Basic welding

BASIC WELDINGBASIC WELDING
• COMMON WELDING PROCESSES
• WELDING TERMINOLOGY
• WELD SYMBOLS / JOINT CONFIGURATION
• WELDER RELATED
• WELDING SAFETY

Common Welding ProcessesCommon Welding Processes
Listed below are some of the more common welding
processes used :
•SMAW -Shielded Metal Arc Welding (stick)
•GMAW -Gas Metal Arc Welding (mig)
•GTAW -Gas Tungsten Arc Welding (tig)
•SAW -Submerged Arc Welding

• SMAW- Shielded Metal Arc Welding uses the heat of an
electric arc between a covered metal electrode and the
work (pipe, plate, etc). Shielding comes from the
decomposition of the electrode flux coating. Filler is
supplied by the electrode core wire and covering (iron
powder and alloys).
This process is usually done manually. The basic
equipment is a power source, an electrode holder, a work
clamp and the electrode. Electrodes operate variously on
alternating current, direct current electrode positive
(reverse polarity) or direct current electrode negative
(straight polarity).

SMAW welding metallurgy
Weld is strengthened by adding alloying elements and by
incorporating iron powder in the electrode
covering(flux). Some ingredients in the covering may
attract and hold moisture (a source of hydrogen) which
causes cracking in certain welds. A group of electrodes
specifically formulated to result in weld deposits having
very low levels of hydrogen are referred to as “Low
Hydrogen” electrodes. These have identification
numbers ending in 5,6 or 8. Once removed from
containers they require electrically heated storage in a
vented oven capable of holding the electrodes between
250 – 350 deg F. (Low hydrogen electrodes should be
stored in their original containers until ready for use)

SMAW ELECTRODE IDENTIFICATION SYSTEM
Strength- Tensile strength (I.E. 70, or 60) 70,000 psi / 60,000 psi
Position: 1= all positions. 2= flat and horizontal fillet position
only
Example: E-7018, E-6010

• SMAW limiting factors
All of the welding manipulations are controlled by
the welder, such as electrode inclination, arc length
and travel speed. The welder must set the proper
current and select polarity if direct current.
• Discontinuities
Almost any discontinuity can be produced, but the
most common is porosity, and slag inclusions.

• GMAW- Gas Metal Arc Welding, sometimes call Mig uses the
heat of an electric arc between a continuous bare wire filler
metal electrode and the work. Shielding is obtained entirely
from an externally supplied inert gas (argon or helium) or
reactive gases (C02 o 02) or a combination thereof. This
process can be semi-automatic or automatic. GMAW process
deposits the weld metal in the joint by one of the following
modes: spray transfer, globular transfer and short circuiting
transfer.

GMAW MODES
•Spray Transfer – Spray transfer occurs with high current and
voltage combinations. Spray transfer mode best defines the arc
and the pool for the welder. Due to high heat capacity this mode
is best suited for flat and horizontal welding.
•Globular Transfer – Occurs at low currents compared to spray
transfer. Low current at the tip produces large irregular drops
without much direction which results in increased amounts of
spatter compared to spray mode.

GMAW MODES
•Short Circuiting Transfer (GMAW-S) – The short
circuiting mode is a rather “cold process” and its
misapplication may result in incomplete fusion. It is
mainly used for very light gauge sheet metal welding.
Most refineries and petrochemical plants do not allow
the short circuiting mode of transfer in their welding
specifications to weld on pressure retaining equipment.

• GMAW Welding Chemistry
Shielded gases protect gas metal arc welds from the
atmosphere. Fluxes are not used in this process. All
deoxidizers and alloying elements are incorporated into the
electrode wire.
• Limiting Factors
The semi-automatic features of gas metal arc welding simplify
the training of the welder and should make work more
consistent, however the short circuiting mode may lead to
incomplete fusion.

GMAW ELECTRODE IDENTIFICATION CHART

Discontinuities
GMAW may result in any of the common
discontinuities with the exception of slag inclusions.
Porosity which is caused by gas trapped in the weld, is
often the discontinuity found in this process.
Incomplete fusion is possible especially in welds made in
the short circuiting transfer mode.

GTAW – Gas Tungsten Arc Welding (TIG) uses an
electric arc between a non consumable electrode
(tungsten) and the work. Shielding is obtained from an
inert gas or inert gas mixture. Filler metal is added as
needed. Welds may be made with or without filler
metal as required.
The most significant feature in GTAW is that the
electrode (tungsten) used is not intended to be
consumed. Only the filler metal is consumed

• Welding Chemistry
The tungsten electrode contributes neither
deoxidation nor fluxing, so it is fortunate that the
melting is essentially slow and that most of the
gases can escape from the weld pool before it
freezes. The filler rod contains the needed
deoxidizers. The slow heating and lower
temperatures combined with slower cooling rates
in GTAW will result in improved weld metal and
heat affected zone mechanical properties.

