complete welding clip

7/27/2019 Complete Welding Clip

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Welding


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Table of Contents

1. Section 1 Fundamentals of Welding

2. Section 2 Welding Metallurgy

3. Section 3 Welding Design

4. Section 4 Welding Equipment & Consumables

5. Section 5 WPS & PQR

6. Section 6 Welding Inspections & Techniques

7. Section 7 Welding Defects, Causes & Remedies 8. Useful Websites


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Section 1

Fundamentals of Welding



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WeldingDefinition 1:

Welding is a complex, metallurgical process involvingmelting, solidification, gas-metal reactions, surface

phenomena and solid state reactions for joining metals.

Definition 2:

Welding is the joining of multiple pieces of metal by theuse of heat and or pressure. A union of the parts iscreated by fusion or re-crystallization across the metalinterface. Welding can involve the use of filler material,or it can involve no filler.


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Major classification of welding Arc Welding Resistance Welding Flash Welding Ox fuel Gas Welding

Solid State Welding Electron Beam Welding Laser Beam welding Brazing

Soldering Adhesive Bonding Thermal Spraying



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Arc Welding :Definition A fusion process wherein the coalescence of the

metals is achieved from the heat of an electric arc

formed between an electrode and the work.


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Arc Welding Processes Shielded metal arc welding (SMAW)/ stick welding

Sub-merged arc welding (SAW)

Gas metal arc and flux cored arc welding (GMAW)

Flux cored arc welding (FCAW)

Gas tungsten arc welding (GTAW)

plasma arc welding (PAW)

Electrogas welding

Electroslag welding


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Shielded Metal Arc Welding(SMAW)/ Stick Welding



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DIAGRAM 1


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DIAGRAM 2


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Overview of ProcessSMAW is an early arc welding process used for ferrous and several nonferrous base metals. It usesa covered electrode consisting of a core wirearound which a concentric clay-like mixture of silicate binders and powdered materials (such asfluorides, carbonates, oxides, metal alloys andcellulose) is extruded. This covering is a source of arc stabilizers, gases to displace air, metal and slag

to protect, support and insulate the hot weld metal.



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Tools & Equipment Electrode (consumable & non-consumable) Electrode Holder Electrode Cable

Welding Machine (AC or DC Power Source) Work Cable Clamp Filler Metal Welding Helmet Protective Clothing



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Advantages Many welding applications with small variety of

electrodes.

Simple, portable,& inexpensive equipment

Self flux provided by electrode

Provides all position flexibility

Weld can be made in Confined location



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Limitations

Used for steels, stainless steels, cast irons.

Not used for aluminum and its alloys, or copper andits alloys (energy density is too high).

Best suitable for joining metals of sections1/8 to 3/4 in.(3 to 9 mm) thickness.

Groove weld joints in plate thickness normally

require edge preparation to allow proper access tothe root of the joint.

Typical current range is between 50 and 300A.



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Limitations contd Special electrodes can be used as high as 600A and

others as low as 30A, allowing weld metal deposition

rates of between 2 and 17 lb/h (1 & 8 KG/Hr). High material cost as 60% of the weight of the

purchased electrodes is deposited as filler metal.


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Applications Construction Pipelines Shipbuilding Fabrication job shops. Maintenance Industries


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Common Defects Porosity Slag inclusions Incomplete Fusions

Inadequate joint penetration. Undercut Overlap Cracks


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SUB-MERGED ARC WELDING (SAW)



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Diagram 1


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Overview of Process In SAW, the arc and molten meta; are shielded by anenvelope of molten flux and a layer of unusedgranular flux particles. When the arc is struck , thetip of the continuously fed electrode is submergedin the flux and the arc is therefore not visible. Theweld is made without the intense radiation thatcharacterizes an open arc process and with littlefumes.



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Tools, Equipment & Materials Electrode (consumable & non-consumable) Electrode Holder Electrode Cable

Power Source (600 to 2000A output) Automatic Wire Feed Tracking System Work Lead Weld Backing Filler Metal Welding Helmet

Protective Clothing



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Advantages

Useful for welding both Sheet and plate.

Thin materials speed up to 200in/min (84mm/sec) can

be achieved.

In thick section applications, high metal deposition

rates of 60 to 100 lb/h (27 to 45 kg/h).

Least Expensive in operating cost

Edge preparation is not required due to the usage of

DCEP (Direct Current Electrode Positive).

Consistent weld quality



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Limitations

Welds can only be made in the flat and horizontal

positions.

Used for all grade of carbons, low alloy and allow

steels. Stainless Steel and some nickel alloys are

also effectively welded or used as surfacing filler

metals with the process.

Power Source, Three Phase 220V or 440V Single phase 440V.



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Applications Used for all grade of carbons, low alloy and alloy

steels. Stainless Steel and some nickel alloys arealso effectively welded or used as surfacing filler Pipelines.

Jobs require deposition of large quantities of filler metal.

Fabrication job shops. Maintenance Industries. Pipelines



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Common Defects Porosity Slag inclusions Incomplete Fusions

Inadequate joint penetration. Undercut Overlap Cracks



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GAS METAL ARC WELDING (GMAW)



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Diagram 1



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Diagram 2



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Overview of Process

GMAW process use a continuous solid wire toprovide filler metal, and use gas to shield the arcand weld metal. The electrode is solid and all of theshielding gas is supplied by an external source. Theshielding gas used has a dual purpose of protectingthe arc and weld zones from air and providingdesired arc characteristics. Gases are useddepending on the reactivity of the metal and thedesign of the joint to be welded.



