How to Read Fabrication Drawings for Welding in South Africa: Views, Dimensions, Weld Symbols, Tolerances & WPS
Quick Answer: How Do You Read a fabrication drawings South Africa?
To read a fabrication drawing correctly, start with the drawing number, revision and title block, identify the projection and views, establish the material and component dimensions, locate the joint, interpret any weld symbols, read applicable notes and tolerances, and then connect the drawing requirement to the correct Welding Procedure Specification (WPS).
Do not begin by looking only for the weld symbol.
A fabrication drawing is a complete set of instructions. The symbol tells you something about the weld, but the rest of the drawing tells you what is being made, where the weld belongs, what size the components are, how the pieces fit together and which revision you are supposed to build.
Read This | What You Are Trying to Establish |
Title block | What drawing and revision am I using? |
Views | What does the component actually look like? |
Dimensions | What size and location must each feature be? |
Material information | What am I fabricating? |
Joint detail | Which components are being joined? |
Weld symbols | What weld is required? |
Notes | Are there additional project instructions? |
WPS reference | How must the specified weld be produced? |
Revision information | Am I working from the latest authorised drawing? |
South African welding training has legitimate reason to treat drawing interpretation as a core fabrication skill. SAIW describes practical welders as workers who interpret engineering drawings, comply with standards and understand welding's effect on materials. SAIW
What Is a Fabrication Drawing?
A fabrication drawing is a technical document used to communicate how a component, assembly or structure is to be manufactured.
Depending on the job, it can show:
component geometry
dimensions
material
plate or section thickness
hole locations
joint locations
welding requirements
machining requirements
surface or finishing requirements
assembly information
item references
parts lists
tolerances
notes
drawing revisions.
ISO 128-1 establishes general principles for the execution of technical drawings, while ISO 7200 covers data fields used in title blocks and document headers. ISO 5457 deals with drawing-sheet sizes and layout. ISO
That is why a fabrication drawing should not be treated as simply a picture of the finished product.
It is a controlled technical instruction.
Why Welders Need to Understand Fabrication Drawings
The welder may be the person physically making the joint, but the required weld exists within a larger fabrication requirement.
A welder who can run a good bead but cannot correctly identify:
the component,
the correct joint,
the drawing revision,
the material,
the required dimensions,
the specified weld,
or the applicable WPS
can still produce the wrong result.
A technically attractive weld in the wrong place does not satisfy the drawing.
Neither does:
the correct weld on the wrong component,
the correct joint made from the wrong revision,
the correct symbol interpreted against the wrong feature,
or a weld produced without checking the applicable procedure.
This is why engineering drawing interpretation has historically appeared within South African manufacturing training. For example, SAQA Unit Standard 335860, Read and interpret engineering drawings, covers engineering drawings, geometry, scales, isometric and orthographic views and sectional views. The unit standard has passed its registration end date, so it should be treated as historical competency context rather than promoted as a currently open qualification route. SAQA
The 10-Step Method for Reading Fabrication Drawings
Use the same sequence every time.
1. Confirm the Drawing Number
Before looking at dimensions or welding symbols, identify the drawing itself.
Look for:
drawing number
project or job number
component name
client or project reference
drawing sheet number if the drawing has multiple sheets.
This prevents a basic but serious error: performing work from the wrong document.
2. Confirm the Revision
The revision may be one of the most important pieces of information on the entire drawing.
Fabrication drawings can change.
A later revision may alter:
dimensions
material
hole locations
joint preparation
weld size
component quantity
notes
tolerances
fabrication sequence.
Do not assume the printed copy on the workshop bench is the latest authorised drawing.
Ask:
What revision am I working from?
Then confirm that against the controlled job documentation.
What Does the Title Block Tell You?
The title block acts as the identity panel for the drawing.
Typical information can include:
drawing title
drawing number
revision
scale
sheet number
organisation
dates
drafter/checker/approver fields
projection information
document status.
ISO 7200 specifically addresses data fields used in title blocks and technical-document headers. ISO
Workshop rule
Read the title block before reading the weld symbol.
The weld symbol belongs to the drawing.
The drawing does not belong to the weld symbol.
3. Identify the Drawing Scale
Technical drawings may show components larger or smaller than their real physical size.
ISO 5455 addresses scales used on technical drawings. ISO
But one practical principle matters enormously:
Do not manufacture by measuring the printed drawing unless the authorised drawing system explicitly permits that practice.
