Visual Weld Inspection South Africa: Common Defects, Causes and Quality Checks
- Jun 30
- 21 min read
Quick Answer: What Is Visual Weld Inspection in South Africa?
Visual weld inspection South Africa is the systematic examination of welding preparation, welding activity and completed welds to determine whether the work complies with the applicable:
drawing;
Welding Procedure Specification;
project specification;
fabrication code;
acceptance standard;
inspection and test plan;
and contractual requirements.
It is not merely looking at a weld and deciding whether it appears attractive.
A proper inspection may examine:
material identity;
joint preparation;
root gap;
bevel angle;
alignment;
cleanliness;
tack welds;
welding process;
consumables;
welding position;
completed weld dimensions;
surface profile;
visible imperfections;
distortion;
repair areas;
and traceable inspection records.
The central rule is:
A weld cannot be accepted or rejected accurately unless the inspector knows which requirements apply.
The same visible imperfection may be acceptable under one contract and rejectable under another because acceptance depends on:
component function;
loading;
material;
joint type;
service environment;
fatigue sensitivity;
quality level;
fabrication code;
and client specification.
Visual inspection is often the first and most economical quality-control method—but it cannot reveal every internal imperfection.
The Brutal Truth: A Beautiful Weld Can Still Be Unacceptable
A smooth, evenly rippled weld can still contain:
incomplete root penetration;
internal lack of fusion;
slag inclusions;
internal porosity;
unacceptable heat input;
incorrect filler metal;
procedure deviation;
or dimensions outside the drawing requirement.
A rough-looking weld may sometimes meet the applicable dimensional and acceptance criteria.
That does not mean appearance is irrelevant.
It means appearance alone is not proof of integrity.
A competent inspector separates three questions:
What can be observed?
What does the specification require?
What additional testing is needed to evaluate what cannot be seen?
Without those distinctions, inspection becomes opinion.
Imperfection vs Defect: The Terminology Matters
The words imperfection and defect should not automatically be treated as synonyms.
Weld imperfection
An imperfection is a departure from the ideal weld geometry or continuity.
Examples include:
porosity;
undercut;
excess reinforcement;
misalignment;
incomplete penetration;
slag inclusion;
and cracking.
Weld defect
An imperfection becomes a defect when it exceeds the applicable acceptance criteria or otherwise makes the component unacceptable for its intended use.
Therefore:
Not every imperfection is automatically a rejectable defect.
The inspector must identify and measure the imperfection, then compare it with the governing requirement.
ISO 6520-1 provides a classification system for geometric welding imperfections.
ISO 5817 provides quality levels for specified imperfections in fusion-welded joints in steel,
nickel, titanium and their alloys, excluding beam welding.
The quality levels are commonly identified as:
B — highest requirement;
C — intermediate requirement;
D — moderate requirement.
These are not arbitrary rankings chosen after fabrication.
The required quality level should be specified through the design, contract, application standard or fabrication documentation.
Do not assume that every project automatically requires Level B.
Visual Inspection Does Not Replace the Welding Specification
A visual inspector should not inspect from memory alone.
The inspection package may include:
approved fabrication drawing;
weld map;
Welding Procedure Specification;
Procedure Qualification Record;
welder qualification;
material certificates;
consumable certificates;
inspection and test plan;
repair procedure;
applicable code;
acceptance standard;
and client-specific requirements.
Before inspection begins, confirm:
Question | Why it matters |
What component is being inspected? | Determines service and risk |
Which joint is involved? | Determines required geometry |
What weld process was specified? | Affects expected appearance and defects |
What material was used? | Affects procedure and inspection |
Which WPS applies? | Establishes controlled variables |
Which code or standard applies? | Provides acceptance requirements |
What quality level is required? | Determines permitted imperfections |
Is the weld complete? | Prevents premature final acceptance |
Is additional NDT required? | Visual inspection may be only one stage |
Who is authorised to accept or reject? | Prevents unauthorised disposition |
A weld gauge cannot compensate for a missing acceptance standard.
ISO 17637 and the Visual Inspection Process
ISO 17637 addresses visual testing of fusion-welded joints and may also be applied to the joint before welding.
Where the standard is specified, the inspection process generally includes:
suitable access;
adequate illumination;
clean examination surfaces;
appropriate viewing position;
suitable measuring equipment;
visual inspection before welding;
visual inspection during welding;
examination of the finished weld;
and examination of repaired welds.
For direct viewing under ISO 17637 principles, commonly referenced conditions include:
surface illumination of at least approximately 350 lux;
approximately 500 lux recommended;
the eye positioned within about 600 mm of the examination surface;
and a viewing angle of at least approximately 30 degrees.
Where direct access is impossible, remote viewing equipment may be required.