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GMAW Process Variations

In GMAW, the common variations of shielding gases, power sourcesand electrodes have significant effects that can produce threedifferent modes of metal transfer across the arc. These are:1) Spray Transfer It describes an axial transfer of small discrete droplets of metal at

rates of several hundred per second.2) Globular Transfer In this process variation, carbon dioxide -rich gases are used toshield the arc and welding zone.3) Short Circuiting Transfer In this transfer, the average current and deposition rates can belimited by using power sources which allow metal to be transferredacross the arc only during intervals of controlled short circuitsoccurring at rates in excess of 50 per second.



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Tools, Equipment, Material A variable speed motor and motor control Welding gun Gas Nozzle on gun A system of cables, hoses, electrical connections andcasings. A mount for the spooled or coiled electrode. A control station containing the relays, solenoids andtimers.

A source of shielding gas. Power Source (2KW to 20 KW) Water supply

Shielding gas argon, nitrogen, helium



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Advantages

Long welds can be made without starts and stops.

Minimal skill required.

Minimal cleaning of surface before weld Allows welding in all positions

High deposition frequency around 95-100% with solid

electrodes, 80-85% with gas-shielded cored

electrodes and 80-85% with the self shielded cored

electrodes.



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Limitations Ferrous metals welding in all positions if they are

less than in (6mm) thickness.

Globular and spray transfer are restricted towelding steels in the flat and horizontal positions.



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Applications



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Common Defects Porosity Slag inclusions Incomplete Fusions Inadequate joint penetration. Undercut Overlap Cracks



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FLUXED CORE ARC WELDING (FCAW)



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Diagram



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Overview of ProcessFCAW process uses cored electrodes instead of solid electrodes for joining ferrous metals. The fluxcore may contain minerals, ferroalloys and

materials that provide shielding gases, deoxidizersand slag forming materials.



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Tools, Equipment, Material

A variable speed motor and motor control Welding gun Gas Nozzle on gun

A system of cables, hoses, electrical connectionsand casings. A mount for the spooled or coiled electrode. A control station containing the relays, solenoids

and timers. A source of shielding gas. Power Source (2KW to 20 KW) Water supply



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Advantages

Long welds can be made without starts and stops.

Minimal skill required.

Minimal cleaning of surface before weld

Allows welding in all positions

80-85% with gas-shielded cored electrodes and 80-

85% with the self shielded cored electrodes.



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Limitations

Used Cored electrodes instead of solid electrodes.

Used for ferrous metals.


d l f ld


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Applications

Ferrous metals in all positions. Produce vertical welds at deposition rates in

excess of 5 lb/h(2 kg/h).


F d l f W ldi


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Common Defects Porosity Slag inclusions Incomplete Fusions Inadequate joint penetration. Undercut Overlap Cracks


F d l f W ldi


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GAS TUNGSTEN ARC WELDING (GTAW)


F d l f W ldi


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Diagram 1



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F d t l f W ldi


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Overview of ProcessGTAW uses a non-consumable tungsten electrodewhich must be shielded with an inert gas.The arc isinitiated between the tip of the electrode and workto melt the metal being welded, as well as the filler

metal, when used. A gas shield protects theelectrode and the molten weld pool, and providesthe arc characteristics.


F d t l f W ldi


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Tools, Equipment, Material

Welding TorchTungsten Electrode Inert Gas Pressure regulators and flow meters Welding face shield Protective clothing Gas Nozzle on gun

A source of shielding gas. Power Source (8KW to 30 KW)

Current range 200A to 500A) High Frequency Oscillator

Welding wire


F d t l f W ldi g


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Advantages

Welds with or without filler metal Precise control of welding variables (heat)

Low distortion

Higher quality root pass.

Accommodate wide range of thickness, positions and

geometries.

Portable Equipment

Combination with GMAW or SMAW produce good

results for pipe welding.


F d t l f W ldi g


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Limitations

More training time required as GMAW & SMAW.

More expensive than SMAW

Requires greater welder dexterity than MIG or stick

welding

Lower deposition rates

More costly for welding thick sections


F ndamentals of Welding


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Applications

Most commonly used for aluminum andstainless steel. For steel

Except for thin sections or where veryhigh quality is needed




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Common Defects

Porosity Incomplete Fusions Inadequate joint penetration. Cracks




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Definition: This is a group of fusion welding processes that

use heat and pressure to make the coalescence.

The heat comes from electrical resistance tocurrent flow at the site of the weld.

The processes include:

Spot Welding Projection Welding Seam Welding

Resistance Welding




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Diagram




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Spot Welding A process typically used in high-volume, rapid welding

applications. The pieces to be joined are clamped between two

electrodes under force, and an electrical current is sentthrough them.

The advantages of spot welding are many andinclude the fact that it is:

An economical process Adaptable to a wide variety of materials including low

carbon steel, coated steels, stainless steel, aluminum,

nickel, titanium, and copper alloys Applicable to a variety of thicknesses A process with short cycle times A robust process Tolerant to fit-up variations

Resistance Welding




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There are three major processes within this group:

1- oxyacetylene welding

2- oxyhydrogen welding

3- pressure gas welding.

Gas Welding




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General Gas Welding Procedures

Oxyfuel gas welding (OEW) is a group of welding processes which join metals by heating with a fuel gas flame or flares with or withoutthe application of Pressure and with or without the use of filler

metal.

