tools for welding safety avoid making stupid...

Tools for welding Safety Avoid making stupid mistakes

5 Things that will kill you

1. Moving

You're going to have to move high pressure cylinders at some point. If you're in a hurry or distracted, you might try to move them without the protective cap. If the cylinder should fall or the valve otherwise gets knocked off, you would have 2500 psi escaping out of a tiny hole, turning the cylinder into a potentially deadly missile.

2. Carrying acetylene and oxygen cylinders

Carrying cylinders of oxygen and acetylene in your car, truck, or even truck toolbox can be dangerous. Small leaks can build up and if there's a tiny spark the cylinders can become a bomb. It's possible that even a massive amount of heat - such as built up in a truck toolbox in the summer - could lead to an explosion.

3. Welding in water

This may seem like common sense, but it is actually a mistake that is extremely easy to make. For example, you might be working on welding a pipe and there's a puddle of water that you didn't dry completely, or that you didn't notice until you started to work. Don't keep working! Even though the current used in welding is high amperage and low voltage, you can still be injured or killed.

4. Welding a container that held something flammable

This can be a very dangerous situation. If you're in a hurry or don't clean the container properly, you could be looking at an explosion. If you take special precautions - such as washing the container well with soap and water followed by purging with argon - it can be pretty safe. If you forget or are not thorough enough, you could be in trouble.

5. Having a lighter

This is a mistake that happens simply because you can easily forget that you have a lighter. It's also very dangerous, because if you weld while carrying a lighter in your shirt pocket - a common place for many people - you are playing with fire. If there's a spark, then you may as well have had a stick of dynamite in your pocket. This is definitely one mistake that can kill you.

Subtitles & Transitions

FOR EXAMPLE…

5

Arc Welding Safety

• Protect yourself and others from potential hazards including:

– Fumes and Gases

– Electric Shock

– Arc Rays

– Fire and Explosion Hazards

– Noise

– Hot objects

Leather Steel Toed Work Boots

Gas Welding Cutting

Goggles

Flint Striker

Tip Cleaners

OSHA Eye Protection

8

Fumes and Gases • Fumes and gases can be

hazardous to your health

• Keep your head out of the fumes

• Use enough ventilation, exhaust at the arc, or both, to keep fumes and gases from your breathing zone and the general area

• See product labeling and MSDS for ventilation and respirator requirements

9

Electric Shock • Electric shock can kill

• Do not touch live electrical parts – Primary Voltage –230, 460

volt input power

– Secondary Voltage – 6 to 100 volts for welding

• Insulate yourself from work and ground

• Follow all warnings on welding equipment

Do not make repairs yourself, alert your

instructor immediately!

Tombstone welder

Waterfalls and Circuits: The Common link

• Electrical Circuits can be thought of as a waterfall

• Voltage (V) – Height of Waterfall – Measured in volts

• Amperage or Current (I) – Amount of water falling at

one point at any moment – Measured in amperes

• Resistance (R) – Constriction of water – Measured in ohms

15

Arc Rays

• Arc rays can injure eyes and burn skin

• The welding arc is brighter than the sun

• Precaution must be taken to protect your eyes and skin from UV radiation

• Wear correct eye and body protection

16

Fire and Explosion Hazards • Welding sparks can cause fires

and explosions

• Sparks and spatter from the welding arc can spray up to 35 feet from your work

• Flammable materials should be removed from the welding area or shielded from sparks and spatter

• Have a fire extinguisher ready

• Inspect area for fires 30 minutes after welding

17

Noise protection

• Loud noises can damage your hearing

• Keep loud noises at a safe level by using proper hearing protection such as:

– Ear plugs

– Ear muffs

Ear Plugs/pre-shaped foam type Ear muffs

18

Protective Clothing Welders must wear protective

clothing for – Protection from sparks, spatter and UV radiation

– Insulation from electric shock

• Protective clothing includes … – Fire-proof clothing without rolled sleeves, cuffs or

frays

– Work boots

– Welding gloves, jackets, bibs, and fire-proof pants

– Welding cap, helmet and safety glasses

– Ear protection – ear plugs and muffs

Protection

What is wrong with picture?

Chipping Slag Hammer

Carbon steel wire brush

Stainless steel wire brush

Carbon VS Stainless Steel

• Carbon steel brushes can be used on ferrous metal, concrete, masonry, and building materials.

