Welding Inspection Training

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WELDING INSPECTION TRAINING
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Overview

• Welding Terminologies and Definitions
• Welding Processes
• Safety
• International Standards/Code
• Welding Procedure Qualification
• Welder Qualification
• Welding Defects
• Visual Inspection

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WELDING TERMINOLOGIES DEFINITIONS
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Welding Terminologies and Definitions
What is weld?
A union of pieces of metal made by welding.
What is welding?

• Is a joining process that produces union of
  materials by heating them
• with or without application of pressure.
• with or without filler materials.

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Types of Wed
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Welding Terminologies and Definitions

• What is joint?

• The junction of members or edges of members that
  are to be joined or have been joined (AWS)
• A configuration of members (BS499)
• with or without application of pressure.
• with or without filler materials.

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Types of Joint
Butt Joint A connection between the ends or edges of two parts making an angle to one another of 135 to 180 inclusive in the region of the joint.
T Joint A connection between the end or edge of one part and the face of the other part, the parts making an angle to one another of more than 5 up to and including 90 in the region of the joint
Corner Joint A connection between the ends or edges of two parts making an angle to one another of more than 30 but less than 135 in the region of the joint
Lap Joint A connection between two overlapping parts making an angle to one another of 0 to 5 inclusive in the region of the weld or welds

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Features of the Weld Preparations

• Angle of bevel The angle at which the edge of
  a component is prepared for making a weld.
• Included angle The angle between the planes of
  the fusion faces of parts to be welded.
• Root face The portion of a fusion face at the
  root that is not beveled or grooved. Its value
  depends on the welding process used, parent
  material to be welded and application
• Gap The minimum distance at any cross section
  between edges, ends or surfaces to be joined. Its
  value depends on the welding process used and
  application.

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Features of the Weld Preparations
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Features of the Completed Weld

• Parent metal Metal to be joined or surfaced by
  welding, braze welding or brazing
• Filler metal Metal added during welding, braze
  welding, brazing or surfacing.
• Heat-affected zone (HAZ) The part of the
  parent metal that is metallurgical affected by
  the heat of welding or thermal cutting, but not
  melted.
• Weld face The surface of a fusion weld exposed
  on the side from which the weld has been made.
• Root The zone on the side of the first run
  furthest from the welder.

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Features of the Completed Weld
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WELDING PROCESSES
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Factors

• Factors determines the selection of a welding
  process
• The specific application
• The joint design
• Joint location
• The materials being joined
• Material dimensions
• Operator skill
• Equipment costs
• Labor costs

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Specific Applications

• Shielded Metal Arc Welding (SMAW)

• Gas Tungsten Arc Welding (GTAW)

• Gas Metal Arc Welding (GMAW)

• Submerged Arc Welding (SAW)

• Oxy-Acetylene Welding (OAW)

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Shielded Metal Arc Welding

• An arc welding process that produces a
  coalescence of metals by heating with an arc
  between a covered metal electrode and the work
  pieces.

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Shielded Metal Arc Welding
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Shielded Metal Arc Welding
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Shielded Metal Arc Welding

• Advantages
• The equipment is relatively simple.
• Inexpensive and portable.
• Auxiliary gas shielding or granular flux is not
  required.
• Less sensitive to wind and draft than gas
  shielded arc welding.
• The process is suitable for most of commonly used
  metals and alloys.

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Shielded Metal Arc Welding

• Disadvantages
• Low deposition rate compared to GMAW.
• Production factor is typically lower.
• chipping slag.
• Fumes and spatters.
• Large Heat Affected Zone (HAZ).

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Successful Completion of SMAW

• To get successful completion of the SMAW

• Properly protect yourself and others while
  welding.
• Set up and operate SMAW equipment.
• Strike and maintain an arc.
• Make welds in four positions using different
  electrodes.
• Understand a weld inspection process.
• Apply the AWS electrode classification system.
• Take the next step to becoming a certified
  welder.

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Power Supply

• DC WELDING MACHINES
• Direct Current Electrode Positive (DCEP)
• Direct Current Electrode Negative (DCEN)

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Gas Tungsten Arc Welding

• An arc welding process that produces coalescence
  of metals by heating them with an arc between a
  tungsten (non-consumable) electrode and the work
  piece.

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Gas Tungsten Arc Welding

• An arc is formed between a nonconsumable tungsten
  electrode and the metal being welded.
• Gas is fed to shield the electrode and molten
  weld pool. 
• Filler wire is added to the weld pool
  separately. 