Fuel gas and oxygen are mixed in the proper proportions in amixing chamber which may be part of the welding tip assembly.

Molten metal from the plate edges and filler metal, if used, intermix

in a Common molten pool. Upon cooling, they coalesce to form acontinuouspiece.


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Brazing

Process OverviewBrazing is a group of welding processes inwhich the joint is heated to a suitabletemperature in the presence of a filler metalhaving a liquidus above 840 F (450 C) andbelow the solidus of the base metal.

Major Considerations: Joint Design

Filler Metal Uniform heating Protective or reactive shielding




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Various Brazing Processes

Torch Brazing

Furnace Brazing

Induction Brazing Dip Brazing

Infrared Brazing

Diffusion Brazing



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Various Soldering Processes

Dip Soldering (DS) Iron Soldering (INS)

Resistance Soldering (RS)

Induction Soldering (IS) Torch Soldering (TS)

Furnace Soldering (FS)

Infrared Soldering (IRS) Ultrasonic Soldering




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Adhesive BondingProcess OverviewAdhesive Bonding is a joining process which isgaining acceptance as an assembly method for joiningmetals.

Advantages: Minimal Training. Capable of joining dissimilar metals like metals to

plastics

Bonding very thin sections without distortion Very thin sections to thick sections Joining heat sensitive alloys Producing bonds with unbroken surface contours. Low Cost




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Adhesive Bonding

Dis-advantages: Joints produced, may not support shear or impact

loads. Must have adhesive layer less than 0.005 in

(0.13mm) thick. Joints can not sustain operational temperatures

exceeding 500 F (260 C)Surfaces to be bondedrequires special cleaning.

Some adhesives are to be used quickly after mixing. NDT of adhesive joints is difficult.




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Welding Processes in Descon

Shield Metal Arc Welding (SMAW)

Gas Tungsten Arc Welding (GTAW)

Sub-Merged Arc Welding (SAW)Adhesive Bonding

BACK TO TOC



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SECTION 2Welding Metallurgy


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OVERVIEW OF JOININGPROCESSES

Welding Metallurgy
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General Metallurgy

Understanding of welding metallurgy requires a broad knowledgeof general metallurgy.

Structure of Metals

Solid metals have a crystalline structure in which the atoms of each crystal are arranged in a specific in a specific geometricpattern. This orderly arrangement of the atoms, called a lattice, isresponsible for many of the properties of metals.

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Structure of Metals

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Solidification Process

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Phase Transformations

Critical TemperatureA specific temperature at which metals change their crystallographic structure.

Phase DiagramA drawing showing metallurgical events such as phase changesand solidification. ( Sometime referred to as an equilibriumdiagram or a constitution diagram)

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IRON CARBON DIAGRAM

Welding Metallurgy
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Figure 1 shows the equilibrium diagram for combinations of carbon in a solid solution of iron.The diagram shows iron and carbons combined to form Fe-Fe 3C at the 6.67%C end of thediagram. The left side of the diagram is pure iron combined with carbon, resulting in steelalloys.Three significant regions can be made relative to the steel portion of the diagram.1- Eutectoid E2- Hypoeutectoid A3- Hypereutectoid B.

The right side of the pure iron line is carbon in combination with various forms of ironcalled alpha iron ( ferrite ), gamma iron ( austenite ), and delta iron .The black dots mark clickable sections of the diagram.Allotropic changes take place when there is a change in crystal lattice structure.From 2802-2552F the delta iron has a body-centered cubic lattice structure.

At 2552F, the lattice changes from a body-centered cubic to a face-centered cubic latticetype. At 1400F, the curve shows a plateau but this does not signify an allotropic change.It is called the Curie temperature, where the metal changes its magnetic properties.Two very important phase changes take place at 0.83%C and at 4.3% C. At 0.83%C,the transformation is eutectoid, called pearlite .gamma (austenite) --> alpha + Fe 3C ( cementite )

At 4.3% C and 2066F, the transformation is eutectic, called ledeburite .--> +

g gy

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Properties of metals can be divided into fivegeneral groups:

Mechanical

Physical

Corrosion

Optical Nuclear

Properties of Metals

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Table of Metal Properties

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Yield StrengthThe stress level at which the metal exhibits itsspecified deviation from the proportionality of stress and strain.

Tensile StrengthThe ratio of the maximum load sustained by atensile test specimen to the original cross-sectionalarea is called the ultimate tensile strength.

Mechanical Properties

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Fatigue StrengthFatigue fractures developed because eachapplication of the tensile applied stress, even atnominal tensile stresses lower than yield pointstress, causes the tip of a crack to advance aminute mount (stable crack growth).

DuctilityThe amount of plastic deformation that anun-welded or welded specimen undergoes in amechanical test carried to fracture is considered amajor of the ductility of the metal or the weld.


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Fracture ToughnessToughness is the ability of a metal to resist fracturein the presence of a notch, and to accommodate

the loads by plastic deformations.


g gy

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Thermal ConductivityThe rate at which heat is transmitted through amaterial by conduction is called thermalconductivity or thermal transmittal.

Melting Temperature:The temperature at which metal starts melting.

Thermal expansion and contraction:Change in volume of metals when they heated andcooled during welding.

Physical Properties

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The corrosion properties of a metal determine itsmode and rate of deterioration by chemical or electrochemical reaction in the surroundingenvironment.

