ch4 2 welding joint preparation

7/23/2019 CH4 2 Welding Joint Preparation

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Weld Joint Preparation

(ISO 9692)


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Edge Preparation - NeedPoor penetration

Poor strength

Good penetration

Good strength

(100% jointefficiency)


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Edge PreparationFactors which influence choice of edge preparation

- Thickness

- Material

- Welding process

- Extent of penetration required

- Welding distortion

- Cost


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Basic Joint Types

butt

tee

lap

corner

edge


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Basic Weld TypesGroove welds

Fillet weldPlug / slot weld

Spot / seam weld


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Applicable Welds for Butt jointSquare Groove weld V Groove weld

U Groove weldBevel Groove weld

J Groove weld


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Applicable Welds for Butt joint

Double V Groove weld

Double U Groove weld

Double Bevel Groove weld

Double J Groove weld


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Applicable Welds for Tee joint


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Applicable Welds for Lap joint

Plug / slot weldSpot / seam weld

Fillet weld


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Applicable Welds for Corner Joint


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Applicable Welds for Edge Joint

Edge weld


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Butt jointSquare Groove weld

Root gap


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Butt jointSingle V Groove weldGroove angle

Root face

Root gap


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Weld Reinforcement

Correct

reinforcement

Minimum cost

Good joint

strength

Excess

reinforcement

High cost

Poor joint strength

Under

reinforcement

Poor joint strength


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Butt joint Complete Joint penetration

Weld from face side

Back gouging

Back weld


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Butt joint Complete Joint penetration

Backing weld

Back gouging


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Butt joint Complete Joint penetration(welding from one side)

TIG / SMAW

welding

Consumableguide


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Butt Joint Double V grooveLess weld metal

Less distortionHigher edge preparation cost

Better for thickness > 20 mm

More weld metal

More distortion

Lower edge preparation cost

Better for thickness < 20 mm

Double V groove

Single V groove


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Butt Joint U groove

Good access at the root

Less weld metal

Higher edge preparation cost


Groove angle

Root face

Root gap

Root radius


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Butt Joint Bevel groove

Double bevel groove

Single bevel grooveBevel angle 40 to 50

Difficult to approach

the root

Weld defects

Back gouging toremove root defects

Good weld quality


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Butt Joint J groove

Good access at the root

Back gouging and back welding to get good weld quality

Less weld metal

Higher edge preparation cost



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Tee Joint Full strength joint

leg

leg throat

throat = 0.707 x legleg = 1.414 x throat

In a full strength

joint, leg = 0.75 x

thickness


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Tee Joint Full penetration joint

leg = throat leg = throat

45 or 60


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Tee Joint

Theoretical throat

Actual throat

AWS D 1.1 recommendation when gap > 1.6 mm

to increase leg size of fillet by the amount of gap


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Lap Joint

AWS D 1.1 recommendation

Overlap = 5 x thickness (1 inch minimum)

Gap between mating faces = 1.6 mm max

overlap


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Welding Position Groove

1 G

2 G

3 G

4 G


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Welding Position Groove

1 G 2 G

5 G 6 G

45


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Welding Position Fillet

1F

2F

3F

4F


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Welding Position Fillet

1F

2F

5F


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Welding Positions Groove

Position Inclination of axis Rotation of face

Flat 0 to 15 150 to 210

Horizontal 0 to 15 80 to 150

210 to 280

Overhead 0 to 80 0 to 80

280 to 360Vertical 15 to 80 80 to 280

80 to 90 0 to 360


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Welding Positions Fillet

Position Inclination of axis Rotation of face

Flat 0 to 15 150 to 210

Horizontal 0 to 15 125 to 150

210 to 235

Overhead 0 to 80 0 to 125

235 to 360Vertical 15 to 80 125 to 235

80 to 90 0 to 360


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Joint preparation

According to I SO 9692

Welding and allied processes -Recommendations for joint preparation

Part 1:Manual metal-arc welding, gas shielded metal-arc welding, gas

welding, TIG welding and beam welding of steels


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ch4 2 welding joint preparation

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