The applicable procedure must define whether devices such as the following are permitted:
inspection mirrors;
magnifiers;
borescopes;
videoscopes;
cameras;
or remote visual systems.
The inspector must confirm that the viewing method provides enough resolution and access for the required examination.
Visual Inspection Begins Before Welding
Many expensive welding defects can be prevented before the first arc is struck.
Material verification
Check:
material grade;
dimensions;
thickness;
identification;
heat number where traceability is required;
surface condition;
laminations or visible damage;
and compatibility with the drawing and WPS.
Using the wrong material cannot be corrected through excellent welding technique.
Joint preparation
Inspect:
bevel angle;
root face;
root opening;
joint type;
groove preparation;
edge condition;
cleanliness;
machining marks;
and preparation consistency.
Incorrect preparation may contribute to:
lack of penetration;
lack of fusion;
excessive penetration;
burn-through;
excessive weld volume;
and distortion.
Fit-up and alignment
Check:
root gap;
mismatch;
angular alignment;
hi-lo condition;
component orientation;
branch location;
tack position;
restraint;
and accessibility.
Misalignment can affect:
load transfer;
root fusion;
internal flow;
dimensional accuracy;
and fatigue performance.
Cleanliness
The joint should be free from harmful:
oil;
grease;
moisture;
rust;
paint;
scale;
cutting residue;
and contamination.
Different processes tolerate contamination differently, but no welding process benefits from poor preparation.
Tack welds
Inspect tack welds for:
cracks;
porosity;
poor fusion;
incorrect size;
incorrect position;
excessive length;
and suitability for incorporation into the final weld.
Defective tack welds can become embedded in the completed joint.
Backing and purge arrangements
Where applicable, confirm:
backing type;
fit;
cleanliness;
temporary or permanent status;
purge dam location;
purge gas;
flow arrangements;
and protection of the root.
Inspection During Welding
Inspection should not wait until the weld is complete.
By then, some problems may already be buried beneath later passes.
Process and equipment
Confirm that the actual process matches the WPS.
Examples include:
SMAW or Stick;
GMAW or MIG/MAG;
GTAW or TIG;
FCAW or Flux Core;
and approved combination processes.
Consumables
Check:
classification;
diameter;
batch control;
storage;
condition;
baking or holding where required;
shielding gas;
filler-metal identity;
and contamination.
Welding parameters
Where inspection responsibility includes process monitoring, verify variables such as:
current;
voltage;
polarity;
wire-feed speed;
travel speed;
gas flow;
electrode diameter;
tungsten type;
preheat;
interpass temperature;
and heat-input controls.
The inspector should not change production variables without proper authority.
Pass cleaning
Before the next pass, examine whether:
slag has been removed;
spatter obstructing the joint has been cleared;
stop-start areas are sound;
visible cracks are absent;
surface porosity has been removed;
and defects have been repaired correctly.
Root pass
The root pass is often critical.
Where accessible, inspect:
root fusion;
penetration;
consistency;
concavity;
excessive penetration;
burn-through;
suck-back;
oxidation;
and start-stop tie-ins.
Inter-run profile
Check for:
trapped slag risk;
deep valleys;
excessive convexity;
incomplete sidewall fusion;
contamination;
and unsuitable bead placement.
A defect buried beneath the next pass may require expensive excavation later.
Inspection After Welding
The completed weld should be examined only after:
slag has been removed;
spatter has been removed where required;
the surface is sufficiently clean;
temporary attachments are addressed;
and the component is cool enough for accurate examination where temperature could affect measurement or safety.
The inspector may evaluate:
completeness;
location;
length;
weld size;
reinforcement;
throat;
leg length;
profile;
surface continuity;
undercut;
overlap;
porosity;
cracking;
crater condition;
arc strikes;
misalignment;
distortion;
root appearance;
and overall workmanship.
The base metal adjacent to the weld also requires examination.
Damage may include:
grinding gouges;
arc strikes;
flame damage;
excessive tool marks;
lamination;
mechanical damage;
or unauthorized welds.
Common Weld Defects, Possible Causes and Quality Checks
1. Weld Cracks
Cracks are among the most serious welding imperfections.
They may appear:
longitudinally;
transversely;
at the weld toe;
through the weld centreline;
in the crater;
in the heat-affected zone;
at the root;
or beneath the surface where visual inspection cannot detect them.
Possible contributors
hydrogen;
high restraint;
rapid cooling;
unsuitable consumable;
excessive hardness;
poor crater termination;
incorrect preheat;
excessive stress;
contamination;
unsuitable welding procedure;
or material-related cracking susceptibility.