Chemical PropertiesThe chemical composition of the base metal is amajor factor in determining the choice of the

electrodes to be used for welding. The chemicalcomposition of the base metal influences the needfor preheating and post heating are use toprevent the weld area from becoming brittle andweak.

Corrosion Properties

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Type of steel PreheatLow-Carbon Steel Room Temperature or up to 200 Degrees

Fahrenheit (93 Degrees Centigrade)Medium-Carbon Steel 400 500 Degrees Fahrenheit (205 260 Degrees

Centigrade)

High-Carbon Steel 500 600 Degrees Fahrenheit (260 315 DegreesCentigrade)

Low Alloy NickelLess than (6.4 mm)thickMore than (6.4 mm)thick

Room Temperature500 Degrees Fahrenheit (260 Degrees Centigrade)

Low Alloy Nickel-ChromeSteelCarbon content below .20%

Carbon content .20% to.35%

200-300 Degrees Fahrenheit (93-150 DegreesCentigrade)600-800 Degrees Fahrenheit (315-425 DegreesCentigrade)

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Type of steel Preheat Carbon content above .35% 900-1100 Degrees Fahrenheit (480-595 Degrees

Centigrade)Low Alloy Manganese Steel 400 600 Degrees Fahrenheit (205-315 Degrees

Centigrade)

Low Alloy Chrome Steel Up to 750 Degrees Fahrenheit (400 DegreesCentigrade)

Low Alloy MolybdenumSteelCarbon content below .15%Carbon content above .15%

Room Temperature400 650 Degrees Fahrenheit (205-345 DegreesCentigrade)

Low Alloy High TensileSteel

150 300 Degrees Fahrenheit (66-150 DegreesCentigrade)

Austenitic Stainless Steels Room Temperature

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Type of steel Preheat Ferritic Stainless Steel 150 500 Degrees Fahrenheit (66-260 Degrees

Centigrade)

Martensitic Stainless Steel 150 300 Degrees Fahrenheit (66-150 DegreesCentigrade)

Cast Irons 700 900 Degrees Fahrenheit (370-480 DegreesCentigrade)

Note: The actual preheat needed may depend on several other factors such as the thickness of the base metal, the amount of joint

restraint, and whether or not low-hydrogen types of electrodesare used. This chart is intended as general information; thespecifications of the job should be checked for the specific preheattemperature to be used.

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A weld joint consists of weld metal (which has beenmelted), heat affected zones and unaffected basemetals. The metallurgy of each weld area is relatedto the base and weld metal compositions, thewelding process and the procedures used.When a weld is deposited, the first grains to solidifyare nucleated by the un-melted base metals, andthese grains maintain the same crystal orientation.Depending upon composition and solidificationrates, the weld solidifies in cellular or dendriticgrowth mode. Both modes cause segregation of alloying elements. Consequently, the weld matter may be less homogenous than the base metal.

Metallurgy of Welding

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Figure

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The weld heat-affected zone is adjacent to the weld metal.

The heat-affected zone is that portion of the base metal that hasnot beenmelted, but whose mechanical properties or microstructure

have been altered by the heat of welding.

The width of the heat-affected zone is a function of the heatinput.

Heat-affected zones are often defined by the response of thewelded joint to hardness variation or micro structural changes.

Heat Affected Zone

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Fusion Weld Structure

HAZWeld metal

HAZBasemetal

Fusion line

Weld preparation


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Thermal Gradients in Haz

Time

Temperature

Fusion lineFusion line + 2mmFusion line + 5 mm

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Haz Structure

High peak temperature High temperature gradient

Variable cooling rate Superimposed HAZs in multipass welds

Welding stresses affect transformation

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Multi pass Fusion Weld

Last weld run

Previous weld run

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Weld Properties Weld metal has different composition & thermal

history to base metal

Welding heat modifies adjacent base metal (HAZ)

Variation in strength, ductility & corrosionresistance across welds

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Definition of Weldability

The capacity of a material to be welded under the

imposed fabrication conditions into a specific,

suitably designed structure & to perform

satisfactorily in intended service.

(ANSI / AWS A3.0)

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Factors Affecting Weldability

WELDABILITY is often considered to be amaterial property, however the effect of other

variables should not be ignored.

Design of WELDMENT

Its service conditions

Choice of welding process

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Residual Stresses

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XX XX

Residual Stress in a Butt Weld

ss x ss y

ss x

0 TensionCompression

XX XX

s y Tension

Compression

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When a weld is made: the metal in and around the weld joint is heated to a

range of temperatures as the distance from the weld joint increases.(temperature gradient)

Because of the Uneven heating, the strength, ductility, grain size and

other metal properties may vary greatly and affect the strength of themetal in the weld area.

Welder will use, as per WPS: preheating

concurrent (continuous) heating and/or

post heating to avoid temperaturegradients in the weld area.

Heat Treatment of Metals for Welding

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Heat Treatment of Metals

Heat-treating serves following purposes: Develop ductility. Improve machining qualities. Relieve stresses.

Change grain size. Increase hardness or tensile strength. Change chemical composition of metal surface as

in case hardening. Alter magnetic properties. Modify electrical conduction properties. Induce toughness. Recrystallize metal, which has been cold, worked. (.contd.)