Melting
protection
Reinforcement
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Gas Tungsten Arc Welding
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Gas Tungsten Arc Welding

• The three most common shielding gas options for
  GTAW are
• 100 percent argon
• 100 percent helium
• Argon/helium mix
• You can use these shielding gases for all
  materials.

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Gas Tungsten Arc Welding

• 100 percent argon
• Welders use Argon for GTAW primarily due to its
  availability, cost and arc starting
  characteristics.  Argon produces consistent high
  frequency arc starts due to its lower ionization
  potential and produces a more stable arc compared
  to that of helium.

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Gas Tungsten Arc Welding

• 100 percent helium 
• Because it has higher thermal conductivity than
  argon, helium can be used for GTAW to produce
  higher heat inputs. These higher heat inputs
  result in faster travel speeds and higher
  depth-to-width ratios and are good for welding
  thicker materials.

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Gas Tungsten Arc Welding

• Argon/helium 
• An argon/helium mix is typically used to achieve
  the higher heat inputs of helium while
  maintaining the superior arc starts offered by
  argon. These mixes commonly contain 25 to 75
  percent helium. As helium content increases, the
  arc becomes hotter but high frequency arc
  starting performance and stability decrease.

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WHY GTAW

• GTAW gives the operator greater control over the
  weld produce by other welding processes such as
  SMAW,MIG.

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WHY GTAW

• Pin point control
• Arc heat is intense and highly concerned.
• Narrow heat affected zone
• Weld chemistry is easy to controlled
• Weld more metals
• No sparks or spatter
• No flux or slag
• No smoke or fumes
• Good for welding thin metals

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WHY GTAW

• Lower filler metal deposition rates
• Good hand-eye coordination a required skill
• Brighter UV rays than other processes
• Slower travel speeds than other processes
• Equipment costs tend to be higher than other
  processes

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Gas Metal Arc Welding

• An arc welding process that produces coalescence
  of metals by heating them with an arc between a
  continuous filler metal (consumable) electrode
  and the work.

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Gas Metal Arc Welding

• GMAW is commonly referred to as MIG or Metal
  Inert Gas welding
• A solid metal wire is fed through a welding gun
  and becomes the filler material

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Gas Metal Arc Welding

• GMAW was originally created for welding aluminum
  and other non-ferrous materials.
•  
• It is now used for steels, as it requires less
  time than other welding methods. Since GMAW can
  be used for a variety of metals.
• GMAW technique can be applied in any industry
  where these materials are employed.

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Gas Metal Arc Welding

• Advantages 
• A solid Higher welding productivity.
• Greater deposition rates.
• Less post welding cleaning .
• No wasted Time caused by changing electrodes.
• Better weld pool visibility.
• Low skill factor required .
• Positional welding offers no problems when
  compared to other processes.

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Gas Metal Arc Welding

• Disadvantages 
• A solid Higher welding productivity.
• Requires more equipment than SMAW.
• Is not portable as other welding processes.
• Can not be used in windy environment.
• More expensive than SMAW process.

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Gas Metal Arc Welding

• THE POWER SOURCE FOR MIG WELDING MUST BE
  CONSTANT VOLTAGE

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Submerged Arc Welding

• Submerged-arc welding (SAW) is a common arc
  welding process that involves the formation of an
  arc between a continuously fed electrode and the
  workpiece.

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Submerged Arc Welding

• Advantages 
• Higher deposition rate is obtained.
• A shielding gas is not required.
• Heat loss is extremely low.
• Spatter-free.

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Submerged Arc Welding

• Disadvantages 
• Welding can mostly be done in the flat position
  because of high fluidity of the weld pool.
• It is operated as a fully-mechanized or
  automatic.

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Oxy-Acetylene Welding

• Oxy-acetylene welding is a process that relies on
  the combustion of oxygen and a fuel gas,
  typically acetylene. You might hear this type of
  welding referred to as gas welding.