• Limiting Factors
The outstanding factor of GTAW is the exceptional
cleanliness that can be obtained in the weld,
producing crack free welds in alloys that are difficult
to weld in other process. However the limiting factor
is the high skill level necessary to produce high
quality welds is acquired by long experience in
manipulating the electrode and feeding the filler
wire when used.

• Discontinuities
All of the common types of discontinuities are
possible with the exception of slag inclusions.
Porosity is a common discontinuity due to the
processes low tolerance for contamination. Tungsten
inclusions may also result from accidental touching
(dipping ) of tungsten into the molten weld pool.

WELDING TERMINOLOGYWELDING TERMINOLOGY
LISTED BELOW IS SOME COMMON WELDING TERMS
• AIR ARC (ARC GOUGE) – The process of removing metal by means of a
carbon arc rod (electrode) connected to a welding machine and air
• BACKWELD – The process of completely welding the one side of a
component, and then back grinding or back gouging the other side and
applying a weld from that side
• BACKING WELD – The process of applying a weld pass to the back side of
the weld to provide a backing. And then completely welding out the
opposite side
• BACKING PLATE OR STRAP – The installation of a plate, strip of plate,
usually of the same material as base metal to the back side of the
weldment to aid in welding up large root openings in a weldment

• Cap- The finished portion of the weld (last pass)
• Consumable insert – A type of spacer that is installed in
the root spacing of a pipe or plate to keep the specified
root opening and is made of the same material as the
base metal. This insert acts as the filler metal for the root
and is melted (consumed) with the welding process
normally with GTAW.
• Discontinuity – an imperfection in the weld
• Defect – a discontinuity of sufficient size, length, type that
will render that particular object unsuitable for intended
service base on a criteria in an applicable code

• Destructive testing- a sampling of the weld that is actually
taken from the weldment and is subjected to a bend,
tension, or other form of test that usually destroys the
test coupon.
• Essential variables- are those which a change, is
considered to affect the mechanical properties of the
weldment and shall require requalification of the WPS
• Filler metal- The consumable electrode that is used in
most welding processes to fill the weld groove
• Flux- The coating on welding electrodes that when
decomposes during welding forming a shielding gas
around the weld.

• Heat Affected Zone (HAZ)- The portion of the base metal that
has not been melted, but whose mechanical properties or
microstructure have been altered by the heat of welding and
cutting
• Preheat- the process of applying heat to a weldment before
welding. This process reduces the thermal gradients within a
weldment and slows down the cooling rates, resulting in a
more ductile structure with lower residual stress. Preheat also
aids in removing moisture and helps remove hydrogen.

• Post Weld Heat (PWHT)- also known as stress relieving in
carbon and low alloy steels. The metals temperature is
raised to just below the lower transformation
temperature and held for a prescribed time and allowed
to cool at a controlled rate. This process is done to help
eliminate the residual stress in metals and to reduce the
hardness of the weld and adjacent HAZ after welding to
back within acceptable limits, thereby reducing the
possibility of cracking
• Porosity- a discontinuity in a weld when gas is trapped in
the solidifying metal which is caused by gas released in
the welding process or gas released from chemical
reactions occurring during the welding process.
• Repair – any rework on a completed weld that requires
re-welding to correct a fault discovered by visual or non-
destructive testing and is beyond the standard limits of
acceptability

• Root Bead- The first or stringer bead that initially joins
two sections of pipe, plate or fitting
• Welding Procedure Specification (WPS)- a written
procedure (recipe) prepared to provide direction for
making production welds to a code requirement. It is
supported by a PQR (procedure qualification record)
which is a record of actual variables used in the welding of
the test coupon.
• Procedure Qualification Record (PQR) –documentation of
what occurred during welding the test coupon and the
test results of the coupon

JOINT CONFIGURATIONJOINT CONFIGURATION
Butt Weld
• 1= Groove Face
• 2= Root Opening
• 3= Groove Angle
• 4= Root Face
• 5=Plate thickness
• 6=Bevel Angle 1
2
3
4
5
6

• Root Opening – A separation at the joint root between the
two work pieces
• Root Face – The portion of the groove face adjacent to the
joint root
• Groove Face – The surface of a joint member included in
the groove
• Groove Angle – The total included angle of the groove
between the two work places
• Bevel Angle – The angle formed between the prepared
edge of a member and a plane perpendicular to the
surface of the member
• Groove weld size – The joint penetration of a groove weld
• Plate thickness – The thickness of the base metals to be
welded

Parts of a butt weld
Weld Face
Weld Root
Toe of Weld
both side
Face or Weld
Reinforcement

Examples of Butt Weld Edge Prep

Example of Fillet weld Joint Configuration

WELDER RELATEDWELDER RELATED
• A Welder Performance Qualification test is given to
determine the ability of the welder or welding operator to
make sound welds.
• When a welder has not welded with a process for a period
of 6 months or more his qualification shall expire, unless
within the six month period prior to his expiration date,
the welder has welded using a manual or semiautomatic
welding process for that process for which he was
qualified. (Recommend to use a welder continuity sheet)
• Or when there is specific reason to question his ability to
make sound welds.