• Stainless steel brushes are more resistant to oxidation, stainless steel brushes are ideal for use with aluminum, stainless steel and other non-ferrous alloys.

Welding Pliers

Linesman Cutting Pliers

Needle Nose Pliers or Mig Welding Tool

Soap Stone & Holder

Measuring Tape

Torpedo Level

Combination Square

Clecos

• Reusable blind rivet system used to secure overlapping panels.

Drill

• Drill 1/8” holes for the Clecos.

• Drill 5/16” holes for spot welds

Cut Off Tool

• Abrasive disc used to cut sheet metal panels.

Tin Snips

• Aviation tin snips allow right and left hand cuts without deforming the metal.

Roloc Angle Grinder

• Roloc discs are designed to remove surface contaminates from the metal without thinning the metal.

Electric grinder

Safety: 1. Condition 2. Grounding 3. Cord condition 4. Application

Wire wheel

Safety 1. Electrical connections 2. Grounding 3. Gloves 4. Face shield

Files

Panel Crimper

• Used to crimp the edge of the panel for an offset lap weld.

Vice Grips

• Holding and securing panels for welding.

Metal Hole Punch

• 5/16” Metal Hole Punch.

• Used for making holes in sheet metal for plug welds.

Hand Break

Horizontal Band Saw

Vertical Band Saw

Iron Worker

Safety 1. Emergency stop 2. Circuit Breaker 3. Start Switch 4. Pedal

5 Essentials (SMAW)

• Electrode Diameter – Use largest possible

• Current – Puddle size – Sticking

• Arc Length – Diameter of rod

• Travel Speed – The Eye oval

• Electrode Angle – Push angle – Drag angle

Types of welding Voltages

• DCEN

• DCEP

• AC

Shielded Metal Arc Welding

Flat Cross Weld

Side View Flat Cross Weld

Tee Joint

Shielded Metal Arc Electrodes

SMAW Electrode Designation System

E 6 0 1 1

• E designates Electrode

E 7 0 X X • 70 represents Tensile Strength in KSI

• 70 = 70,000 pounds per square inch

E 7 0 X 4 • Second to last digit represents POSITION

electrode will operate in… – 1 = all positions, vertical up

– 2 = flat & horizontal fillet only

E X X X X Last digit represents the Operating Characteristics

Current type 3/32" 1/8" 5/32" Characteristic Coating Grouping

EXX10 DCEP 40-80 65-130 90-165 Deep Penetration Cellulose-sodium F-3

EXX11 AC/DCEP 50-90 75-125 110-160 Deep Penetration Cellulose-potassium F-3

EXX12 AC/DCEN 50-95 70-130 125-200 Shallow Penetration Rutile-sodium F-2

EXX13 AC/DC 50-95 75-125 120-165 Shallow Penetration Rutile-potassium F-2

EXX14 AC/DC 65-95 110-140 130-200 Shallow Penetration Rutile-Iron powder F-2

EXX15 DCEP 75-110 90-145 120-210 Medium Penetration Low hydrogen-sodium F-4

EXX16 AC/DCEP 70-100 80-130 120-170 Medium Penetration Low hydrogen-potassium F-4

EXX18 AC/DCEP 75-110 90-145 120-210 Medium Penetration Low hydrogen/

Iron powder

F-4

EXX24 AC/DC 60-120 110-150 170-220 High deposition/

Medium penetration

Rutile-Iron powder F-1

E308 DCEP 45-85 65-120 65-170

Terms

• Direct Current Electrode Negative (DCEN) - The direction of current flow through a welding circuit when the electrode lead is connected to the negative terminal and the work lead is connected to the positive terminal of a DC welding machine. Also called direct current, straight polarity (DCSP).

• Direct Current Electrode Positive (DCEP) - The direction of current flow through a welding circuit when the electrode lead is connected to a positive terminal and the work lead is connected to a negative terminal to a DC welding machine. Also called direct current, reverse polarity (DCRP).

MILD STEEL ELECTRODES

E7018

– E 7018 E - electrode

– E7018 70 - tensile strength in KSI(kilopound per square inch, a unit of stress or pressure)

– E7018 1 - position;

• 1 – All positions – flat, horizontal, overhead, & vertical up

• 2 – flat & horizontal fillet only

– E7018 8 - operating characteristics

Welding rods

• *6010 arc welding rods are most commonly used for welding root passes in pipe and even for the fill passes on pipelines.