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Oxy-Acetylene Welding
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Brazing

• A process which a filler metal is placed at or
  between the faying surfaces, the temperature is
  raised high enough 800F (427C) to melt the
  filler metal but not the base metal.
• The molten metal fills the spaces by capillary
  attraction

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WORKSHOP
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SAFETY
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Fumes and Gases

• Keep your head out of the fumes. Do not breathe
• the fumes.
• If inside, ventilate the area and/or use local
• forced ventilation at the arc to remove
  welding
• fumes and gases.
• If ventilation is poor, wear an approved air-
  
• supplied respirator

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Fumes and Gases
Do not weld on coated metals, such as galvanized,
lead, or cadmium plated steel, unless the coating
is removed from the weld area, the area is well
ventilated, and while wearing an air-supplied
respirator. The coatings and any metals
containing these elements can give off toxic
fumes if welded.
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Electric Shock

• Do not touch live electrical parts.
• Wear dry insulating gloves and body protection.
• Disconnect input power or stop engine before
• installing or servicing this equipment.

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Arc Rays

• Wear an approved welding helmet fitted with a
  proper shade of filter lenses to protect your
  face and eyes when welding or watching.

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Hot Parts

• Do not touch hot parts bare handed.
• Allow cooling period before working on gun or
  torch.
• To handle hot parts, use proper tools.

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Ultraviolet Radiations
The process produces intense ultraviolet
radiation, which can cause a form of sunburn and,
in a few cases, trigger the development of skin
cancer. Ultraviolet (UV) light is -
electromagnetic radiation with
a wavelength shorter than that of visible light,
but longer than X-rays
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Buildup of Gas

• Welders are also often exposed to
• dangerous gases
• Shielding gases can displace oxygen and
• lead to asphyxiation
• Shut off shielding gas supply when not
• in use.
• Always ventilate confined spaces or use
• approved air-supplied respirator.

BUILDUP OF GAS can injure or kill
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Cylinders

• Shielding gas cylinders contain gas under high
  Pressure If damaged, a cylinder can explode
• Protect compressed gas cylinders from-
• excessive heat.
• Mechanical shocks
• physical damage
• open flames
• sparks and arcs.

Cylinders can explode
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WELDING INTERNATIONAL STANDARD CODE
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International Standards Code
Many aspects of the design and fabrication of
welded components are governed by documents known
as codes and standards.
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Why Welding Codes Exist

• The purpose of each of the welding codes is to
  have a uniform way to approach welding that
  reflects the best practices developed and proven
  to work overtime.
• They have the effect of improving welder skills,
  equipment, and processes.
• The result is growth in the profession when it
  comes to skill, quality, and welder efficiency.

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Why Welding Codes Exist

• The purpose of each of the welding codes is to
  have a uniform way to approach welding that
  reflects the best practices developed and proven
  to work overtime.
• They have the effect of improving welder skills,
  equipment, and processes.
• The result is growth in the profession when it
  comes to skill, quality, and welder efficiency.

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International Standards Code

• Other names used for such documents include
  guides, recommended practices, regulations,
  rules, and specifications.
• They are also used by the manufacturer to assist
  in the development and implementation of their
  welding quality system
• Such specifications may be limited in application
  and related only to that customers situation and
  requirements. 

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International Standards Code

• such documents become law and are often referred
  to as Codes or Regulations.
• The welding inspector should be aware of what
  codes or standards are applicable within their
  jurisdiction, understand the requirements of the
  relevant documents and perform their inspection
  accordingly.

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International Standards Code

• Welding codes are developed by a variety of
  organizations to set requirements for
• Inspection
• Testing
• Repair
• Approved materials
• Fabrication
• Design specifications
• Welding itself

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Sources Of Codes and Standards
Each group sets and adapts codes that pertain to
their area of interest.

• Four groups set the foundation for the codes.
• American Welding Society (AWS)
• American Petroleum Institute (API)
• American Society of Mechanical Engineers (ASME)
• American Society for Non-Destructive Testing
  (ASNT)

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Sources Of Codes and Standards
Codes are also recognized by the American
National Standards Institute (ANSI).
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Sources Of Codes and Standards
American Welding Society (AWS)

• Probably the largest producer of welding codes
  and standards in the USA.
• The AWS publishes many documents addressing the
  use and quality control of welding.
• These documents include such general subjects as
  Welding Definitions and Symbols, Classification
  of Filler Metals, Qualification and Testing,
  Welding Processes, Welding Applications, and
  Safety.