Use the stated dimensions.
A drawing reproduced through:
PDF export
photocopying
screen scaling
printing
scanning
may no longer physically match its original printed scale.
The dimension is the requirement.
The ruler is not a substitute for it.
4. Identify the Projection and Views
A three-dimensional fabrication component normally needs to be represented on a two-dimensional drawing.
This may involve:
front view
plan or top view
side view
sectional view
detailed view
auxiliary view
isometric view.
ISO 5456 covers projection methods, including orthographic representation. ISO
Why Multiple Views Matter
One view may show the length and height.
Another may reveal:
plate thickness
hole spacing
bracket position
offset
joint orientation.
A section view may reveal something that cannot be seen clearly from the outside.
That means the question is not:
“What does this picture look like?”
It is:
“How do all the views describe the same component?”
Orthographic Views Explained Simply
Orthographic drawings normally represent an object from defined directions.
Think of looking directly at the fabrication from:
the front,
above,
and the side.
The welder or fabricator must mentally combine those views into one physical object.
Example
Imagine a welded bracket.
The front view may show:
overall height
bolt-hole positions.
The top view may show:
plate width
bracket offset.
The side view may show:
plate thickness
gusset angle.
Looking at only one view could give you an incomplete picture of the joint.
Isometric View vs Fabrication View
An isometric view can make a component easier to visualise because it looks more three-dimensional.
But it should not automatically be treated as the primary source for fabrication dimensions.
The controlled dimensions and detailed views govern the work.
Use the isometric view to help understand the component.
Use the actual dimensions and drawing instructions to manufacture it.
5. Find the Component and Joint Before Reading the Weld
This is where welding-symbol reading and fabrication drawings reading separate.
In the dedicated Welding Symbols South Africa topic, the emphasis is:
arrow
reference line
weld type
arrow side
other side
size
length
pitch
supplementary information.
Here, the first question is different:
Which actual pieces are being joined?
Identify:
component A
component B
location of the joint
orientation
material thickness
relationship to surrounding parts.
Only once that is clear should the welding instruction be interpreted.
6. Read the Dimensions — Not the Shape
A drawing that looks approximately square may not be square.
A bracket that looks centred may not be centred.
A hole that appears halfway along the plate may not actually be halfway.
Dimensions control fabrication.
ISO 129-1 sets out general principles for presenting dimensions and associated tolerances on technical drawings. The 2018 edition remains published, although ISO is working on its eventual replacement. ISO
Depending on the drawing, dimensions may define:
length
width
height
thickness
diameter
radius
angle
hole location
spacing
offset
joint location.
Do Not Add Dimensions in Your Head Unless Necessary
A common fabrication mistake is making assumptions from several different dimensions.
Where possible, use the dimension explicitly provided for the required feature.
Unnecessary calculation introduces another opportunity for error.
If a critical dimension is:
missing,
contradictory,
unreadable,
or dependent on an uncertain interpretation,
stop and obtain clarification.
7. Read Tolerances
A nominal dimension tells you the target.
A tolerance tells you how much variation may be permitted.
These are not the same thing.
A component may need to be:
within dimensional limits,
within an angular requirement,
positioned relative to another feature,
or controlled by other drawing specifications.
Do not assume that:
“close enough” = acceptable.
Nor should the welder independently create a tolerance when one is not understood.
ISO 129-1 addresses the presentation of dimensions and associated tolerances, while more specialised tolerancing rules can involve further ISO GPS standards depending on what the drawing specifies. ISO
8. Confirm the Material
Before welding, establish what material the drawing specifies.
Depending on the job, information may appear through:
material notes
parts lists
item references
material specifications
project documentation.
Possible fabrication materials include:
carbon steel
stainless steel
aluminium
different structural sections
plate of different grades and thicknesses.
The material matters because welding requirements may change with:
material type
thickness
process
consumable
joint preparation
preheat requirements
procedure limitations.
Do not identify material by appearance alone when controlled documentation exists.
What Is a Parts List or Bill of Materials?
An assembly drawing may identify individual components using item numbers.
Those items can link to a:
parts list,
material list,
or bill of materials.