Visual quality checks
Look for:
fine linear indications;
branching indications;
crater splitting;
cracks extending into the parent material;
and suspicious dark lines at the toe or root.
Use additional methods where required, such as:
penetrant testing;
magnetic-particle testing;
ultrasonic testing;
or radiographic testing.
Cracks are commonly unacceptable under major fabrication codes, but formal disposition must follow the applicable specification.
Do not merely grind over a crack and weld on top of it.
The extent and cause must be addressed.
2. Surface Porosity
Porosity appears as rounded cavities or pinholes caused by gas becoming trapped during solidification.
It may be:
isolated;
uniformly scattered;
clustered;
linear;
or concentrated at stops and starts.
Possible contributors
moisture;
oil;
rust;
paint;
contaminated base metal;
poor shielding gas;
gas leaks;
excessive gas flow causing turbulence;
wind;
long arc length;
incorrect torch angle;
damp electrodes;
contaminated filler;
or poor surface preparation.
Visual quality checks
Record:
number;
diameter;
distribution;
location;
and whether the cavities are open to the surface.
Visible surface porosity may indicate additional internal porosity, but visual inspection alone cannot confirm the internal extent.
3. Undercut
Undercut is a groove melted into the parent metal adjacent to the weld toe or root that is not filled with weld metal.
Possible contributors
excessive current;
high voltage;
excessive travel speed;
incorrect electrode angle;
long arc;
poor manipulation;
wrong bead placement;
or insufficient filler at the toe.
Why it matters
Undercut can:
reduce effective section thickness;
create a stress concentration;
increase fatigue sensitivity;
and reduce corrosion allowance.
Visual quality checks
Measure:
depth;
length;
continuity;
location;
and whether it occurs at one or both toes.
A weld may have only slight undercut yet still fail a strict fatigue-sensitive requirement.
Do not judge it by appearance alone.
4. Overlap
Overlap occurs when weld metal flows onto the parent metal without proper fusion at the toe.
It often appears as a lip or rolled edge.
Possible contributors
excessive filler deposition;
slow travel speed;
low heat input;
incorrect torch or electrode angle;
oversized electrode;
poor manipulation;
or unsuitable welding position technique.
Visual quality checks
Look for:
an unfused edge;
rolled weld metal;
abrupt toe profile;
and a narrow crevice beneath the overlap.
Overlap should not be confused with smooth, properly fused reinforcement.
5. Lack of Fusion
Lack of fusion occurs when weld metal fails to fuse properly with the parent metal or a previous weld pass.
It may occur at:
the sidewall;
between passes;
at the root;
or beneath an apparently sound surface.
Possible contributors
low heat input;
excessive travel speed;
incorrect electrode angle;
poor joint preparation;
oxide or scale;
slag left between passes;
incorrect bead placement;
oversized weld pool;
or unsuitable parameters.
Visual limitations
Visual inspection may reveal surface-connected lack of fusion, but buried lack of fusion often requires:
ultrasonic testing;
radiographic testing;
destructive testing;
or macro examination.
A smooth weld surface cannot prove complete fusion.
6. Incomplete Root Penetration
Incomplete penetration occurs when the weld does not extend through the joint root as required.
Possible contributors
insufficient root gap;
excessive root face;
low current;
fast travel;
incorrect electrode size;
poor access;
misalignment;
incorrect torch position;
or unsuitable procedure.
Visual quality checks
Where the root is accessible, inspect:
continuity;
unfused root faces;
visible gap;
irregular penetration;
and root profile.
Where the root cannot be viewed, visual inspection from the face cannot prove complete penetration.
7. Excessive Penetration
Excessive penetration is weld metal projecting beyond the root more than permitted.
Possible contributors
excessive heat input;
excessive root gap;
thin root face;
slow travel;
incorrect backing;
incorrect keyhole control;
or excessive filler.
Why it matters
It may:
obstruct internal flow;
create notch effects;
trap product;
reduce fatigue performance;
and violate dimensional requirements.
Visual quality checks
Measure the accessible root projection and compare it with the applicable criteria.
8. Burn-Through
Burn-through is an opening created when excessive heat causes the molten weld pool to collapse through the joint.
Possible contributors
excessive current;
excessive root gap;
insufficient root face;
slow travel;
poor fit-up;
thin material;
or inadequate backing.
Visual quality checks
Look for:
holes;
irregular root openings;
heavy local penetration;
and evidence of attempted filling.
A filled burn-through area may still require formal repair control.
9. Root Concavity
Root concavity occurs where the root surface is recessed below the adjacent base-metal surface.
In TIG pipe welding it may sometimes be referred to informally as suck-back.
Possible contributors
excessive heat;
inadequate filler;
poor purge conditions;
excessive travel speed;
incorrect root technique;
or shrinkage of the molten root.