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Heat Treatment of Metals

During heat treatment there are three factorsof great importance:

1. Temperature to which the metal is heated.

2. Length of time that the metal is held at thattemperature

3. Speed of cooling (a time factor).

BACK TO TOC


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Section 3Welding Design

Welding Design


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Design Basics

WeldmentA weldment is an assembly that has componentparts joined by welding. It may be a bridge, abuilding frame, an automobile, a truck body, atrailer hitch, a piece of machinery, or an offshoretubular structure.Basic Objectives:1) Will perform its intended functions.2) Will have the required reliability and safety

3) Is capable of being fabricated, inspected,transported and placed in service at minimumtotal cost

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Knowledge & Experience required for Designer of Weldments:

Basic design concepts Cutting and shaping of metals Assembly of components Preparation and fabrication of welded joints Weld acceptance criteria, inspection, mechanical testing and

evaluation.ill perform its intended Mechanical and physical properties of metals and weldments Welding processes, costs and variations in welding procedures. Filler metals and properties of weld metals

Thermal effects of welding. Effects of restraint and stress concentrations Control of distortion Communication of weldment design to the shop, including the use of

welding symbols A licable weldin and safet standards.

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Design Program

Analyses of existing designWhen designing an entirely new machine or structure,information should be obtained about similar units,including those of other manufacturers or builders.If a new design is to replace an existing design , thestrengths and weaknesses of the existing design should bedetermined first. Following questions can help in that:1) Hat are the opinions of customers and the sales force

about the existing products?

2) Hat has been the performance history of the existingproducts?

3) What features should be retained, discarded, or added?4) What suggestions for improvements have been made?

Welding Design


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Major Design Factors

Strengths and stiffness requirements Realistic Safety factor Good appearance Deep, symmetrical sections Rigidity Tubular sections or diagonal bracing Standard rolled sections, plate and bar Accessibility for maintenance Standard commercially available components


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Welding Design


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Designing the Welded Joints

Definitions Joints - Arrangements of members being joined

Butt, tee, lap, corner, flare

Welds - Geometry of weld detail selected to makethe joint Butt, fillet, plug & slot

Welding Design


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Joint Types

Butt Tee

Lap Corner

Edge

Welding Design


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Weld Types

Butt weld Between mating members Best quality High weld preparation cost

Fillet weld Easy preparation Asymmetric loads, lower design

loads Plug & slot welds

Modified fillet welds in lap joints,using holes through one member

Welding Design


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Fillet Welds

Simple & cheap to assemble & weld Stress concentrations at toes & root Notch at root (fatigue, toughness) Critical dimension is throat

thickness Root gap affects throat thickness Radiography & ultrasonic testing is

of limited use Large fillets use a lot of weld metal

& therefore are uneconomic

Welding Design


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Fillet Weld Terms

Root

ToeWeld face

Toe Throatthickness

Apparent leg length

Gap

Welding Design


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Types: Double welded butt Permanent or temporary backing Single welded butt

Lower stress concentration Easier ultrasonic testing or radiography Expensive preparation

Butt Welds

Welding Design


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Butt Weld Types

Single veecan be singleor double welded

Single bevel Double vee

Backed butt (permanent or temporary)

Welding Design


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Butt Weld TermsFusion face

Root face

Rootgap

Included angle

Bevel angle

Root run Toe

Toe

Reinforcement

Welding Design


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J & U Preparations

Land

Root radiusU preparation

Double U butt

Welding Design


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Structural Tubular Connections

Tubular members are being used in structures such asdrill rigs, space frames, trusses, booms and earth

moving & mining equipment.

They have the advantage of minimizing defections under load because of their grater rigidity when compare to

standard structural shapes.

Various types of welded tubular connections, the

component designations and nomenclature are shown in

next figure.


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Welding Design


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AS1101.2 Drawing Symbols

Tail

Arrow points to weldlocation

OTHER SIDE

ARROW SIDE

Weld type symbol

Reference line

Welding Design


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Typical AS1101.2 Symbols

6mm6 CJP

BACK TO TOC


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Section 4Welding Equipments & Consumables

Welding Equipment & Consumables


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Welding Electrode

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Solder Wire

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Electrode Holder

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CO 2 Regulator Welding & Cutting Torch

Electric Welder

Welding Equipment and Tools

Air HosesBACK TO TOC
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Section 5WPS & PQR

WPS & PQR


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Welding Procedure Specification (WPS)

A document providing in detail the required variablesfor specific application to assure repeatability by

properly trained welders.

Procedure Qualification Record (PQR)

A document used for recording the results of qualification tests.

WPS & PQR


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Welder Performance Qualification (WPQ)Welders or welding operators ability to producewelded joints that meet prescribed standards.

Certification

The results of welding procedure or performancequalification must be certified by an authorizedrepresentative of the organization performing thequalified tests.

WPS & PQR


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Welder Procedure Major Parts

Welding procedure consists of three parts as follows:

A detailed written explanation of how the weld is to be

made A drawing or sketch showing the weld joint design

and the conditions for making each pass or bead

A record of the test results of the resulting weld.

WPS & PQRWhy we need WPS for welding


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Why we need WPS for weldingAs welding becomes a modern engineering

technology it requires that the various elementsinvolved be identified in a standardized way.A welding procedure is used to make a record of all of the different elements, variables, and factors that areinvolved in producing a specific weld or weldment.Welding procedures should be written whenever it isnecessary to: Maintain dimensions by controlling distortion Reduce residual or locked up stresses Minimize detrimental metallurgical changes Consistently build a weldment the same way Comply with certain specifications and codes.

