Post on 18-Nov-2014
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