welding design

WELDING DESIGN,WELDING PROCEDURE

AND PERFORMANCE QUALIFICATION

Edge Preparation - Need

Poor penetration

Poor access at root

Poor strength

Good penetration

Good access at root

Good joint strength

Basic Joint Types

butt

teelap

corneredge

Applicable Welds for Butt joint

Square Groove weld V Groove weld

U Groove weldBevel Groove weld

J Groove weld

Applicable Welds for Butt joint

Double V Groove weld

Double U Groove weld

Double Bevel Groove weld

Double J Groove weld

Applicable Welds for Tee joint

Applicable Welds for Lap joint

Plug / slot weldSpot / seam weld

Fillet weld

Applicable Welds for Corner Joint

Butt jointSingle V Groove weld

Groove angle

Root face

Root gap

Groove angle

Root gap

Root radiusSingle U Groove weld

Root face

Double V Groove weld

Weld Reinforcement

Correct reinforcement

Minimum cost

Good joint strength

Excess reinforcement

High cost

Poor joint strength

Under reinforcement

Poor joint strength

Butt joint – Complete Joint penetration

Weld from face side

Back gouging

Back weld

Backing weld from root side

Back gouging from face side

Weld from face side

Tee Joint

leg

leg

leg

leg throat throat

leg

leg throat

Flat profile Convex profile

Concave profile

Tee Joint – Full penetration joint

leg = throat leg = throat

Groove angle

Welding Position – Groove

1 G

2 G

3 G

4 G

Welding Position – Groove

1 G 2 G

5 G 6 G

45°

Welding Position – Fillet

1F

2F3F

4F

Welding Position – Fillet

1F

2F

5F

Dilution

Dilution is the amount of base metal present in the weld metal and given by (Area B / (Area A + Area B))

Dilution depends on the welding process and heat input.

High dilution alters the chemical composition of weld metal

Area A

Area B

Weld Metal Requirements

• Matching strength with the parent metal

• Good notch toughness at the operating temperature

• Corrosion resistance

• Creep resistance for elevated temperature application

• Resistance to wear, erosion etc

Filler Metal Selection

• Mechanical / chemical properties required

• Welding process

• Type of electrode, current, power range

• Metal to be joined and its thickness

• Weld joint design and welding position

• Shop or Field weld / surface condition

• Number of passes / amount of weld metal

Welding Procedure Specification

It is a written document that provides direction to the welder for making production welds in accordance with code requirements.

Any WPS must be qualified by the manufacturer.

WPS specifies the condition (ranges) under which welding must be performed called variables.

WPS addresses essential, supplementary essential and non essential variables

Purpose of WPS Qualification

To determine that the weldment is capable of providing the required properties for the intended application.

WPS establishes the properties of the weldment and not the skill of the welder.

Procedure Qualification

PQR is a record of welding data to weld a test coupon. It also contains test results.

Completed PQR shall document all essential variables including ranges.

PQR to be certified accurate and shall not be subcontracted.

If more than one process is employed then weld deposit thickness for each process and filler metal to be recorded.

Base Metal Classification

Base metals classified into various P Nos depending on composition, weldability & mechanical properties.

P1 - P11 Steel

P21 - P25 Al alloys etc.

Group nos within P nos classify metals for procedure qualification where notch toughness requirements are specified.

Filler Metal Classification

F Numbers are based on usability characteristics i.e ability of welders to make satisfactory welds with given filler

e.g. F1 - E XX20, F2 - E XX12, F3 - E XX10, F4 - E XX18 etc.

A Numbers are based on chemical composition

e.g. A1 - Mild steel A2 - C - Mo steel etc.

WPS for SMAW

Essential variables

Change in qualified Thickness

Change in P no

Change in F no of filler metal

Change in A no of filler metal

Change in deposited metal thickness

Decrease of more than 100° F in preheat

Change in PWHT

WPS for SMAW

Welded Qualified

Px – Px Px – Px

Px – Py Px – Py

P3 – P3 P3 – (P3 / P1)

P4 – P4 P4 – (P4 / P3 / P1)

P5A – P5A P5A – (P5A / P4 / P3 / P1)

P5A – (P4 / P3 / P1) P5A – (P4 / P3 / P1)

P4 – (P3 / P1) P4 – (P3 / P1)

Procedure Qualification Thickness limits

T (mm) Range of T max t Tests

<1.6 T - 2T 2t 2T, 2 FB, 2 RB

1.6 – 10 1.6 - 2T 2t -do-

10 - 19 4.8 - 2T 2t -do-

19 - 38 4.8 - 2T 2t if t<19 2T, 4 SB

2T if t>19

>38 4.8 - 203 2t if t<19 -do-

203 if t>19

Welding Performance Qualification

The performance qualification tests are intended to determine the ability of welders to make sound welds

A welder is qualified by radiography of a test coupon or by radiography of initial production welding or by bend tests taken from a test coupon

Welding Performance Qualification

Variables for SMAW

Removal of backing

Change in Pipe diameter

Change in P number

Change in F Number

Change in thickness of weld deposit

Change in welding position

Change in vertical welding

Welding Performance Qualification

Thk (mm) Max tk of dep. Metal Test

<13 2t 1FB, 1RB

>13 Max to be welded 2SB

OD of test coupon Range of OD qualified

<25 Size welded - unlimited

25 - 71 25 - unlimited

> 71 71 - unlimited

Welding Performance Qualification

Welded Qualified

Without Backing

Fx Fx

With Backing

F1 F1

F2 F2, F1

F3 F3, F2, F1

F4 F4, F3, F2, F1

F5 F5, F1

Welding Performance Qualification

Weld Plate & pipe Pipe of OD>610 mm OD 71- 610 mm

Plate 1G F F

Plate 2G F, H F, H

Plate 3G F, V F Plate 4G F, O F

Pipe 1G F F

Pipe 2G F, H F, H

Pipe 5G F, V, O F, V, O

Pipe 6G All All

Thank you