• 6011 arc welding rods are the kissing cousin of 6010 and are designed to be used on AC.

• 6013 arc welding rods are the farmers welding rod and the welding rod most people use first when learning to weld.

• 7014 Mild Steel Electrode Heavy sheet metal, frames, shelving, general maintenance and fabrication.

• *7018 stick welding electrode is used for pipe welding and structural steel welding and a all kinds of repair welding.

• 7024 stick rod is used to lay down a heap of weld fast...a really hot and big puddle to get things done quick if its flat or horizontal...and run sweet on AC

Types of Welds

• Numerous welds can be applied to the various types of joints

• Considerations when choosing joint geometry and weld types:

– accessibility to the joint for welding

– type of welding process being used

– suitability to the structural design

– cost of welding

Types of Welds

• There are nine categories of welds associated with weld symbols – Groove welds – Fillet Welds – Plug or Slot welds – Stud welds – Spot or projection welds – Seam welds – Back Or Backing welds – Surfacing welds – Flange Welds

Types of Welds Groove Welds

• A groove weld is “ a weld made in a groove between the work pieces”

• There are eight types of groove welds – Square-groove

– Scarf

– V-groove

– Bevel-groove

– U-groove

– J-groove

– Flare-v-groove

– Flare-bevel-groove

Groove Welds Square and double square-groove

welds

• Square-groove welds are the most economical to use, but are limited by thickness of the members

• Welds for one side are normally limited to a 1/4 inch or less

Groove Welds V-and double V-groove welds

•With thicker materials joint accessibility

must be provided for welding to ensure weld

soundness and strength

Groove Welds Bevel- and double-bevel-groove

welds

• Bevel- and J- groove welds are more

difficult to weld than V- or U- groove welds

• Bevel welds are easier in horizontal

Types of Welds U-groove and Double U-groove

• Welds in using J- and U-grooves can be used to minimize weld metal

• These welds are very useful in thicker sections

Groove Welds J-and double-J-groove welds

• J-groove are more difficult to weld because of the one vertical side (except in horizontal)

• J-and U- are used when economic factors outweigh the cost of edge preparation

Groove Welds flare-bevel and flare-v-groove welds

• Flare -bevel and flare-v-groove welds are used in connection with flanged or rounded member

Groove Welds Scarf

• Scarf is used for brazing

Groove Welds • Their names imply what the actual

configurations look like when viewed in a cross section

• Single groove welds are welded from only one side

• Double groove welds are welded on both sides

• Groove welds in many combinations are used selection is influenced by accessibility, economy, adaptation to structural design

Fillet Weld

• Fillet welding refers to the process of joining two pieces of metal together whether they be perpendicular or at an angle. These welds are commonly referred to as Tee joints which are two pieces of metal perpendicular to each other or Lap joints which are two pieces of metal that overlap and are welded at the edges.

Striking the Arc

1. Safety 2. Striking

1. Clean 2. Check Welder setup

1. DCEN, DCEP 2. Adjust electrode 3. When done Clean up power down

3. Scratching and taping 4. Pull back and form puddle (puddle size of rod) 5. Keep in the eye 6. 2- 2 ½ weld rod bead diameters

Pad of Beads Flat position

• Flat position

• Crater Filling

• In general 90 ⁰ start work angle 5⁰- 15⁰ drag travel angle

• Work angle is the gun position relative to the angle of the welding joint

• Travel angle is defined as the angle relative to the gun in a perpendicular position

Passes

• Weld Pass - A single progression of welding along a joint. The result of a pass is a weld bead or layer

Tips

• Stay on the leading edge of the puddle

• Clean your Welding Hood lens

• Drape the cable over your shoulder or knee

• Get Comfortable

• Watch the puddle, not the arc

• Concentrate on steady travel speed and arc length

Ending bead

• Wait for puddle to come to rod

• Shorten Arc wait for puddle

• Whip up and back to end Arc

Electrode Size depends upon:

– Welder skill

– Metal thickness

– Size of groove being filled

– Welding codes or standard

Choosing Electrode Size

• Large diameter electrodes:

– Disperse large amounts of filler metal

– Require more skill

– Run hotter

• Small diameter electrodes require:

