4.annexure-iii-scope of work (sow)

8/19/2019 4.Annexure-III-scope of Work (Sow)

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ANNEXURE-III

SCOPE OF WORK

Sub: Repair of Regeneration Columns C-1202 and C-1302 of GSU-12 and GSU-13 Plants at

ONGC Uran Plant, Uran

The GSU units of plant removes the shore content like H2S & CO2 from hydrocarbon gas before

extracting the LPG,C2C3,LAN and sweet lean gas.

During the turnaround inspection of the columns C-1202 and C-1302, it is found that there is

thickness loss at various location on columns from inside as well as outside also. The thickness

loss has to be repaired for the service of the remaining life of the columns.

The repairing of columns has to be done by lap band repair at some of the location, at other

locations by weld build up. At some location SS cladding (inside the column C-1302) is

damaged, hence an internal repair including the replacement at some portion and patch weld/

weld build up repair at some location of clad/column is to be carried out.

Details of columns(C-1202 & C-1302)

SL no. Details Specification values

1 Design pressure (Ks/cm2g) 5.7

2 Operating pressure

(Ks/cm2g)

0.5/0.7

3 Design temperature ( ̊C) 97.3(top)/125.7(bottom)

4 Service Sulfinol-X solvent+H2S+CO2+hydrocarbon gas traces

5 ID 2550mm(top)/3500mm(bottom)

6 Capacity 129.2m3

7 Thickness of shell (mm) 12(9+3) top 3 mm clad up to 5 m from top,15mm in

middle,19 mm at bottom

8 Max height of columns

(meter)

25.7+1.15

9 MOC of shell/clad SA516Gr.60/ SA516Gr.60+A240-321

10 Insulation thickness(mm) 105

11 Joint efficiency 1.0/0.85

12 Code ASME Sec.VII DIV.I 1986

A .Repair locations of C-1202:

Area of Corroded Zone

(mXm) of external surface of Shell

Fillet Weld patches area

(mXm)

Weld overlay area ( mXm)

1.0X0.5 1.2X0.8 Nil

0.5X0.5 Nil 2.0X2.0


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B. Repair locations of C-1302:

S.No LOCATION Nom

inal

thick

ness(

mm)

Observ

ed min.

thickne

ss(mm)

Area of

corrod

ed

zone(m

xm)

Type of repair

Area

to

be

repaired

Internal

3mm S

cladding are

to b

replaced (m

X m)

1 A/1ST shell from

top

12 6.4 1.0x0.3 Area of Lap bands

(M X M) OD of shell-

2.74m

8.6x1.0 1.5 X1.0

2 B/1ST shell from

top

12 4.5 2.0x1.2

5

8.6x2.0 2.5x1.5

3 B/1ST shell from

top

12 7.0 1.0x1.0 8.6x1.5 1.5x1.0

4 D/5th shell fromtop

15 9.4 1.5x1.0 Fillet weld patchesarea M2

1.5x1.0 Nil

5 E/5th shell from

top

15 7.7 1.0x1.0 Fillet weld patches

area M2

1.5x1.0 Nil

6 F/5th shell from

top

15 8.6 1.0x1.0 weld overlay area m2 2.0 Nil

7 G/5th shell from

top

15 8.9 0.2x0.2 weld 1.0overlay area

m2

2.0 Nil

8 H/5th shell from

top


9 I/5th shell from

top


Detail scope of work:

1. Erection/dismantling of scaffolding at periphery of columns prior to the shutdown as per

the instructions of Engineer in charge is in the scope of contractor. Scaffolding material and

all tools/tackles including consumables like paint removers, Rustolene, Brass Wire brushes,

waste clothes is in the scope of contractor.

2.

Erection/dismantling of scaffolding at inside of column, (if require,) shall be done as per the

instructions of Engineer in charge and same is in the scope of contractor.

3. The removal/installation of insulation shall be in scope of ONGC. The scrap of insulation

shall be removed by ONGC

4. The removal of composite coating shall be in scope of contractor (if required).


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5. After shut down blinding/DE blinding of columns shall be performed by contractor as per

instruction of EIC.

6. The repair is to be done at identified locations inside as well as outside of columns which

are at various height. The contractor may visit the site so as to get first hand details about

the job to be carried out.7. The supply of all the material required (including logistics, loading/unloading etc.) to

execute the job as per SOW is in the scope of contractor.

