GTAW on mild steel

what is the recommended electrode inclination for 1G

0 to 15 degrees for hand

electrode inclination for mild Steel gtaw

0 to 30 degrees forehand for all positions

given the choice what position would you use for the most productive fill it welding

1 f

what is the recommended gas flow rates and amperes for orange yellow red and black tungsten electrodes

10 to 20 cubic feet per hour with argon as shielding gas and 40 to 210 amps note that these electrodes are used for mild steel with dcen

what is the ratio for sharpening tungsten to a conical tip

2 to 6 * the diameter

as a general rule what thickness of material should joint preparation be considered for full penetration Groove weld

3/16

what is the recommended bevel angle range for single v-groove weld on pipe

30 to 37.5 degrees

beveling pipe

30 to 37.5 degrees bevel is normally used on pipe resulting in an included joint angle of 60 to 75 degrees 4 wall thickness less than 1/2 inch the bevel angle most often use is 30° the most common equipment to use for cutting carbon steel pipe is a pipe beveler equipped with oxy-fuel torch 0 to 1/16 root face

how many attacks are recommended for joining 6 in normal pipe

4

what is the recommended electrode angle for a 2f weld on 10 gauge material

45° to the vertical and horizontal planes

advantage and disadvantage of high-frequency start

Advantage no contamination disadvantage ceramic nozzles only

advantage and disadvantage of lift start

Advantage no high-frequency needed disadvantage not all the machines are equipped

most common shielding gas used for mild Steel

Argon

most common electrode preparation shape for mild Steel

Colonial 2 to 6 * diameter

what is the most common current type for gtaw on mild Steel

DC straight polarity

most common electrode type for welding on mild Steel

EWTh-2 red

a short Arc

Narrows the puddle and has deeper penetration along or spreads the Heat and increases puddle fluidity

continuous feed technique

Rod is added and not removed until the world is complete the filler Rod is held at 15 to 20 degrees directly in front of the weld

weld procedure specifications

WPS is a document providing details of their required variables for a specific welding application to assure quality and repeatability by properly trained welders and Welding operators

Stringer fill

a Stringer fill is made with a series of overlapping Stringer beads planned to blend into a finish Contour

fall through

a localized area of excessive penetration

what is fall through

a localized area of excessive penetration

fall through

a localized area of excessive penetration in a root causing a grape

how long should the tack welds be for a plate welded projects

a quarter inch to 3/8

tack

a weld of short length used to hold parts and Alignment in preparation for the final weld application

advantage and disadvantage of touch start

advantages DC without high frequency disadvantage electrode contamination

what positions can you do surface welding with gtaw

all positions

cross the weld Center at a speed that allows the puddle to remain liquid but does not

allow it to become so hot that fall through or suck back occurs

number 6 gas nozzle

allows good visibility and produces adequate shielding for the electrode sizes suggested the smallest nozzle usable is one whose lip does not melt In the Heat of the Ark

suck back

an area of root bead that has been drawn back into the groove, leaving the root side concave in Contour generally caused by overheating the root pass during the second pass

suck back

an area of the root that has been drawn back into the groove leaving the root side concave in Contour since the Ark of the gtaw process produces no pressure or Ark force on the puddle molten metal is drawn back to the hottest point by surface tension suck back is a result of the breakdown of surface tension

what is suck back and how may it occur

an area of the rupee that has been drawn into the groove leaving the root side concave in Contour caused by overheating the root pass during the second pass application suck back during the welding of the root pass is caused by to slow travel Speed, high current settings, excessive Arc Length or failure to add filler Rod deep enough into the backside of the groove

what does a burr or rag cause when fitting up bars for fillet welds

artificial space or a gap

the flat position is the most common

as the weld is being drawn straight down into the root by gravity and is performed from above the joint it is generally the easiest and most productive position for welders to work in

tax on pipe

attack becomes part of the root bead it can be a maximum length of half inch they should be feathered and the root face should not be ground thinner nor the Gap wider. Starts in the root maybe feathered similar to tax

a WPS list the welding variables required to give sufficient detail for confident welder to consistently produce acceptable weld using

base Metals, filler Metals, position, preheat, post Heat, join configuration, technique, any other details pertaining to the weld