WPS & PQR


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Essential Variables

Essential variables are those factors which must berecorded and if they are changed in any way, theprocedure must be retested and re-qualified.

Non- Essential Variables

Nonessential variables are usually of less importanceand may be changed within prescribed limits and theprocedure need not be re-qualified.

WPS & PQREssential Variables


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Essential Variables

Essential variables involved in the procedure usuallyinclude the following: The welding process and its variation The method of applying the process The base metal type, specification, or composition The base metal geometry, normally thickness The base metal need for preheat or postheat The welding position The filler metal and other materials consumed in

making the weld The weld joint, that is, the joint type and the weld Electrical or operational parameters involved Welding technique.

WPS & PQR


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Non- Essential Variables

Some specifications include nonessential variablesare following:

The travel progression (uphill or downhill)

The size of the electrode or filler wire Certain details of the weld joint design The use and type of weld backing The polarity of the welding current.

WPS & PQR


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Descon Systems

MS for WPS

FormatsWPQ , WPS , PQR , WQT

WPS & PQRTools & Equipments
http://localhost/var/www/apps/conversion/tmp/scratch_3/Plz%20dont%20make%20anymore%20desktop%20folder%20plz/Welding%20PPT/Final%20PPT/QA%20QC%20Module/QC_MS_M_07%20Welding%20Procedure%20Qualification.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_3/Plz%20dont%20make%20anymore%20desktop%20folder%20plz/Welding%20PPT/Final%20PPT/QA%20QC%20Module/QA&QC%20Mech%20FRM_64%20Welding%20Procedure%20Qualification.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_3/Plz%20dont%20make%20anymore%20desktop%20folder%20plz/Welding%20PPT/Final%20PPT/QA%20QC%20Module/QA&QC%20Mech%20FRM_66%20Welding%20Procedure%20Specification(WPS).pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_3/Plz%20dont%20make%20anymore%20desktop%20folder%20plz/Welding%20PPT/Final%20PPT/QA%20QC%20Module/QA&QC%20Mech%20FRM_67%20Procedure%20Qualification%20Record(PQR).pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_3/Plz%20dont%20make%20anymore%20desktop%20folder%20plz/Welding%20PPT/Final%20PPT/QA%20QC%20Module/QA&QC%20Mech%20FRM_68%20Welder%20Performance%20Qualification%20Record.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_3/Plz%20dont%20make%20anymore%20desktop%20folder%20plz/Welding%20PPT/Final%20PPT/QA%20QC%20Module/QA&QC%20Mech%20FRM_68%20Welder%20Performance%20Qualification%20Record.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_3/Plz%20dont%20make%20anymore%20desktop%20folder%20plz/Welding%20PPT/Final%20PPT/QA%20QC%20Module/QA&QC%20Mech%20FRM_67%20Procedure%20Qualification%20Record(PQR).pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_3/Plz%20dont%20make%20anymore%20desktop%20folder%20plz/Welding%20PPT/Final%20PPT/QA%20QC%20Module/QA&QC%20Mech%20FRM_66%20Welding%20Procedure%20Specification(WPS).pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_3/Plz%20dont%20make%20anymore%20desktop%20folder%20plz/Welding%20PPT/Final%20PPT/QA%20QC%20Module/QA&QC%20Mech%20FRM_64%20Welding%20Procedure%20Qualification.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_3/Plz%20dont%20make%20anymore%20desktop%20folder%20plz/Welding%20PPT/Final%20PPT/QA%20QC%20Module/QC_MS_M_07%20Welding%20Procedure%20Qualification.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_3/Plz%20dont%20make%20anymore%20desktop%20folder%20plz/Welding%20PPT/Final%20PPT/QA%20QC%20Module/QC_MS_M_07%20Welding%20Procedure%20Qualification.pdf


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Tools & Equipments Welding rectifier or other applied welding

equipment. Tong tester/Multi Meter Welding gauge Vernier caliper Measuring tape Stop watch Inspection torch Temple sticks (as required) Welding inspection mirror

Desicator Oven Temperature Recorder White marker

WPS & PQRSpecific References from ASME Section 9


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Specific References from ASME Section 9

Article II Welding Procedure Qualifications QW-200 General . . . . . . . . . . . . . . . . . . . . . .13QW-210 Preparation of Test Coupon . . . . 16QW-250 Welding Variables. . . . . . . . . . . . . 18

Article III Welding Performance Qualifications QW-300 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47QW-310 Qualification Test Coupons . . . . . . . . . . . . . 50QW-320 Retests and Renewal of Qualification. . . . . 51QW-350 Welding Variables for Welders . . . . .. . . . . . 52QW-360 Welding Variables for Welding Operators . .53QW-380 Special Processes . . . . . . . . . . . . . . . . . . . . . 54

BACK TO TOC
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Section 6Welding Inspection & Techniques


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Welding Inspection & Techniques


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NDE Requirements

All NDE methods must include the following to render valid examination results:

A trained operator

A procedure for conducting the tests

A system for reporting the results

A standard to interpret the results



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Non-Destructive Examination Methods

Visual inspection, with or without optical aids (VT) Liquid Penetrant (PT) Magnetic Particle (MT) Radiography (RT) Eddy Current (ET) Ultrasonic (UT) Acoustic emission (AET) Heat Transfer

Ferrite Testing



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Visual inspection (VT)

With eyes where access With mirror Illumunator

Boroscopy For record keeping using the camera



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References

ASME Section I, Power Boilers ASME Section VIII, Divisions 1 & 2. Pressure

Vessels ASME B31.1, Power Piping API 620 & API 650, Welded Steel Tanks


Acceptance Standards


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Acceptance StandardsThe following minimum acceptance standardsapply to visual examinations performed on all weldsduring and after welding. The following indicationsare unacceptable:

All external surface cracks.

