QAQC References 2

QA vs QC vs INSPECTION
1)
a)
b)
c)
d)
Aim of Quality Assurance

Improve Quality and reducing faults(salah) and wastage(pembaziran).
Improve Quality and reduce costs.
Improve Quality whilst keeping costs to an acceptable level.
Improve system used to implement Quality Assurance is Quality System.
2)
a)
Benefits(faedah) of adopting(menerima tanggungjawab) Quality Assurance

Implemented and managed Quality System should ensure that the company
focuses on market needs and requirements.
Lead to a reduction of costs due to a reduced number of faults and wastage.
Measure of performance which will anable any areas for improvement
to be indentified.
b)
c)
3)
a)
b)
c)
What is Quality Assurance

Quality Assurance should be considered(menimbang) as management tool when
used within as management tool when used within a organization (internal
Quality Assurance).
Quality Assurance provides the Objective evidence(bukti) needed to give
maximum confidence(keyakinan) for Quality.
All those planned or systematic actions necessary to provide adequate(cukup)
confidence that a product or services will satisfy given requirement for Quality.
4)
a)
Scope of Quality Assurance

Encompass(merangkumi) all parts of organization an activity
i.e : planning, design, production, inspection, maintenance, administration, and
callabration with suppliers and purchasers,should also organization Quality System.
5)
a)
b)
Inspection vs Quality Assurance

QA is not inspection
Inspection is one of important elements within system of Quality Assurance
i.e : planning, design, production and etc.
6)
a)
Inspection vs Quality Control

operational techniques and activities is to full fill for Quality
i.e : manufacturing Quality Control is more explanatory(penjelasan).
QA vs QC vs INSPECTION
7)
a)
b)
c)
8)
a)
Quality Control vs Quality Assurance

Quality Control deals which the actual measurement of Quality performance,
this performance compare(berbanding) against what is required and action is
taken on the difference(perbezaan) QC is ask the question, action being performed
correctly.
Quality Control will rarely do anything to correct problems relateting to
management documention training and motivation.
Quality Assurance apply to all aread which have and affects on Quality, action
being performed correctly.
Quality Assurance Standards
Bitish Standards (BS 4778 Part 1)
OBJECTIVE OF VISUAL WELDING INSPECTOR AND WELDING INSPECTION
1)
a)
b)
c)
Main Responsibility
Code Compliance
Workmanship control
Documentation control
2) Personal Attributes
a) Honestly
b) Integrity
c) Knowledgeable
d) Good communicator
e) Physically fit
3) Duties Of Visual Welding Inspector And Welding Inspector
a) Duties Before Welding
b) Duties During Welding
c) Duties After Welding
d) If Any Repair
4) Basic
a) Observe
b) Record
c) Compare
5) Welding Checklist
a) Before Welding
Familiarization to the relevant code and specification
Check welding equipment and calibration certificates
Material identification (size, type and condition)
Consumables ( size, type, condition, storage and handling)
Review/withness WPS and PQR test and record
Joint preparation(check)
Welder qualification test( review/withness)
Welding process involved
Check pre-heating before welding( if required)
b)
During Welding
Check weather condition
Check clearance for welding/welder
Check welder indentification for weld
Check consumables as per wps used
Check welding parameters as per wps used
Check distartion control
Check interpass cleaning
Check run out length
Check interpass temperature
Check usage of line up clamps
Maintain daily log book
c)
After Welding
Perform visual inspection
Weld and welder indentification ( check)
Post weld heat treatment (if required)
Non-destructive testing (withness)
Acceptance standards of NDT
Repairs (if any)
Dimensional check (as per drawing)
Document control (welding reports)
d)
In the event of repair

Authorization for repair
Removal and preparation for repair
Testing of repair (visual and NDT)
6)
Duties and Responsibility of a welding inspector

Basically, Duties and Responsibility of a welding inspector are divided into 3 main
section where it's not more then duties and responsibiles before welding,
during welding and after welding completion.
1)
2)
3)
4)
5)
6)
7)
8)
9)
Before welding, the welding inspector shall be collect and familiarization with
all relevant document or information aid (membantu) to welding activities such as :
Familiarization with applicable codes, standards or clent specifications.
Approved and latest revision drawing (AFC).
Approved welding procedure specification carried with procedure qualification record.
To check, qualified welder with relevant valid certificates and expired date.
Also check the joint preparation to make sure it is are being prepared as per needed
by AFC drawing and as allowed by WPS or code, the joint preparation shall be
clean an free from contamination (percemaran).
Inspect the material size, type and condition, carried with mill or test certificates.
Check the consumables size, type and condition for electrode check type of flux
covering, i.e : basic, rutile, celloluse. Also check the treatment, storage and
handling of the electrode. Check the temperature shoukd baked the electrode.
Carried with batch certificate, when inspect.
Check the condition of welding machine, also review all calibration certificate for
measuring devices, i.e: welding machine, measuring tape, calipers,
electrode baking oven, pwht machine, pressure gauge and etc.
Check the preheat i.e: minimum and maximum interpass temperature and preheat
use flame type. The heating rate must be uniform.
5)
6)
During welding, the welding inspector should once again check :

Consumables to confirm( pastikan), condition and storage. The inspector also
should check electrode use as per wps.
Check the weather conditions.
He also shall check travel spped current characteristic such as ampare, voltage,
in order to control heat input. Welding polarity is also one of the element where he
should look into interpass cleaning and interpass temperature is to ensure that
soundness of weld metal.
Check the welder identification to ensure the welder qualified to weld welding
position as per wps.
He also should monitor the preheat temperature as per wps.
In order to control destortion, welding sequence should be taken into consideration
7)
at the welding inspector.

The inspector also shall maintain the daily log book.
1)
2)
3)
4)
1)
2)
3)
4)
1)
Right after welding the inspector may perform visual inspection immediately to
detect all kind of surface defect and weld size
Before visual inspection carried out, the welded joint must be cleanliness and free
from oil or grease.
The inspector must withness Non-Destructive Testing( NDT) activities.
Inspector should monitor and withness pwht it the procee is required.
All the relevant record and report document involve during fabrication must submit
to higher authorities.
Event of the repair :
If the is any sign at detect are detected during his visual inspection and all repair
process shall be done before NDT and Pwht process.
2)
Report to higher authorities reagarding the repair.
3)
Marking detect area for repair.
4)
5)
6)
7)
Liaise with higher authorities for weld repair procedure.

Monitor repair work, as per weld repair procedure.
Withness the NDT if required.
Collate all the relevant record and report document for repair work and submit to
higher authorities.
WELD TERMINOLOGY
1)
a)
Welds
To joint two material by the aplication of heat or pressure.
2)
a)
Joints
A configuration of members.
3)
a)
b)
c)
d)
e)
f)
Type of joints
Edge
Corner
Lap
Tee
Cruciform
Butt
4)
a)
b)
c)
d)
e)
f)
Type of weld
Fillet
Spot
Butt
Edge
Plug
Compound
5)
a)
b)
c)
d)
e)
Type of joint preparation

Gap
Root face
Angle of bevel
Included angle
Root radius
d
c
b
a
WELD TERMINOLOGY
6)
a)
b)
c)
d)
e)
f)
g)
h)
Weld zone terms

Root
Fusion zone
Weld metal
Weld zone
Heat affectect zone
Weld junction
Fusion penetration
Parent metal
D
C
E
A
F
F
7)
a)
b)
c)
Shape of a fillet weld in cross section by 3 terms :

Mitre fillet
Convex fillet
Concave fillet
8)
a)
Type of joint design

Single "v"- Butt
Included angle 60 - 70
b)
Single Bevel - Butt

Angle of bevel 40 45
2 - 3mm
mmmm
c)
Angle of bevel
30 - 35mm
Single "u" - Butt
d)
Single "J" - Butt

Angle of
bevel
15 - 20
Included angle 15 -20
Root radius 5mm

2 - 3mm
* Single "V" or single bevel for plate (Less thickness plate)
* Single "U" or single "J" for plate (Thicker thickness plate)
Land
WELD TERMINOLOGY
e)
weld toes
weld
toes
1 = Root of Penetration
2 = Hot pass
3 & 4 = Fill pass
5,6 & 7 = Capping
f)
A = weld width
B = excess weld metal
C = excess penetration
D = root width
E = thickness of parent metal
g)
b
d
To check throat thickness

Design = 0.7 x material thickness ( 6mm)
= 6mm x 0.7 (formula)
= 4.2 + 0.5mm(formula)
= 4.7
= 4.2mm (minimum) , 4.7mm (maximum)
A = Nominal design
B = Actual throat thickness
C = Horizontal leg length
D = Vertical leg length
WELD TERMINOLOGY
*
To check leg length

Material thickness (6mm)
so, leg length = 6mm (minimum)
material thickness (6mm)
= so, (+) 3mm = 9mm (maximum)
h)
A-B = Lack of sidewall fusion

B-C = Lack of RootFusion OR Lack of
RootPenetration.
A
B
C
9)
Welding Positions (ISO 6947)

A
B
C
Vertical up
PF (3G)
A = Overhead (PE) (4G)

B = Horizontal overhead (PD)
C = Horizontal (PC) (ZG)
D = Horizontal vertical (PB)
E = Flat (PA) (1G)
a)
vertical position(pipe fixed horizontal) = PF,PG = 5G
b)
inclined position fixed = H - L 045 = 6G
45
c)
inclined position rotated = L45/PA = 1 FR
45
Vertical down
PG (3G)
WELDING PROCESS
1)
a)
General
Welding is the process of joining two or more pieces of material together by
bringing the atoms of each piece into such close contact that an atomic bond
takes place, i.e: the separate pieces fuse together to form one.
2)
a)
Type Of Welding
Smaw = shielded metal( menyelamatkan logam) Arch welding( lengkungan
menyatukan) (AWS)
Mma = manual metal Arch (BS)
b)
GTAW = gas tungsten Arch welding (AWS)

TIG = tungsten inert - gas (BS)
c)
GMAW = gas metal Arc welding (AWS)

MIG = metal inert-gas (BS)
MAG = metal active- gas (BS)
d)
SAW
e)
FCAW = flux cored Arc welding
f)
PAW
= plasma Arc welding
g)
ESW
= electroslag welding
= submerged Arc welding
WELDING PROCESS
2a)
1
2
3
4
5
6
7
8
Manual Metal Arch & Shielded Metal Arc Welding

Process Characteristics
Process Diagram
Equipment Diagram
Variables
Consumables
Typical detects
Advantages & Disadvantages
Safety
mma is an arc welding process, uses an arc between a molten tip of convered
electrode to the base metal (OR) mma is an arc welding process, uses an arc
between an electrode with flux covering to the weld pool.
manual welding process.
mma, type of power source is constant curent or drooping arc characteristics.
a)
b)
c)
Y
20
15
100 105
O.C.V. (open circuit voltage)

I
:- MMA, TIG, SUB-ARC > 1000 Amps

2
Process Diagram
Power supply
1 OR 3
Power source
( Constant Current)
Electrode
welding cable
Return cable
Ground cable
Base
metal
Welding
table
WELDING PROCESS
3
a)
b)
c)
d)
4
Types of welding machine (Plant)

Transformer
Dc Rectifier
Engine Driven
Inverter
Type of flux covering used
a)
Basic = E 7018 CO
b)
c)
Rutile = E 6013 CO
Cellulose = E 6010 H
a)
b)
c)
d)
e)
6
a)
b)
c)
Functions of flux covering