Visual quality checks
Where accessible, measure:
depth;
length;
continuity;
and remaining wall thickness where relevant.
Root concavity must not automatically be confused with incomplete penetration.
10. Excessive Weld Reinforcement
Reinforcement is weld metal extending above the surface of a groove weld.
Some reinforcement may be permitted.
Excessive reinforcement may create:
stress concentration;
poor profile;
additional weight;
machining problems;
or interference with assembly.
Possible contributors
excessive filler deposition;
slow travel;
low voltage;
incorrect technique;
narrow joint preparation;
or too many passes.
Visual quality checks
Measure:
reinforcement height;
width;
transition at the toes;
and continuity.
A high weld is not automatically a strong weld.
11. Underfill
Underfill occurs when the weld face or root remains below the adjacent parent-metal surface.
Possible contributors
insufficient filler;
fast travel;
low wire-feed rate;
excessive grinding;
incomplete pass sequence;
poor joint-volume calculation;
or incorrect technique.
Visual quality checks
Measure:
depth;
area;
continuity;
and impact on required weld size.
Underfill can reduce effective section thickness.
12. Incorrect Fillet-Weld Size
A fillet weld may be too small, too large or geometrically incorrect.
Too small
Possible consequences include insufficient design capacity.
Too large
Possible consequences include:
wasted consumables;
increased heat input;
distortion;
increased residual stress;
and longer production time.
Visual quality checks
Measure:
leg length;
effective throat where specified;
profile;
length;
pitch;
and termination.
Do not accept a fillet weld merely because it looks substantial.
13. Excessive Convexity
A convex weld has an outwardly rounded profile.
Some convexity may be normal depending on:
process;
position;
weld type;
and specification.
Excessive convexity can create poor toe transition and stress concentration.
Possible contributors
slow travel;
low voltage;
excessive filler;
incorrect electrode angle;
and poor manipulation.
Visual quality checks
Evaluate the profile against the specified weld size and acceptance criteria.
14. Excessive Concavity
A concave fillet weld curves inward.
Concavity can reduce effective throat thickness if excessive.
Possible contributors
high travel speed;
high voltage;
insufficient filler;
excessive heat;
incorrect torch angle;
or poor bead placement.
Visual quality checks
Measure the actual throat or profile using an appropriate fillet gauge.
A visually smooth concave weld may still be undersized.
15. Misalignment
Misalignment may be:
linear;
angular;
axial;
or rotational.
Pipe mismatch is often called hi-lo.
Possible contributors
poor fit-up;
weak clamping;
tack failure;
thermal movement;
incorrect component dimensions;
or poor fabrication control.
Visual quality checks
Measure:
offset;
angular deviation;
component position;
root mismatch;
and compliance with the drawing.
Welding cannot correct all fabrication misalignment.
16. Distortion
Distortion is dimensional change caused by uneven heating and contraction.
It may appear as:
bowing;
angular distortion;
twisting;
shrinkage;
buckling;
or loss of flatness.
Possible contributors
excessive heat input;
poor welding sequence;
inadequate restraint;
unbalanced welding;
large weld size;
poor fit-up;
or unsuitable joint design.
Visual quality checks
Use:
straightedge;
level;
tape;
square;
templates;
and dimensional inspection equipment.
Distortion is not merely an appearance problem.
It can prevent assembly and create service stress.
17. Slag Inclusion
Slag inclusion occurs when non-metallic slag becomes trapped in the weld.
Surface-breaking slag may be visible, but internal slag usually requires additional NDT.
Possible contributors
incomplete cleaning;
low heat input;
poor bead placement;
narrow joint access;
incorrect electrode angle;
undercut between passes;
or poor manipulation.
Visual quality checks
Inspect between passes for:
residual slag;
dark linear cavities;
trapped material;
and poor inter-run profile.
The best time to prevent slag inclusion is before the next pass.
18. Tungsten Inclusion
Tungsten inclusion may occur during GTAW/TIG when tungsten enters the weld pool.
Possible contributors
touching the tungsten to the pool;
dipping into filler metal;
incorrect tungsten preparation;
unstable arc;
excessive current;
or contaminated electrode handling.
Visible tungsten contamination may appear as metallic particles, but embedded inclusions may require additional examination.
The contaminated area should be addressed according to the approved repair procedure.
19. Spatter
Spatter consists of metal droplets expelled during welding and deposited around the weld.
Possible contributors
incorrect voltage;
excessive current;
unstable transfer;
incorrect polarity;
poor shielding;
long arc;
contaminated material;
or unsuitable process settings.
Visual quality checks
Evaluate:
quantity;
location;
interference with coating or assembly;
and project cleanliness requirements.
