Theory Training

This page provides an overview of the topics that are covered in the Theory Training.

Welders will learn about steel and the important factors relevant to weld repairs

Understanding Steel
1. Types of Steel and their properties
2. Product types
3. Chemical Composition
4. Carbon Equivalent
Basics of heat treatment and microstructure and how it alters the mechanical properties
How to identify different types of steel

Welders will gain an understanding of what fatigue cracking is and why it occurs

Understanding fatigue cracking and why it occurs
Endurance Limit and Fatigue Life
Stress direction and crack orientation
Crack growth path and growth rate
Critical crack size
Effects of Residual Stresses
Stress Concentrators
1. Design factors
2. Geometrical notches
3. Weld Defects
4. Metallurgical notches
Identifying crack initiation locations
Estimating crack depth
Fractography

A review of the fundamental welding theory that all welders should know before doing repairs of mining equipment

Weld Terminology
Weld joint types
Welding
1. Welding process overview
2. Parameters
3. Heat input
Metallurgical effects of Welding
1. Heat Affected Zone
2. Importance of Preheat
3. Interpass temperature
4. Understanding Working Temperature range
5. Distortion and Residual Stress
Hydrogen
1. Causes and prevention of cold-cracking
Welding Consumables
1. Understanding classifications and strength grades
2. Basis for selecting which to use
Shielding gases

Welders will learn how to work within the MWC requirements

Welders will learn the best practices for crack repair welding

Welding equipment maintenance
Safety
Earthing
NDT methods
Repair Considerations and Planning
1. Repair Scenarios
2. Residual Stress control
3. Available time
Working Temperature
1. Application
2. Measurement
3. Management
Gouging
1. Techniques
2. Do's and Don'ts
3. Full thickness repairs
Weld Preparation
1. What is important to consider
2. Geometry
3. Carbon enrichment
Run-on/off tabs
Start/stops
Stringer vs Weave

Welders will learn how to optimise the fatigue life of a repair

Welders will learn methods for Residual Stress Control

Repair geometry factors
1. Weld metal volume
2. Depth to width ratio
3. Overall length
Weld techniques to minimise residual stress
1. Back-step
2. Balance welding
3. Cascading runs
4. Block sections
Consumable strength
1. Under-matching strength and when to use them
Inter-run Peening
1. Equipment required
2. Method

Welders will learn what important factors they should consider during the repair process

Understanding nature and cause of cracking to improve repair effectiveness
1. Crack initiation location(s)
2. Crack orientation/type
3. Crack depth
Material Identification methods
Universal Repair Parameter Sheets
1. How to select and use
2. Working Temperature
3. Consumable
Repair decisions
1. Selection of appropriate repair methodology
2. Repair Decision diagrams

Welders will be taught the key factors to consider and methodologies to apply for each of the Repair Scenarios

Repair Depth
1. Shallow and Partial Depth Cracking
2. Full Thickness Double Sided Access
3. Full Thickness Single Sided Access with Backing Strip
4. Full Thickness Single Sided Open Root
Repair Types
1. Fillet Weld Repairs (toe, transverse, from root)
2. Cracks through doubler or wear plates
3. Multiple, Branching or Complex cracks
4. Pad weld build-up
5. Access Windows and replacement sections
6. Internal Cracking
7. Casting Repairs
Repair Requirements
1. Crack Arrest
2. Temporary repair methods
3. Use of MMAW
  - Restricted access
  - Rusty/dirty/greasy
  - Field conditions
  - Efficiency and ease of access

It is essential for Welders to understand what they need to achieve, and be able to self assess their welds prior to any formal inspection.

The Welders will gain understanding of what they will need to do for the Assessment Coupon

Report abuse