To provide shielding gas to the weld pool to avoid atmospheric contamination.
To stabilise th arc
Easy to strike the arc
Improve the mechanical properties of weld metal
Act as deoxidiser by addition of xlloying elements ( e.g : silicon)
Types of polarity
DC + = (Direct current reverse polarity)
DC - = (Direct current staight polarity)
AC = (Alternative current)
DC +
DC -
* Shallow Penetration
WELDING PROCESS
7
a)
b)
c)
d)
e)
f)
8
Variables
Current
Voltage
Travel Speed
Electrode andle
Open circuit voltage ( O.C.V)
Polarity
Consumables
a)
Size : - min 1.6 mm & max 8 mm
b)
c)
d)
Type : - basic, rutile, cellulose or iron powder

Condition : - concentricity, laps, chips
Stroge & handling : (i) E 7016/ E 7018 = Basic = 1) Baked at 350C - 1 Hour OR as
per manufacturer Recommendation.
2) Holding oven at 150C
3) Quiver at 70C - 80C
(ii) E 6010/ E 6011 = Cellulose = 1) Never bake or what so ever ( Organic
compound + titania )
(iii) E 6013 = Rutile = 1) may be dried at 120C - 1 hour ( titania)
Materials
a)
Size : - min 3.0 mm & max 25.0 mm
b)
Type : - carbon steel, alloy steel, stainless steel
c)
Condition : - some tolerance on the surface preparation
10
a)
b)
c)
d)
e)
f)
Safety
Fumes
Electric shock
Burn skin
Arc rays
Fire
Explosion
WELDING PROCESS
11
a)
b)
c)
12
a)
b)
c)
13
Welder Contorls
Arc length
Angle of electrode
Speed of travel
Main Electrode Covering Types
Rutile = general purpose > 20 ml / 100 g
Basic = low hydrogen < 10 ml / 100 g
Cellulose = deep penetration / fusion = up to 70 ml / 100 g
Typical Of Detects
Overlap, porosity, slag inclusions, excessive spatter, stray flash, incomplete
penetration, excess penetration, undercut, crater cracks and lack of fusion.
14
a)
15
a)
Current ( amperage)- control the depth of penetration

Amperage too low = poor penetration (tembusan) or fusion, unstable arc,
irregular(tidak sama) bead shape, slag inclusions, parasity,
electrode freezes to the weld, possible stray arc- strikes.
Voltage
Voltage too low = poor penetration, electrode freezes to work, possible stray arcs,
fusion detects, slag inclusions, unstable arc, irregular bead shape.
b)
Voltage too high = Parasity, spatter, arc wander, irregular bead, slag inclusions,
very fluid weld pool, positional welding difficult.
16
Speed of travel - the speed of travel affects heat input and therefore also effects
metallurgical and mechanical conditions.
a)
Travel speed too fast = norrow thin bead, slag inclusion, fast cooling,
(metallurgical problems), undercut, poor fusion/ penetration.
b)
Travel speed too slow = excessive deposition, cold laps, slag inclusions, irregular
bead shape.
WELDING PROCESS
Advantages
17
a)
b)
c)
d)
e)
f)
g)
h)
i)
18
a)
b)
c)
d)
e)
f)
g)
h)
19
can be used in any welding position

cheap welding equipment
choice of consumable
no need gas for shielding
versatile ( can use anywhere)
simple equipment
simple set-up, easy to use
can be used to weld thin material
wide range of consumables
Disadvantages
low productivity
wastage of consumable
need proper interpass cleaning
produce fumes
not suitable for reactive material ( tatinium or zirconium)
need oven to bake or dry the electrode
not suitable for thick material
high skill welder required
Equipment Diagram
A
1
B
1
C
1
D
1
E
1
F
1
G
1
H
1
I
= Consumables electrode
= Core wire
= Arc
= Flux covering
A
1
D
F1
B
1
E
C
1
= Evolved gas shield

=
=
=
=
Slag
Parent metal
Weld pool
Weld metal
I1
H
1
G
1
WELDING PROCESS
2b)
1
1
2
1
3
1
4
1
5
1
6
1
7
1
1
a)
b)
c)
Tungsten inert - gas & gas tungsten arc welding

Process Diagram
Types of tungsten
Variables
Types of detects
Safety
TIG is an arc welding process usess an arc between a non- consumable electrode to
the weld pool.
TIG may be used with or without filler rod ( Autogeneous)
Type of power source is constant current or dropping arc characteristic.
u
O.C.V (open circuit voltage)
I
:- Increase voltage, small changes in current
1
1
1
1
2
1
3
1
d)
e)
- Arc blow/ wander

arc blow is the deviation of the arc due to magnetic influnes.
- To control arc blow
if the procedure allows change to welding current from d.c to a.c
3300C to melting electrode/ filler root
1200C to melting molten pool
TIG is a manual welding process but if can be mecharised.
Tecnique to initiate the arc : 1) scratch start
2) high frequency start
3) pulsed start
4) lif-up start
WELDING PROCESS
2
1
Process Diagram
Power supply
1 or 3
regulator
gas
silinder
Power source ( c.c )

filler rod
welding cable
base metal
return cable
welding
table
earth
3
1
a)
Types Of Tungsten
THORIATED (Red colour)
1 % = High current
2 % = Low current
} steel DC -
b)
ZIRCORNIATED (Bround / grey colour)

- AL - magnezium = AC
c)
CERIATED (Orange colour)
+ dageours caused cancer
- STEEL = DC d)
LATHANUM (Black colour)

- STEEL = DC -
i.e :
AC - AI, mg
DC - Steel
Grind
Grind
WELDING PROCESS
4
1
a)
b)
c)
5
1
Types Of Polarity
DC + (Direct Current Reverse Polarity)
DC - (Direct Current Straight Polarity)
AC ( Altternative Current) - All mg
} steel
Affects of polarity
DC +
DC -
AC
1) Electric charactertics
(+)
(+)
(+)
(-)
(-)
(-)
(-)
2) Heat distribution
2/3
(heat
)
1/3
1/2
(-)
(+)
2/3
1/2
3) Penetration
shallow
6
1
a)
b)
7
1
a)
b)
Types of welding machine

Transformer/rectifier
Inverter
Types of torch
Air cool torch
Water cool torch
deep
moderate
WELDING PROCESS
8
1
Equipment Diagram
A1
C1
B1
K1
G1
D1
E1
F1
J1
9
1
a)
b)
c)
d)
10
A = current conductor
B = shielding gas in
C = welding torch
D = contact tube
E = non consumable tungsten electrode
F = gaseous shield
G = welding wire
H = arc
I = weld metal
J = optional copper backing bar
K = gas nozzle
H1
Types of gas
Argon = Low ianisation, stable arc, easy to start the arc
Helium = Hotter arc, less stable, deep penetration
Argon + Helium
Argon + H2 ( stainless steel
Variables
a)
b)
current
voltage
11
Consumable
a)
b)
c)
size : -min 1.6mm - max 4.0 mm

type : -as per parent metal
condition : -store at clean and dry area or keep inside it orginal container.
12
a)
b)
c)
c)
d)
travel speed
gas flow rate
d)
e)
f)
electrode extension
torch angle
polarity
Material
size : -min 1mm - max 15mm
type : -can weld most materials including reactive material such as Ti and ZR
condition : -must be very clean
WELDING PROCESS
13
Advantages
a)
b)
c)
d)
e)
f)
g)
smooth weld profile

minimal cleaning required
suitable for thin material
can be used for out of position
high quality welding process
less wastage of consumables
low hydrogen
14
a)
b)
c)
d)
e)
f)
15
Disadvantages
high skill required
complex welding machine
h.frequency start can interfere the electronic devices
o zone (gas)
not suitable for thick material
low productivity
Types of detects
a)
b)
c)
d)
e)
tungsten inclusion
silica inclusion (ferritic steel)
porosity
solidification crack (autogenous TIG with fusible insert ring)
root concavity
f)
crater pipe
g)
arc strike
16
a)
b)
c)
d)
e)
f)
Safety
arc rays
fumes
burn skin
electric shock
fire
explosion
WELDING PROCESS
2c)
Gas Metal Arc Welding & Metal Inert-Gas & Metal Active- Gas
1
1
2
1
3
Process characterics
Modes of transfer
Process diagram
Equipment diagram
Advantages & disadvantages
Variables
Typical of detects
Safety
1
4
1
5
16
1
7
81
1
1
1
a)
b)
Process characterics
MIG process, normally gas used : -Argon, Helium, Ar + Helium
MAG process, normally gas used : -CO , CO + Argon
2
: -Argon + O ( stainless steel)

2
c)
d)
MIG/MAG is an arc welding process used an arc between a continous filler wire to
the weld pool.
Type of power source is constant voltage or flat characterictics.
v
2V - 2V
Eregeny
100
200
100 A Gauges
2
1
a)
b)
Modes of transfer
short circuiting or diptransfer : -voltage <2Z amperage <200
(for thin materials and all welding position)
spray transfer : -voltage >27 amperage > 220
(i) (for thick materials and high deposition, non ferrous( AL,mg))
(ii) (flat and horizontal welding position)
(iii) (argon or helium as a shielding gas >80 %)
WELDING PROCESS
c)
globular transfer : -(i) (between dip & spray transfer current)

(ii) (mechanized,co2 shielding gas,spatter level high)
d)
pulsed transfer : -(i) (utilised spray transfer during high current and low current for
background current)
(ii) (thin & thicker material welding, better fusion, low heat input)
}
2
3
1
more spatter caused high current & nozzle touch

parameter, avoid to not touch nozzle with
parameter
not torch,just high current to spray
Process diagram
Power supply
1 or 3
regulator
Power source
gas
silinder
Wire feeder
Wire spool
Torch
welding cable
base metal
return cable
Ground
earth
welding
table
WELDING PROCESS
4
1
Equipment diagram
A1
A1
B1
C
B1
C1
D1
E
E1
F1
G
5
1
Type of welding machine

Transformer/ rectifier
Inverter
6
1
Type of welding torch

Air cool (steel & thin material)
Water cool (all & thick)
7
1
Type of condiut linear

Steel linear - steel
Teflon or nylon - AL
a)
b)
a)
b)
a)
b)
8
1
Type of roller
V Groove - steel
U Groove - AI
Knurled - FCAW
9
1
Variables
a)
b)
c)
G1
~Gas nozzle
~Contact tube
~Nozzle to work distance
~Arc length
~Electrode extension
~Contact tube to work distance
~Work piece
a)
Current
b)
c)
d)
e)
f)
g)
Voltage
Travel speed
Electrode ectension
Gas flow rate
Contant tube to work distance
Nozzle to work distance
10
Consumables
size : -min 0.8mm - max 1.6mm
Type : -as per parent metal
Condition : -store at clean and dry area or keep inside it orginal container
a)
b)
c)
WELDING PROCESS
11
a)
b)
c)
d)
12
a)
b)
c)
13
a)
b)
c)
d)
e)
f)
g)
Type of gas
CO (deeper penetration)
Argon (for non-ferrous material{aluminium} / not suitable for steel because poor
cap profile)
Helium
Argon + CO (less spatter butt less penetration)
Types of material
Size : -min 0.8mm - max 15mm
Type : -carbon, alumi, stainless steel & alloy steel
Condition : -moderate cleaning
Type of detects
Lack of sidewall fusion (dip transfer)
Solidification cracking (spray transfer)
Porosity
Undercut
Spatter
Crater pipe (star)
Silica inclusions (ferritic steel)
a)
b)
c)
d)
Safety
Arc rays
Fumes
Burn skin
Electric shock
e)
Fire
f)
Explosion
15
Advantages
less wastage of consumables
high productivity
can weld thin and thick materials
can weld most materials
range of modes of metal transfer
can be used for out of position (all welding position) < dip transfer spray } check
can be magenacel
minimum cleaning
14
a)
b)
c)
d)
e)
f)
g)
h)
WELDING PROCESS
16
a)
b)
c)
d)
e)
f)
g)
h)
2d)
1
1
2
1
3
4
1
5
1
6
1
7
1
8
1
9
1
1
1
a)
Disadvantages
expensive welding machine
need gas for shielding
a lot of spatter (dip transfer)
difficult to manipulate the torch
high maintenance
high o zone level
need proper shielding when use on site
not suitable for restricted access
Submerged Arc Welding
Process characteristics
Types of flux
Types of power source
Types of polarity
Variables
Consumables
Materials
Types of detects
b)
SAW is an arc welding process uses an arc between a continous bare wire to the
base metal.
The arc is shielded by a fused or aglomerated flux.
c)
The arc and molten weld metal are completely submerged beneath the layer of
shielding flux and are not visible to the eye, protection against the arc light is
d)
2
1
a)
therefore unnecessary.
Submerged arc welding is normally fully mechanised,but may be used manually or
in a fully automatic mode.
Types of flux
Fused : - (i) flacky appearance
(ii) high resistance to moisture absorbtion
(iii) good recycle
(iv) smooth profile
(v) good properties
WELDING PROCESS
b)
3
1
a)
b)
c)
d)
e)
f)
g)
Aglomerated : -(i) granular appearance