Spatter may be mainly cosmetic in one application and unacceptable in another.
20. Arc Strikes
Arc strikes are unintended areas where the welding arc contacts the parent material outside the specified weld.
Why they matter
Arc strikes may create:
local hardening;
cracking;
surface damage;
stress concentration;
and traceability concerns.
Visual quality checks
Look for:
small fused areas;
local craters;
discolouration;
and grinding marks used to hide the strike.
Repair and examination requirements must follow the project specification.
21. Crater Pipe and Crater Cavities
A crater defect occurs at the termination of a weld bead.
Possible contributors
abrupt arc termination;
inadequate crater filling;
poor slope-down control;
insufficient filler;
or poor stop-start technique.
Visual quality checks
Inspect stops and starts carefully for:
depressions;
cavities;
cracks;
porosity;
and incomplete tie-in.
Crater cracks can propagate beyond the visible termination.
22. Poor Stop-Start Tie-In
A stop-start area may contain:
excessive build-up;
low spots;
porosity;
lack of fusion;
crater defects;
or abrupt profile changes.
Possible contributors
poor restart positioning;
contamination;
inadequate removal of the previous crater;
unstable arc initiation;
and incorrect travel control.
Visual quality checks
Inspect every restart—not only the centre of the weld.
23. Excessive Grinding and Base-Metal Damage
Grinding can remove defects, but uncontrolled grinding can create new ones.
Possible consequences
reduced wall thickness;
gouges;
sharp notches;
loss of weld size;
altered profile;
and hidden repair history.
Visual quality checks
Inspect:
grind depth;
smooth transition;
remaining material;
unauthorized excavation;
and whether the repair area was re-examined.
Grinding marks should not be mistaken for proof that the defect was removed.
Visual Weld Inspection Tools
A professional inspection kit may include:
inspection torch;
calibrated light meter where required;
inspection mirror;
magnifier;
steel rule;
tape measure;
straightedge;
square;
vernier caliper;
bridge-cam gauge;
fillet-weld gauge;
hi-lo gauge;
undercut gauge;
depth gauge;
pit gauge;
contour gauge;
temperature-measuring equipment;
camera;
markers;
inspection forms;
and approved reference documents.
Weld gauges do not make decisions
A gauge measures geometry.
It does not determine:
applicable acceptance criteria;
structural significance;
repair method;
root fusion;
internal quality;
or service suitability.
The inspector provides the judgement by combining:
measurement;
specification;
technical knowledge;
and authorised responsibility.
Calibration and verification
Inspection equipment should be:
suitable;
identifiable;
maintained;
checked;
and calibrated or verified where the quality system requires it.
A damaged or unverified gauge can create false acceptance evidence.
Process-Specific Visual Clues
Stick Welding / SMAW
Common visible concerns may include:
slag inclusion risk;
undercut;
excessive convexity;
stop-start defects;
arc strikes;
spatter;
porosity;
and incomplete cleaning.
MIG/MAG or GMAW
Common visible concerns may include:
lack of fusion;
excessive spatter;
porosity;
burn-through;
undercut;
overlap;
poor bead placement;
and irregular transfer evidence.
TIG or GTAW
Common visible concerns may include:
tungsten contamination;
oxidation;
underfill;
incomplete fusion;
root concavity;
excessive penetration;
crater defects;
and poor purge evidence.
Flux Core or FCAW
Common visible concerns may include:
slag entrapment;
porosity;
worm tracks;
undercut;
excessive reinforcement;
inconsistent bead placement;
and poor inter-run cleaning.
Pipe Welding
Pipe inspection may require particular attention to:
root penetration;
hi-lo;
internal oxidation;
root concavity;
excessive penetration;
starts and stops;
tie-ins;
cap width;
cap height;
and consistency around changing positions.
Visual Inspection vs Other NDT Methods
Visual testing evaluates accessible surface condition and geometry.
It cannot reliably detect every internal discontinuity.
Method | Main capability | Important limitation |
Visual Testing | Surface condition, geometry and accessible defects | Cannot prove internal soundness |
Penetrant Testing | Surface-breaking defects in suitable non-porous materials | Does not detect buried defects |
Magnetic-Particle Testing | Surface and near-surface indications in ferromagnetic materials | Limited to magnetisable materials |
Ultrasonic Testing | Internal planar and volumetric imperfections | Requires suitable procedure, access and trained personnel |
Radiographic Testing | Internal volumetric and some planar imperfections | Radiation controls and geometric limitations apply |
Eddy-Current Testing | Surface and near-surface conditions in conductive materials | Application and interpretation are specialised |
Leak Testing | Leakage through pressure boundaries or sealed systems | Does not define all structural imperfections |
Additional NDT must be selected according to:
material;
joint geometry;
thickness;
defect type;
code;
service;
access;
and project specification.