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Sources Of Codes and Standards
American Welding Society (AWS)

• The AWS sets welding codes for the following
• Certifying welding inspectors
• Aluminum welding (gas arc welding, gas tungsten
  welding, plasma arc welding)
• Sheet Steel welding Applications and capacities
  for sheet metal
• Aerospace fusion welding materials and processes
• Construction bridge highway welding codes
• Structural Steel Welding All types of welding
  processes

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Sources Of Codes and Standards
American Welding Society (AWS)

• AWS D1.1 Fabricating and Erecting Welded Steel
  Structures
• AWS D1.2 This is the Structural Welding
  Code-Aluminum
• AWS D1.3 Structural Steel Welding Code -Sheet
  Steel
• AWS D1.4 Structural Welding Code for Reinforcing
  Steel
• AWS D1.5 Bridge Welding Code
• AWS D1.6 Stainless Steel Structural Welding Code

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Sources Of Codes and Standards
American Society of Mechanical Engineers (ASME)

• This society is responsible for the development
  of the Boiler and Pressure Vessel Code, which
  contains eleven sections and covers the design,
  construction, and inspection of boilers and
  pressure vessels.
• ASME also produces the Code for Pressure Piping,
  which consists of seven sections. Each section
  prescribes the minimum requirements for the
  design, materials, fabrication, erection, testing
  and inspection of a particular type of piping
  system. Both of these documents are American
  National Standards.

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Sources Of Codes and Standards
American Society of Mechanical Engineers (ASME)

• Section IX is one of the most commonly used
  welding codes for qualifying welders. 
• Section VIII Division 1 is used with section IX
  when using codes applied to fabrication.

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Sources Of Codes and Standards
American Society of Mechanical Engineers (ASME)
This section covers the requirements for Weld
Procedure Specifications (WPS), Procedure
Qualification Records (PQR), and certification
requirements for tackers, welders, welding
operators, and brazing personnel.
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Sources Of Codes and Standards
American Petroleum Institute (API) 
This institute publishes many documents relating
to petroleum production, a number of which
include welding requirements. The most well known
is possibly API Std 1104 Standard for Welding
Pipelines and Related Facilities.
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Sources Of Codes and Standards
American Petroleum Institute (API) 
API 570 Piping Inspection Sets requirements for
the inspection, alteration, repair and re-rating
of in-service piping systems. It was created for
the chemical process and petroleum refining
industries. It is also broadly applied to piping
systems. The code was written for groups that
have access to or maintain an authorized
inspection agency, a repair group, and
technically qualified piping engineers,
inspectors and examiners.
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Sources Of Codes and Standards
American Petroleum Institute (API) 
API 620 Welded Steel Tanks for Storage This
standard applies only to tanks whose entire
bottom is uniformly supported and to tanks in
non-refrigerated service that have a maximum
operating temperature of 90C (200F).
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Sources Of Codes and Standards
American Petroleum Institute (API) 
API 620 Welded Steel Tanks for Storage This
code standard is for the design, material,
erection, fabrication and testing requirements
for vertical, cylindrical, above ground, closed
and open-top, welded steel storage tanks in
various sizes and capacities for internal
pressures approximating atmospheric pressure
(internal pressure not exceeding the weight of
the roof plates), but a higher internal pressure
is permitted when additional requirements are
met.
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Sources Of Codes and Standards
American Petroleum Institute (API) 
API 1104 Welding of Pipelines and Related
Facilities This standard covers the arc and gas
welding of fillet, butt, arc and gas, and socket
welds in carbon and low-alloy steel piping used
in the compression, pumping, and transmission of
crude petroleum, petroleum products, fuel gases,
carbon dioxide, and nitrogen, and where
applicable, covers welding on distribution
systems.
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Sources Of Codes and Standards
American Petroleum Institute (API) 

• API 1104 Welding of Pipelines and Related
  Facilities
• It applies to both new construction and
  in-service welding.
• The welding may be done by a shielded metal-arc
  welding, submerged arc welding, gas tungsten-arc
  welding, gas metal-arc welding, flux-cored arc
  welding, plasma arc welding, oxyacetylene
  welding, or flash butt welding process or by a
  combination of these processes using a manual,
  semi-automatic, or automatic welding technique or
  a combination of these techniques.