(ii) very good mechanical properties
(iii) need to bake prior to use- 400C - 1 hour or per manufacturer
recommendation
(iv) high weld quality
(v) easy slag removal
(vi) smooth weld profile
Functions of flux
to provide shielding gas to avoid atmospheric contamination
to stabilise the arc
to improve the properties of the weld metal by addition of alloying elements
to add deoxidant to avoid surface contamination
current control the depth of penetration
voltage control the bead shape
- (i) increase voltage = more flux melting
= change the properties
Welding head arrangement
- (i) single head with single wire
-(ii) single head twin wire
-(iii) tandem wire
A1
C1
h)
B1
A1
B1
C1
Granular flux
Electrode
Copper contact block connected to
power supply unit
WELDING PROCESS
4
1
Process diagram
Power supply
1 or 3
Power source
Flux
Torch
welding cable
base metal
return cable
Ground
earth
5
1
Types of power source

constant voltage < 1000A
constant current > 1000A
6
1
Types of polarity
a)
b)
a)
b)
c)
7
1
DC + = (deep penetration)
DC - = (higher deposition)
AC = (prevent arc blow at higher current)
Variables
a)
current
b)
voltage
c)
d)
e)
f)
g)
travel speed
electrode extension
wire size
flux depth
direction of travel
8
1
a)
b)
c)
d)
welding
table
Consumables
Size : -min 2.0mm - max 4.0 mm
Type : -as per parent metal
Condition : -size,store dry and clean area or keep inside it orginal container(wire)
Flux : (i) fused : -no bake required
(ii) aglomerated : -baked as per manufacturer recommendation
WELDING PROCESS
9
1
Materials
Size : -min 6mm - max 15.04mm
Type : -carbon, stainless steel, alloy steel
Condition : -moderate cleaning
10
1
Types of detects
Solidification
Excessive weld metal
Burnthrough
Porosity
Lack of sidewall fusion
Slag inclusions
Root cancavity
Undercut
11
Advantages
Flux can be recycle
Low weld metal cost
Easily automated
Low levels of o zone
High productivity
No visible arc light
12
1
Disadvantages
Restricted welding positions
Arc blow on DC current
Shrinkage defects
Difficult penetration control
a)
b)
c)
a)
b)
c)
d)
e)
f)
g)
h)
a)1
b)
c)
d)
e)
f)
a)
b)
c)
d)
WELDING PROCESS
3)
Type of current
a)
constant current or drooping arc characteristics

* when voltage increase,current will be
change
Current large
change
I
b)
constant voltage or constant potential or flat characteristic

V
Duty cycle % = the ratio of arc time to the total time base on 10 minutes.
Everywelding have (O.C.V)
O.C.V ( AC = ~120V OR DC = ~80V )
~ = 60% Duty cycle at 350A

desired current = 400A ?
~ = Duty cycle % = (rated current / desired current) x rated duty cycle
100% = ((rated current) / (desired current)) x rated duty cycle
(desired current) = (rated current) x rated duty cycle
= (350) x 0.6
= 271A
4)
a)
b)
c)
d)
4 factor before welding

current
avoid atmospheric (shielding gas from flux covering)
provide the oxidization
sound weld
WELDING PROCESS
5)
Fusion welding factor( 4 factors 'essential' for fusion welding )
a)
b)
fusion is achieved by melting using a high intensity heat source.

the welding process must be capable of removing any oxide and contamination
from the joint.
atmosphere contamination must be avoided.
the welded joint must process the mechanical properties required by the
specification being adapted.
c)
d)
6)
a)
b)
c)
Type of polarity
AC = Altternative current
DC + = Direct current electrode positive/ direct current srect positive
DC - = Direct current electrode negative / direct current reverse negative
a
AC
50%
= Even
50%
+
b
70%
DC +
= (+) more
-
30%
30%
c
DC -
= (-) more
(work piece (+)/ torch(-) for melt electrode
70%
6)
<Sample>
1)
GTAW = usually used DCEN (-)

Reason : - a thickness of material
no excess for grind and re-weld at another side of welding such
b
as piping.
2)
SMAW = usually used DCEP(+)

Reason : most efficient for fast deposited weld metal.
a
3)
FCAW & SAW = usually used DCEP(+)

Reason : most efficient for fast deposited weld metal.
a
WELDING IMPERFECTIONS
1
1
Imperfections
any discontiniuties that the size below the "ACCEPTANCE CRITERIA" of
"CODE & SPECIFICATIONS"
2
1
Defects
any discontiniuties which the size above the "ACCEPTANCE CRITERIA" of any
"CODE & SPECIFICATIONS".
defects can be lead to : -(i) Brittle failure
(ii) Fatigule failure
(iii) Stress concentration area(initiation point)
defects : -(i) volumetric(3 dimensional),type of defects which produce less stress
raisers.
(ii) planar(2 dimensional),type of defects which produce significance stress
raisers.
a)
a)
b)
c)
3
1
Definition
This is achieved as long as the following features apply:
Welds should consists of solid metal throughout a cross section at least equal to
that of parent metal.
(ii) All parts of a weld should be fully fused to the parent metal.
(iii) Welds should have smoothly blended weld.
a)
(i)
4
1
a)
Weld Defects
Defects which may be defected by visual inspection can be grouped under seven
headings.
~
~
~
~
~
~
~
Root defects
Contour defects
Surface irregularities
Cracks
Lack of solid metal
Lack of fusion
Miscellaneous
5
1
Cracks
a) Process cracks
(i) Haz hydrogen cracking
(ii) Weld metal hydrogen cracking
(iii) Solidification cracking
(iv) Lamellar tearing
b)
(i)
Caused generally, classified by shape and position

~ classified shape = longitudinal
~ classified position = HAZ
Longitudinal parent metal cracks
(ii)
~ classified shape = transverse
~ classified position = centreline(hot cracks)
Transverse weld metal cracks
(iii)
~ classified shape = longitudinal
~ classified position = centreline(hot cracks)
Longitudinal weld metal cracks
(iv)
~ classified shape = chevron
~ classified position = fusion zone
Lamellar tearing
(v)
~ classified shape = brached
~ classified shape = crater
Crater cracks
6
1
~
*
*
~
*
*
a)
Incomplete penetration
other terms for the some defects are :
lack of penetration
lack of root penetration
in the case of double sided welds terms :
lack of inter-penetration
lack of cross- penetration
Face
(i)
Incomplete filled groove
(ii)
Poor cap profile
(iii)
Incomplete filled groove(+) lack of sidewall fusion
b)
(i)
Root
Incomplete root fusion
(ii)
Incomplete root penetration
(iii)
Lack of interun fusion
7
1
a)
1)
2)
3)
4)
5)
6)
7)
b)
Causes Of Weld Defects

Incomplete root penetration
Causes
root faces too large
root gap too small
arc too long
wrong polarity
electrode too large for joint preparation
incorrect electrode angle
travel speed too high for current
Root Concavity
~ A shallow groove,which may occur in the root of a butt weld
1)
2)
3)
4)
5)
Causes
Insufficient arc power to produce positive bead
Excessive backing pressure(GTAW)
Lack of welder skill
Slag flooding in backing bar groove
Root face too large
c)
Underfill / Incomplete filled groove
A weld with thickness less than that of the parent metal

Causes
1)
2)
Insufficient weld metal

Irregular weld bead surface
d)
Inter-run imperfections
~ Irregular along the fusion line between weld beads
Causes
Low arc current resulting in low fludity of weld pool
Too high travel speed
Inaccurate bead replacement
Poor inter-run cleaning
1)
2)
3)
4)
e)
1)
2)
3)
4)
5)
f)
1)
2)
3)
4)
g)
Lack of root fusion

~ Failure of weld to extend into root of a joint
Causes
Excessively thick root face, insufficient root gap or failure to cut back sound metal in
a "back gauging" operation
Low heat input
Excessive inductance in GMAW dip transfer
SMAW electrode too large(low current density)
Use of vertical down welding
Lack of side wall fusion
~ Lack of fusion between weld metal and parent metal at one side of weld
Causes
Low heat input to weld
Molten metal following a head of arc
Oxide or scale on weld preparation
Excessive inductance in GMAW dip transfer welding
1)
2)
3)
4)
Excess weld metal (reinforcement)

~ Reinforcement is the extra metal which produces convevity in fillet welds and a
weld thickness than the parent metal plate in butt welds.
Causes
Excess arc energy (GMAW,saw)
Shallow edge preparation
Faulty electrode manipulation
Incorrect electrode size
h)
Excess penetration
~ Projection of the root penetration bead beyond a specified limit
1)
2)
3)
4)
Causes
Weld input energy to high
Incorrect weld preparation i.e, excessive root gap, thin edge preparation & lack of
backing
Use electrode unsuited to welding position
Lack of welder skill
i)
1)
2)
3)
Root coking / oxidized root

Causes
Loss or insufficient back purging gas
Most commonly occurs when welding stainless steels
Purging gases include argon, helium and occasionally nitrogen
Welding process : TIG