The list may identify:
Item | Typical Information |
Item number | Links component to drawing |
Description | Identifies component |
Quantity | Number required |
Material | Material specification |
Size | Section/plate/component size |
Drawing reference | May point to another detail drawing |
ISO's technical-product-documentation catalogue includes standards dealing with parts lists and component references, demonstrating that item identification forms part of controlled technical documentation. ISO
9. Read the Welding Symbol in Context
Now locate the welding symbol.
The current published ISO 2553:2019 defines rules for symbolic representation of welded joints on technical drawings. ISO currently notes that a replacement edition is under development. ISO
The welding instruction can communicate matters such as:
weld type
side
size
length
spacing
joint preparation
contour
supplementary information.
But this is crucial:
The welding symbol does not replace the drawing.
Consider a fillet weld symbol.
You still need to know:
which components form the joint,
their thickness,
where the joint sits in the assembly,
which drawing revision applies,
and which WPS governs the welding operation.
That is why the complete reading sequence matters.
Drawing First, Symbol Second
A useful mental model is:
DRAWING → JOINT → SYMBOL → DIMENSIONS → WPS → WELD
Not:
TRIANGLE → START WELDING
That second approach is exactly how avoidable fabrication errors occur.
10. Connect the Drawing to the WPS
The fabrication drawing tells you what is required.
The Welding Procedure Specification controls how an applicable weld is produced within its qualified or approved scope.
Depending on the WPS and job, information can include:
welding process
base material
thickness range
joint design
welding position
filler material
shielding gas
current
voltage
polarity
heat-related requirements
preheat/interpass conditions
pass sequence.
The precise contents depend on the procedure and governing requirements.
The practical sequence is:
Drawing says WHAT
↓
WPS controls HOW
The welder should not replace the WPS with assumptions based only on what appears on the fabrication drawing.
Worked Example: Reading a Fabrication Drawing Before Welding
Imagine a fabrication drawing for a support bracket.
The drawing includes:
drawing number: FB-204
revision: C
10 mm carbon-steel base plate
vertical plate
gusset
several dimensions
weld-symbol callout
WPS reference.
A disciplined reader does not immediately start with the weld.
Step 1 — Document
Confirm:
FB-204 Revision C
Not Revision A.
Not a workshop photocopy with an unreadable revision.
Step 2 — Identify the Assembly
Locate:
base plate
vertical plate
gusset.
Determine how the three physical components relate to each other.
Step 3 — Read the Views
Use the front and side views to establish:
vertical plate position
gusset orientation
base-plate dimensions.
Step 4 — Read the Dimensions
Confirm:
plate dimensions
material thickness
offsets
joint locations.
Do not estimate from the apparent proportions of the drawing.
Step 5 — Identify the Joint
Find the precise joint to which the weld arrow points.
Step 6 — Read the Weld Symbol
Interpret:
weld family
side
size
extent
any supplementary requirements.
Use the standard or convention specified by the job documentation.
Step 7 — Find the WPS
Confirm the referenced or applicable welding procedure.
Check that:
process
material
thickness
joint
position
fall within the required procedure controls.
Step 8 — Verify Before Welding
The result should be a clear mental and documented answer to:
“I know which drawing, which revision, which component, which joint, which dimensions, which welding instruction and which WPS I am working from.”
If you cannot say that confidently, the next step should be clarification — not welding.
How Revision Errors Can Create Fabrication Problems
Consider this scenario:
Revision B
Base plate hole spacing = one configuration.
Revision C
Hole spacing changed.
If the welder or fabricator works from Revision B after Revision C has been released, the workmanship could be excellent while the component itself is wrong.
This is one reason revision control must be part of drawing-reading behaviour.
The drawing is not simply information.
It is controlled information.
Common Fabrication Drawing Mistakes Welders Should Avoid
Mistake 1: Looking Only at the Weld Symbol
A symbol without the surrounding drawing can be incomplete context.
Better approach: identify the component and joint first.
Mistake 2: Ignoring the Revision
Older drawings may contain superseded dimensions or requirements.
Better approach: confirm the authorised revision before manufacture.
Mistake 3: Measuring the Drawing With a Ruler
Printing or screen scaling can change physical scale.
Better approach: use stated dimensions.
Mistake 4: Reading Only One View
A feature may be obvious in the side view and invisible in the front view.
Better approach: combine relevant views mentally.
Mistake 5: Confusing a Drawing Dimension With a Weld Dimension
The component dimension and weld-symbol dimension can control different things.
