

On another occasion, passivation air had been

lined-up to CO2 compressor, while compressor re-

mained on circulation for more than six hours, that

resulted in accumulation of air in the circuit and

lowering down the molecular weight of resultant

gas from 44 to 36 and compressor started surging

due to handling of lighter gas.



8. Damaged Auto Recirculation valve (ARV)

of BFW Pump.

On Jun 26, 2010 at about 1000 hrs, an abnormal

sound was observed from the BFW pump Auto

Recirculation valve (ARV). The minimum flow

ARV was found damaged after only one month of

operation. The ARV lets down BFW from a pres-

sure of 160 kg/cm2(g) to 1 kg/cm

2(g).

Background:

During reliability checks of the BFW pumps, the

pump was kept running for long duration on total

recirculation through ARV. The BFW header pres-

sure is 165 kg/cm2 when the pump is operated on

ARV. By closing the pump discharge valve, it will

let all the flow back to deaerater which is operated

at atmospheric pressure. On observing abnormal

sound from the ARV, the valve inspection of was

carried out and it was found badly damaged as

shown in fig 10.

Fig: 10 BFW Pump damaged ARV

Key findings

When the BFW is let down from 165 kg/cm2 to 1

kg/cm2 velocity of liquid reaches to its maximum,

the liquid temperature may reach its boiling point

and liquid flashes to form bubbles. These bubbles

collapse with explosive force (~10,000 psi) near

metal surface causing metal to be destroyed. To

avoid this, high alloy and low velocity designs are

used. The material of ARV was upgraded.

9. Medium Pressure Absorber, C-01 Trays

Damage:

After 11 hrs of urea plant startup, the ammonia

feed pump, P-01 tripped on suction filter high dif-

ferential pressure. The stand-by pump was started

but it also tripped on same cause after 20 minutes.

Both filters were found choked with carbamate in-

dicating CO2 slippage from the medium pressure

absorber, C-01. However, process data (tempera-

tures of C-01) did not show any indication of CO2

slippage. C-01 was opened for inspection; and all

five trays (each comprising of five segments) were

found disengaged, fig. 11. Investigation revealed a

design flaw in the mechanical joints of tray seg-

ments. To strengthen the trays & avoid recurrence,

the segments were tack welded to existing joint

scheme.

Fig. 11 Disengaged segment of bottom tray

found at C-01 bottom.

10. Carbamate Control Valve to Urea Reac-

tor, HV-1009, Damage

In the first start-up, when HV-1009 was operated

to establish carbamate flow to the reactor, an ab-

normal sound and high vibrations were observed in

valve vicinity. After 20 minutes, the valve glands

started leaking. Leakage increased rapidly & after

about 45 minutes, the carbamate feed had to be cut

due to excessive leakage in the area.



Key findings

Initial investigation revealed an unsupported actua-

tor as main cause of valve failure. The actuator

support was installed but the same problem ap-

peared in subsequent start-up. Further investigation

suggested the provision of cage around the valve

stem. Due to being unsupported and at very high

differential pressure across the vale, the stem and

plug experienced very high vibrations against the

flow direction. That also explained the high noise

and vibrations observed during the start-up. Even-

tually that vibration resulted in the failure of teflon

gland packing of the valve. It was also proposed

that vendor should review the design.

11. Ammonia Feed Pump Rotor Failure:

On 29th December, 2010; ammonia feed pump, P-

01B tripped on high vibration security just after 20

minutes of startup. Pump was restarted but it

tripped again and its rotor seized. Issue was com-

municated to vendor to send the pump service ex-

pert.

Key findings

The ammonia feed pumps to urea reactor (P-

01A/B) have eight stages each with a discharge

pressure of 240Kg/cm2(g). The pump was disas-

sembled in presence of the vendor expert, its eight

stage impeller was found dislocated from its posi-

tion towards the DE (Drive End) by 8mm and had

rubbing marks (see fig. 12). Further study revealed

a design flaw in the balance of axial thrust along

the 8th stage impeller. As per design, axial thrust

should be on the NDE side (towards impeller suc-

tion eye) and a split ring had been provided to re-

strict impeller movement. But due to longer hub of

8th stage impeller, original thrust was towards DE

side (impeller discharge end), which resulted in the

dislocation of 8th stage impeller. To resolve this is-

sue impeller hub was shortened.

The same modification was proactively carried out

on P-01A.