Material
: Stain less steel
Plate/pipe linear misalignment

(HI - LO)
j)
1)
2)
3)
4)
5)
Poor fit-up
Angular misalignment
Gas pores/porosity
~ Gas pores trapped within the weld metal
~ Formed by entrapped gas during the solidification of molten metal
~ Other terms which relate to entrapped gas in welds are :
* Blowhole = a cavity generally over 1.5mm
* Wormhole (piping) = an elongated or tubular cavity
* Hollow bead = elongated porosity in the root bead (pipe line terminology)
* Herving bone porosity = wormholes side by side taking on a herring bone pattern
Causes
Damp fluxes/corroded elctrode
Grease/hydrocarbon/water contamination of prepared surface
Air entrapment in gas shield
Too high arc voltage/ arc length
Incorrect/ insufficient deoxidant in electrode, filler or parent metal
k)
1)
2)
3)
4)
l)
1)
2)
3)
4)
5)
m)
Surface porosity
~ Gas pores which break the surface of the weld
Causes
Damp or contaminated surface of electrode
Low fluxing activity
Excess sulphur (particularly free-cutting steels) producing sulphur oxide
Loss of gas shield gas due to long arc or high breezes(GMAW)
Crater pipe
~ other terms for the same defects are :
* crater crack
* star crack
~ A shrinkage cavity at the end of a weld run where the arc is terminated (the welder
remove the welding holder were fast from parent metal)
Causes
Lack of welder skill due to using process with too high current
Inoperative crater filler (GTAW)
Too fast a coding rate
Deoxidization reactions and liquid to solid volume change
Contamination
1)
Arc strikes
~ Random area of fused metal where the electrode, the holder, or current return
clamp accidentally touched the work and produced a short duration arc
Causes
Poor access to work
2)
Missing insulation on electrode holder or torch
3)
Failure to provide on insulated resting place for the electrode holder or torch when
4)
not is use
Loose current return clamp
n)
1)
2)
3)
4)
Spatter
~ small droplets of electrode material can be projected clear of the weld and may
fused to the parent metal
Causes
High arc power
Magnetic arc blow
Incorrect setting for GMAW process
Damp electrode
o)
1)
2)
3)
4)
p)
1)
2)
3)
4)
q)
Undercut
~ An irregular groove at the toe of a run in the parent metal or in previously deposited
welding,
Causes
Melting of top edge due too high welding current (especially at free edge) or high
travel speed
Attempting on HV fillet weld leg length > 9mm
Excessive / incorrect weaving
Incorrect electrode angle
Overlap
~ An imperfection at the toe of a weld caused by metal flowing on the surface of the
parent metal without fusing to it,
Causes
Poor electrode manipulation
High energy input/ low travel speed causing surface flow of fillet weld
Incorrect positioning of weld
Electrode having too high a fluidity
Misalignment
~ The non-alignment of two abutting edges in a butt joint
1)
2)
* Linear misalignment
* Angular misalignment
Causes
Inaccuracies in assembly procedures or distrotion from other welds
Excessive "out of flatness" in hot rolled plate or sections.
r)
Burn through
1)
2)
3)
4)
~ a localized collapse of the weld pool due to excessive penetration resulting in a hole
in the root run
~ RT film = burn through = black
Causes
High amps/ volts
Small root face
Large root gap
Slow travel speed
s)
Inclusions
~
*
*
*
~
1)
2)
3)
4)
5)
8
1
They are 3 types of inclusions

Slag inclusions
Tungsten inclusions
Copper inclusions
Slag or other matter trapped during welding. The imperfection is of an irregular
shape and thus differs in apperance from a gas pore
Causes
Heavy mellscale, rust on work surface
Incomplete slag removal from underlying surface of multipass weld
Slag flooding a head of the arc
Entrapment of slag in work surface
Unfused flux due to damage coating
Type of defects, suitbe record for exam
~ mechanical damage can be defined as any surface material damage cause during
the manufacturing process
Defects Type
Porosity
Cluster parosity
Undercut
Lack of sidewall fusion
Excessive weld metal
Underfill /incomplete filled groove
Burn through
8) Spatter
Record
only
Area (L,W)
L,D
L Only
L,H
L,D
L Only
9) Overlap
L Only
1)
2)
3)
4)
5)
6)
7)
10)
11)
12)
13)
14)
15)
16)
17)
18)
19)
20)
Arc strike
Mechanical damage
Crack
Lack of root fusion
Excessive Penetration
Root concavity
Poor cap profile
Linear misalignment
Poor stop /start
Crater pipe
Slag inclusions
Area (L,W)
Area (L,W)
Area (L,W)
L Only
L Only
L,H
L,D
L Only
L,H
L,H
Only
L,W
MECHANICAL TESTING
1
1
Mechanical testing is destructive testing of welded joints are usually carried out to :
Approve welding procedures
Approve welders
Production quality control
2
1
Definition of mechanical testing

The ultimate means by which the mechanical strength and toughness of a prepared
test object can be determined by subjecting it to mechanical forces beyond the limits
of its own mechanical resistance.
3
1
Properties of steel
~ mechanical properties :
Hardness - a measure of the resistance to penetration
Tensile strength - a metal's ability to with stand stress in tension
Compresive strength - a metal's ability to with stand a pressing or squeezing together
Shear strength - a metal's ability to resist a sliding past type of action
Fatigue strength - ability to take repeated loading
Toughness - ability to resist shock
Ductility - ability of a metal's to stretches before it breaks
Brittleness - metal does not stretches before it fracture
a)
b)
c)
a)
a)
b)
c)
d)
e)
f)
g)
h)
4
1
a)
b)
Mechanical testing is the following test have units and are termed qualitative tests
Macro testing
Bend
5
1
Hardness testing
hardness test for measurements made by indenting the metal with a penetrator under
a known load
b) determined by :
(i) load applied
(ii) how load is applied
(iii) configuration of penetration
a)
c)
(i)
(ii)
(iii)
(iv)
Various methods
Brinell
Rockwell
Vicker
Knoop
MECHANICAL TESTING
c(i)
~
~
~
BRINELL HARDNESS TESTING

Hardned steel ball of given diameter is subjected for a given time to a given load
Load divided by area of indentation given Brinell hardness in kg/mm
More suitable for on site hardness testing
HB =
P
D
c(ii)
~
~
c(iii)
~
~
~
X ( DD - a
D = Size of indentor
d = Depth of indentation
P = Load
ROCKWELL HARDNESS TESTING

Measure the hardness by the depth on indentation made by a constant load
impressed upon the indentor
Most common indentor is a diamond, ground to 120 degree cone with spherical
VICKERS HARDNESS TESTING (micro skop)
square based pyramid
indenter pressed into specimen with a lead of between 1 and 100kg for 15 seconds
length of diagonals measured using adjustable shutters and a built in microscope
HV = 1.825 P = 350VPN
d
c(iv)
KNOOP MICROHARDNESS TESTING
This test is similar principal to brinell and vickers
Utilised low load that less than 1 kg
6
1
~
a)
Charpy Impact test

objectif of test
to determine the amount of energy absorbed in fracturing a standardised test place
MECHANICAL TESTING
J
Ductile
T(c)
-20
-10
carbon
10
20
Brittle change to ductile

1
1
2
1
3
1
4
1
b)
Specimens are usually taken in groups of there to allow for scatter results
Test temperature should be specified
Test result are give in joules
Tough specimens absorb more energy than brittle specimens
Charpy Impact Test (size of specimen)
45
2 mm
10
10
55
c)
root radius 0.25mm
Izod Impact Test

Direction of impact
TEST SPECIMEN
28 mm
Vice type fixture
d)
~
1
1
2
1
3
1
4
1
5
1
6
1
2 mm
10 mm
Comparison of charpy test result (Bcc material)

Reporting results
Location and orientation of notch
Testing temperature and soaking time
Energy absorbed in joules
Description of fracture(brittle or ductile)
Lateral expansion
Dimension of specimen
75 mm
30
MECHANICAL TESTING
7
1
Tensile Test
a) Various methods
(i) Transverse tensile
(ii) All - weld metal tensile test
(iii) Cruciform tensile test
(iv) Short tensile test
a(i)
~
~
TRANSVERSE TENSILE TEST

Objectif of test : to measure the transverse tensile strength of a butt joint under a
static load.
Maximum load applied = 220 KN
Least cross sectional are = 2.5mm x 12mm
u.t.s
= maximum load applied = u.t.s = 733.33 N/mm

Least c.s.a
1
1
2
Reporting results
Type of specimen ( e.g - reduced section)
Whether weld reinforcement is removed
Dimensions of test specimen
1
5
1
6
The ultimate tensile strength in N/mm, psi or mpa

Location of fracture
Location and type of any flows present if any
1
3
1
4
a(ii) ALL - WELD METAL TENSILE

~ Object of test
1
Ultimate tensile strength
1
2
1
3
1
Yield stength
Elongation % (ductility)
Elongation = EXTENSION
X 100
ORGINAL LENGTH
original gauge length = 50mm

increased gauge length = 64
Elongation % = Increase of gauge length

original gauge length
X 100
(144.9 psi 1 N/mm)
MECHANICAL TESTING
~
Elongation % = 14 X 100
50
Elongation = 28 %
Reporting results
Type of specimen (e.g. reduced section)
Dimensions of test specimen
The u.t.s, yield
1
1
2
1
3
1
8
1
1
1
2
1
3
~
a
1
b
c
1
d
1
e
1
4
~
a
1
b
1
c
d
1
e
9
1
~
a)
b)
(i)
(ii)
(iii)
Macro/ Micro
Objectif of test
Macro/microscope examinations are used to give a visual evaluation of a
cross- section of a welded joint.
Carried out on full thickness specimens
The width of the specimen should include HAZ, weld and parent place
test :- macro
cut the specimen
grind of file
polishing ( P200,P400,P600,P800,P1200)
etching nital - 2% - 5% (1% - 2%)
magnification x 10 ( x1000)
They maybe cut from a stop/ start area on a welders approval test
macro/micro (will reveal)
weld soundness
distribution of inclusions
number of weld passes
metallurgical structure of weld,fusion zone and HAZ
location and depth of penetration of weld
Bend Test
object of test
To determine the soundness of the weld zone. Bend testing can also be used to
given an assessment of weld zone ductility
There are three ways to perform a bend test :
Face bend
Root bend
Side bend (generally for materials above 12mm thickness)
MECHANICAL TESTING
Compression
Tension
~
1
1
2
1
3
1
4
1
5
1
Reporting result
Thickness and dimensions of specimen
Direction of bend (root,face or side)
Angle of bend (90,120,180)
Diameter of former (typical 47T)
Appearance of joint after bending (e.g. type and location of any flaws)
~
a)
b)
c)
d)
e)
Fillet Weld Fracture Test

objectif of test
to break open the joint through the weld to permit examination of the facture surfaces
specimens are cut to the required length
a saw cut approximately 2mm in depth is applied along the fillet welds length
fracture is usually made by striking the specimen with a single hammer blow
visual inspection for defects
~
a)
b)
Reporting results
Thickness of parent material
Throat thickness and leg length
c)
Location of fracture
d)
Appearance of joint after fracture
e)
f)
Depth of penetration
Defects present on fracture surfaces
10
1
MECHANICAL TESTING
~
a)
b)
c)
d)
e)
Nick Break Test

Objectif of test
to permit evaluation of any weld defects across the fracture surface of a butt weld
specimens are cut transverse to the weld
a saw cut approximately 2mm in depth is applied along the welds root and cap
fracture is usually made by striking the specimen with a single hammer blow
visual inspection for defects
~
a)
b)
c)
d)
e)
Reporting results
Thickness of parent material
Width of specimen
Appearance of joint after fracture
Depth of penetration
Defects present on fracture surfaces
11
1
WELDABILITY
1
1
a)
(i)
(ii)
Factors which affect weldability

Design
access
restraint
b)
(i)
(ii)
Metallurgical properties
structure and properties of the weld metal
structure and properties of the h.a.z
c)
(i)
(ii)
(iii)
(iv)
Physical properties
thermal resistance
coefficient of thermal expansion
elastic modulus
viscosity of molten material
d) Chemical properties
(i) oxidation resistance
(ii) surface films
(iii) impurities
2
1
a)
(i)
(ii)
(iii)
Classification of steel
Plain carbon steels
low carbon steel 0.01 - 0.3%
medium carbon steel 0.3 - 0.6%
high carbon steel 0.6 - 1.4%
b)
~
Plain carbon steels contain only :

iron & carbon as main alloying elements traces of mm,si,AI,S & D may also prevent
c)
~
Alloy
a mixture of two or more elements and one of the element is steel
: Low alloy steels < 7%
: High alloy steels > 7%
Carbon
WELDABILITY
3
1
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
l)
4
1
a)
b)
c)
Steel weld metallurgy

carbon
: major element in steels, influences strength, toughness and ductility
manganase : secondary only to carbon for strength toughness and ductility,
secondary deoxidiser and also acts as a desulphuriser
silicon
: primary deoxidiser
molybdenum : effects hardenability and has high creep strength at high temperature
steel containing molybdenum are less susceptible to temper
brittleness than other alloy steels
chromium : widely used in stainless steels for corrosion resistance, increases
hardness and strength but reduces ductility
nickel
: used in stainless steels, high resistance to corrosion from acids,
increase strength and toughness
aluminium : deoxidiser, grain refinement
sulfur
: machineability
tungsten
: high temperature strength
titanium
: elimination of carbide precipitation
vanadium : fine grain - toughness and strength
cooper
: corrosion resistance and strength
The grain structure of steel will influence its weldability, mechanical properties and
in-service performance. The grain structure present in a material is influenced by :
the type and number of elements present in the material
the temperature reached during welding and or PWHT
the cooling rate after welding and or PHWT
1
1
1
12
1
3
1
4
15
1
2
1 3
1
Liquid solid metal