– Less skill

– More time

Electrode Heat

• Rounded ripples indicate uniform cooling

• If ripples are pointed, weld is cooling too slowly

• Weld bead at a high amperage is wide & flat with deep penetration

• Chill plate: large piece of metal or copper plate that absorbs excessive heat

Shielded Metal Arc Welding

The effect of the molten weld pool caused by heat input

•

Electrode Current Setting

• Too high:

– Causes electrode to overheat, discolor, crack & lose some of the chemicals in the covering causing poor arc stability

– may lead to excessive spatter, porosity, & slag inclusions

Discolored flux due to excessive heat

•

Arc length too high

•

If the flux is broken off the end completely or on one

side, the arc can be erratic or forced to one side •

Electrode Current Setting

• Too low:

– will result in poor fusion

– poor arc stability

– slag & gas inclusions

– the arc length tolerance will be short which will result in frequent shortening & sticking of the electrode

Common Joints

Common Joints

• Five basic joints used in welded metal fabrication

– Butt

– T

– Lap

– Corner

– Edge

• It is important to be able to identify individual features that make up the joint geometry

• Certain weld & weld symbols are applicable to these

Fixing Welds

• Filing

• Grinding

• Oxygen / Acetylene Cutting

• Plasma

• Carbon Air Arc Gouging

Carbon-Air Arc Gouging

Oxy/acetylene

• Basic characteristics of Oxygen – Oxygen is 99.9% pure

– Odorless, tasteless, colorless

– Non flammable, but supports combustion

– Represented by green color

– Right hand thread

• Basic characteristics of Acetylene – Made of calcium carbide & water

– Highly explosive – never use above 15 psi

– Strong odor of garlic – added for safety

– Represented by color red

– Left handed threads

– Only open cylinder 1 ½ turns

Oxygen & acetylene produces one of the hottest flames 5900 degrees F to 6300 degrees F

SETTINGS

• Welding

– 5 psi acetylene / 5 psi oxygen

• Cutting

– 10 or 12 psi acetylene/ 30 psi oxygen

NEUTRAL FLAME – a balance of oxygen & fuel gas

Most commonly used flame because it adds nothing to the weld metal

OXIDIZING FLAME – excess amount of oxygen

Highest temperature, may put oxides in the weld metal

CARBURIZING FLAME – excess amount of fuel gas

Lowest temperature, may put extra carbon in the weld metal

Used to surface harden parts

Hand Cutting

• It is important to be steady

– Be comfortable

– Free to move the torch

• Practice cutting movement before lighting torch

• Brace the torch with the non-dominant hand

• Lay out is an important part of cutting

– a line to be cut with a piece of soapstone

To start a cut on the edge of a plate

– Point torch to start cut at the very edge

– Hold torch at a right angle to the surface

– Kerf is the space/loss of metal caused by the cutting process

• Inner cones of the flame should be 1/8 – 3/8 inch from the surface plate

– Called the coupling distance

• Never use a cutting torch to cut open a used can, drum, tank, or other sealed containers

The Chemistry of a Cut

• A high-pressure stream of pure oxygen is directed on the metal preheated to its kindling point

• Kindling point is the lowest temperature at which a material will burn

• Works on any metal that rapidly oxidizes – Iron, low carbon steel, magnesium, titanium, zinc

• Some metals release harmful oxides when they are cut – you may need extra ventilation and a respirator

The Physics of a Cut

• A record of the cut is preserved on both sides of the kerf

• Record shows what was correct or incorrect with:

– Preheat flame

– Cutting speed

– Oxygen pressure

Correct cut

• Cutting speed should produce drag lines

• Drag lines should have a slight slant backward

CHARACTERISTICS OF CUT

• Pressure is correct

– Cut sides are flat, smooth

• Pressure too high

– Cutting stream expands

• Pressure too low

– Cut may not go completely through the metal

Pressure Regulators • Gases are supplied in pressurized cylinders

– Pressure in cylinder is reduced by use of a regulator

• Regulators reduce gas pressure from the cylinder – Size of the regulator determines its ability to hold the working

pressure constant over a wider range of flow rates.