8. The welder/welders deputed for the job shall be a qualified welder and requisite associated

manpower shall be made available at the site so as to complete the job within stipulated

time.

9. The procedure given for carrying out the repair shall be followed and as per the guidelines

of ASME Sec IX and ASME Sec II Part C.

10. The type of repair like lap banding, fillet weld of patch, weld overlay and clad (inside the

column) replacement have been provided above in the table but same is indicative only. If

needed repair work in more area shall be performed in addition to above. And the

contractor has to adopt the appropriate procedure to do all said repairing work accordingly.

11. Suitable NDT to be done after every root and final weld run. After completion of the

repair, radiography shall be done by the contractor as per the instructions of Engineer-in-

charge.

12. On completion of repair, two coats of high temperature & corrosion resistance

paint shall be applied over the repaired surface as well as on whole surface of columns after

properly cleaning and corrosion removing as per the standard procedure with minimum DFT

after each coat 20 microns.

13. The scrap generated during the execution of the repair job will become the property of

the contractor and shall be taken out of ONGC premises. Accordingly the bidder has to

quote the price for the safe disposal and comply all statutory requirement.

14. All the jobs to be carried out shall be executed as per the instructions of Engineer-in-

charge and within the given time period.

15. The columns shall be flushed and washed the whole column from inside properly by

contractor followed by oxygen test before taking repair job either from inside or from

outside of columns.

16. If needed the contractor has to remove nearly 7 trays, do the repair/replacement work

inside the column and then refit same trays properly.

17. Bidder has to do hydro test of column at test pressure for leak test at 1.5 times of design

pressure.

18. The contractor has to paint the railing, grating, ladder platform of the column with

suitable paint as per procedure.


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19. Contractor has to arrange PPE (Personal Protective Equipments) like safety shoes, safety

belts, helmets etc. for all his personals to be engaged during execution of job at site.

20. The contractor has to get gate pass for men and equipment himself. ONGC shall assist

him. Providing all required documents and police verification shall be responsibility of

contractor.21. On accident if any for employees of contractor, ONGC shall not any responsibility for

same and ONGC shall transport the victim up to ONGC plant occupational health center.

Transportation of patient from ONGC premises to required hospital and treatment shall be

responsibility of contractor.

22. Following procedures of repairing of damaged at different portion of columns can be

adapted by bidder. Replacing the section or component containing the defect for clad

pad portion.

1. Damaged or eroded shell plates (reduced thickness) area may be repaired by

removing a section and replacing the plate as per required thickness and

material specification.

2. Full penetration groove weld to be provided.

3. The welds are radio graphically tested with applicable construction code.

Ultrasonic examination by an industry qualified UT shear wave examiner. May

be substituted by radiography if NOE procedure is approved.

4. All patch plates corners that do not extend to existing longitudinal or

horizontal weld shall be rounded having a 1 in. (2Smm) minimum radius. Weld

proximity to existing weld shall be reviewed by the engineer.

Fillet weld patches:Following procedure should be used for fillet weld patches or weld build up:

Fillet weld patches may be used to make temporary repairs to damaged,

corroded or eroded areas of pressure vessel components. Temporary repairs

using fillet welded patches shall be approved by an inspector and engineer.

The use of fillet welded patches may be subject to the acceptance of the

governing jurisdiction.

Fillet welded patches require special design consideration specially related to

weld joint efficiency, filler welded patches may be applied to internal or

external surface of shell, heads and header provided that in the judgment of

the engineer, either of the following is true:- The fillet welded patches provide design safetyequivalent to reinforced

openings designed according to the applicable construction code.

a. The fillet welded patched are designed to absorb the membrane strains of

the parts so that in accordance with the rules of the applicable

construction code, the following result:


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b. The allowable membrane stress is not exceeded in the vessel part or

patches.

c. The strain in the patches does not result in fillet weld stresses that

exceed allowable stress for such welds.

Lap band repairs:

The band is designed to contain full vessel design pressure,

All longitudinal seams in the repair band are full penetration butt weld with the

design joint efficiency and inspection "consistent with the appropriate code,

The circumferential fillet welds attaching the band to the vessel shall are

designed to transfer the full longitudinal load in the vessel shell, using a joint

efficiency of 0.45,

Appropriate surface NDE shall be conducted on all attachment welds,

The band material and weld material are suitable for contact with the

contained fluid at the design conditions and an appropriate corrosion

allowance is proved in the band.