Undercut on the surface which is greater than 1/32inch deep or ten percent (10%) of the wallthickness, whichever is less.

Surface porosity. Lack of fusion on the surface. Incomplete penetration (when inside surface is

accessible for examination) except for partialpenetration welds.


Penetrant Testing (PT)


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Penetrant Testing (PT)

For Open to the Surface Defects Pin Hole Under Cutting Cracks Grinding Marks etc.

Types of PT Solvent Remover Simple Method Penetrant Developer Cleaner



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Reference Codes

ASME Sec. VClient Specifications

Acceptance Standards ASME VIIIClient Specifications.

Welding Inspection & TechniquesMT (Magnetic Particle Testing)


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( g g)

For Open to the Surface Defects Just below the Surface Under Cutting Use only for Ferro Magnetic Material

Types of MTVisible Method (Iron Oxide Ink)

Black & White ContrastFluorescent Method Fluorescent Magnetic Ink UV Light


Magnetic Particle Testing Equipment (MT)


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Magnetic Particle Testing Equipment (MT)

Hand Yoke AC & DC Central Conductor Unit Magnetizing Coil Prude Conductor

Field Indicator References Code

ASME V Clients Specifications

Equipment AC Hand Yoke type Equipment



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Acceptable Standards

ASME VIIIClient Specifications.


Ultrasonic Flaw Detection (UT)


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Ultrasonic Flaw Detection (UT)1) Ultrasonic Flaw Detection Machine Internal Defects Thickness Measurements

Principles High Frequency Sound Waves 0.5 MHz to 25 MHz Human Hearing Range 20 MHz to 20 KHz Scan of the Body on maximum Thickness upto 5 meters Depending upon Probe Capacity

Defect Sizing Defect Location Thickness Measurement Permanent Record at the Shape of graph




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2) Vacuum Box Detection of leak

Vacuum Box Testing Equipment Vacuum Box (API 650) Devices (Calibrated Gauges) Vacuum Drawn 3 PSIG Minimum

Vacuum Box Overlap 50 mm Minimum


A li i


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Application

Soap Solution10 ~ 50 C Surface Cleaning Illumination Properly Observation not less than 10 sec. Marking of Leakage Portion Inspection Report


Radiographic Testing (RT)


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Radiographic Testing (RT)1) Ultrasonic Flaw Detection Machine Internal Defect detection

Equipment Xray Machine Gama Rays Projector

Radio Isotope Source IR192\

CO 60

CS 137Video

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Section 7Welding Defects, Causes &

Remedies

Welding Defects, Causes & Remedies


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Each weld should be: Adequately designed to meet the intended service for

the required life. Fabricated with specified materials and in accordance

with the design concepts. Operated and maintained properly.Quality considerations are: Physical features, normally examined by inspectors Hardness

Chemical composition Mechanical properties

Porosity

Sl I l i

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Slag Inclusions

Entrapped slag discontinuities typically occur only withthe flux shielded welding processes: shielded metal arc,flux cored arc, submerged arc, and electro slag welding.

Entrapped slag is: A reaction product of the flux and the molten weld metal

Oxides, nitrides and other impurities may dissolve in the

slag to refine the weld metal

F i l f l



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Factors preventing release of slag:

High viscosity weld metal

Rapid solidification

Insufficient welding heat

Improper manipulation of the electrode

Undercut on previous passes

Common Causes and Remedies of Porosity



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Cause Remedies

Excessive hydrogen, nitrogen, or oxygen inwelding atmosphere

Use low-hydrogen welding process, filler metalshigh in deoxidizers, increase shielding gas flow

High solidification rate Use preheats or increases heat input.

Dirty base metal Clean joint faces and adjacent surfaces.

Dirty filler wire Use special cleaned and packaged filler wire,

and stored in clean area. Improper arc length, welding current or electrodemanipulation

Change welding conditions and techniques.

Volatization of zinc form brass Use copper-silicon filler metal, reduce heatinput.

Galvanized steel Use E6010 electrodes and manipulate the archeat to volatize the zinc ahead of the moltenweld pool.

Excessive moisture in electrode covering or on joint surface

Use recommended procedures for baking andstoring electrodes preheat the base metal.

High sulphur base metal Use electrodes with basic slagging recreations

Common Causes and Remedies of Slag Inclusions



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Common Causes and Remedies of Slag Inclusions

Cause Remedies Failure to remove slag Clean surface and previous weld bead

Entrapment of refractory oxides Power Wire brush the previous weldbead

Tungsten in the weld metal Avoid contact between the electrodeand the work. Use larger electrode

Irnproper joint design Increase groove angle of joint

Oxide inclusions Provide proper gas shielding

Slag flooding ahead of the welding arc Reposition work to prevent loss of slag control

Poor electrode manipulative technique Change electrode or flux to improveslag control

Entrapped pieces of electrode Use undamaged electrodes Covering

Common Causes and Remedies of Inadequate Joint Penetration



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Common Causes and Remedies of Inadequate Joint Penetration

Causes Remedies Excessively thick root face orinsufficient root opening

Use proper joint geometry

Insufficient heat input Follow welding procedure

Slag flooding ahead of weldingarc.