how do you fix a crater

before striking the arc clean the original bead in the Creator area with a chipping hammer and wire brush if this is not done nonmetallic residue could be trapped under the stop-start area do not restart the Ark in the original crater start the ark 1/8 to 1/4 behind the crater within the weld zone out of the crater move it back into position so that the new weld blends with the completed portion of the weld

if the weld pool becomes too hot the surface of the puddle begins to

bounce and my eject a few Sparks resulting and melt through suck back has likely occurred

how many you increase root beet penetration

change electrode inclination, slow travel speed, shorten Arc Length, increase amperage, add filler metal closer to the back of the groove preparation, change configuration of land and Gap

how to increase penetration on a 1G

change the electrode inclination to a more perpendicular position, slow down travel speed so that the puddle becomes more fluid and gravity has time to pull it down, shorten the arc length to concentrate the heat, increase amperage use a lighter land or wider Gap

changing the inclination of the electrode holder in relation to the direction of travel

changes the depth of penetration

adding a root in a Groove weld

cross the weld Center at a speed that allows the puddle to remain liquid but not to be so hard that fall through or suck back occurs pause on the edges to allow heat to melt the parent metal allowing the puddle to flow and fusing the root Edge and filler rod

how is the work positioned in a 1ft joint

each member is at 45 degrees to the horizontal plane

a keyhole is more detrimental than helpful in the ones you position as

fall through is likely to occur

dip technique

filler Rod must be added at the Leading Edge of the puddle until the desired filled is attained and then removed from the puddle to progress forward establish the puddle on the end of attack at first the puddle appear is cold and lack of fusion as the puddle begins to flow the appearance changes indicating that full Fusion has been obtained you must add filler Rod at this point to prevent the puddle from becoming too hot and forming a keyhole as when the key hole forms excess heat melts the root edges away leaving to fall through or suck back depending upon welding position

continuous feed technique

filler metal remains in the weld for the entire root bead so the puddle progresses forward without interruption the filler Rod occupies the space in the Gap as it feeds continuously in front of the puddle this is comparable to welding a consumable insert this technique uses a short arc length and requires the puggle to take a teardrop shaped indicating full Fusion when welding a root make sure the puddle is reasonably fluid and has flat to slightly concave appearance as you add the filler rod the torch must aim at the puddle at all times so it does not melt and separate the filler rod from the puddle

what is the inclination of torch and filler metal in the 1G position

filler metal should be 20 degrees from 180 and torch should be 15 degrees from 90

plane

flat surface on which straight line joining any to points on it would be a Wholly line

what is the normal electrode extension beyond the gas nozzle

flush to 6.4 mm or quarter inch you may use a stick out equivalent to 2 times the electrode diameter

when is the dip feed technique generally used

for aluminum magnesium and weld bead starting a stopping also known as crater fill it's generally done in the root passes of fill it and groove welds on materials welded with dcen both techniques can be used to place surfacing beads in any position

lift start

found on many inverter design a newer generation gtaw compatible welding power sources it has eliminated the need for high-frequency current starting where electrode and weld metal contamination must be prevented lift start must be built into your power source it is not currently available as an aftermarket accessory item the main output current contact does not energize until the electrode contacts the work as you lift the torch the main welding current begins without overheating contamination or causing the electrode to stick to the base metal the main difference between Lyft start and touch start is that lift start does not start until you lift the Torch versus touch start it starts immediately as it touches

what is likely to happen if a keyhole forms in the 1G position

full through

Phil and finish pass

generally a heavy pass design to both fill the groove and produce a finish surface at the same time

root face and GAP dimension

given recommended before tacking because Tacs do shrink the gap the reason for a larger Gap is to allow the filler Rod to be placed between the root faces when using continuous adding technique. some welders use 3/16 Gap to ease the placement of filler rod for the dip technique you may find the Gap can be narrowed by approximately 1/16

preheat

heat applied to the weldmeant before starting the weld

post heat

heat applied to the weldment after welding has been done

when is dip technique beneficial

helps obtain full Fusion at tie in points and is useful when crater filling it's beneficial when a small amount of fill is required when completing thin wall Groove welds with zero Gap fit and on AC continuous high frequency when cleaning action needs to take place before the filler metal is added

dip feed technique

incorporates the adding filler metal at intervals as a weld progresses the filler rod is added directly in front of the puddle at an angle of 15 to 30 degrees always place the rod directly into the puddle when adding when it is withdrawn from the puddle try to keep the hot end of the filler Rod inside the gas Shield to prevent atmospheric contamination