Welding procedure:

Following process may be used to obtain the finish weld.

Contractor shall establish suitable WPS & PQR as per mandatory

requirement of ASME Sec. IX, Also applicability of suitable welding rod,

electrode and filler metal as per ASME Sec, II part C.

The process may be SMAW or GTAW.

Consumables for GTAW as per ASME SFA 5.18- AWS ER 70S2, for SMAW

as per ASME SFA 5,1 - AWS E7018.The lap band can be partially or fully pre-fabricated according to design given

by designer in accordance with appropriate code.

Safe installation procedure to adopt by contractor for welding of

circumferential fillet weld between band and shell. Pre heating to 150 deg. Or

higher to be maintained during welding.

Weld overlay of corroded area (clad repair procedure)

The SS clad has been removed by erosion. It needs weld overlay over CS plate to protect the

same. Following procedure shall be used1. Mark clearly the area that needed to be repaired,

2. Ensure proper qualified welder who is doing welding jobs

3. Welding electrode used for SS are ER309 electrode by GTAW OR SMAW process.

4. Proper size electrode to be used and continuous run to be made over CS surface as per

required thickness of SS clad.

5. Current to be properly controlled as excess current may burn out the base metal.


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6. After complete welding of required thickness proper flushing (grinding) to be done

smooth surface.

7. NDT as MPI or LPT to be done on ground surface for defects.

Welding process:-Following process may be used to obtain the finish weld. Contractor shall

establish suitable WPS & PQR as per mandatory requirements of ASME

Sec. IX. Also contractor has to establish applicability of suitable welding rod.

Electrode & filler wire as per ASME Sec. I! Part C.

1. SMAW

2. GTAWProcedure:-

Surface cleaning: Care to be taken previously installed paint / insulation is

properly cleaned. Method like chipping, grinding can be used to achieve surface

preparation.

Marking: Prior to cutting, all affected members (where surface thinning is

observed) shall be properly marked with appropriate length. Cutting can be done

by gas cutter or by any other suitable method. During cutting method should be

such selected that during the process it should not lead to distortion of the

structure or any increase in joints.

Welding: Prior to welding edge preparation, bevelling shall be carried out using

grinding machine for proper joint preparation. Only qualified welders shall be

deployed for welding as per ASME Sec IX or equivalent. All weldings shall be in

minimum 2 passes. Welding shall be followed by suitable NOT (RT, UT and MPI)

etc. to ensure the quality of weld.Precaution for repair: All sharp, rough, broken edges and the edge of joints shall

be cleared out so as to avoid defects and to install or fabricate equipment and

defect free joints. Precaution for repair shall be taken into consideration that it

does not alter the mechanical properties of the material.

In the ONGC’s scope:

a. Low tension power supply and connections shall only be provided by ONGC.

b. Water and air at 4-6 kg /cm2 pressure shall be provided by ONGC.

c. Any power supply up to the column bottom for grinders etc. however, long cable from

bottom to top of column to be arranged by contractor.

Special Terms & Conditions:

Payment terms:

No advance payment shall be made. 100%Payment shall be made on successfully

completion of each column repair job as per Scope of Work and terms and conditions of the

contract.


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Bidder has to submit the bill/invoice in triplicate with all required documents in the name of

DGM (F&A), ONGC, Uran and should get tracking number from our HR/ER Section. The bill

after tracking no. shall be forwarded to concerned Engineer in charge by HR/ER for

certification, verification, and final release. Payment shall be released within 21 days from

the date of submission of bill to concerned Engineer-In-Charge.

Completion Schedule: Contractor has to complete the job of repair of each column within

20 days from the date of handing over the respective columns.

Mobilization: Maximum 15 days shall be allowed for mobilization of men, equipment and

machinery etc. from date of LOA.

Contract period: Contract period for the jobs will be 18 Months from placement of LOI.

Inspection: Inspection shall be carried out by ONGC representative/ TPI(arranged by ONGC)

Guarantee/Warrantee: Contractor has to furnish a guarantee/warrantee for a period of one

year from the date of completion of job. During the period if any defect is observed in the

executed job, the same shall be rectified by the contractor at free of cost within a minimum

possible time.


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