A weld that passes visual inspection may still require UT, RT, MT or PT.
When Should Visual Findings Trigger Additional NDT?
Escalation may be appropriate when:
cracking is suspected;
root condition cannot be seen;
lack of fusion is suspected;
internal penetration cannot be confirmed;
repeated surface porosity appears;
a repair has been made;
arc strikes require further assessment;
the component is fatigue-sensitive;
the weld is pressure-retaining;
service risk is high;
dimensions suggest procedure deviation;
or the code requires additional examination.
The inspector should not select additional NDT casually.
The inspection plan, responsible welding coordinator, engineer, client or authorised inspection authority may need to determine the method.
Acceptance Criteria: The Most Common Inspection Failure
The most serious reporting error is:
“The weld looks bad, therefore it fails.”
Or:
“The weld looks neat, therefore it passes.”
Both statements are inadequate.
Acceptance must be based on a specified requirement such as:
ISO 5817;
AWS D1.1;
ASME construction code;
project specification;
client requirement;
product standard;
approved drawing;
or another applicable acceptance document.
ISO 5817 quality levels
ISO 5817 quality levels B, C and D relate to permitted levels of specified imperfections.
They do not automatically define:
component service category;
inspection extent;
NDT method;
welder qualification;
WPS approval;
or company certification.
The contract must identify the requirement
Before production starts, the fabrication system should identify:
which acceptance standard applies;
which quality level applies;
what percentage is inspected;
who performs inspection;
what NDT follows VT;
how non-conformances are recorded;
and how repairs are authorised.
Inspection should not become a debate after the weld is complete.
Who Is Competent to Perform Visual Weld Inspection?
Different levels of inspection responsibility require different competence.
Welder self-inspection
Every competent welder should be able to check:
preparation;
cleanliness;
process setup;
bead appearance;
undercut;
porosity;
weld size;
obvious cracks;
and stop-start quality.
Self-inspection helps prevent defective work from moving to the next stage.
It does not automatically replace independent inspection.
Supervisor or quality-control inspection
A supervisor may inspect within the limits of:
training;
company procedure;
appointment;
experience;
and project requirements.
Qualified welding inspector
Higher-risk fabrication may require personnel with recognised inspection qualifications and experience.
In South Africa, dedicated welding-inspector pathways are offered through SAIW.
Certified NDT Visual Testing personnel
Where ISO 9712-certified Visual Testing is required, the individual must meet the relevant:
training;
examination;
experience;
vision;
certification;
and employer-authorisation requirements.
A welding-course certificate does not automatically qualify a person as an NDT inspector.
Visual Inspection Reporting
An inspection result that exists only in the inspector’s memory has limited audit value.
A proper report may include:
project;
client;
component;
drawing number;
weld identification;
weld map reference;
material;
thickness;
joint type;
welding process;
WPS number;
welder identification;
inspection date;
inspection stage;
examination conditions;
equipment used;
acceptance criteria;
imperfections observed;
measurements;
photographs;
disposition;
repair reference;
reinspection result;
inspector identity;
and signature or electronic approval.
Use objective language
Poor report:
“Ugly weld. Welder must redo.”
Better report:
“Continuous undercut observed along approximately 85 mm of the upper weld toe. Maximum measured depth recorded as 1.2 mm. Acceptance pending comparison with the specified ISO 5817 quality level and project requirements.”
The report should separate:
observation;
measurement;
acceptance decision;
and corrective action.
Non-Conformance and Repair Control
A rejected weld should not automatically be repaired by whoever is closest with a grinder.
A controlled repair process should identify:
The non-conformance.
The applicable acceptance requirement.
The extent of the imperfection.
The authorised disposition.
The repair procedure.
The person authorised to repair.
The excavation method.
Confirmation that the defect was removed.
Rewelding controls.
Required reinspection.
Additional NDT.
Closure of the record.
Repeated repairs can affect:
material properties;
distortion;
residual stress;
dimensional accuracy;
and component reliability.
Repair history should be traceable.
Visual Weld Inspection Myths
Myth 1: A neat weld is automatically strong
Appearance does not prove internal fusion, penetration, filler identity or procedure compliance.
Myth 2: Every visible imperfection is rejectable
Acceptance depends on the specified criteria.
Myth 3: Visual inspection happens only after welding
Effective VT begins with material, joint preparation and fit-up.
Myth 4: A weld gauge makes someone an inspector
Tools support measurement. They do not create competence or authority.
Myth 5: Grinding makes defects disappear
Grinding may hide surface evidence without removing the full imperfection.