Adjust electrode or work position

Electrode diameter too large Use small electrodes in root or increaseroot opening

Misalignment of second side weld Improve visibility or back gouge

Failure to back gouge whenspecified

Back gouge to sound metal if required inwelding procedure specification.

Bridging of root opening Use wider root opening or smallerelectrode in root pass.

Common Causes and Remedies of Cracking



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Causes Remedies

WELD CRACKING

Highly rigid joint PreheatReliever residual stresses mechanicallyMinimize shrinkage stresses using back step orblock welding

Excessive dilution SequenceChange welding current and travel speedWeld with covered electrode negative, butter the

joint faces prior to welding

Defective electrodes Change to new electrode, bake electrode to removemoisture

Poor fit-up Reduce root opening, build up the edges with metal.

Small weld bead Increase electrode size, raise welding current,reduce travel speed

Higher sulphur base metal Use filler metal low in sulphur.

Angular distortion Change to balanced welding on both sides of joint.

Crater cracking Filler crater before extinguishing the arc, use awelding current decay device when terminating the

weld bead.

Common Causes and Remedies of Cracking



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g

HEAT AFFECTED ZONE Hydrogen in welding atmosphere Use low-hydrogen welding process,

preheat and hold for 2h after welding orpost weld heat treat immediately

Hot cracking Use low heat input, deposit thin layers,

change base metal. Low ductility Use preheat anneal the base metal.

High residual stresses Redesign the weldment change weldingsequence, apply intermediate stress-relief heat treatment.

High hartdenability room Preheat increase beat input, heat treatwithout cooling to temperature.

Brittle phase in the microstructure. Solution heat treat prior to welding.

SAWAN GAS DEVELOPMENT PROJECT PROJECT No. : 6430 / 6431

COMMON WELDING DEFECTS, CAUSES AND CURES DURING THE WELDING OF D.S.S

DEFECTS CAUSES CURES

Common Welding Defects, causes and cures during the welding of DSS


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1 2

3

4

5 6 DECREASE IN CORROSION RESISTANCE

HEAT INPUT AS PER WPS

CHROMIUM DEPLETION MAINTAIN INTERPASS

TEMPERATURE AS PER W PS

FORMATION OF CHROMIUM

NITRIDES

MAINTAIN ELE CTRICAL

CHARACTERISTICS AS PER WPS

IMPROPER SET UP AND FIXTURING TACK OR CLAMP PARTS SECURELY

CONTAMINATION WITH C.S. POOR SHOP DISCIPLINE USE SEPARATE CONSUMABLES /TOOLS FOR C.S. AND D.S.S.

USE PROPER BEAD SEQUENCEIMPROPER BEAD SEQUENCE

DO PURGING AS PER WPS

USE PROPERLY PREPARED AND

SHARP TIPPED TUNGSTENELECTRODE

CURRENT AND VOLTAGE SHOULD

BE AS PER WPS

MAINTAIN TRAVEL SPEED AS PER

WPS

MAINTAIN TRAVEL SPEED AS PER

WPS

ELECTRICAL CHARACTERISTICS AS

PER WPS

PROPER ROOT GAP TO BEMAINTAINED

IMPROPER POINTING OR GRINDING

OF TUNGSTEN ELECTRODE

EXCESSIVE ARC LENGTH

HIGH HEAT INPUT

TACK WELD PARTS WITH

ALLOWANCE FOR DISTORTION

IMPROPER TRAVEL SPEED

POOR JOINT DESIGN

IMPROPER ROOT GAP

IMPROPER TACK WELDING AND /

OR FAULTY JOINT PREPARATIONWELDING DISTORTION

ARC DESTABILIZATION

POOR PENETRATION

OXIDATION IMPROPER PURGING


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Useful Web Sites

Useful Web Sites


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http://www.aws.org/ American Welding Society http://www.ewi.org/ Welding and Joining Information Network http://www.adtdl.army.mil/cgi-bin/atdl.dll/tc/9-237/toc.htm Welding

Theory and Application, Department of the Army, Washington, DC,7 May 1993

http://www.lincolnwelding.com Lincon Electric (welding supply co.) http://www.weldingengineer.com/ Welding Procedures and Welding

Techniques http://www.cigweld.com.au/litPocketGuide.asp Welding

Consumables & Equipments
http://www.aws.org/http://www.ewi.org/http://www.adtdl.army.mil/cgi-bin/atdl.dll/tc/9-237/toc.htmhttp://www.lincolnwelding.com/http://www.weldingengineer.com/http://www.cigweld.com.au/litPocketGuide.asphttp://www.cigweld.com.au/litPocketGuide.asphttp://www.weldingengineer.com/http://www.lincolnwelding.com/http://www.adtdl.army.mil/cgi-bin/atdl.dll/tc/9-237/toc.htmhttp://www.adtdl.army.mil/cgi-bin/atdl.dll/tc/9-237/toc.htmhttp://www.adtdl.army.mil/cgi-bin/atdl.dll/tc/9-237/toc.htmhttp://www.adtdl.army.mil/cgi-bin/atdl.dll/tc/9-237/toc.htmhttp://www.adtdl.army.mil/cgi-bin/atdl.dll/tc/9-237/toc.htmhttp://www.ewi.org/http://www.aws.org/

complete welding clip

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