TECHNICAL SPECIFICATION

SECTION-A

CMM/MAPS/MM/41537/MANUAL-PO/1291 DT:-

Welding Specification:

1. The tank should be fabricated from steel plate material confirming to IS 2062

Gr-B.

2. Material test certificates, verification&identification mark and visual inspection

of the plate should be made before start of pre-fabrication.

3. Cold bending of steel plate should be done such that no dent marks damage

on the plate.

Welding procedure:

All welding should be done as per approved welding procedure attached

herewith.

Welders Qualification:

All welding joints should be done by the qualified welders as per ASME

Sec.IX.Relevant performance qualification certificate should be produced for

verification before start of the work at any time during the fabrication of the

tank.

Welding inspection:

The type and extent of weld examination as given (Visual,DPT,Radiography)in

Annexure-B should be strictly followed. Inspection should be done by qualified

inspector of the contractor and same to be offered to NPCIL/QAI inspector and

clearance should be obtained at various stages. No welding defects such as lack

of fusion/lack of penetration/insufficient fillet size and any other defects is not

permitted. All nozzle joints and butt joints root side to be ground and one more

welding pass is required at the root side.

All MTC, welding inspection documents should be submitted along with the

supply.

A proposed QA Plan is attached herewith. However the contractor may submit

their own QA plan and the same to be approved by SME (M) before the

commencement of work.

Hydrostatic test:

Before rubber lining and external coating the tank has to be

leak tested by conducting hydrostatic test/water fill test as per the approved

procedure by NPCIL/QAI.

Welding consumables:

Only NPCIL/QA approved brands of consumables like

welding electrodes and penetrant materials to be used for entire welding works

as listed below:

ANNEXURE-B

Type and extent of Non-destructive examination for the weld joints:

Sl

no:

Type of joints Visual DPT Radiography

1. Fillet weld

joints

100% 100% Root pass and

final pass DPT

NA

2. Butt weld

joints

100% 100% Root pass and

final pass DPT

10% Random spot

Radiography .10% of

the entire BW joint

length

Welding Procedure/Specification:

Metals : C.S P1 to P1

Thickness : 1.5mm to 20mm (inclusive)

Process : Manual Metallic Arc

Filler Material : Low Hydrogen Electrodes

Position : All

Preheat : Nil

Post heat : Nil

Process:

Procedure for but and fillet welding of carbon steel pipe/fittings with standard

edge preparation by manual metallic arc process using low hydrogen type

covered electrodes.

Mode of Qualification:

As per section IX of ASME Boiler&Pressure vessel code.

Qualified for thickness:

1.5mm (1/16”) to 20mm (3/4”)(inclusive)

Approved fillet metal/electrodes:

Conforming as per Annexure

Base metal:

Weld able quality carbon steel confirming to the requirements for materials listed

under group P1 of Table Q-11.1 of Section IX of ASME Boiler&Pressure vessel

code.

Electrode characteristics:

DC reverse polarity (DCRP)

Position of welding:

All positions (Vertical upwards only)

Care of electrodes:

The covered electrodes shall be properly stores in their original sealed containers

in a dry place. Prior to welding, electrodes shall be kept in a baking oven and

heated at 3750C+/-250C for a period of one hour to remove all the moisture and

transferred to the storage oven. The storage oven shall be maintained at 1000C

above ambient temperature. The electrodes shall remain identified until

consumed. Electrodes shall be drawn from the oven for the use only to the

extent of immediate necessity to avoid unnecessary exposure to

atmosphere.Electrdes exposed in the t=field for more than one hour shall be

returned to the drying oven and kept at 1000C for at least 2-hours.All the

electrodes which have been exposed to rain or contaminated with water shall be

discarded. The daily requirement of electrodes shall be carefully assessed and

drawn to avoid more than one rebaking and many heating and cooling cycles.

Preparation of base metal:

All butt joints shall have ends prepared preferably by machine as shown in the

attached drawing. All frame cut edges shall be maintained or ground at least

1/16” beyond the deepest indentation.

Cleaning:

Surface for welding shall be cleaned and free from paint, oil, grease,

rust or any other foreign matter. In any event weld metal shall be deposited only

upon bright base metal. Solvent approved by QS to clean the weld groove and its

adjacent area shall be used before welding. Swab used for this purpose shall be

lint free.

Welding Technique:

a) Current and electrode size to be used shall be as recommended by NPCIL/QAI.

b) Accurately align the pipes/fittings. c) The initial alignment for tacking should be secured by means of clamps.

Tacks are recommended at a spacing of 4”, but not less than three

tacks shall be made.

Tack welds shall either be removed completely when they have served their

purpose, or their starting and stopping ends shall be properly prepared by

grinding or other suitable means so that they may be satisfactorily

incorporated into the final weld.

Tacks shall be made by qualified welders and conforming to qualified welding

procedure.