Myth 6: Coded welders do not need inspection
Welder qualification demonstrates competence within a test range. Production welds still require quality control.
Myth 7: Passing visual inspection means no other NDT is needed
Additional testing may still be mandatory or technically necessary.
Welding Quality Responsibility Matrix
Quality activity | Welder | Supervisor | Inspector | Welding coordinator | Employer/manufacturer |
Confirm correct WPS | Follow | Verify use | Check evidence | Control system | Provide system |
Check joint preparation | Self-check | Verify | Inspect as required | Define controls | Provide resources |
Monitor parameters | Follow | Monitor | Witness where required | Establish controls | Maintain equipment |
Check inter-run cleaning | Primary | Verify | Inspect where required | Define expectations | Enforce procedure |
Final visual self-check | Primary | Verify | Independent inspection | Review quality trends | Maintain records |
Accept or reject | No unless appointed | Limited authority | According to appointment | Technical oversight | Define authority |
Approve repair | No | No unless authorised | Record/recommend | Technical approval | Ensure control |
Conduct specialist NDT | No | No | Only if qualified | Coordinate | Appoint competent body |
Maintain quality records | Contribute | Contribute | Complete reports | Review | Retain and control |
Titles alone do not establish authority.
Appointments, competence and procedures matter.
South African Fabrication Scenario
A Cape Town structural-steel contractor completes a series of fillet welds on support brackets.
The workshop supervisor performs a quick visual check and approves the brackets because:
the welds are continuous;
no obvious cracks are visible;
and the beads look smooth.
During installation, the client inspector measures the welds and finds:
undersized fillet legs;
intermittent undercut;
incomplete weld length;
and unauthorized arc strikes.
The welds were not compared with:
the drawing;
specified fillet size;
inspection plan;
or acceptance criteria.
The contractor must:
stop installation;
quarantine the brackets;
issue non-conformance records;
repair selected welds;
replace others;
reinspect;
update documentation;
and absorb the delay.
The failure did not begin when the client rejected the work.
It began when the workshop treated visual inspection as an informal glance rather than a controlled quality process.
Visual Weld Inspection Checklist
Before welding
Correct drawing available
Correct WPS available
Material verified
Material thickness verified
Joint type correct
Bevel angle checked
Root face checked
Root gap checked
Alignment checked
Tack welds acceptable
Surface clean
Backing correct
Purging arrangement correct
Welding access adequate
Welder qualification applicable
During welding
Correct process used
Correct consumables used
Consumables in suitable condition
Polarity correct
Parameters within WPS
Shielding gas correct
Preheat achieved
Interpass temperature controlled
Pass sequence followed
Slag removed
Visible defects removed
Starts and stops controlled
Root appearance checked where accessible
After welding
Weld complete
Correct location and length
Surface cleaned
Weld size correct
Reinforcement measured
Undercut measured
Porosity assessed
Cracks absent
Overlap absent
Root profile acceptable
Fillet profile acceptable
Misalignment measured
Distortion measured
Arc strikes addressed
Grinding damage checked
Temporary attachments controlled
Repairs traceable
Additional NDT completed where required
Report completed
Welding Quality Audit-Readiness Checklist
A fabrication company should be able to produce:
approved drawings;
weld maps;
WPSs;
PQRs;
welder qualifications;
welding-coordinator appointment;
inspector qualifications;
NDT personnel certifications;
material certificates;
consumable certificates;
calibration records;
inspection procedures;
inspection reports;
non-conformance reports;
repair records;
NDT reports;
dimensional reports;
heat-treatment records where applicable;
and final release documentation.
Visual inspection is not an isolated workshop activity.
It is part of the broader welding-quality system.
How Visual Inspection Supports ISO 3834 Welding Quality
ISO 3834 addresses quality requirements for fusion welding.
Depending on the selected level, the manufacturer may need controls relating to:
contract review;
technical review;
subcontracting;
welding personnel;
inspection personnel;
equipment;
welding activities;
consumables;
materials;
post-weld heat treatment;
inspection;
non-conformance;
calibration;
identification;
and quality records.
Visual weld inspection contributes evidence that production welding was:
examined;
measured;
compared with requirements;
and controlled.
It does not, by itself, certify the company to ISO 3834.
Similarly, training welders to recognise defects does not make them company-certification auditors or qualified welding inspectors..
How Swift Skills Academy Supports Better Weld Quality
Swift Skills Academy’s role is to strengthen practical welding competence and defect-prevention capability.
Training can help learners develop stronger understanding of:
joint preparation;
machine setup;
process parameters;
welding positions;
bead placement;
heat control;
penetration;
fusion;
shielding;
cleaning;
defect recognition;
self-inspection;
and repair awareness.