Welder test positions for pipe
•1G- Pipe is horizontal and rotated , welding flat on
or near top of pipe
•2G- Pipe or tube is vertical and not rotated during
welding, welding is horizontal
•5G- Pipe or tube is horizontal fixed, and not
rotatated, weld is vertical, flat and overhead
•6G- Pipe is inclined fixed at a 45 deg angle and
not rotated during welding

Welder test positions for plate
•1G- Plate is horizontal weld position is flat
•2G- Plate is vertical axis of weld is horizontal weld
position is horizontal
•3G- Plate is vertical and axis of weld is vertical weld
position is vertical
•4G- Plate is horizontal weld position is overhead

Common Discontinuities
• IP- or inadequate penetration without hi-low is defined as
the incomplete filling of the weld root. Inadequate
penetration due to hi-low is the condition that exists
when one edge of the root is exposed or un-bonded
because the adjacent pipe or fitting are misaligned.
• Hi-Low- is the mismatch of either the root or the OD
surface of the pipe, plate or fittings
• Slag Inclusion- is a non metallic solid entrapped in the
weld metal or between the weld metal and parent metal
• Burn Thru- is defined as a portion of the root bead where
excessive penetration has caused the weld puddle to be
blown into the pipe

Common Discontinuities cont.
• Concave Root – a root bead that is properly fused to and
completely penetrates the sides of the pipe or plate wall
thickness along both sides but whose center is somewhat
below the the inside surface of the ID wall
• Porosity- can be cluster, wormhole etc. Porosity is entrapped
gas pockets inside the weld
• Undercut- A discontinuity at the edge or toe of the welds
where a groove is created by welding too hot or traveling too
fast during welding.

• Tungsten inclusion- is cause when the welder accidentally
dips his tungsten electrode into the weld puddle, and the tip
of the tungsten electrode breaks off and is left un-fused in
the weld metal.
• Incomplete fusion- due to cold lap is defined as an
imperfection between two adjacent weld beads or between
the weld metal and base metal that is not open to the surface
(condition where the two passes or base metal and weld
metal are not fused together)

WELDING SAFETYWELDING SAFETY
• SAFETY IS AN IMPORTANT CONSIDERATION IN ALL
WELDING, CUTTING AND RELATED WORK
• THE MOST IMPORTANT COMPONENT OF AN EFFECTIVE WELDING SAFETY
PROGRAM IS LEADERSHIP SUPPORT AND DIRECTION. MANAGEMENT
MUST CLEARLY STATE OBJECTIVES AND SHOW IT’S COMMITMENT TO
WELDING SAFETY
• Management must be certain that only approved welding, cutting,
equipment are used. Such equipment includes torches, regulators,
welding machines, electrode holders, and personal protective devices.
• Proper use and maintenance of the equipment must be taught
• Personnel in areas next to welding and cutting must also be protected
from radiant energy and hot spatter

• Where arc welding or cutting is regularly performed next to painted
walls, the walls should be painted with a finish having a low
reflectivity of ultraviolet rays
• Open flame, electric arcs are a ready source of ignition. The best
protection against fire is to do welding and cutting in specially
designated areas or enclosures made of non combustible materials
• Welding helmets containing the appropriate filter plates must be
used by welders and nearby personnel when viewing an arc.
• Sturdy shoes, boots and heavy clothing should be worn to protect the
body from flying sparks, spatter and radiation burns. (cuff less pants
and covered pockets are recommend
• Durable leather gloves or other suitable material should be worn
• Sparks or hot spatter in the ears can be serious, properly fitted , flame
resistant earplugs should be worn whenever such risk is present
• Ear plugs should be worn when performing air arc gouging

• Personnel should be protected from fumes and gases
performed during welding, cutting etc. Protection from
this exposure is usually accomplished by adequate
ventilation
• Where exposure would exceed permissible limits, with
available ventilation, suitable respiratory protection must
be worn
• Last, do not forget x-ray (gamma ray) radiation safety.
Obey all x-ray barrier signs. Do not go into these areas
when radiography is taking place (normally magenta and
yellow tape)
REMEMBER, WELDING SAFETY IS A VERY IMPORTANT PART
OF WELDING

WELDING WRAP UPWELDING WRAP UP
This presentation was only a brief overview of welding,
and was intended to only give a general understanding
and familiarization of some of the more common
processes, safety concerns and terms.
If you have any questions please contact me at
937-418-8489 or Randall@rpsweldingconsultants.com
Thank you for your attendance

Basic welding

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