what is the purpose of pre setting the 2G weld on plate

it compensates for the shrinkage caused by Stringer bead multipass welding

the torch must point of the pole at all times so

it does not melt and separate the filler rod from the puddle

as a general rule material of 3/16 or greater thickness welded from one side side using gtaw requires you to prepare

joint edges to allow for full fusion and full penetration of the weld preparation of Base Metals for grew welding requires cutting the edges to shape they should be no wider than 1/16 for 1/4 inch thick material

which of the following would be most effective in reducing accidents caused by portable Grinders kicking back

keep both hands on the grinder and clamp the work

walking or riding the cup

keep the gas nozzle in contact with the shoulders of joint at all times this maintains a steady arc length and inclination during welding of the root pass the material thickness and Joint preparation must be compatible to allow the nozzle to ride the belt surfaces it may not be practical for fill in cap passes

weave bead

made with side-to-side motion as well as Motion in the direction of travel this results in a higher localized heat input put into the work and a slowed cooling rate the width of a bead depends on the size of the electrode, current setting and the amount of side motion for normal practice, the amount of side motion should not exceed three to four times the diameter of the electrode

travel speed

maintain a fluid puddle approximately 6.4 mm or 1/4 inch wide

arc length

maintain a short as an arc as possible without contaminating the electrode

an appropriate electrode stick out for gtaw

maintains a gas shield around the electrode and the molten weld metal

dip feed technique

method of adding filler Rod at intervals as the weld progresses to completion

technique

method used in making weld includes many variables such as electrode inclination, electrode angle, Arc Place, Stringer bead or weave bead and single or multi pass welding

do soapstone markings normally interfere with gtaw

no

touch start

often called scratch start has the advantage of starting the arc without the need for high-frequency when welding with DC power sources this is of particular importance when using conventional CC power sources for field welding applications the disadvantage to touch start is an increased chance of electrode or weld metal contamination. the instant the electrode touches the material the current starts to flow as soon as the arc is struck lift the torch but not so high as to break the current and incline the torch to the required position to establish the puddle

fillet weld

oh weld that has a triangular shaped cross section and is used to join to Parts that are generally 90 degrees to each other there used on lapped tea and corner joints

continuous feed technique

once a puddle has formed in the filler Rod is added it is not removed with the filler Rod held in place the puddle progresses forward and you follow the Metal Flow until the weld is complete

groove weld

place between two meeting surfaces groove welds are most often used on but joints

if the Gap is unequal after the first two tax have been placed on the pipe joint you should

place the third track at the widest location to even out the Gap

what is the purpose of tailing out prior to Breaking the arc

prevent craters

a WPS is backed or supported by

procedure qualification record or pqr this is a record of a weld test specimen that is completed using the variables listed in the WPS and that has been thoroughly tested to ensure welders consistently yield good welds

tailing out

procedure to minimize or prevent crater cracks when using gtaw is stopped it before it is completed or at completion the puddle is slowly reduced in size by using a remote current control to decrease current or by using a fast travel speed to have the weld bead decrease inside before solidification

what is the maximum electrode extension use for

quarter inch or two times the diameter of the electron the consequence of using too long of an electrode extension is inadequate gas coverage

the root pass is the most likely of any past to crack due to

rapid cooling causing stress in the crater area if the arc is broken with the puddle at full size

what is the most common electrode used for welding mild steel with gtaw

red- EWTh-2 or 2% thorinated

what does removing light surface Mill scale from hot rolled mild steel do

reduces undercut on the cap pass

Stringer bead

single pass weld performed with no side-to-side motion the only movement of the electrode is in the direction of travel the size of a Stringer bead depends on the size of the electrode, current setting, Arc Length, speed of travel and the electrode inclination

what size of gas nozzle is recommended for any gtaw application

smallest nozzle who's lip does not melt In the Heat of the arc yet allows good visibility and adequate shielding gas module recommends number 6

high frequency start

starts the ark without touching the base metal and risking contaminating the electrode non-conductive ceramic nozzles must be used as high-frequency current May Crossfire was metal nozzles you may use high-frequency on DC to start only

using Lyft start high frequency start or touch start are acceptable if no

stray arcs are made outside of the finished weld area stray Arc strikes are considered a serious weld default as they cause hard spots and possible cracking some welding codes and standards may require the total area to be cut out and replaced

the WPS specifies details such as

supporting pqr, latest revision, base metal thickness or diameter, filler metal type and diameter, volts amps and travel speed, shielding gas and flow rate, heat treatment such as preheat post heat or stress relieving, join design including Edge preparation, route Gap, route face, tacking type, backing and weld techniques