• One regulator gauge shows the working pressures – Shows the pressure at the regulator

• One regulator gauge shows the cylinder pressure – Used to indicate the amount of gas that remains in the cylinder

• Cylinders containing liquefied gases, such as CO2, propane, and Mapp gas, must be weighed to determine the amount of gas remaining

• Pressure shown on a gauge is read as pounds per square inch; PSI,PSIG

•

Maximum pressure on Acetelyne is 15 PSI

•

Fittings • A variety of inlet or cylinder fittings are available to ensure

that the regulator cannot be connected to the wrong gas or pressure

– Few adapters are available that will allow some regulators to be attached to a different type of fitting

• Gas flows through flexible hoses

– Torch controls the flow • Mixes the gases in the proper proportion for a good combination at the

end of the tip

• Fittings should screw together freely by hand or require light wrench pressure to be leak tight

Connect free ends of oxygen hose (green with right hand thread) & acetelyne (red with left hand thread)

Reverse Flow & Flashback • A backfire occurs when a flame goes out with a loud snap or pop

• A backfire may be caused by;

1. Operating the torch when the flame settings are too low

2. A loose tip

3. Dirt in the tip

4. Overheating the tip

5. Touching the tip against the workpiece

• A reverse flow valve closes when there is gas pressure from a back flow but will not stop the flame from continuing through the hoses

• A flashback occurs when the flame is burning back inside the tip, torch, hose or regulator and produces a high-pitched whistle

– Close the oxygen valve at once & then close the fuel valve

– A flashback that reaches the cylinder may cause a fire or an explosion

• A flashback arrestor will do the reverse flow valve & will also stop the flame of a flashback

– Most torches must add these safety devices

Safety

• Leak detection

– Solution premixed, must be free flowing

– Set pressure, spray on leak-detecting solution, watch for bubbles

Torchmate: CNC System Plasma

Plasma Cutting

• Plasma cutting is a process that cuts through electrically conductive materials by means of an accelerated jet of hot plasma. Typical materials cut by this process include steel, aluminum, brass and copper though other conductive metals may be cut as well.

Plasma

• States of mater – Solid

– Liquid

– Gas

– Plasma

• Plasma – Adding energy to gases results in ionization. This

Ionization process makes the gas electrically conductive. The ionized conductive gas is called plasma.

Horizontal

1. 1/8″ 7018 rod

2. Start with Padded Beads

3. Stack on bead ½ over other

4. Find settings (current)

5. Angle of electrode

6. Find Speed

7. Find Arc length

Too Cool Too Hot Esta muy caliente

Arc length too short Too long an arc Too Slow

Travel Too Fast Stacked Dimes

Optimal arc

Weaved welding

Voltage

• Is the pushing force that produces electron flow

Wattage

• The intensity of the arc

Understand Duty Cycle

• One way of classifying a welder's "size" is by how much amperage it can generate at a given "duty cycle." Duty cycle is the number of minutes out of a 10-minute period a welder can operate. For example, the Dynasty® 350 TIG unit can deliver 300 amps of welding output at a 60 percent duty cycle. It can weld continuously at 300 amps for six minutes, and then must cool down during the remaining four minutes to prevent overheating

Duty Cycle

• Light Industrial products typically have a 20% duty cycle and a rated output of 230 amps or lower.

• Industrial products typically have a 40-60% duty cycle and a rated output of 300 amps or lower.

• Heavy Industrial products typically have a 60-100% duty cycle and a rated output of at least 300 amps.

Duty Cycle

• Measured in 10 minuet cycles

• Example 40% duty cycle

– 40%@260 amps

– You can weld for 4 minuets strait then cool for 6

Ultraviolet Light (UV)

• UV is generated by all arc processes. Excess exposure to UV causes skin inflammation, and possibly even skin cancer or permanent eye damage. However the main risk amongst welders is for inflammation of the cornea and conjunctiva, commonly known as 'arc eye' or 'flash'.

Arc eye

• Arc eye is caused by UV radiation. This damages the outmost protective layer of cells in the cornea. Gradually the damaged cells die and fall off the cornea exposing highly sensitive nerves in the underlying cornea to the comparatively rough inner part of the eyelid. This causes intense pain, usually described as 'sand in the eye'. The pain becomes even more acute if the eye is then exposed to bright light.

The welding process

• Provides flow of Electrons

• A source of energy in the form of light and heat

• Electrons flow from Negative to positive current flows from positive to negative

• Voltage varies dependent on applications

DCEP or DC+ "Electrode Positive"

• The objective for using DCEP is to put 70% of the heat (that's generated by the electric arc) at the tip of the electrode, which can melt it with a vengeance into the joint. The other 30% ends up dispersed around the work piece.