Tack welds shall be examined visually for defects and if found to be defective,

shall be removed.

d) The root pass shall be completed by manual metallic arc process using covered electrodes.

e) After root pass the same shall be inspected visually as well as by a method required by the relevant specification.

If the weld is visible from inside, it shall be inspected for lack of fusion, lack

of penetration, icicles; etc.the internal reinforcement shall not exceed 1.5mm.

f) Complete the weld with the same technique.

g) The final weld shall have a convex, smooth and uniform appearance having no undercut. Defects such as cracks, gas pockets, pinholes, overlaps, abrupt ridges, valleys etc are not permissible in the weld metal. The outside reinforcement for different pipe wall thickness shall be as given below:

Pipe wall thickness Thickness of

reinforcement (Maximum)

Up to 13mm incl. 1.5mm

Over 13mm to 20mm 2.5mm

h) The width of the head should not exceed three times the core wire diameter,

except for the final pass. The thickness of each pass shall generally about 3mm.

i) No interruption of welding except for inspection of root pass is generally

permitted.

j) Fillet weld shall have a convex profile with equal legs.

k) The arc should be struck either on a striker plate and carried over the joint, or

in the joint where the metal surface will be fused into the weld.

l) Peening is not permitted.

Inter pass cleaning:

All traces of slag and flux shall be removed by means of wire brushes or chisels

before successive beads or layers are deposited.

Defects:

Any defect that appears in the weld shall be removed by chipping and grinding.

Whenever arc gouging is permitted grind or file back at least 1.5mm beyond the

deepest indentation before depositing the weld metal. Magnetic particle, liquid

dye penetrant or radiography inspection should be used to check that defect has

been completely removed prior to weld repair.

Preheat: Not required.

Stress relieving: Not required.

Inspection: As per the approved QA plan (which has to be Submitted by the

contractor

and approved by MAPS Engineer)

Technical Specification for Rubber Lining and Anticorrosive coating of

Bulk Soda Storage Tank

1. Reference Drawing No.M-1/71616/7577/DD/R-4.

Description of work:

Internal rubber lining has to be done to a thickness of 6mm. Cleaning and

surface preparation, rubber lining of tank internal surfaces as per IS 4682 (Part-

I): 1994 reaffirmed 1999 testing as per QA requirements to ensure bonding

strength and defect free lining, preparation of outside surface complete

including nozzles and corrosion protection FRP coating on the outer surface as

per IS no. 12643: 1983 reaffirmed 2000.

1. Design of Rubber lining: The material used should be of Neoprene

rubber. The rubber used should not be of Recycled or poor quality

material. It should satisfy the chemical and physical condition of the tank

and have non-stain properties. It should not deteriorate with continuous

contact of 33%. HCL. The rubber lining has to be done after sufficiently

satisfying each of the following steps.

i) Surface preparation by Grit / Sand blasting: The surface to be

rubber lined should be thoroughly cleaned free of duct, residues,

and debris left by either sand or fine metal ball grit blasting.

Immediately after grit blasting the surface to be protected against

rusting.

ii) Bonding the neoprene rubber sheet and Hot vulcanizing with

steam:

1. The rubber lining shall be bonded to the substrate. The adhesive system

shall be suitable for the type of rubber & for the service conditions. The

adhesive shall be applied to the primed substrate surface by brush, roller

or spray, any solvent in the adhesive being allowed to evaporate between

the successive coats or subsequent application of lining. The raw rubber

is to be tailored to fit the surface to be lined. Preshrinking and necessary

shall be carried out as first step.

2. The surface of the rubber, which will be lined on the metal, has to be

coated with rubber adhesive solution till it gets tackness. During the same

time the adhesive compound is applied on the prepared & allowed to tack.

Both rubber /metal & rubber / rubber surfaces coated with adhesive

solution shall be allowed to Dry sufficiently to achieve tackness. The type

of end joint shall be strapped Design. This Strapping joint shall be

suitably staggered to get effective smooth surface. The sheets before

laying shall be spark tested to confirm healthiness.

3. Fitting the lining sheets to the surface:

a) Exclusion of air-in the application of lining air shall be allowed to

escape between adjacent layers & metal.

b) Continuity of lining: When fitted all the sheets & strapped joints shall

be free from pinholes & other defects.

4. Lining shall be applied in double layer of each 3mm thick

5. Except when the sheets are prepared by extrusion, the sheets should be

prepared by calendaring, the number of plies for 6mm thick as per IS

4682 (part-I): 1994 is =4(four).

6. Vulcanizing: Steam vulcanization shall be adopted with outlets of tank

covered to reduce steam losses. Steam shall be injected unit

vulcanization temperature is achieved. This temperature shall be

maintenance until required time period. Vulcanization temperature & the

required time period shall be intimated for inspection.

iii) Inspection: The contractor has to offer the tank for inspection to

NPCIL/QAI at each of following stages.