Fig. 12 Modification of 8

th stage impeller hub

12. Polisher Mixed Bed Failure:

On 26th March 2011, during regeneration of mixed

bed 'A'; resin was observed in the neutralization

pit. Trains 'B' and 'C' were also checked and it was

observed that resin is also slipping from these

trains through the chemical effluent drain lines. It

was also observed that the resin level was low in

mixed bed ‘B’ (thru site glass).

Key Findings

On 27th March Mix Bed train B was handed over

for internal inspection. It was decided to unload the

resin and inspect mixed bed Train ‘C’. On inspec-

tion, following were observed.

1. Support channels of inlet distributor had

been bent and twisted.

2. Support channel angles welded to vessel

had also been twisted, two of them were

found dislodged.

3. Several distributor U clamps were found

loose/missing.

4. Distributor piping was found loose from

the threaded connections.

5. Main distributor pipe found bent in U

shape (as if great hydraulic force was ap-

plied from top).



6. Most of the plastic strainers were deformed

and damaged.

Investigation revealed that distributor supports

were not adequately designed for 100% load on the

unit. In addition to that, when contaminated con-

densate with corrosion products (not per mixed bed

design) arrived at the polisher unit, it caused plug-

ging of plastic strainers and created high pressure

drop. Higher than design hydraulic pressure and

chocking resulted in damage of Mix Bed internals.

The origin of the contaminated water was a plant

was shut down for a 60 days gas outage. Some wa-

ter / condensate remained stagnant at low portions

of the piping and as a result corrosion occurred.

During the startup, the system was put online

without flushing the lines, so the dirty water went

into mixed beds resulting into the above mentioned

damages due to increased pressure drops.

Actions Taken

The chemical outlet distributor’s supports were

welded and the rubber liner inside the vessels was

reinstated where damaged. On completion, a holi-

day test was carried out to ensure the rubber liner

properly fixed. All nozzles were again tightened to

ensure that no resin will slip for the coming opera-

tion.

13. Miscellaneous Problems

A. Low pressure steam (LS) injection to air

compressor turbine cut resulting into surging of

Process Air Compressor.

The stopping of LS injection to the air compressor

turbine resulted in the decrease of RPM which re-

sulted in opening of antisurge and process air flow

to the secondary reformer stopped momentarily. As

the high pressure steam valve (HP lift) of the air

compressor turbine responded, the RPM was res-

tored and flow again reestablished. The tuning of

HP lift was carried out to make its response faster

so speed would not drop under similar changes.

B. Level indication of common Surface Con-

denser of synthesis, air and ammonia compres-

sor turbines remained problematic.

The level indication at common vacuum condenser

of synthesis, ammonia and air compressor was a

differential pressure indication between the va-

cuum and the liquid head pressure in the condenser

hot-well. During start-up of the synthesis compres-

sor, even a slight variation in the vacuum resulted

in huge disturbances in the level indication but the

actual level in the condenser sight glass (mechani-

cal level glass) remained unchanged. Modification

was carried out and a displacer type level transmit-

ter was provided to show the actual level in con-

denser in place of differential type level indication

at DCS.

C. Purge and leak Test of reformer furnace was

not getting cleared, resulting in delay of startup

activities for hours.

The required pressure of 1 kg/cm2 was not being

maintained in the fuel headers as the individual

burner valves were heavily leaking-through and the

limiters allowed the valve to over travel. The re-

sulting pressure was reduced below 0.9 kg/cm2

within 12 min. It has been observed that the valve

stopper on some of the valves allows the valves to

travel beyond the fully closed position resulting in

depressurization of the header within the limits of

timer and lead to a failure of leak and purge test.

The limiters of the valves were replaced. Fig. 13

shows an example of over travelling of lever.

Fig: 13 Over-travel of lever beyond full close position



D. Water Ingress in Syn Compressor Dry Gas

Seal

During the hydro testing of the nitrogen header to

dry gas seal system of synthesis and refrigeration

compressor, water ingressed into the synthesis

compressor seal system. A blind at nitrogen supply

line to secondary vent of dry gas seal was found

missing. The dry gas seal of compressor was sent

to the vendor and was reinstalled after inspection

and cleaning (removal of debris that the hydro test

water carried).

E. aMDEA towers high and low level switches

abnormal behavior.