Corse HAZ (low toughness)
Refine HAZ (improve toughness)
Intercritical HAZ
Tempereded HAZ
4
1
5
1
WELDABILITY
5
1
HAZ
the extent of changes will be dependent upon the following :
material composition
cooling rate, fast cooling higher hardness
heat input, high inputs wider HAZ
the HAZ can not be eliminated in a fusion weld
Formula calcute arc energe
~
a)
b)
c)
d)
ARC ENERGY = V X A
T.Speed
= T.Speed = mm = Heat input

S
= ARC Energy X k(Thermal efficiency)

mma = ~0.8
TIG = ~1.2(Autogenous)
MIG/MAG = ~ 0.8
SUB-ARC = ~ 1.0
~
Question
Amps = 200 Volts = 32
Travel speed = 240mm/min
Heat input
= Amps X volts
Travel speed mm/sec X 1000
Heat input
= 200 X 32 X 60
240 X 1000
Heat input = 1.6 KJ/ mm
WELDABILITY
6
1
Heat Input
a)
(i)
(ii)
high heat input-slow cooling

low toughness
reduction in yield strength
b)
(i)
(ii)
(iii)
Low heat input-fast cooling

increased hardness
hydrogen entrapment
lack of fusion
7
1
a)
b)
c)
d)
e)
Carbon Equipvalent
the C.E of steel primarily relates to its hardenability
higher the C.E, lower the weldability
higher the C.E, higher the susceptibilty to brittleness
the C.E of given material depends on its alloying elements
the C.E is calculate using the following formula
~ C.E = C +
mn
6
cr + mo + v
5
~ Ceq% < 0.4% = No preheat

> 0.4% ~ < 0.6%
> 0.6%
cu + Ni
15
Preheat ~ 150 - 200C

Low H2 consumables
Preheat ~ 300C
Pwht
Low H2 consumables
WELDABILITY
f)
List of elements present in a steel

1
FE = Iron
21
C = Carbon
1
3
mn = manganese
14
cr = chromium
1
5
V = vanadium
6 mo = molybdenum
Ni = nickel
7
8 Si = silicon
9 Ti = titanium
1
10 Nb = niobium
1
11 AI = aluminium
112
Sn = tin
1
13 S = sulphur
14
1
15
1
g)
= phosphorus
cu = copper
List of Gas
1
H = Hidrogen
21 HE = Helium
1
3
NE = Neon
14
Ar
= Argon
1
5 Kr = Kripton
6 Xe = Xeon
7 Rn = Radon
8 F = Fluorin
9
1
10
1
11
1
12
1
13
14
1
15
1
16
CI = Klorin
Br = Bromin
I
= Iodin
O
S
Se
N
P
= Oksigen
= Sulphur
= Selenium
= Nitrogen
= Fosforus
17 C
= Karbon
= Boron
18
WELDABILITY
8
1
a)
b)
c)
d)
Weldability
weldability can be defined as the ability of a material to be welded by most of the
common welding processes,and retain the properties for which it has been designed
a steel which can be welded without any real dangerous consequences is said to
possess good weldability
a steel which can not be welded without any dangerous consequences occuring is
said to possess poor weldability. Poor weldability normally generally results in the
accurrence of some sort of cracking problem
Weldability is a function of many inter-related factors but these may be
summarised as :
1) composition of parent material
2) joint design and size
3) process and technique
4) access
e)
There are many factors which affects weldability

1) material type
2) welding
f)
Other factors affecting weldability are welding position and welding techniques
POST WELD HEAT TREATMENT(P.W.H.T)

T C
900
e)
2
1
a)
b)
c)
3
1
a)
b)
c)
d)
Annealing(slos cool)
c)
d)
Temperin
g
a)
b)
Normalisin
g(AIRCOO
L)
1
1
QUENCHING
723
UPPER CRITICAL TEMPERATURE
LOWER CRITICAL TEMPERATURE
C%
Structural forms of steel

Ferrite : almost a pure iron and has a little carbon and is a very weak steel
Cementite : actually a compound of iron and carbon known as iron carbide
contain lots of carbon,as much as 1.6% - 1.8% or 2%.
It strong and hard.
Pearlite : solid solution,a mixture between ferrite and cementite.
Austenite : It occurs at elevated temperature. It is not magnetic,as the steel heated
to an elevated temperature where it becomes austenite.
It structure changes from Bcc to Fcc.
Martensite : Iron at room temperature that has previously been heated and
suddenly quenched. Martensite is the strongest and hardnest and
more a brittle structures.
All heat treatment are basically cycles of there elements
Heating
Holding (soaking)
Cooling
The relevant variables for heat treatment process, which must be carefully
controlled are as follows
the heating rate
temperature attained
the time at the attained temperature(soak time)
cooling rate

4
1
a)
b)
c)
d)
5
1
a)
b)
c)
d)
e)
f)
Objectif of P.W.H.T
Post weld heat treatments are used to change the properties of the weld metal,
controlling the formation of structure. Pre-heat treatments are used basically to
increase weld ability,control expansion and contraction forces during welding.
PWHT process in which metal in the solid state is subjected to one or more
controlled heating cycles after welding
PWHT is normally carried out for the purpose of stress relief, i.e : the reduction
of localised residual stresses.
This pwht process methods for stress relief of a welded assembly.
The basic heat treatment are :
Annealing
Hardneng/Quenching
Normalising
Stress relieving
Tempering
Pre-heating
5(a) Annealing
~ similar with normalizing except that cooling takes place still more slowly in
temperature controlled oven.
5(b) Hardnenig/Quenching
~ a controlled cooling process which causes metals to harden
~ materials must be heated at any elevated temperature, but if hardness in
important, the materials should be heated above the upper critical temperature
5(c) Normalizing
~ involved heating the material above the upper critical temperature and cooling it
slowly in room temperature
1
1
2
1
3
1
4
1
5
1
6
1
7
1
Annealing & Normalizing

(EFFECTS)
softens
weakens the materials
causes ductility
removes internal stresses
removes distortion trends
removes cracking trends
Is a slow cooling process
Quenching
(EFFECTS)
hardens
strengthens
causes brittleness
causes internal stresses
causes distortion
causes cracking
Is a fast cooling process
5(d) Stress relieving

(a) Stress relief
(i) ~ temperature : 550 to 680 hold for sufficient time
(ii)~ cooling : slow cool in air
(iii)~ resulit : relieves residual stresses improves mechanical properties and
increases toughness,may also be used to reduce hydrogen levels
(b) Post hydrogen release
(i) ~ temperature : approximately 250hold up to 10 hours
(ii) ~ cooling : slow cool in air
(iii) ~ result : relieves residual hydrogen
5(e) Tempering
(i) ~ the process of reheating the steel after hardening or quenching to a temperature
which is below the lower critical temperature followed by any rate of cooling.
(ii)~ tempering is generally done between 149C - 649C and msut be done
immediately after quenching.
(iii)~ norminaly temperature for pwht is 500C - 650C
(iv)~ effects of tempering
a)
b)
c)
d)
e)
f)
g)
h)
Hardness = Decreased
Strength = Decreased
Toughness = Increased
Brittleness = Decreased
Ductility
= Increased
Internal stresses = Decreased
Distortion = Reduced
Cracking = Reduced

5(f) Pre-heating
(1) ~ we can pre-heat metals and alloys when welding for a number of reasons.
Primarily we use most pre-heat to achieve one or more of the following :
(i)
to control the structure of the weld metal and HAZ on cooling
(ii) to improve the diffusion of gas molecules through an atomic structure
(iii) to control the effects of expansion and contraction
(2)~ Pre-heat controls the formation of un-desirable microstructures that are produced
from rapid cooling of certain types of steels. Martensite is a desireable grain
structure very hard and brittle, it is produced by rapid cooling form the austenite
region.
(3)~ Pre-heat temperature depends on
(i) Carbon equipment
ceq% < 0.4 = no preheat
> 0.4 - 0.6 = 100c - 200c
> 0.6 = preheat 300c
(ii)
Combined Thickness
t1
t1
t1
t2
t2
t4
t3
t2
t3
tc = t1 + t2
tc = t1 + t2 + t3
tc = t1 + t2 + t3 + t4
CRACK
1
a)
b)
c)
2
a)
b)
c)
d)
3
a)
b)
c)
4
a)
5
a)
b)
c)
d)
Process cracks
hydrogen induced cold cracking (HICC)
solidification cracking (HOT TEARING)
weld decay
When considering any type of crack mechanism, three elements must be present
for it's occurrence :
Stress = stresses > 0.5 of the yield stress
Temperature = < 300C
Hardness = > 350 VPN
Hydrogen content = 15ml / 100gm of deposited weld metal
Cracks
characteristics
causes influence
controllor avoidavce
Hydrogen cracking
Hydrogen causes general embrittlement and in welds may lead directly to cracking
Hydrogen cracking
causes :
1 microstructure
~ How to control hydrogen cracking(prevention) :

Preheat
Control carbon equivalent
High heat input
Post heat
2
a)
b)
c)
1 HARDNESS > 350VPN(vykers pyramid number)

2 FAST COOLING
3 HIGH CARBON
Stress
Thermal contraction
1
2
Poor joint design
Thickness
~ Stress > 50% of yield strength of parent metal

~ How to control stress cracking(prevention) :
Good fit-up
Pwht
Lowest strength weld metal
CRACK
Hydrogen
1 Hydrogen
2 Hydrocarbon
3 Hydrated oxides
4 Damp flux
a)
b)
c)
d)
6
a)
b)
c)
d)
e)
f)
g)
h)
~ Temperature < 200c

~ How to control Hydrogen(prevention) :
Low hydrogen electrodes
Low hydrogen welding process
Post heat
Clean surface of material
Hydrogen cracking(characteristics)
also known as hydrogen induced cold cracking, delay cracking, underbead cracking
and chevron.
hydrogen is the major influence to this type of cracking.
source of hydrogen may be from maisture or hydrocarbon such as grease, paint on
the parent material, damp welding fluxes or from condensation of parent material.
hydrogen is absorbed by the weld pool from the arc atmosphere.
during cooling,much of this hydrogen escapes from the solidified bead by the
diffusion but some also diffuses into the HAZ of the parent metal.
type of cracking is intergranular along grain boundaries or transganular.
requires susceptible grain structure, stress and hydrogen and low temperature is
reached.
most likely in HAZ for carbon manganese steel and in weld meatl for HSLA steel.
micro alloyed steel
(hydrogen induced weld
metal cracking)
a)
Precautions for controlling hydrogen cracking

Pre-heat, removes moisture from the joint preparations, and slows down the cooling
rate.
CRACK
b)
c)
d)
e)
f)
g)
h)
Ensure joint preparations are clean and free from contamination.