Better approach: establish exactly what each number belongs to.
Mistake 6: Assuming Material
Two visually similar pieces of metal may have different specifications.
Better approach: use controlled material documentation.
Mistake 7: Ignoring Notes
Important requirements may sit outside the drawing geometry.
Better approach: read general notes and detail notes before work starts.
Mistake 8: Treating the WPS as Optional
A drawing does not normally contain every welding parameter.
Better approach: connect the drawing requirement to the applicable procedure.
Mistake 9: Guessing an Unclear Dimension
Guessing converts uncertainty into physical fabrication.
Better approach: stop and clarify before cutting or welding.
Fabrication Drawing Checklist for Welders
Before beginning work, you should be able to answer:
Document
What is the drawing number?
What is the revision?
Is this the authorised drawing?
Is there more than one sheet?
Component
Which components am I fabricating?
What item numbers apply?
What material is specified?
What thickness or section applies?
Geometry
Which view am I reading?
Are there section or detail views?
What is the scale?
What dimensions locate the joint?
Are there tolerances?
Welding
Which joint does the arrow reference?
What weld family is specified?
Which side?
What size?
What length or spacing?
Are supplementary symbols present?
Is additional information given in notes or tail information?
Procedure
What WPS applies?
Does it cover the material and joint?
Have required preparation and fit-up been confirmed?
Control
Is anything unclear?
Has any ambiguity been formally resolved before work begins?
Why Employers Should Care About Drawing Interpretation
Drawing-reading capability affects more than the welder.
It can affect:
supervisors
fabricators
boilermakers
welding coordinators
quality personnel
inspectors
production managers.
Where fabrication depends on controlled drawings, employers should consider whether
personnel can consistently:
identify the correct drawing;
recognise the revision;
locate the correct component;
read the relevant views;
interpret dimensions;
recognise welding instructions;
connect the requirement to the WPS;
escalate uncertainty appropriately.
A useful competency discussion is not:
“Can he weld?”
It is also:
“Can he establish what he is supposed to weld?”
Engineering Drawings and Welding Careers in South Africa
Drawing interpretation is relevant well beyond an entry-level welding exercise.
SAIW's current practical-welding material explicitly says welders interpret engineering drawings and adhere to standards as part of their work. SAIW
The skill can therefore support development across work involving:
welding
fabrication
boilermaking
structural fabrication
pipe work
workshop production
maintenance
quality control
supervision.
It should not be treated as a substitute for the specific qualification, procedure, authorisation or competence requirements applicable to a particular job.
Fabrication Drawings vs Welding Symbols: What Is the Difference?
Fabrication Drawing | Welding Symbol |
Describes the overall component or assembly | Describes a welding instruction |
Shows geometry | Identifies weld characteristics |
Contains dimensions | Can contain weld dimensions |
May identify materials | Does not replace material specification |
Shows component relationship | Points to a particular joint/feature |
Carries revision control | Exists within the controlled drawing |
May reference WPS/procedures | Can carry additional welding information |
This distinction prevents cannibalisation between the two SSA guides:
Fabrication Drawings article
How do I understand the entire fabrication document?
Welding Symbols article
How do I interpret the welding callout itself?
What Should You Learn First: Welding Symbols or Fabrication Drawings?
Learn them together, but in this order:
1. Basic drawing orientation
Understand views, scale, dimensions and components.
2. Joint identification
Recognise the physical relationship between parts.
3. Welding-symbol interpretation
Learn what the symbol requires.
4. WPS awareness
Understand how the procedure connects to the drawing requirement.
5. Practical application
Use the drawing during marking, fit-up, preparation and welding.
This creates a much stronger foundation than memorising welding symbols in isolation.
What If a Fabrication Drawing Is Unclear?
Do not improvise.
Ambiguity can include:
two conflicting dimensions
unreadable revision
missing material
unclear arrow
unspecified joint detail
uncertain projection
missing drawing sheet
discrepancy between drawing and WPS
unclear tolerance
unfamiliar technical symbol.
The correct response is to use the employer's authorised clarification process.
Depending on the workplace, that may involve:
supervisor
welding coordinator
inspector
draughtsperson
engineer
authorised technical representative.
The person who physically performs the weld should not unilaterally redesign the fabrication because the drawing is unclear.
A Fabrication Drawing Is Part of a System
For significant fabrication work, think beyond the page.