• Reverse polarity

DCEN or DC- "Electrode Negative"

• This is "straight polarity". Now 70% of

the heat gets focused on the work plates, and only 30% reaches the tip of the electrode. This situation is desirable when working with thin metal stock or a joint that doesn't require deep penetration.

Welder output

Arc Blow

• Arc blow occurs in DC arc welding when the arc stream does not follow the shortest path between the electrode and the workpiece and is deflected forward or backward from the direction of travel or, less frequently, to one side

Arc Blow

• Situation in which to use AC polarity is to remedy arc blow problems. This is a phenomenon in which the arc wanders or blows out of the joint, and is more common when using large diameter electrodes at higher current levels. While there are other remedies to arc blow problems that can be used with DC polarity, switching to AC is often an effective fix.

Overcoming arc blow

• Use as short an arc length as possible (lower arc voltage) and the lowest current that is practical for the affected joint (possibly a smaller diameter electrode)

• Backward arc blow tends to occur when welding in a direction towards the current return connection, or earth connection, and forward arc blow when welding in the other direction. As it is likely to be easier to control a backward deflecting arc than a forward deflecting one during SMAW welding, it is usually better to weld towards the return or earth connections. Use of multiple earth connections may solve the problem altogether.

Cellulose-Based Flux

• E6010 and E6011

• Forceful deep penetrating arc

• Little slag

• Starting electrode

• No rod oven

• Root welds

• Plate and pipe

Mineral-Based Flux

• E7016 & E7018

• Medium penetration

• Arc is smooth and easy

• Lots of Slag

• Require special handling (OVEN)

• Pretty welds

• Strong welds more difficult

• Porosity is common

Arc Length Review

•Longer arc lengths = increased puddle heat, flatter welds, deeper penetration

•Shorter arc lengths = less puddle heat, flatter welds, less penetration

•Use arc length to control puddle size, penetration, and burn through.

•Normal arc length is 1/16” - 1/8”

•Use a slightly longer arc length during a start or restart.

Stringer beads

• Used to establish machine settings

• Surfacing materials

Push Vs Pull

• Dragging (Pull) means the electrode is pointed back towards the puddle, leading it. This enables maximum penetration and a robust-looking weld.

• For heat-sensitive or thin metals, or when welding in the vertical-up position, welders "push" the torch, which means pointing the electrode forward. When welding vertical-up, the molten metal wants to fall downward, so directing the heat away from the puddle allows the weld to solidify quickly. The drawback to pushing is that penetration into the base metal is much less than when dragging (pulling) the arc.

Push VS Pull (Drag)

Grounding

• Safety

• Completion of welding circuit

• Required for good welding

• Better ground = better performance

• All equipment must have ground!

GMAW (Gas Metal Arc Welding)

• GMAW sometimes referred to by its subtypes metal inert gas (MIG)welding or metal active gas (MAG) welding, is a welding process in which an electric arc forms between a consumable wire electrode and the workpiece metal(s), which heats the workpiece metal(s), causing them to melt, and join.

GMAW weld area. (1) Direction of travel (2)Contact tube (3) Electrode (4) Shielding gas (5)Molten weld metal (6) Solidified weld metal (7)Workpiece.

TIG

• TIG stands for Tungsten Inert Gas and is technically called Gas Tungsten Arc Weldingor GTAW. The process uses a non-consumable tungsten electrode that delivers the current to the welding arc. The tungsten and weld puddle are protected and cooled with an inert gas, typically argon.

Part 2

Reference arrow

• A reference line must have an arrow and be drawn Horizontally

AWS

• The American Welding Society (AWS) was founded in 1919, as a non-profit organization with a global mission to advance the science, technology and application of welding and allied joining and cutting processes, including brazing, soldering and thermal spraying.

Fillet Weld

• A=Weld Leg • B=Weld Toe • C=Weld Face • D=Effective Throat • E=Joint Root • F=Theoretical Throat • G=Actual Throat • H=Weld Interface • I=Fusion Face • J=Depth of Fusion

Oxygen acetylene cutting

• The cutting is a burning process where the fast temperature rise creates a clean curf (Groove or notch)This is facilitated through oxidation

• Stainless steel does not burn it will just melt and leave a very sloppy mess .

• Cast iron tends to melt and high carbon steel tends to harden with the cutting process requiring special cutting procedures.

Kerf

• Kerf is defined as the width of material that is removed by a cutting process.