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Sources Of Codes and Standards
American Petroleum Institute (API) 
API 1104 Welding of Pipelines and Related
Facilities This standard also covers the
procedures for radiographic, magnetic particle,
liquid penetrant, and ultrasonic testing as well
as the acceptance standards to be applied to
production welds tested to destruction or
inspected by radiographic, magnetic particle,
liquid penetrant, ultrasonic, and visual testing
methods
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Sources Of Codes and Standards
What The Welding Code and Standard Generally
Provides
The Scope and General Requirements This is
found at the beginning of the document and is
important as it will normally provide a
description as to the type and extent of welding
fabrication for which the document was developed
and intended to be used. It may also provide
information relating to the limitations for the
use of the document. Care should be taken to use
codes and standards that are applicable for your
particular application.
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Sources Of Codes and Standards
What The Welding Code and Standard Generally
Provides
Design If the document provides a section for
design, it may refer the user to a secondary
source of information, or it may contain minimum
requirements for the design of specific welded
connections.
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Sources Of Codes and Standards
What The Welding Code and Standard Generally
Provides
Qualification This section of the document will
typically outline the requirements for
qualification testing of welding procedure
specifications (WPS) and also those requirements
for qualification of welding personnel. It may
provide the essential variables, these being the
change limitations that govern the extent of
qualification. Such variables are typically the
welding process, type and thickness of base
metal, filler metal type, electrical parameters,
joint design, welding position, and others.
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Sources Of Codes and Standards
What The Welding Code and Standard Generally
Provides
Qualification This section of the document may
also provide the qualification testing
requirements. Usually this is divided into
welding procedure and welder performance testing
requirements. Typically, it will provide the
types and sizes of test samples to be welded and
prepared for testing, the testing methods to be
used, and the minimum acceptance criteria to be
used for the evaluation of test samples.
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Sources Of Codes and Standards
What The Welding Code and Standard Generally
Provides
Fabrication This section, when included in the
document, will typically provide information
associated with the fabrication methods and/or
workmanship standards. It may contain information
and requirements on such items as base materials,
welding consumable classification requirements,
shielding gas quality, heat treatment
requirements, preparation and care of base
material, and other welding fabrication
requirements.
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Sources Of Codes and Standards
What The Welding Code and Standard Generally
Provides
Inspection This section of the document will
typically address the welding inspectors
qualification requirements and responsibilities,
acceptance criteria for discontinuities, and
requirements relating to procedures for
nondestructive testing.
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Key Terms
WPS A WPS is the welding procedure
specification. It shows the welder an overall
direction, shows the welding materials and joint
design. It also lists important code
requirements, techniques, parameters and welding
materials.
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Key Terms
PQR The PQR is the procedure qualification
report. It is a record of testing results for any
welds created in accordance with the welding
procedure specification (WPS).
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Key Terms
WQTR The WQTR or welder qualification test
record describes the results of a test to
determine if a welder is qualified to weld to a
certain welding procedure specification.
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Key Terms
Code A standard is a code when it has been
adopted by one or more governmental bodies and is
enforceable by law, or when it has been
incorporated into a business contract.
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WELDING PROCEDURE QUALIFICATION
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Welding Procedure Qualification

• Inspection and Testing for Welding Procedure
  Qualification
• Welding Procedures are the guidelines used to
  perform a weld. 
• They are designed to provide a record of the
  welding variables used and the inspection results
  obtained during the procedure qualification test. 

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Welding Procedure Qualification

• Inspection and Testing for Welding Procedure
  Qualification
• They can also provide the instructions for the
  welder to use in production in order to produce
  acceptable welds. 
• Usually welding procedures are developed in
  accordance with a welding code or standard, and
  with few exceptions, require that physical weld
  samples be produced, inspected, and tested to
  establish qualification.

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Welding Procedure Qualification

• Inspection and Testing for Welding Procedure
  Qualification
• Welding procedures are usually divided into two
  categories
• Procedure Qualification Record (PQR)
• Welding Procedure Specification (WPS).

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Welding Procedure Qualification

• Procedure Qualification Record (PQR)
• Procedure Qualification Records are the
  documented values used during the actual welding
  test and all the inspection and test results
  obtained from the actual test samples.

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Welding Procedure Qualification
Welding Procedure Specification (WPS). Welding
Procedure Specifications are usually documented
work instructions that can be used by the welder
to conduct welding operations, and are based on,
but not necessarily the same as, the parameters
used for the Procedure Qualification Record.
92
Welding Procedure Qualification
Qualification testing of a welding procedure
normally requires documentation to show all the
variables used during the welding test and the
documented inspection and test results.
93
Welding Procedure Qualification
The variables required to be documented are
typically such items as

• welding process used.
• Welding size.
• type and classification of filler alloy,
• type and thickness of base material welded,
• type and polarity of welding current,
• amps and volts recorded.
• travel speed during welding.
• welding position.
• preheating temperature.
• type and dimensions of joint design.
• Inter-pass temperature, post weld heat treatment
  details.