The complete technical system may involve:
FABRICATION DRAWING
↓
PROJECT SPECIFICATION
↓
MATERIAL DOCUMENTATION
↓
WPS
↓
WELDER QUALIFICATION / AUTHORISATION
↓
FABRICATION
↓
INSPECTION / ACCEPTANCE
The drawing is important.
But it does not exist alone.
Frequently Asked Questions About Fabrication Drawings for Welding
What is a fabrication drawing?
A fabrication drawing communicates the technical information needed to manufacture or assemble a component. It may include geometry, views, dimensions, materials, tolerances, joint information, welding symbols, notes, item references and revision information.
Do welders need to know how to read engineering drawings?
Drawing-reading ability is highly relevant to fabrication welding because the welder needs to understand the component, joint and technical requirements before producing the weld. SAIW's current practical-welding material specifically refers to welders interpreting engineering drawings. SAIW
What should I look at first on a fabrication drawing?
Start with the title block and confirm the drawing number, revision and document identity before moving to views, dimensions, materials and welding instructions.
What is the difference between a fabrication drawing and a welding symbol?
The fabrication drawing describes the component or assembly as a whole. A welding symbol communicates specific information about a welded joint within that drawing.
Should I measure a printed fabrication drawing?
Use the stated dimensions rather than assuming the physical printout is accurate to scale. PDF viewing, printing, copying and resizing can alter the printed scale.
What does a drawing revision mean?
A revision identifies a controlled change to the drawing. A later revision may alter dimensions, material, joint details, notes or other requirements. The authorised revision should be confirmed before work begins.
What is a sectional view?
A sectional view represents the component as though it has been cut through to expose internal or otherwise hidden details. It can make joint preparation, thickness or internal geometry easier to understand.
What is a WPS?
A Welding Procedure Specification is the welding-procedure document used to control how welding is performed within its applicable scope. It can contain process, material, joint, filler, position and other welding requirements.
Does the fabrication drawing replace the WPS?
No. The drawing communicates what is to be fabricated and can reference welding requirements. The WPS provides welding-procedure controls applicable to producing the weld.
What should a welder do if the drawing is unclear?
Do not guess. Follow the workplace's authorised clarification process through the appropriate supervisor, welding coordinator, inspector, engineer or other responsible technical person.
Sources
Authoritative Source | What It Supports |
ISO 128-1:2020 — Technical product documentation | General principles and fundamental requirements for technical drawing representation. ISO |
ISO 7200:2004 — Data fields in title blocks and document headers | Role and structure of technical-document title-block information. ISO |
ISO 5456 series — Projection methods | Orthographic and other technical drawing projection methods. ISO |
ISO 5457:1999 — Drawing sheets | Layout and sheet requirements for technical drawings; confirmed current in 2026. ISO |
ISO 129-1:2018 — Dimensions and tolerances | General principles for presentation of dimensions and associated tolerances. ISO |
ISO 2553:2019 — Welded joints on drawings | Symbolic representation of welded joints; ISO notes a replacement edition is in development. ISO |
Southern African Institute of Welding | Current South African practical-welding context explicitly includes interpretation of engineering drawings. SAIW |
SAQA Unit Standard 335860 | Historical South African competency context for reading and interpreting engineering drawings; status has passed its registration end date. SAQA |
Read More
Read More | Why Read It |
Welding Symbols South Africa: How to Read Weld Symbols & Drawings | Go deeper into arrow/reference-line logic, weld families, side, size, length, pitch and symbol systems. |
Coded Welding South Africa: Cape Town Training Guide | Understand how procedure-controlled welding, test conditions and welder qualification connect. |
Visual Weld Inspection South Africa | Learn how drawing requirements and the finished weld connect to visual inspection and quality awareness. |
Final Word
Being able to weld and being able to fabricate from a controlled drawing are related skills — but they are not the same skill.
A disciplined welder does not see a drawing and immediately look for a triangle.
The sequence is:
DRAWING NUMBER → REVISION → VIEWS → MATERIAL → DIMENSIONS → JOINT → WELD SYMBOL → WPS → VERIFY → WELD
That single habit can prevent a long list of avoidable fabrication errors.
And that is the real objective of drawing literacy: not merely being able to recognise lines and symbols, but being able to convert technical information into the correct physical component and the correct weld.