Delayed Cracking

• Improper termination of the SMAW electrode & shrinking of the weld pool

Defect • A flaw or flaws that by nature or accumulated

effect render a part or product unable to meet minimum applicable acceptance standards or specifications. The term designates rejectability.

Discontinuity • An interruption of the typical structure of a

material, such as a lack of homogeneity in its mechanical, metallurgical, or physical characteristics. A discontinuity is not necessarily a defect.

Weld Joint Discontinuities

• Misalignment (hi-lo)

• Undercut

• Underfill

• Concavity or Convexity

• Excessive reinforcement

• Improper reinforcement

• Overlap

• Burn-through

• Incomplete or Insufficient

Penetration

• Incomplete Fusion

• Surface irregularity

– Overlap

• Arc Strikes

• Inclusions – Slag

– Wagontracks

– Tungsten

• Spatter

• Arc Craters

• Cracks – Longitudinal

– Transverse

– Crater

– Throat

– Toe

– Root

– Underbead and Heat-affected zone

– Hot

– Cold or delayed

• Base Metal

Discontinuities

– Lamellar tearing

– Laminations and

Delaminations

– Laps and Seams

• Porosity

– Uniformly Scattered

– Cluster

– Linear

– Piping

• Heat-affected zone

microstructure alteration

• Base Plate laminations

• Size or dimensions

Misalignment (hi-lo)

• Definition: Amount a joint is out of alignment at the root

• Cause: Carelessness. Also due to joining different

thicknesses (transition thickness)

• Prevention: Workmanship. Transition angles not to exceed

2.5 to 1.

• Repair: Grinding. Careful on surface finish and direction of

grind marks. Inside of Pipe /Tube difficult.

Undercut

• Definition: A groove cut at the

toe of the weld and left unfilled.

• Cause: High amperage, electrode

angle, long arc length, rust

• Prevention: Set machine on scrap metal. Clean metal

before welding.

• Repair: Weld with smaller electrode, sometimes must be

low hydrogen with preheat. Sometimes must gouge first.

Insufficient Fill

• Definition: The weld surface is below the adjacent surfaces of the base metal

• Cause: Improper welding techniques

• Prevention: Apply proper welding techniques for the weld

type and position. Use stripper beads before the cover pass.

• Repair: Simply weld to fill. May require preparation by

grinding.

Insufficient Fill on the Root Side (suckback)

• Definition: The weld surface is below the adjacent surfaces

of the base metal at the weld root.

• Cause: Typically improper joint preparation or excessive

weld pool heat.

• Prevention: Correct cause. (see next slide)

• Repair: Backweld to fill. May requireremoval of weld

section by grinding for access to the joint root.

Cause for Insufficient Fill at the Root

Some liquids, like water or molten steel, try to cover as much surface area of whatever they are in contact with as possible.

Welding a root pass too wide can also cause the bead to sag (overhead position).

Excessive Concavity or Convexity

• Definition: Concavity or convexity of a fillet weld which exceeds the specified allowable limits

• Cause: Amperage and travel speed

• Prevention: Observe proper parameters and techniques.

• Repair: Grind off or weld on. Must blend smoothly into the

base metal.

Concavity

Convexity

Reinforcement

• Excessive

• Insufficient

• Improper contour

Face Reinforcement

Root Reinforcement

The amount of a groove weld which extends beyond the surface of the plate

Excessive Reinforcement

• Definition: Specifically defined by the standard. Typically, Reinforcement should be flush to 1/16”(pipe) or flush to 1/8” (plate or structural shapes).

• Cause: Travel speed too slow, amperage too low

• Prevention: Set amperage and travel speed on scrap plate.

• Repair: Remove excessive reinforcement and feather the

weld toes to a smooth transition to the base plate.

• Definition: When the weld exhibits less than a 1350

transition angle at the weld toe.

• Cause: Poor welding technique

• Prevention: Use proper techniques. A weave or whip motion

can often eliminate the problem.

• Repair: The weld face must be feathered into the base plate.

1350

Improper Weld Contour

Overlap

• Definition: When the face of the weld extends beyond the

toe of the weld

• Cause: Improper welding technique. Typically, electrode

angles and travel speed.

• Prevention: Overlap is a contour problem. Proper welding

technique will prevent this problem.

• Repair: Overlap must be removed to blend smoothly into

the base metal. Be careful of deep grind marks that run

transverse to the load. Also be careful of fusion

discontinuities hidden by grinding. Use NDT to be sure.