94
Welding Procedure Qualification

• The typical types of inspection and testing for
  each sample for Welding Procedure Qualification
  are
• Inspection and Testing for Fillet Welds (Tee
  Joints)
• Inspection and Testing for Groove welds (Butt
  Joints)

95
Welding Procedure Qualification
Inspection and Testing for Fillet Welds (Tee
Joints)

• This involves visual inspection of the completed
  weld, followed by two macro etches, and one
  fillet weld break test. 
• The welded sample is first inspected for any
  visual discontinuities and then sectioned, and
  two small samples removed at predetermined
  locations. 

96
Welding Procedure Qualification
Inspection and Testing for Fillet Welds (Tee
Joints)

• The small samples are polished across their
  cross-section and then etched using some type of
  mild acid mixture, dependent on the base material
  used.  
• The remaining welded sample is used as the fillet
  weld break test and is broken against the weld to
  reveal the internal structure of the weld for
  inspection.

97
Welding Procedure Qualification
Inspection and Testing for Groove welds (Butt
Joints)

• This involves visual inspection, followed by two
  transverse tensile tests, two root bend test and
  two face bend tests.
• (These tests are typical but may differ
  dependent on material thickness, type and
  standard requirements. 
• Different and/or additional testing, such as
  side bends, all weld tensile tests, impact
  testing or other testing may be required.) 

98
Welding Procedure Qualification
Inspection and Testing for Groove welds (Butt
Joints)

• The completed weld coupon, after visual
  inspection, is divided into predetermined small
  sections. Each section is prepared, usually by
  machining, to specific dimensions as prescribed
  by the standard. 
• Each small sample is then tested mechanically to
  determine its characteristics. 

99
Welding Procedure Qualification
Inspection and Testing for Groove welds (Butt
Joints)

• These samples are then inspected to determine
  their acceptability, against specified acceptance
  criteria, as laid down by the applicable code or
  standard. 
• Samples that are found not to have
  discontinuities that exceed these specified
  limits, and that meet or exceed the minimum
  values as specified in the standard, will be
  acceptable, and the welding procedure will be
  qualified.

100
Welding Procedure Qualification
The welding procedure is an important part of the
overall welding quality system, as it provides
documented evidence that inspection and testing
has been performed to ensure that welding can be
conducted to meet a recognized standard.
101
WELDER QUALIFICATION
102
Welder Qualification
Welder qualification is a process which evaluates
a welders capability to create welds to an
industry standard following a welding procedure,
this qualification can then lead to welder
certification.
103
Welder Qualification

• How the performance qualification test is carried
  out?
• The welder is asked to weld a test coupon in
  accordance with the qualified welding procedure
  specification (WPS), then visual inspection and
  LPI/MPI (if applicable) are carried out as per
  the approved procedure.
• Thereafter the final welded test coupon is sent
  for the Radiography test RT (or Ultrasonic Test
  UT) and Mechanical tests (if applicable, as per
  the requirements of the code of construction).
• After a satisfactory test report, the welder may
  be employed for the production welding (or
  fabrication welding).

104
Welder Qualification

• Following important factors shall always be
  considered before conducting the welder
  qualification test (WQT)
• Welding Procedure Specification (WPS)
• Welding Process
• Size of test coupon
• Position of the test coupon
• Filler metal/Electrode

105
Welder Qualification

• Position of the test coupon
• For plate welding, we have four different welding
  test positions flat, horizontal, vertical
  overhead 1G,2G,3G,4G OR 1F,2F,3F,4F.
• For pipe welding also we have multiple positions
  for example 1G,2G,5G,6G
• If the welder qualifies in the 2G position then
  he can weld in horizontal (2G) and flat (1G)
  position only.
• On the other hand, if the welder qualifies in
  2G, 3G, and 4G positions then he qualifies for
  all positions (As per ASME Section IX).

106
WELDING DEFECTS
107
Welding Defects
Welding defects are formed in welding work due to
the weak or poor technique used by inexperienced
or untrained welders or due to structural
problems in the welding operation. Weld
discontinuities can be defined as "an
interruption of the typical structure of a weld,
such as a lack of homogeneity in the mechanical,
metallurgical or physical characteristics of the
weld.
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Welding Defects

• Weld discontinuities include
• Porosity.
• Slag inclusions.
• Incomplete fusion.
• Incomplete joint penetration.
• ETC.