4 lap joints the torch may be angled slightly towards the

supporting side of the joint as there is a larger mass of material to heat

a procedure used to help prevent weld bead crater cracking is

tailing out prior to Breaking the Ark

pipe coupons or nipples

talked with the pipe access placed vertically to check for alignment on the inside surfaces generally a mark is made and this becomes the location of the first Tac

in the 2G position you are required to hold the filler Rod near

the backside of the groove which prevents gravity and surface tension of the weld pool from drawing the molten metal back into the groove resulting and suck back

electrode sizes determined by

the current levels for the application

since gtaw has no Arc Force

the filler Rod must be placed where reinforcement is required with the dip technique the penetration obtained is only flush to the root side because filler metal cannot be placed through the opening into the back side

in multipass weld which passes more susceptible to cracking

the root pass

root pass

the route passes the first or penetrating bead made at the root of a joint

fill pass

the second or filling bead wear beads on thick material are to be made more than one fill past may be required fill passes maybe a Stringer or weave bead

Stringer padding

the use of stringer beads to build up a surface each successive bead is applied to partially overlap the previous bead so that the crowns the beads come out level with no valleys between the beads Stringer padding is used to build up where surfaces and to applied clad overlays by welding

acceptable ranges are documented in the WPS are generally permitted on

thickness, diameter, voltage, amperage, welding speed, materials, join type, gas flow rate

suck back during the welding of the root pass caused by

to low of a Travel speed, current settings to high, excessive Arc Length, failure to add filler Rod deep enough into the backside of the groove call Ma too high current settings and too low of a travel speed on the fill pass

what are the three ways to strike an arc with gtaw

touch start, lift start and high frequency start

what is the likely will progression for a single pass 3F on 10 gauge material

uphill

the progression for 3F with gtaw is

uphill dcen at 90 amps

tacking up pipe

use a length of rod in a V shape equal to the root space required it can be 1/8 5/32 or 3/16 talk at 12 then 6 you may find that the Gap is slightly unequal on the sides in this case use weld shrinkage by placing your third tack at the widest location nominal pipe sizes smaller than 4 inch need three tax 6 inch pipe and larger need 4 tax or more

fill pass on a 1G

used to add filler metal to the Joint to Aid in preventing melt through of the root on subsequent passes

weave patting

used to build up where surfaces weave beads are placed to blend with the previous be leaving the smooth even solid layer

cover pass or wash coat

weave bead coating used to produce a good blend with the material surface the cover pass should eliminate undercut and produce a good finish over top of the fill pass or passes

what are some pass and fill pass techniques on 1G

weave which gains good sidewall Fusion, adding the filler Rod to the center of the root bead causes the rod to absorb heat preventing melt through and suck back, make sure you cross quickly to avoid melting the root pass and full Fusion is happening if slag floats in front of the puddle

When selecting a welding technique factors to take into consideration are

weld quality, speed and cost, the amount of residual stress or Distortion, positions in which the technique will give satisfactory results and the time it takes to master the technique

how should you lay the beads when surface welding for build-up work

when them so that they form a solid layer of weld metal

tailing out

when welding is stopped at Crater may be left in the basement which has a tendency to crack of the Ark is broken quickly to prevent or reduce the possibility of cracking in the crater area use tailing out procedure the puddle is slowly reduced in size by decreasing current using a hand or foot operated remote control unit or using fast travel speed to have the weld bead decrease in size before solidification

torch inclination

you must position yourself so that you can see the puddle reactions without changing the electrode inclination the inclination has a large bearing on the penetration of the weld metal into the basement LOL the more perpendicular the inclination the more penetration is gained this requires faster travel speed and if it is increased greater than 30 degrees from vertical the shielding gas flow can cause venturi action as it exits the nozzle causing atmospheric air to be drawn into the weld Zone which leads to porosity