A Case Study on Weldability Test

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A Case Study on Weldability Test

WeLSPun, BhuJ

Jigar Patel

Weldability, in this case-study, refers to “the ability of a metal to be welded under given fabrication conditions, in a specific weldment, and to perform satisfactorily in service”. Thus, weldability assessment through full-scale test pieces and laboratory tests ensures satisfactory field performances. The field welding conditions and parameters, like welding position and groove geometry are replicated in the test-piece, to ensure that coherent results are obtained.

The criticality in the project mentioned in this case study was to achieve a straight HAZ in the welded zone. The major steps taken to ensure satisfactory results were:

1. Machining of the test coupon with excellent dimensional accuracy and finish

2. Fit-up and inspection of the test coupon

3. Alignment of the welding torch with the groove

4. Clamping of the test coupon in the correct position

Crack Top Opening Displacement (CTOD) testing becomes very important to test the coupons, and the results determine the soundness of the weld.

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Test Specimen

A. Specimen Acceptance Criteria–1

Specimen notches shall sample at least 80% of the scribe length in the central 60% of the specimen thickness within 0.5 mm of the fusion line.

B. Specimen Acceptance Criteria–2

Within the central 60% of the section thickness, 25% of the weld metal adjacent to the fusion line on the square edge side of the weld groove is unrefined-columnar weld metal.

C. Requirements


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3. Revised Welding Procedure Specification for hhI 15.88 mm WT

A. Machining of Test Coupon

l Size of Test Coupons for the Weldability: 600 mm length × 320 mm wide × 15.88 mm WT.

l Quantity: 2 nos. for 1 set

l Weld Geometry: Single bevel and one side straight edge.

B. Fit Up and Inspection of Test Coupon

1. Measure the dimensions of plate viz. Angle of Plate, Root Face

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2. Level the plate on machined surface table and attached the stiffner on back side of the plate to restrict the distortion.

C. Groove and Torch Alignment

Following steps to be followed for alignment w.r.t. welding torch, inspection and clamping of test coupon at planomiller bed:

1. First mark the plate at four locations in equal quadrant and check the perpendicular on straight and bevel edge of the plate for uniform alignment.


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2. Levelling of test coupon by plunger dial gauge during fit up at Plano Miller.

3. Longitudinal Z-Axis positioning and degree of torch measured at Plano Miller.

D. Clamping of Test Coupon

l Clamping is done at all four corners of weld test coupon to avoid any movement.

l Bakelite blocks were provided at base and top of the plates for insulation.

l The loose bolt clamps were tightened after the measurement and prior to welding of test coupon.

To maintain uniform straight edge, sickout, welding torch angle shall be uniform throughout the straight edge and recorded in the welding set up and parameter data sheet.

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Metallography

Metallography Submitted for evaluations (hhI)

Metallography Submitted for evaluations (hhI Visible hAZ)


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Metallography Submitted for evaluations (LhI)

Metallography Submitted for evaluations (LhI Visible hAZ)

CTOD Testing

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Tangible Significances

3 Customer Satisfactionl Fulfillment of critical requirements of the project.

3 Unfolding the Personnel Skillsl Unfolded the skills of Welder with a loborious job which was never

attempted before (Plate Thickness 31 mm)l Welding with settings to achieve straight HAZ on the un-beveled side.l Time required to weld 1 joint:

HHI: Np. of passes required to weld 1 mtr length = 16 (average)Time consumed = 16 hours.LHI: No. of passes required to weld 600 mm length = 46 (average)Time consumed per joint = 32 hours

3 Monetary Influencel Cost of outside sourced welder : 2 lakh per jointl No. of joints = 20l Total Cost Saved = 40 Lakhs

Intangible Benefits

3 Setting Landmarkl Welspun, first company in India to execute weldability, increasing

company's value as a business.

3 Competitive Edgel Now Welspun can reach more customers, producing more competitive

bids

Test Results for HHI


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Test Results for LHI

Welspun, Bhuj

Documents

A Case Study on Weldability Test