Training pathways include:
introductory workshop skills;
Grinders and Power Tools;
Gas Welding;
Stick Welding;
MIG/CO₂ Welding;
Flux Core Welding;
TIG Welding;
Pipe Welding;
Coded Welding development;
ARPL support;
and Red Seal preparation.
The strongest starting point is the central welding pathway:
Related authority guides
Swift Skills Academy should not be presented as issuing independent SAIW or ISO 9712 inspector certification unless the Academy holds and can document the applicable approval.
Learners seeking a dedicated professional welding-inspector or certified NDT Visual Testing pathway should verify the relevant SAIW entry, training, examination, experience and certification requirements.
Employer Buyer Checklist Before Booking Welding Training
Ask the training provider:
Does the training include defect recognition?
Will learners inspect their own welds?
Are weld dimensions measured?
Are acceptance criteria explained?
Are learners taught the difference between an imperfection and a defect?
Are common process-specific defects covered?
Is corrective feedback documented?
Do learners repeat failed exercises?
Are practical assessments retained?
Does the certificate describe the training actually completed?
Does the programme support progression into coded-welding preparation?
Can employer groups receive task-specific practical training?
A course that teaches learners only to produce a bead leaves a major quality gap.
Final Executive Warning
The most expensive weld defect is not always the largest one.
It is often the defect discovered:
after painting;
after assembly;
after installation;
during pressure testing;
during client inspection;
after radiography;
or after the component enters service.
Visual weld inspection should detect avoidable problems as early as possible.
But inspection works only when:
the acceptance criteria are known;
the inspector is competent;
the weld is accessible;
lighting is adequate;
measuring equipment is suitable;
findings are recorded;
and additional NDT is used where visual examination cannot provide the answer.
Do not ask:
“Does the weld look good?”
Ask:
Is it the correct weld?
Is it in the correct location?
Is it the correct size?
Was it made to the correct WPS?
Are the dimensions acceptable?
Are visible imperfections within the specified limits?
Is the root acceptable?
Is further NDT required?
Is the evidence traceable?
Who is authorised to release the component?
That is the difference between workshop opinion and welding quality control.
Frequently Asked Questions
1. What is visual weld inspection?
Visual weld inspection is the systematic examination of the joint before, during and after welding to verify preparation, dimensions, workmanship and visible imperfections against specified requirements. It is a recognised non-destructive testing method but cannot establish every internal condition.
2. What are the most common visible welding defects?
Common visible imperfections include cracks, surface porosity, undercut, overlap, incorrect weld size, excessive reinforcement, underfill, crater defects, arc strikes, misalignment, distortion, spatter and poor stop-start tie-ins. Some internal imperfections may produce no visible surface evidence.
3. Can a weld pass visual inspection and still fail ultrasonic or radiographic testing?
Yes. Visual inspection mainly evaluates accessible surfaces and dimensions. Internal lack of fusion, slag inclusions, internal porosity, incomplete penetration and subsurface cracks may require UT, RT, MT, PT or destructive testing, depending on the material, code and joint.
4. Does ISO 5817 automatically apply to every weld in South Africa?
No. ISO 5817 applies only when it is specified through the relevant contract, product standard, drawing or fabrication requirement. The required quality level—B, C or D—must also be identified. Other projects may use AWS, ASME or client-specific acceptance criteria.
5. Does welding training qualify someone as a welding inspector?
No. Welding training can improve defect recognition and welder self-inspection, but professional welding inspection or certified NDT Visual Testing requires separate competence, training, experience, examination, certification and employer authorisation where applicable.
Swift Skills Academy Contact Details
Swift Skills Academy (Pty) Ltd 6 Monaco Road Killarney Gardens Cape Town
Telephone: 021 828 0772
WhatsApp: +27 60 998 7412
Website: Swift Skills Academy
Sources
Source | Type | Why it matters |
International standard | Defines visual testing of fusion-welded joints before, during and after welding | |
International standard | Provides current quality levels for specified welding imperfections | |
International standard | Provides classification and terminology for geometric imperfections in fusion welds | |
International standard | Establishes qualification and certification requirements for NDT personnel | |
International standard | Explains selection of welding-quality requirement levels | |
International standard | Defines comprehensive welding-quality requirements | |
International standard | Defines standard welding-quality requirements | |
International standard | Defines elementary welding-quality requirements | |
International standard | Defines welding-coordination tasks and responsibilities | |
South African industry authority | Shows the structured South African route covering visual inspection, quality assurance and welding inspection | |
South African NDT authority | Provides ISO 9712-aligned Visual Testing pathways | |
Primary provider page | Connects visual defect recognition to process-specific practical welding development | |
Internal authority resource | Explains welding-quality systems, audit evidence and workforce competence |