The low & high level switches of aMDEA towers;

(stripper, absorber and flash vessel) were wrongly

actuated numerous times and resulted in the trip-

ping of circulation even though the level transmit-

ter and local glass gauge remained in normal range.

This abnormal behavior of switches is still un-

known. Security trips were then moved to level

transmitters.

F. Cryogenic nitrogen plant tripping because of

excessive CO2 venting.

The ammonia plant front end was started and nor-

malized - leading to significant CO2 production.

Due to some issues at the CO2 compressor, CO2

was vented for longer durations. The CO2 being

heavier than air and because of wind direction set-

tled towards the suction of raw air compressor be-

cause of wind direction.

The compressed air to nitrogen unit is passed

through molecular sieves to separate oxides. The

sieves were designed for very low limits of CO2

(atmospheric CO2 concentration). The high con-

centration of CO2 exhausted the molecular sieve

and CO2 / oxides slipped to the cold box resulting

into tripping of the nitrogen plant numerous times.

Restart of the nitrogen plant takes around six

hours, during that time, nitrogen to compressor dry

gas seals is through liquid nitrogen storage which

obviously had limited quantity of nitrogen availa-

ble. A number of liquid nitrogen bowsers (tankers

used for liquid transportation) were purchased to

meet the demand.

Plant Trippings

Complete plant trippings (I-1 actuations) were

faced a few times due to following reasons;

1. Cooling water low pressure was observed

during pump changeover resulting into I-1

actuation.

2. A wrong signal was generated by cooling

water pumps ESD which resulted in nuis-

ance actuation of I-1.

3. On Nov 9th, 2010, I-1 actuated on power

failure to reformer induced draft (ID) fan

speed probes due to tripping of power dis-

tribution cabinet.

4. On Nov 29th, 2010, I-1 was manually acti-

vated due to fire at synthesis machine.

5. On Mar 15th, 2011, I-1 actuated when air

compressor tripped and protection steam in

air convection coil was not established in

time due to slow response of protection

steam flow control valve.

Safety Performance

The primary emphasis and main focus during the

project was prevention of accidents that could re-

sult in injury or fatality to the workers or damage

to the property. All the contractor employees were

taken through Engro's well-established safety

orientation and training. Approximately, 50 million

man-hours were worked at the Daharki site to

complete the project. There were no disabling inju-

ries. However, there were two lost workday inju-

ries to contract workers during the construction

phase.

Housekeeping with special emphasis on proper

placement of fire extinguishers was ensured

throughout the project duration. The traffic regula-



tion compliance was ensured with due considera-

tion paid to crane operation and rigging.

Potential adverse effects on health and applicable

exposure control of the materials like feed and

product residue, catalyst dust, and chemicals were

identified and were satisfactorily handled.

Upon completion of the project, the total recorda-

ble incident rate (TRIR) was recorded at 0.27

which is a highly commendable achievement for a

construction site.

Conclusion

After adequately furnishing themselves with every

tool in their weaponry, Engro’s operations team

exhibited splendid display of their skills in the

field. The journey which started from P&ID Sys-

temization, manpower built-up, training, Procedure

development, pre-commissioning, commissioning

& startup came to a successful end. The result of

untiring efforts of the entire team and in-depth

planning by leadership that led to the successful

startup of world’s largest single train Urea com-

plex. Following main factors contributed to the

success of this project;

• Extensive training of manpower and well-

structured utilization of OTS helped a long

way towards smooth startup of plant.

• Thorough and ‘once through’ pre-

commissioning also resulted in saving of a

lot of time during commissioning.

• Good quality workmanship also played a

vital role in successful commissioning.

• Several layers of audits performed before

bringing in the natural gas to the site prior

to feed-in. Hundreds of points were picked

and closed before feed-in.

• All critical circuits were pressure tested

with nitrogen / air.

• Frontend was pressure tested with nitrogen

and leak test was carried out with soap so-

lution.

• Synthesis loop was tested at 200 Kg/cm2

pressure with nitrogen for duration of 04

hours.

Acknowledgements

Authors acknowledge all the colleagues of Engro

who helped in collection of data for this paper, es-

pecially Mr. Abul Fazal Rizvi, Mr. Mohsin Mukh-

tar, Mr. Wasim Yasin, Mr. Ahmad Shakoor, Mr.

Syed M. Ali, Mr. Majid Latif, Mr. Hafiz Samad &

Mr. Imran Haider.


Documents

Commissioning Experience of World's Largest Single-Train