The use of a low hydrogen welding process such as TIG OR MIG/MAG
Ensure all welding is carried out under controlled enviromental conditions.
Ensure good fit-up as to reduce stress.
The use of a pwht with maintaning the pre-heat temperature.
Avoid poor weld profile
use low hydrogen electrodes and baked as per manufacturer instructions.
Solidification cracking
causes :
metallurgical
1
a) wide freezing range sulphur phosporous carbon pick up
b) surface tension can cave depth to width ratio
c) solidification phase ferrite % high heat input
Prevention for metallurgical = (a) wide freezing range

control sulphur and phosphorous + add manganese
control carbon
clean joint preparation
control dilution%
a)
b)
c)
d)
10
Prevention for metallurgical

(b) surface tension &
(c) solidification phase
a)
b)
convex
control depth to width ratio
c)
control ferrite%
11
Solidification cracking
causes
2 mechanical
a) stresses thick materials poor joint design
b) restraint poor fit-up
12
a)
b)
Prevention for mechanical

(a) stresses & (b) restraint
Pre heating
Ensure good fit-up
CRACK
13
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
Solidification Cracking (characteristics)

Also known as hot cracking or center line cracking or crater cracking. Solidification
is observed frequently in castings and in gots can also occur in fusion welding.
Solidification cracking is intergranular type of cracking that is along the grain
boundaries of the weld metal.
It occurs during the terminal stages of solidification, when the stresses developed
across the adjacent grains exceed the strength of the almost completely solidification
weld metal.
Impurities such as sulphur and phosphorous and carbon pick-up from parent metal
increase the risk of cracking.
High joint restraint which produce high residual stress will increase the susceptibility
to this type of cracking.
Occurs during weld solidification process from liquidus to solidum and at the last
area to solidified.
Steels with high sulphur content(low ductility at elevated temperature) where by
produce hot shortness to the weld metal.
Fes form films at the grain boundaries whereby reduce the strength of the weld metal.
Addition of manganese will form mns and forms globules instead of films.(Fes)
Occur longitudinally down centre of weld.
Welding process that most susceptible to this type of cracking are SAW and
MIG/MAG with spray transfer due to high.
A
B
= Solid crack
= Sulfur anrich liqued/filler
= Shrinkage stain
C
14
a)
b)
c)
d)
e)
f)
g)
h)
Precaution for controlling solidification cracking

use low dilution welding process
the use of high manganese and low carbon content fillers
maintain a low carbon content
minimise the amount of stress/restraint acting on the joint during welding
the use of high quality parent materials,low levels of impurities
use proper joint design,use single J instead of single V
clean joint preparations,free from oil,paints and any other sulphur containing
product.
joint design selection depth to width ratios
CRACK
15
16
a)
b)
c)
d)
17
a)
b)
c)
d)
e)
f)
g)
h)
Lamellar Tearing
causes : (a) poor through thickness ductility sulfide or silicate high sulphur
(b) stress poor fit-up poor joint high strength weld metal
(c) hydrogen hydrocarbon hydrated oxides damp flux
(d) Restrain Thick materials
Prevention for lamellar tearing
use Z type material
control sulphur
preheat, casting or forging
low strength weld metal
Lamellar tearing (characteristics)
lamellar tearing has a step like appearance due to the solid inclusions linking up
under the influences of welding stresses.
occurs at beneath of HAZ or near HAZ.
it forms when the welding stresses act in the short transverse direction of the
material (through thickness direction)
low ductile materials containing high levels of impurities are very susceptible.
occurs only in rolled direction of the parent material.
assiociated with restrained,joints subjected to through thickness stresses on
corners,tees and fillets.
presence of elongated stringers such of non-metallic inclusion such as silicates
and sulfides parallel to steels rolling plane will produce poor through thickness
ductility of the plate.
tearing will triggered by this such non-metallic inclusions near the weld or it just
outside HAZ during weld contraction.
i)
susceptible joint types :
Tee fillet weld

(Lamellar Tearing)
CRACK
i)
Precautions for controlling lamellar tearing

The use of high quality parent material,low levels of impurities(Z type material)
Change joint design
Minimise the amount of stress/restraint acting on the joint during welding
The use of buttering runs with low strength weld metal
Hydrogen precautions (e.g. use low hydrogen electrodes)
Shift welding process such as Electro slag welding
Use forging or casting joint
Place soft filler wire between the joint( e.g. T joint to reduce stresses during
expansion and contraction of weld metal)
Pre heating helps on removal of hydrogen on the plate
To avoid stainless steel sensitising temperature (600c - 850c) to hall
18
a)
b)
c)
d)
e)
f)
g)
h)
c > 0.1%
(Do not mix stainless steel material with carbon)
b)
c)
Weld Decay (characteristic)

Weld decay may occurs in unstabilized austenitic stainless steel with carbon content
above 0.1%.
Also known as knife line attack or crack.
Chromium carbide precipitation takes place at the critical range of 600-850C
d)
At this temperature range carbon is absorbed by the chromium,which causes a local
e)
reduction in chromium content by promoting chromium carbides.

Loss of chromium content result in lowering the materials resistance to corrosion
attack allowing rusting to occur.
19
a)
(sensiting temperature).
CRACK
20
a)
b)
c)
21
a)
b)
c)
d)
e)
22
a)
b)
c)
d)
e)
f)
23
a)
b)
c)
d)
e)
,
Precautions for weld decay

The use of a low carbon grade stainless steel (e.g. 304L,316,316L with carbon
content < 0.03%).
The use of a stabilized grade stainless steel( e.g. 321,347,348 recommended for
severse corrosive conditions and high temperature operating conditions).
Standard grades may require PWHT, this involves heating the material to a
temperature over 1100C and quench the material,this restores the chromium
content at the grain boundary, a major disadvantage of this heat treatment is the high
amount of distrotion.
Fatigue Failure(INITIATION POINT + PROPAGATION)
- to avoid fatigue failure :
grinding with burn grinder
P.W.H.T
Painting & coating
Plening
Weld the toe with t.i.g or plasma T.I.G
Fatigue Failure(Characteristics)
Fatigue cracks occur under cycle stress conditions
Fracture normally occurs at a change in section,notch and weld defects(i.e. stress
concentration arc)
All welded materials are susceptible to fatigue cracking.
Fatigue cracking start at a specific point referred to as a initiation point.
The fracture surface is smooth in appearance sometimes displaying beach markings.
The final mode of failure may be brittle or ductile or a combination of both.
Precautions against fatigue cracks
Toe grinding,profile grinding
The elimination of poor profiles.
The elimination of partial penetration welds and weld defects.
Operating conditions under the material endurance limits.
The elimination of notch effects(e.g. mechanical damage cap/ root undercut)
SYMBOLS
1
2
3
1
a)
BS 499 PART 2
BS EN 22533/ISO 2553
AWS 2.4
BS 499 PART 2
Arrow profile
Reference Line
Tail
Arrow Line
Other side information
Arrow side information
b)
Butt Weld profile
SYMBOLS
c)
Fillet weld profile
SYMBOLS
d)
Fillet Weld Dimension
b10
10
10
s = 15
s15
a=7
a7
a = Norminal design throat

b = Leg length
c = Depth of penetration
e)
Intermitent Fillet Weld

n = number of weld
Length of weld
e = Distance between weld element
n X (e)
50
50
100
100
100
v3 x 100(50)
SYMBOLS
f)
Stagered intermittent fillet weld
nx
(e)
other side
g)
Type of Arrow
NDT
WPS
Field weld(site weld)
Welding to be carried out all round

component (peripheral weld)
The component requires NDT Inspection
Addition information,the reference

document is included in the box
Partial penetration single - V-butt
Plug weld
Spot weld
Seam weld
Square butt weld
Single - V butt broad root face
Edge flange weld
10
10
SYMBOLS
h)
Flared flange welding symbols
Joint detail
a)
BS EN 22533 / ISO 2553

Arrow profile
Identification Line(other side information)

reference line(arrow side information)
b)
Butt weld profile
mR
s10
10
Single - V butt with permanent backing strip
SYMBOLS
c)
Fillet weld profile
d)
e)
Type of arrow
Plug weld
Spot weld
Seam weld
Square Butt weld
Steep flanked single- V butt
Surfacing
Arrow profile
Z6
6mm leg
NOTE : fillet weld Z = leg length(EN) / fillet weld b = leg length(BS)
RESIDUAL STRESS
1
Level of residual stress

~ yield strength of parametal at room temperature.
Level of residual stress after P.W.H.T.

~ yield strength of parent metal during P.W.H.T
Disdebion of stress
A'
B'
C'
B'=
D'
C'=
A'=
D'=
4
Normal stress
~ stress arising from a force perpendicular to the cross
Shear stress
~ stress arising from forces which are parallel to and lief in the plane of the cross
sectional are.
Shear stress
example :
most critical (100 % NDT)
RESIDUAL STRESS
6
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
7
a)
b)
c)
Hoop stress
Stress acting circumferentially around a pipe due to internal pressure
Metal contract during solidification and subsequent cooling.

If this contraction is prevented or in hibited.
Residual stress will develop.
The tendency to develop residual stresses increases when the heating and cooling
is localised.
Welding is very localised heating and the presence of liquid and solid metal in
contact can be expected to induce very high levels of residual stresses.
Residual stresses are very difficult to measure with any real accuracy.
Residual stresses are self balancing internal forces and not stresses induced
whilst applying external load.
Stresses are more concentrated at the surface of the component.
The removal of residual stresses is termed stress relieving.
Residual stresses occur in weld in the following directions.
along the weld longitudinal residual stresses.
across the weld transverse residual stresses.
through the weld short transverse residual stresses.
compression
Longitudinal
Tension
Short transverse
Transverse
RESIDUAL STRESS
8
a)
b)
c)
d)
~
~
~
~
~
Factors which affect distortion

material properties and condition
heat input
the amount of restain
the amount of weld metal deposited
Distration will occur in all welded joints if the material are free to move( i.e not
restrained).
Restrained materials result in low distration but high residual stress.
More than one type of distration may occur at one time.
Highly restrained joints also have a higher crack tendency to joints of a low restraint.
The action of residual in welded joints is to causes distrotion.
TYPE OF DISTORTION
Longitudinal Distortion
DIRECTION OF DISTORTION
Bowing Distortion
Transverse Distortion
Angular Distortion
a)
b)
Control of distration my be achived in on of the following way

The used of a different joint design
Offsetting the joints to be welded- so that the metal distorts in the required position.
c)
The use of a balanced welding technique.
d)
The use of clamps,jigs and fixtures.
e)
Use low heat input electrode.
f)
g)
Control the heat input.

