WELDING PRESENTTION PART 1

ETA Engineering. Pvt Ltd

A PRESENTATION ON WELDING TECHNIQUE

Welding Technique Used

For Chilled Water Piping is

SMAW[ Shielded Metal Arc Welding]

SMAW• Shielded Metal Arc Welding : - This method is the most familiar

and common type and is known in the trade as stick welding. A metal wire rod coated with a welding flux is clamped in an electrode holder connected to the power supply with a heavy electrical cable. The metal to be welded is also attached to the power supply. The electric power is supplied to the work at a low voltage and high current and may be either AC or DC, depending upon the type of welding being done. An arc is struck between the rod and the work and produces heat in excess of 10,000deg F, Which melts both the material and the rod. As the flux melts, it releases an inert gas which shields the molten puddle from oxygen in the air and prevents oxidization. The molten flux covers the weld and hardens to an airtight slag cover that protects the weld bead as it cools. This slag must be chipped off to examine the weld.

• Why use welding?Welding is used because it is:

• One of the most cost-effectivemethods of joining metalcomponents.

• Suitable for thicknesses rangingfrom fractions of a millimeter to athird of a meter.

• Versatile, being applicable to awide range of componentshapes and sizes.

Welding Positions

• 1G• 2G• 5G• 6G

• 1F• 2F• 2FR• 4F• 5F

1G Position

Pipe rotated, Electrode is always at the top

Either a split bead or weave technique may be used

PIPE TO PIPE WELDING

2G Position

Pipe Axis Vertical, Weld is Horizontal, Pipe is considered in a “fixed” position.

Always use a split bead technique

Always work from the bottom up.


5G Position

Axis of the Pipe is Horizontal, The weld in vertical.

Progression may be up or down.

A weave bead is best used.


6G Position

Pipe axis is fixed in position at a 45 degree incline. The position includes flat, horizontal, vertical, and overhead welds.

A split bead technique is best used.


1F Position

Pipe is rotated. The pipe axis is at a 45 degree incline. Welding is to occur at the top of the pipe.

Split bead or weave technique may be used.

PIPE TO PLATE WELDING

2F Position

Fixed Position

Best to use a split bead technique


2FR Position

Rotated

A split bead technique is best used.


4F Position

A split bead technique is best used


5F Position

Not Rotated. Progression may be up or down.

Split beads or weaves can be used on 5F-up welds, split beads are best used on 5F-down welds.


75-800 Face angle1-2 mm Root gap1.0 mm land

Butt Joint Preperation

1.0 mm

(Joints without backing)

Root Pass Hot Pass

Fill Pass Cover Pass

Always work from the bottom up when using the split bead technique

Always be careful not to create a tight area where slag may get trapped under the next weld.

It is better to weave slightly than to leave a tight area.

Plan your sequence of beads!

Always work toward the smaller side of the fillet. (It will be easier to get to)

Always be careful not to create a tight area where slag may get trapped under the next weld.

It is better to weave slightly than to leave a tight area.

Plan your sequence of beads!

Techniques• Stringer (push, drag, or whip), or Weave

Progression (vertical)

• Up (Electrode is moved from Down to top)– deeper penetration – Higher deposit rate (lb/hr)– Use near 90 degree travel angle or slightly up

• Down (Electrode is moved from Top to Down)– faster (point to point)– less penetration for thin metal– less dilution– Use steep drag angle

TYPES OF DEFECTS OBSERVED IN WELDING

• Porosity• Pin hole• Cracks• Undercut• Lack of Fusion• Lack of Penetration• Slag Inclusion• Excess Penetration

TYPES OF TESTING DONE ON WELD JOINT

• D.P.T (Dye Penetrant Testing)• M.P.T (Magnetic Particle Testing)• U.T (Ultrasonic Testing)• R.T (Radiography Testing)

NOTE: THESE TESTING ARE KNOWN AS NON - DESTRUCTIVE TESTING.

CARE TO BE TAKEN BEFORE WELDING

1. Check the joint for proper ‘V’ groove .

2. Remove The Mill Scale Or Rust By Buffing Or Wire Brushing The Surface.

3. Ensure the joint is dry, there should be no moisture content on or near the joint surface.

4. Ensure the electrode used for welding is fully dry.

CARE TO BE TAKEN AFTER WELDING

1. Proper cleaning should be done after welding to remove slag & spatters.

Final Pass after Root Pass

Machine settings. You will need to make adjustments depending on how thick the metal is, electrode diameter, and type of electrode.

Note: Machine settings of Amps & Voltage will be given on welding electrode cover.

FOLLOWING ARE SOME OF THE SNAPS OF GOOD & DEFECTIVE WELDING

Snap taken at the root side of the weld joint. (Inside the pipe)

Excess penetration is observed


Lack of penetration is observed.This occurs due to less root gap provided in the weld joint.

Under cut observedThis is due to High current used during welding

Porosity observedThis occurs due to moisture content in the electrode or near the weld joint or due to welder lack of performance

IMPROPER BEADING OBSERVED(THIS IS DUE TO WELDER LACK OF PERFORMANCE)

SPATTERS OBSERVED

SPATTERS OBSERVED


Excess penetration is observed

Lack of penetration is observed.

This occurs due to less root gap provided at the joint During fitup.


Porosity observed

This occurs due to moisture content in the electrode or near the weld joint, or due to welder lack of performance

Porosity Observed

Under cut observed

This is due to High current used during welding

SPATTERS OBSERVED

IMPROPER BEEDING OBSERVED

(THIS IS DUE TO WELDER LACK OF PERFORMANCE)

SPATTERS OBSERVED

IMPROPER BEEDING IS OBSERVEDSLAG INCLUSION IS OBSERVED

BOTH THE DEFECT WILL OCCUR DUE TO LACK OF WELDER PERFORMANCE.

GOOD WELDING

GOOD WELDING, But surface cleaning to be done.

GOOD WELDING

GOOD WELDING

GOOD WELDING, But surface cleaning & Spatters to be removed.

GOOD WELDING

GOOD WELDING

GOOD WELDING

Documents

WELDING PRESENTTION PART 1