WELDING DEFECTS VS. DISCONTINUITIES
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Welding Defects

• Porosity and Blowholes
• Undercut
• Weld crack
• Incomplete fusion
• Slag inclusion
• Excess reinforcement
• Overlap

• Incomplete penetration
• Spatter
• Distortion
• Hot Tear
• Mechanical damage
• Misalignment
• Lamellar tearing

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Porosity Blowholes

• Porosity is a group of small bubbles and
  blowholes are relatively large hidden holes.
• They are mainly caused by trapped gases. Porosity
  is a result of weld metal contamination.

Causes of Porosity Remedies of Porosity
Using insufficient electrode deoxidant. Choosing suitable electrode and filler materials.
Applying too large a gas flow. Checking the gas flow meter and ensuring that it is adapted as needed with appropriate pressure and flow settings.
Using a larger arc. Make sure that the arc distance is correct.
Existence of moisture in the process. Cleaning the metal before starting the welding process.
Unsuitable gas shield. Decreasing welding speed, it will allow the gas to escape.
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Porosity Blowholes
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Undercut

• Undercut in welding makes imperfection, it is the
  formation of grooves in the weld toe, which
  decreases the cross-sectional thickness of the
  base metal.

Causes of Undercut Remedies of Undercut
Incorrect use of angle, which will deliver more heat to the free edges. Using of suitable electrode angle, with more heat delivered towards thicker components.
Because of too fast weld speed. Decreasing the travel speed of the electrode, but should not be too slow.
Using poor welding methods. Applying the multipass technique.
Use of incorrect gas shielding and filler metal. Select the shielding gas with the right structure for the material you are welding.
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Undercut
114
Crack
Causes of Weld Crack Remedies of Weld Crack
Using hydrogen while welding ferrous metals. Using suitable metals.
Applying low current with high welding speed. Utilizing the appropriate welding speed and current.
The design concept is poor. Using proper design concepts.
Not doing preheating before starting welding. Preheating the metal before starting welding.
Contamination of base metal. Cleaning the metal surface before welding.
Residual stress solidification due to shrinkage. Giving decent cooling of the weld area
These are the most dangerous types of welding
defects. It is almost not allowed by all
standards in production. It can appear on the
surface, in the weld metal, or in an area
affected by strong heat.
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Incomplete Fusion
Causes of Incorrect Fusion Remedies of Incorrect Fusion
Contamination of metal surface. Cleaning the welding area of the metal surface before welding.
Using low heat input. Utilizing the proper heat input for welding.
The diameter of the electrode is wrong for the thickness of the material you are welding. Use the correct diameter of the electrode to fit the thickness of the material that you are welding.
Incorrect electrode angle. Ensure the angle of the electrode is suitable for welding.
Employing too fast travel speed. Decreasing the speed of arc travel.
These types of welding defects occur when there
is a shortage of suitable fusion between the
metal and weld. It may also be visible between
adjacent weld beads. This produces a gap inside
the joint that is not filled with molten metal.
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Slag Inclusion
Causes of Slag Inclusion Remedies of Slag Inclusion
Poor chipping and cleaning of previous passes in multipass welding. Through the wire brush, clean the weld bed surface before the next layer is deposited.
Due to the incorrect angle of the electrode. Adjusting the angle of the electrode.
Using too low welding current. Increasing the current density.
Insufficient space for the puddle of molten weld metals. Redesigning the joint to allow sufficient space for proper use of the puddle of molten weld metals.
Maybe cooling is very fast. Decreasing the rapid cooling.
Slag inclusion is welding defects that are
usually visible in welds. The slag is a dangerous
substance that appears as a product of stick
welding, flux-core arc welding, and submerged arc
welding.
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Incomplete Penetration
Causes of Incomplete Penetration Remedies of Incomplete Penetration
There was too much space between the metal that you are welding with. Assuring that the surface is jointly fine.
You are moving the bead too fast, which does not allow sufficient metal to accumulate in the joint. Decreasing the arc travel speed.
You are using a very low amper setting, which results in the current not being strong enough to melt the metal properly. Selecting a decent welding current.
Using improper joints. Improving the design of the joint.
Wrong position of the electrode. Make sure the position of the electrode is very accurate.
In these types of welding defects, penetration is
defined as the distance from the uppermost
surface of the base plate to the maximum extent
of the weld nugget.
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Spatters
Causes of Spatter Remedies of Spatter
Contamination of metal surface. Cleaning metal surfaces before welding.
The working angle of the electrode is much more rigid. Decreasing the arc length and increasing the electrode angle.
Utilizing too high amper current and too low voltage settings. Using proper polarity with adjusting the weld current.
Using the larger arc and wet electrode. Make sure to use the proper arc and electrode according to the welding.
Spatters are tiny metal particles that are
ejected from the arc during welding and
accumulate on the base metal throughout the weld
bead along its length. This is particularly
common happens in gas-metal arc welding.
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Distortion
Causes of Distortion Remedies of Distortion
Employing incorrect welding orders. Ensure to use the correct welding order.
Using a large number of passes with small diameter electrodes. Using the appropriate number of weld passes.
Because of high residual stresses in the plate to be welded. Make sure you use the appropriate amount of weld metal as required by the joint. This will decrease contraction forces.
Due to the slow speed of arc travel. Maintaining the speed of arc travel.
Not using any measuring instrument for dimension purposes. If required you can use a measuring instrument, so that dimensional accuracy is accurate.
Using too much time for the welding process. Decreasing the time of the welding process so that the volume around the metal is not even expanded.
Distortion is the difference in size and location
between the positions of the two metal plates
before and after welding due to the temperature
grade present at several points along the weld
joints.
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VISUAL INSPECTION
121
Visual Inspection (VT)
Visual inspection is a non-destructive testing
(NDT) weld quality testing process where a weld
is examined with the eye to determine surface
discontinuities. It is the most common method of
weld quality testing.
122
Visual Inspection (VT)
Inspections requiring Ultrasonic, X-Ray
equipment, Infra-red, etc. are not typically
regarded as Visual Inspection as these Inspection
methodologies require specialized equipment,
training and certification.
123
Visual Inspection (VT)