Pwht after weld.
WELDING CONSUMABLES
1
a)
b)
c)
d)
e)
Objectif
Consumables used in arc welding may be a combination of wire and flux, or bare
solid wire.
Flux may be present either as a core-for some m.a.g applications.
Flux coating present for SAW process.
M.I.G and T.I.G process which use bare solid wire and no flux.
Consumables which are added separately to the weld pool may be know as filler rods
or filler wires,if they are part of the welding circuit providing one end of the arc,they
are know as electrodes.
Electrode code(samples)
BS EN 440 1994( G 463 M G3 Si 1)
G = wire electrode and/or deposit/ gas shielded metal arc welding.
46 = strength and elongation in the all weld metal condition(i.e 460 minimum yield
strength N/mm, 530-680 tensile strength N/mm, 20% minimum elongation).
3 = impact properties,temperature for minimum average impact energy of 47J.
m = shielding gas as to BS EN 439. The symbol "m" for mixed gasses,the symbol "c"
for shielding gasses.
G3 Si 1 = chemical composition of the wire electrode(i.e silicon,manganese,aluminium
etc. contents.)
2
a)
b)
Aws (E 7018m)
E = electrode
70 = 70,000 psi specified minimum ultimate tensile strength.
1 = welding position suitable (all position)
8 = flux type and electrical characteristic
m = resistant to moisture pick up
c)
Aws (E 7018G)
E = Electrode
70 = 70,000 psi specified minimum ultimate tensile strength
1 = Welding position suitable(all position)
8 = Flux type and electrical characteristic
G = Low alloy steel (alloy content)
WELDING CONSUMABLES
d)
BS E 51 33B 160 2 0(H)

E = Electrode
51 = Strength
33 = Toughness
B = Covering
160 = Efficiency(%)
2 = Positional capability
0 = Electrical capability
(H) = Low hydrogen potential
3) Electrode content
(i)a) MMA/SMAW (i) Basic
1
2
3
Note : Polarity DC + OR AC
(ii) Rutile
1
2
3
E7016 = Potasium
E7018 = Iron powder,calcium carbonate
E9015 = Sadium
E6013 = Titania oxide,potasium

E6012 = Sodium
E6014 =
Note : Polarity DC + OR DC- OR AC

(iii) Cellulose
1
2
Note : Polarity DC +
(iv) Iron powder
b)
E6010 = Sodium,organic compound

E6011 = Potasium,organic compound
E7024 = Flat welding position
MIG/MAG = Filler wire gasses = ER 70 S-G

ER = Rod or electrodes
70 = Strength
s = Solid
g = Electrical charasteristic,manufacturer impormation,alloys
c)
d)
e)
TIG = Filler rod gases

SUB ARC & SAW = Filler wire flux
OFW = Filler wire gases flux
WELDING CONSUMABLES
(ii)a) Each consumables is critical in respect to
(i) Size
(ii) Classification/supplier
(iii) Condition
(iv) Handling and storage
(v) Treatments (e.g baking/drying)
(iii)a) Welding consumables for mmA/SMAW
(1) Consist of a core wire typically between 350 - 450mm in length and from 2.5-6mm
in diameter.
(2) The wire is covered with an extruded flux coating.
(3) The core wire is generally of a low quality rimming steel.
(4) The weld quality is refined by the addition of refining agents in the flux coating.
(5) The flux coating many elements and components that all have a variety of functions
during welding.
Sample :
E 51 33B
compulsory
b)
160 20H
optional
Rutile electrodes :
used mainly on general purpose work
low pressure pipe work,support brackets
c)
Flux constituents include :
Titanium dioxide,slag former and arc stabilizer
Cellulose - slag and improve viscosity
Potasium silicate - ioniser and binder
d)
Advantages for rutile electrodes

Easy to use
Low cost/control
Smooth weld profiles
Slag easily defachable
High deposition possible with the addition of iron powder
1
2
3
4
5
WELDING CONSUMABLES
e)
1
2
3
4
f)
1
2
3
4
g)
1
2
3
h)
1
2
3
4
5
i)
Disadvantages for rutile electrodes

High in hydrogen
High crack tendency
Low strength
Low toughness values
Cellulose electrodes :
Used mainly for pipeline welding
Suitable for welding in all position especially vertical down,stove technique
They produce a gas shield high in hydrogen
Deep penetration/fusion characteristic
Cellulose,natural organic compounds
Titanium dioxide - slag former
Sodium silicate - main ionizers
Advantages for cellulose electrodes
Deep penetration/fusion
Suitable for welding in all positions
Fast travel speeds
Large volumes of shielding gas
Low control
Disadvantages for cellulose electrodes

High in hydrogen
High crack tendency
Rough cap appearance
High spatter contents
j)
1
2
3
Low deposition
Basic electrodes :
Used mainly for high pressure work and for materials of high tensile strength.
They are capable of producing welds of a low hydrogen content.
Prior to use they may be baked to give a low hydrogen potential typically 300C for
1 hour plus.
WELDING CONSUMABLES
k)

Limestone (calcium carbonate) - gas former
Fluorspar - improve fluidity of slag
Sodium silicate/potassium silicate - main ionizers
1
2
3
l)
Advantages for basic electrode

High toughness values
Low hydrogen contents
Low crack tendency
1
2
3
m)
1
2
3
4
5
Disadvantages for basic electrodes

High cost
High control
High welder skill required
Convex weld profile
Poor stop/start properties
(iv)a) TIG welding consumables

(i) Consists of a wire and gas,though tungsten electrodes being classed as
non-consumables may be considered consumables (dia 1.6 - 10mm).
b) MIG/MAG welding consumables
(i) Consists of a wire and gas the same quality as for TIG wire.
c) Solid wire Aws 5.18 (ER XXS - X)
ER = Designates an electrodes or rod
XX = Indicates minimum tensile strength (with co2)
S
= Indicates a bare solid electrode or rod
= Specifies chemistry,impact properties and hence applications
(v)
Electrodes's baked at temperature and holding time.
a)
Electrode : 7016 & 7018

: Baked at 350C 1 Hour OR as per manufacturer recommendation.
: Holding oven at 150C
: Quiver 70C 80C
WELDING CONSUMABLES
b)
Electrode : E6013
: Dried max 120C
c)
Electrode : E6010
: Never baked or dried
: Batch certificate
WELDER PROCEDURES AND WELDER TEST

1)
WELDING PROCEDURE
(i)a)
~
~
~
~
~
A welding procedure showns all the variable involved with the production welding
Welding process
Technique
Consumable type
Material
Preheat
b)
Once the content of a written procedure has been approved, a weld is made in
accordance with the requirements of that procedure,this is known as a welding
procedure test or welding procedure qualification test (PQR).
c)
The welding procedure made,this will depend on whetever the proposed change is an
essential or non-essential variable.
d)
Do all welding procedures need to be written most production welding procedure are
formatted on written documents or computer spread sheet,but they need not be
written and may be a product of experience.
e)
Other variable specific to the welding process

(i.e : flux type for submerged arc welding shielding gas and gas flow rate for gas
shielded processes.)
f)
Inspection of welding procedure test welds,when a procedure weld has reached

ambient temperature or when otherwise specified it undergoes examination by NDT
and destructive testing. Welding inspector to mark up the areas on the weld which
require the removal at test coupons for mechanical testing. These test areas are
normally specified in the applicable specification.
(ii)
Approval of welding procedure
a)
Once the weld has been completed it is usually visually inspected,then radiography
or ultrasonic testing is usually applied.
b)
Finally, and most important mechanical test are performed to ensure that the desired
level of mechanical properties have been meet.

c)
If a desired properties have been meet,then a procedure qualification record

(PQR or WPAR) is completed with all the test results,and the procedure than
becomes qualified.
d)
From this data, a workable document for production welding is prepared and called a
welding procedure specification(WPS).
e)
A cswip 3.2 senior welding inspector is normally responsibles for the testing welding
procedure specification.
(iii) Welding procedure approval terms

* Definitions
a)
Essential variables : variable which influence the mechanical and metallurgical

properties.
b)
Range of approvals : the extent of approvals for an essential variable.
c)
Examining body : organisation who verifies compliance.
(iv)
Welding procedure approval term (example of extent of approval include :)
a)
b)
c)
d)
Diameter of pipe or thickness of plate.

Welding position,amperage range or number of runs.
Welding process( on multi process procedures only)
Change of consumable to one of the same classification
e)
Heat input range
(v)
Welding procedure approval(code BS) BS EN 288 Part 3
(vi)
a)
b)
c)
d)
e)
f)
g)
Welding procedure (producing a welding procedure involves :)

Planing the tasks
Collecting the data
Writing a procedure for use of for trial
Making a test welds
Evaluating the results
Approving the procedure
Preparing the documentation

(vii) Welding variables list showns the variables which are likely to encountered on
welding procedure:
a) Welding process
b) Joint design
c) Welding position
d) Joint cleaning,jigging and tack welding
e) Welding technique
f)
Back gounging
g) Backing
h) Filler metal classification,manufacture,trade name and dimension
i)
Filler metal and flux drying procedure
j)
Electrical parameters(type current,amperage,voltage,polirity(d.c))
k) Travel speed and wire feed speed(mechanized welding)
l)
Preheat temperature
m) Interpass temperature
n) Past weld heat treatment
o) Material
(viii) Approving the procedure
a) When the data has been collected,the procedure must be validated by producing a
test weld,weld procedure test(WPT).
b) A number of standards provides information.
(xi) Object of a welding procedure test
a) To give maximum confidence that the welds mechanical and metallurgical properties
meet the requirements of the applicable code/specification.
b)
Each welding procedure will show a range to which the procedure is approved
(extent of approval)
(xii) Welding procedure specification

a) A document providing in detail the required variables for a specific application to
ensure repeatability.
(xiii) Procedure qualification record
a) A record comprising all relevant data from the welding of a test piece needed for
approval of a welding procedure specifications as well as all results from the testing
of the weld test.

(x) Welding variables
a) Essential variables
~ Essential variables are those in which a change,as described in the specific
variables,Is considered to affect the mechanical properties of the weldment,and shall
require requalification of the WPS (e.g. base metal thickness,P no. or F no and etc).
b)
~
Non essential variables

Non essential variables are those in which a change, as described in the specific
variables, may be made in the WPS without requalification.
(e.g. change groove design,etc)
c)
Supplimentary essential variables

~
Variables are required for metals for which other section specify notch- toughness
test are in addition to the essential variables for each welding process.
(e.g. change group no,base metal thickness limit,pwht, preheat temperature and etc)
(xv) ASME
a) Shall
~ a mondatory practise which will require change of WPS if not followed.
b)
Should
~ a recommended practise.
2)
(i)
a)
WELDER TEST
Objectif
A welder test,also known as a welder qualification test (W.Q.T), or welder approval
test is carried out to ensure the welder is a able to produce a sound weld that meets
the requirements of the relevant welding procedure and application specification.
b)
If a change was proposed outside a specified limitation, a new welder qualification

test would have to be made,because this would be a change of an essential variable.
c)
To give maximum confidence that the welder meets the requirement of the approved
procedure(WPS)
d)
The test weld should be carried out on the some material and some conditions as for
this site welds.
e)
The welder who carries out the procedure qualification weld automatically qualify
when the procedure qualifies.

f)
1)
2)
3)
4)
5)
6)
7)
Welding variables
Parent material type
Consumable or shielding gas type
Dimensions of parent material
Welding position
Types of joint
Preheat temperature
Post weld heat treatment procedure
(ii)
a)
b)
Welder qualification test

To determine the welder's ability to deposit sound weld metal.
The purpose of the qualification test for the welding operator is to determine the
welding operator's mechanical ability to operate the welding equipment.
(iii) Welder approvals

a) Once the procedure has been approved it is then important to test each welder, to
ensure that he has the skill to reach the minimum level of quality in the weld,as laid
down in the application standard.
b) There is no need to carry out the mechanical test of the procedure,although bend
tests are often weld to ensure good sidewall fusion.
c) Normally,visual,x-ray,bends,fracture and macro are used in welder approval tests.
(iv)
a)
Welder approval standards

EN 287 : Part 1 - steel
Part 2 - aluminium and its alloys
b)(i) Defines
Welder approval
(iv)
Testing requirements
(ii) Essential variables
(v)
Acceptance requirements
(iii) Range of approvals
(vi)
Re test
(vii) Period of validity

(v)
a)
b)
c)
Information that should be included on a welders test certificate are :

Welders name and identification number
Date
etc

NOTE :
1
2
3
A welding procedure test proves the weld/welding

A welder qualification test proves the welders ability to weld in
accordance with procedure.
Preliminary WPS
PQR Qualification
Record
result ok
Final WPS
transfed
NON-DESTRUCTIVE TESTING
1
2
3
4
5
Penetrant Testing
Magnetic Particle Testing
Eddy Current Testing
Ultrasonic Testing
Radiographic Testing
NOTE :
1
2
(i)
a)
(i)
(ii)
(iii)
b)
c)
d)
e)
f)
g)
Penetrant & magnetic