Overlap Overlap is measured with a square edge such as a 6” rule. No amount of overlap is typically allowed.

Burn-through (non-standard)

• Definition: When an undesirable open hole has been

completely melted through the base metal. The hole may or

may not be left open.

• Cause: Excessive heat input.

• Prevention: Reduce heat input by increasing travel speed,

use of a heat sink, or by reducing welding parameters.

• Repair: Will be defined by standards. Filling may suffice.

Otherwise, removal and rewelding may be required. Some

standards may require special filler metal and/or PWHT.

Incomplete or Insufficient Penetration

• Definition: When the weld metal does not extend to the

required depth into the joint root

• Cause: Low amperage, low preheat, tight root opening, fast

travel speed, short arc length.

• Prevention: Correct the contributing factor(s).

• Repair: Back gouge and back weld or remove and reweld.

Incomplete Fusion

• Definition: Where weld metal does not form a cohesive

bond with the base metal.

• Cause: Low amperage, steep electrode angles, fast travel

speed, short arc gap, lack of preheat, electrode too small,

unclean base metal, arc off seam.

• Prevention: Eliminate the potential causes.

• Repair: remove and reweld, being careful to completely

remove the defective area. This is sometimes extremely

difficult to find.

Arc Strike

• Definition: A localized coalescence outside the weld zone.

• Cause: Carelessness

• Prevention: In difficult areas, adjacent areas can be

protected using fire blankets.

• Repair: Where applicable, arc strikes must be sanded

smooth and tested for cracks. If found, they must be remove

and repaired using a qualified repair procedure and

inspected as any other weld.

Inclusions

• Slag

• Wagontracks

• Tungsten

• Definition: Slag entrapped within the weld

• Cause: Low amperage, improper technique, Trying to weld

in an area that is too tight. Slow travel in Vertical Down

• Prevention: Increase amperage or preheat, grind out tight

areas to gain access to bottom of joint.

• Repair: Remove by grinding. Reweld.

Slag Inclusion

• Definition: Slang term for a groove left at the toe of a root

pass which becomes filled with slag and is trapped in the

weld.

• Cause: The contour of the root pass is too high, or the weld

toe is not bonded to the base metal

• Prevention: Use proper technique to deposit the weld root.

• Repair: Best repaired before applying the hot pass.

Carefully grind the root pass face flat. be careful not to

gouge other areas on the weldment.

Wagon Tracks (non-standard)

Inclusions

• fix when you see it. otherwise grind out & fix

Whiskers

• Unsightly

• Inhibits material flow in piping

• Are inclusions

• Can break off in pipes and damage equipment downline

Spatter

• Definition: Small particles of weld metal expelled from the

welding operation which adhere to the base metal surface.

• Cause: Long arc length, severe electrode angles, high

amperages.

• Prevention: Correct the cause. Base metal can be protected

with coverings or hi-temp paints.

• Repair: Remove by grinding or sanding. Sometimes must be

tested as if it were a weld.

Arc Craters

• Definition: A depression left at the termination of the weld

where the weld pool is left unfilled.

• Cause: Improper weld termination techniques

• Prevention:

• Repair: If no cracks exist, simply fill in the crater. Generally

welding from beyond the crater back into the crater.

Cracks

• Longitudinal

• Transverse

• Crater

• Throat

• Toe

• Root

• Underbead and Heat-affected zone

• Hot

• Cold or delayed

Repairs to Cracks

• Determine the cause

• Correct the problem

• Take precautions to prevent reoccurrence

• Generally required to repair using a smaller electrode

Base Metal Discontinuities

• Lamellar tearing

• Laminations and Delaminations

• Laps and Seams

Porosity

• Single Pore

• Uniformly Scattered

• Cluster

• Linear

• Piping

Uniformly Scattered Porosity

• Typically judged by diameter and proximity to a start or stop

• often caused by low amperage or short arc gap or an unshielded weld start

Cluster Porosity

• Typically viewed as a single large discontinuity

Linear Porosity

• being linear greatly affects the severity of this discontinuity

Piping Porosity

• Generally has special allowable limits

Porosity

• preheat will help eliminate

• may need an electrode with more deoxidizers

• Use run-on/run-off taps

• restart on top of previous weld and grind off lump

Hydrogen

• Electrolysis of water

• Reforming organic substances