• Disadvantages
• Inspector training necessary
• Good eyesight required or eyesight corrected to
  20/40
• Can miss internal defects
• Report must be recorded by inspector
• Open to human error

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Visual Inspection Tools
Fillet Weld Gauge

• Weld handheld fillet gauge measures
• The flatness of the weld
• Convexity (how the weld is welded outward)
• Concavity (how the weld is rounded inward)

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Visual Inspection Tools
Fillet Weld Gauge
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Visual Inspection Tools

• Protective lenses with pocket viewer and shade
  lens for use when observing the  welding process
• A magnifying glass per the code in your area
• Flashlight
• Chisel and/or welding hammer for spatter and slag
  removal before the weld is inspected
• Temperature device (Tempe stick, Pyrometer)  to
  determine the preheating, inter-pass and
  post-heating temperatures.
• Magnet to indicate the type of material being
  welded
• Tape measure
• Calipers

127
Visual Weld Quality Testing Steps
128
Visual Inspection Before Welding

• This type of inspection is typically associated
  with checking the preparation of the welding
  joint and verification of parameters that would
  be difficult or impossible to confirm during or
  after welding
• The dimensional inspection of root openings.
• Groove weld bevel angles
• Joint alignment
• Plate surface condition and cleanliness
• Check drawings
• Check fillet welding symbols.
• Does the procedure align with local codes and the
  weld specification
• preheat verification, temperature and heating
  method.

129
Visual Inspection During Welding

• This is the inspection that is carried out during
  the welding operation and is concerned mainly
  with the requirements of the welding procedure
  specification (WPS). This inspection includes
  such items as
• Inter-pass cleaning methods.
• Inter-pass temperature control.
• Welding current settings.
• Welding travel speed.
• Shielding gas type.
• Gas flow rate.
• Welding sequence.
• Environmental conditions that may affect the
  quality of the weld such as, rain, wind, and
  extreme temperatures.

130
Visual Inspection Post Welding

• This inspection typically conducted to verify the
  integrity of the completed weld.
• Many non-destructive testing (NDT) methods are
  used for post-weld inspection.
• However, even if the weld is to be subjected to
  NDT, it is normally wise to conduct visual
  inspection first.
• One reason for this is that surface
  discontinuities, which may be detected by visual
  inspection, can sometimes cause misinterpretation
  of NDT results or disguise other discontinuities
  within the body of the weld.

131
Visual Inspection Post Welding

• The most common welding discontinuities found
  during visual inspection are conditions such as
• Undersized welds.
• Undercut, overlap.
• Surface cracking.
• Surface porosity.
• Under fill.
• Incomplete root penetration.
• Excessive root penetration.
• Burn through.
• Excessive reinforcement.

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