Ultrasonic & radiography
surface defects
internal defects
Penetrant Testing
Objectif
also known as a
Dye Penetrant inspection(DPI)
Penetrant flaw detection(PFD)
Liquid penetrant inspection(LPI)
this surface inspection con't applicable to all non-parous,non-absoring material.
penetrating fluid(penetrant) applied on to component and drawn into defect by
capillary action.
this type of testing uses the forces of capillary action to defect surface breaking
defects.
it is impossible to defects which do not break the surface with this method.
but it can be used on both magnetic and non-magnetic materials providing they are
non-porous.
there are several types of penetrant system,this included the following which are
shown in a descending order of flaw detection sensitivity.
(i) Post emulsifiable

(ii) Solvent based
(iii) Water based
fluorescent
"normally use at dark place "
(iv) Solvent based

(v) Water based
colour contrast
h)
Fluorescent penetrant require the use of an ultraviolet(UV-A) light to view indications,

whilst colour contrast penetra are viewed with the naked eye.
i)
One of the most common site used penetrant systems use solvent based colour
contrast penetrants in aerosls. A typical sequence of operations on a steel test item
is as follows.
(ii)
How to apply
a)
clean are using wire brush,cloth and solvent. On aluminium,other soft alloys and
plastic,wire brushing should not be used,as there is a danger that surface breaking
defects may be closed.
b)
apply penetrant- leave for 15 minutes.colour contrast penetrants are normally red in
colour and should remain on the part long enough to be drawn into any surface
discontinuities. This time can vory from about ten minutes to several hours depending
on the type of material and size/type of defects sought.
c)
remove surface penetrant using cloth and solvent. Apply solvent to the cloth and not
directly on to the work piece. Clean thoroughly.
d)
apply developer- leave for 15 minutes. The developer draws any penetrant remaining
in any surface breaking discontinuities with a blotting action.
e)
interpet area. Any discontinuities are indicated by a red mark, (e.g. line or dot
againts a white background. Fluorescent penetrants would show green-yellow when
viewed with an ultraviolet(UV-A) light.
(iii)
Advantages
a)
b)
c)
very sensitive
can be uses on non-ferrous metals,some plastics and class
small objects with complex geometry can be inspected
d)
no power supply needed
e)
great skill not require
f)
can be applied in batches (Low operator skill)
(iv)
a)
b)
c)
d)
e)
f)
g)
Disadvantages
can only detect defects open to the surface
surface penetration is critical
the method is time consuming
messy process
interpretation sometimes difficult
do not applied to pointed objects
effluent problem with waste
2
(i)
Magnetic Particle Testing

Objectif
a)
This method of NDT may defect surface and in certain cases,slight sub-surface
discontinuities up to 2-3 mm below the surface.
b)
Test method for the detection of surface and sub-surface indications in

ferromagnetic materials.
c)
Defects revealed by applying ferromagnetic particles.
d)
Magnetic field induced in component.
e)
Defects disrupt the magnetic flux.
f)
This process can scan 10mm of parent metal.
g)
A magnetic field is introduced into a specimen to be tested,fine particles of

ferromagnetic powder, or ferromagnetic particles in a liquid suspension, are then
applied to the test area. Any discontinuity which interupts the magnetic lines of force
will create a leakage field,which has a north and south pole on either side of it. This
attracks the ferromagnetic particles in great numbers.The discontinuity may show as
black indication against the contrasting background usually a dark violet background.
h)
When m.p.i. is carried out using fluoresent inks the use of an ultraviolet(UV-A) light is
necessary to cause fluorescence of the particles,although there is no need to aplly
a contrast paint.
i)
Fluorescent ink methods are more sensitive than black ink methods.
(ii)
a)
b)
c)
d)
e)
f)
Advantages
Will detect some sub-surface defects
Rapid and simple to unders
Pre-cleaning not as critical as with DPI
Will work through thin coatings
Cheap rugged equipment
Direct test method (simple tv use, little surface preparation requires)
(iii)
a)
b)
c)
d)
e)
f)
3
Disadvantages
Ferromagnetic materials only
Requirement to test in 2 directions
Demagnetisation may be required
Odd shaped parts difficults to test
Not suited to batch testing
Can damage the component undertest
Ultrasonic testing
Probe
CRT
Screen
couplant
CRT
A-C (Current)
material
crystal
ultrasonic
(>20,000 herts)
First signal
50 mm
back signal
100 mm
(i)
Advantages
a)
It is good for planar defect (e.g. crack,lack of fusion,lack of root penetration)

(may be battery powered)
b)
Deep of defects
(Both surface & sub-surface detection)
(Safe)
(Capable of measuring the depth defects)
(Portable)
4
(i)
a)
b)
Radiographic Testing
Types of Radiographic testing
X-ray
Gamma ray
1) X or gamma radition is imposed upon

a test object.
2) Radiation is transmitted to varying
degrees depent.
with asses
Dence
inclusions
Low dence
-inclusion,porosity,slag
-darker
Film
(ii)
Density - relates to the degree of darkness

contrast-relates
Film interpet
(0.40)
Sensivity = Thickness wire visiable X 100

Parent metal (16)
Darker
= 2.5 %
Lighter
Inoder 2%
2 x 16
100
UT( disadvantages)
Trained & skilled operator required
Requires high operator skill
Good surface finish required
Defect identification
Couplant may contaminate
No permanent record
= 0.32
Advantages RT
1)
2)
3)
4)
5)
6)
Permanent record
Little surface preparation
Defect identificates
No material type limitation
No so reliant upon operator skill
Thin material
Disadvantages
1)
2)
3)
4)
5)
6)
7)
8)
Expensive consumables
Bulky equipment(X-ray)
Harmful radiation
Can't defect lamination
Defect require significant depth in relation to the radiation beam
Slow result
Very little indication of depth
Access to both side required
ETC
1
a)
AWS
~ American Welding Society
b)
ASNI
~ American National Standards Institute
c)
ASME
~ The American Society Of Mechanical Engineers
d)
ASNT
~ American Society Of Non destructive Testing
e)
ASTM
~ American Society For Testing and Material
f)
WPS
~ Welding Procedure Specification
g)
PQR
~ Procedure Qualification Record
h)
PJP
~ Partial Joint Penetration
i)
CPJ
~ Completed Joint Penetration
j)
WOQ
~ Welding Operator Qualification
k)
WQT
~ Welder Qualified Test
l)
WQR
~ Welding Qualified Test
m)
WPQR
~ Welding Performance Qualification Record
ETC
n)
AFC
~ Approved For Construction
o)
PWHT
~ Post Weld Heat Treatment
p)
CR
~ Calibration Records
q)
ITP
~ Inspection Test Plan
r)
MIR
~ Material Inspection Record
s)
WTR
~ Weld Traceability Record
t)
MRN
~ Material Received Note
u)
NDT
~ Non Destructive Testing
v)
DT
~ Destructive Testing
w)
RT
~ Radiographic Testing
x)
UT
~ Ultrasonic Testing
y)
DPT
~ Dye Penetrant Testing
z)
RIS
~ Radiation Imaging System
ETC
A)
MPI
~ Magnetic Particle Inspection
B)
API
~ American Petrolium Institute
C)
JIS
~ Japan Industrial Standards
D)
BS
~ British Standards
E)
CSWIP
~ Certification Scheme For Welding and Inspection Personnel
F)
PCN
~ Personnel Certifiation in Non-Destructive Testing
(A) Section stamp

(i)
u
~ Vessel (ASME & Dev 1)
(ii)
u
~ Vessel (ASME & Dev 2)
(iii)
S
~ Boiler (ASME 1)
(iv)
P
~ Piping (ASNI B31.1)
(v)
R
~ Repair work boiler
ETC
(B)
ASME CODE
(i)
ASME 1(I)
~ Boiler/ fired vessel fabrication
(ii)
ASME 2(II) PART A

~ Material ferrous(kandungan besi)
(iii)
ASME 2(II) PART B

~ Material non-ferrous (kandungan tanpa besi)
(iv)
ASME 2(III) PART C

~ Consumeables/electrodes
(v)
ASME 5(V)
~ Non-Destructive Testing
(vi)
ASME 8(III) Dev 1

~ Pressure vessel
(vii)
ASME 8(VIII) Dev 2

~ Pressure vessel(special design)
(viii)
ASME 9 (IX)
~ WPS & Welder performance
(ix)
ASNI B 31.1
~ Power Piping(boiler)
(x)
ASNI B 31.3
~ Chemical plant
ETC
3
a)
b)
c)
d)
CALIBRATION CALCUTION
3 reading (x),(y),(z)
(A) = Actual
(P) = Preset
(D) = Deviation
x+y+z
3
A-P
P
= A
X 100 =
maximum 10%
1%
minimum
if (-)
rejected
10
1
preset - 100
actual reading(average) - 92
% maximum +10% & % minimum -1%
1)
Position of welding for plate only
a)
~ Down hand & position 1G/F
b)
~ Horizontal & position 2G/H
c)
~ Vertical & position 3G/V
d)
~ Overhead & position
100
-(-) 92
(-) 8 ACCEPT
ETC
2)
Plate preparation for WQT

4"
4"
8"
4 " = 101.6mm
8 " = 203.2mm
3)
How to select pressure gauge ?
Test required is 500 p.s.i
required test 500 p.s.i x not less than 1.5 = 750 p.s.i
(we can select pressure gauge not less than 750 p.s.i)
preferably 500 p.s.i x 2 = 1000 p.s.i

(select pressure gauge more than 1000 p.s.i)
According to ASME I - PW 5A Hydrostatic Test.

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What are the main responsibilities of a visual welding inspector?

What are the main responsibilities of a visual welding inspector?

What are the duties of a visual welding inspector before welding?

What are the duties of a visual welding inspector before welding?

QA vs QC vs INSPECTION

Aim of Quality Assurance

Benefits(faedah) of adopting(menerima tanggungjawab) Quality Assurance

What is Quality Assurance

Scope of Quality Assurance

Inspection vs Quality Assurance

Inspection vs Quality Control

Quality Control vs Quality Assurance

OBJECTIVE OF VISUAL WELDING INSPECTOR AND WELDING INSPECTION

OBJECTIVE OF VISUAL WELDING INSPECTOR AND WELDING INSPECTION

In the event of repair

OBJECTIVE OF VISUAL WELDING INSPECTOR AND WELDING INSPECTION

Duties and Responsibility of a welding inspector

OBJECTIVE OF VISUAL WELDING INSPECTOR AND WELDING INSPECTION

During welding, the welding inspector should once again check :

at the welding inspector.

Report to higher authorities reagarding the repair.

Marking detect area for repair.

Liaise with higher authorities for weld repair procedure.

Type of joint preparation

Weld zone terms

Shape of a fillet weld in cross section by 3 terms :

Type of joint design

Single Bevel - Butt

Single "u" - Butt

Single "J" - Butt

Included angle 15 -20

Root radius 5mm

To check throat thickness

To check leg length

A-B = Lack of sidewall fusion

Welding Positions (ISO 6947)

A = Overhead (PE) (4G)

vertical position(pipe fixed horizontal) = PF,PG = 5G

inclined position fixed = H - L 045 = 6G

inclined position rotated = L45/PA = 1 FR

GTAW = gas tungsten Arch welding (AWS)

GMAW = gas metal Arc welding (AWS)

FCAW = flux cored Arc welding

= plasma Arc welding

= submerged Arc welding

Manual Metal Arch & Shielded Metal Arc Welding

O.C.V. (open circuit voltage)

:- MMA, TIG, SUB-ARC > 1000 Amps

Types of welding machine (Plant)

Functions of flux covering

Size : - min 1.6 mm & max 8 mm

Type : - basic, rutile, cellulose or iron powder

Size : - min 3.0 mm & max 25.0 mm

Type : - carbon steel, alloy steel, stainless steel

Condition : - some tolerance on the surface preparation

Current ( amperage)- control the depth of penetration

can be used in any welding position

= Evolved gas shield

Tungsten inert - gas & gas tungsten arc welding