1. Surface preparation.

2. Raw material – rubber with test certificate from NCPIL approved

laboratories.

3. Spark test on raw arterial.

4. Laying of joint – no patch permitted.

5. Hot steam vulcanization.

6. Hardness test = Hardness shall be =60 Shore A + or -5.

7. Spark – test after vulcanization to ensure defect free lining.

8. Overall visual.

External Anti-corrosive coating:

The outside surface has to be coated with anticorrosive coating of Epigen 4029

of 500micron thick.The complete tank outer surface including pipe spools,

flanges, man hole covers and support pads have to be coated with adequate

bonding and shall have excellent chemical resistance.

The top layer shall be of ultraviolet coating with polyurethane paint of grey

colour.

Surface preparation:

The cleaned surface is to be grit blasted uniformly unit grey –white surface is

formed. Suitable enclosure shall be arranged to contain blast debris.

For Best Result ensure that surface is free from rust,dust,moisture, Oil

and Grease

Mix Resin and Hardener thoroughly till it becomes a Homogeneous mixture. The mixed materials have to be used within 30 minutes.

The contract has to submit Tentative QA plan along with offer and submit full

QAP after receipt of evaluated work order.

QAP shall indicate all stage inspections, acceptance norms and methods of

testing. The QAP will be approved by NPCIL. Contractor has to execute the

works as per approved QAP and procedures.

Specification:

1. IS 4682 (part-1): 1994 reaffirmed 1999 for rubber lining.

2. IS no.12643 :1983 reaffirmed 2000

PROPOSED QAP FOR SODA STORAGE TANK

Name of the equipment Bulk Soda

St-Tank

P.O NO: CMM/MAPS/MM/

Client NPC/MAPS Date

MAPS Drg no:MAPS/71616/7577/DD/R4

Sl

no

Item description Type of check Quantum

of check

Ref.Doc/Accepta

nce Std

Format of

record

01 Material Identification:

a)Plate&Pipe

Visual&Inspection 100%

Approved drg

SIR or Check

Test TCs

Material Test Certificates shall be submitted. In case of Non-condition with material TC,Check Analysis shall be done for tensile and

chemical(except CarbonEquivalent)Analysis.

02 Welding Qualification

a)Procedure

b)Performance

Witnessing 100% ASME Sec.IX WPS/PQR/WPQ

03 Dished Ends:

a)Long seam fit up

b)Welding

Visual&Dimensional

Visual Root &Final DPT

100%

100%

Approved drg

Approved drg

SIR

---

c)After forming

d)Knuckle radius(Both

inside and outside)

Visual&Dimensional

Visual,DPT&RT for

Weld joint

100%

100%

Approved drg

Approved drg

SIR

LPIR/RIR

04

Shell

a)Long seam fit up

b)Cir seam Fit-up

c)Welding

Visual&Dimensional

Visual&Dimensional

Root DPT/

Final visual DPT

RT

100%

100%

100%

100%

10%

Spot

Approved drg

Approved drg

Approved drg

Approved drg

Approved drg

SIR

SIR

SIR

SIR

RIR

05 Shell with Dish Ends:

a)Fit-up(Cir-seam)

b)Final Welding

Visual&Dimensional

Visual&RT&Final DPT

100%

10%

Spot

Approved drg

Approved drg

SIR

SIR

Sl

no

Item description

Type of check

Quantum

of check

Ref.Doc/Accepta

nce Std

Format of

record

06 Nozzle:

a)Orientation Marking

b)Nozzle Fit-up

c)Final Welding

Visual&Dimensional

Visual&Dimensional

Visual&Dimensional

100%

100%

100%

Approved drg

Approved drg

Approved drg

SIR

SIR

SIR

07 External Attachments(Lifting Lug,Name Plate,Pad plate)

a)Fit-up Visual&Dimensional 100% Approved drg SIR

b)Final welding Visual 100% Approved drg SIR

08 Final Dimensional

check

Visual&Dimensional 100% Approved drg SIR

09 Water Fill Test Visual 100% Approved drg SIR

10 Rubber Lining Visual

Hardness test

Holiday/spark test

100%

100%

100%

Approved drg

Approved drg

Approved drg

SIR

SIR

SIR

Separate QAP for Rubber Lining shall be submitted after Tank Fabrication

11 Anti-corrosive

Coating(outside)

Visual 100% Approved drg

SIR

12 Final Inspection

Clearance

Visual 100% Approved drg

SR

LEGEND:

W - Witness

LPIR -Liquid Penetrant Inspection Report

R - Document review SIR

- Stage Inspection Report

WPS - Welding Procedure Specification WPQ

-Welder Performance Qualification

PQR - Procedure Qualification Record RIR

- Radiography Inspection report

I - Inspection SR -Shipping Release