Class: Senior Secondary School 2 (SS2 / SSS2)
Term: Second Term
Week: 7
Age: 16 years
Duration: 45 minutes
Subject: Metal Work
Curriculum Theme: Pre-Vocational Studies
Previous Lesson: Factors.
Topic: Welding Positions and Joints
Subject Matter: Welding positions (horizontal welding, vertical welding, overhead welding), welding joints (arc welding joints)

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain:

Define welding positions and joints.
Identify different types of welding positions.
List various types of welding joints.
State factors governing the selection of welding positions.

Affective Domain:

Appreciate the importance of correct welding positions for quality welds.
Show interest in learning safe welding practices.
Recognize the significance of different joint types in fabrication.

Psychomotor Domain:

Demonstrate the correct posture for at least one welding position.
Attempt a basic setup for welding in a specified position.
Identify the components of a welding joint.

Work collaboratively with peers during practical demonstrations and setup.
Adhere to safety guidelines while observing or attempting practical welding.

Reference Materials

The following resources were used in planning this lesson:

Senior Secondary Schools Education Curriculum
State Unified Scheme of Work
Basic Metalwork Technology for Senior Secondary Schools by A.O. Akeem
Links for Reference materials:
- https://www.twi-global.com/technical-knowledge/job-knowledge/welding-positions
- https://www.esabna.com/us/en/education/blog/welding-joints-and-types.cfm

Instructional Materials

The teacher will teach this lesson with the aid of:

Mild steel plates
Welding machine
Electrodes
Welding helmet, gloves, and apron
Charts or diagrams illustrating different welding positions and joints

Rationale for the Lesson

Understanding welding positions and joints is important for pupils to produce strong and high-quality welds in various fabrication and repair tasks. This knowledge helps them select appropriate techniques, ensuring safety and the structural integrity of welded components in real-world applications.

Prerequisite/Previous Knowledge

Pupils have a basic understanding of welding safety precautions and the fundamental components of welding equipment.

Lesson Content/Board Summary

Welding Positions and Joints

Introduction to Welding Positions

Welding positions refer to the orientation of the workpiece and the angle at which welding is performed. Different positions are used depending on the design of the structure and accessibility.

Factors Governing Welding Positions

Type of joint being welded.
Thickness and type of material.
Accessibility to the joint.
Required weld quality and appearance.
Welder’s skill and experience.

Common Welding Positions

Flat Position (1G/1F): Welding is performed on the upper side of the joint, and the face of the weld is approximately horizontal. This is generally the easiest position.
Horizontal Position (2G/2F): Welding is performed on a horizontal seam on a vertical surface. The weld axis is horizontal, and the weld metal is deposited against gravity.
Vertical Position (3G/3F): Welding is performed on a vertical seam. Welding can be done either uphill (from bottom to top) or downhill (from top to bottom).
Overhead Position (4G/4F): Welding is performed from the underside of the joint. This is generally the most difficult position due to gravity pulling the molten metal downwards.

Welding Joints

Welding joints are configurations of two or more pieces of metal joined together by welding. The type of joint selected depends on the design requirements, load conditions, and material thickness.

Common Types of Arc Welding Joints

Butt Joint: Two pieces of metal are joined edge-to-edge in the same plane. This is a common joint for plates and pipes.
Lap Joint: Two pieces of metal overlap each other, and the weld is made along the edge of the overlapping pieces.
Corner Joint: Two pieces of metal are joined at an angle, forming a corner. It can be an open or closed corner.
Tee Joint: One piece of metal is joined perpendicular to another, forming a ‘T’ shape.
Edge Joint: The edges of two or more pieces of metal are brought together and welded along the edges, often used for thin sheets.

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids, Practical Session

Instructional Procedures

Step 1: Introduction

Time: 5 minutes
Teaching Skill: Set Induction
Teacher’s Activity: The teacher greets the pupils, reviews the previous lesson briefly, and then introduces the topic “Welding Positions and Joints” by asking pupils about different ways metal pieces can be held or joined together during welding.
Pupils’ Activity: Pupils respond to the questions and listen attentively to the introduction of the new topic.
Learning Point: Pupils are mentally prepared for the lesson and recall prior knowledge related to welding.

Step 2: Explanation of Welding Positions

Time: 10 minutes
Teaching Skill: Explanation/Illustration
Teacher’s Activity: The teacher explains what welding positions are, using charts or diagrams to illustrate the Flat, Horizontal, Vertical, and Overhead positions. The teacher also discusses the factors that govern the choice of a welding position.
Pupils’ Activity: Pupils observe the diagrams, listen to the explanations, and take notes.
Learning Point: Pupils understand the concept of welding positions and can identify the different types.

Step 3: Explanation of Welding Joints

Time: 10 minutes
Teaching Skill: Explanation/Visualisation
Teacher’s Activity: The teacher explains the concept of welding joints, defining what they are and why different types are used. The teacher then illustrates and describes common arc welding joints such as Butt, Lap, Corner, Tee, and Edge joints using diagrams or physical examples.
Pupils’ Activity: Pupils observe the illustrations, listen to the explanations, and take notes.
Learning Point: Pupils understand the concept of welding joints and can identify various types.

Step 4: Teacher’s Demonstration of a Welding Position and Joint

Time: 5 minutes
Teaching Skill: Demonstration/Practical Application
Teacher’s Activity: The teacher demonstrates how to set up for a basic welding position (e.g., Flat Position) and a simple joint (e.g., Butt Joint) using the welding machine, steel plates, and electrodes, emphasizing all necessary safety precautions.
Pupils’ Activity: Pupils observe the demonstration carefully, paying attention to the setup, posture, and safety measures.
Learning Point: Pupils gain visual understanding of practical application and safety in welding.

Step 5: Pupils’ Guided Practice

Time: 5 minutes
Teaching Skill: Guided Practice/Supervision
Teacher’s Activity: The teacher guides pupils, in small groups or individually, to briefly attempt to set up for a specific welding position or make a very short practice weld bead on provided scrap material, under strict supervision and with full safety gear.
Pupils’ Activity: Pupils, under supervision, briefly engage in setting up or making a practice weld, following the teacher’s instructions and safety rules.
Learning Point: Pupils get hands-on experience and begin to develop basic practical skills in welding positions and joints.

Step 6: Discussion and Clarification

Time: 5 minutes
Teaching Skill: Question and Answer/Feedback
Teacher’s Activity: The teacher facilitates a brief discussion, asking pupils about their observations during the demonstration and their experience during the guided practice. The teacher addresses any questions or misconceptions.
Pupils’ Activity: Pupils ask questions, share their observations, and seek clarification on points they found challenging.
Learning Point: Pupils clarify their understanding and reinforce learning through peer interaction and teacher feedback.

Step 7: Evaluation/Review

Time: 5 minutes
Teaching Skill: Questioning/Assessment
Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

Define welding positions.
List three common welding positions.
Mention two factors that influence the choice of a welding position.
Name three types of welding joints.

Pupils’ Activity: Pupils answer orally and in writing.
Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 5 minutes
Teaching Skill: Summarisation/Assignment
Teacher’s Activity: The teacher summarizes the key points of the lesson, emphasizing the importance of mastering welding positions and joints for quality work and safety. The teacher assigns homework for pupils to draw and label different welding joints.
Pupils’ Activity: Pupils listen to the summary and copy down the homework assignment.
Learning Point: Pupils consolidate their learning and prepare for further study.

Lesson Keywords

Welding Positions – The orientation of the workpiece and the angle at which welding is performed.
Horizontal Welding – Welding performed on a horizontal seam on a vertical surface.
Vertical Welding – Welding performed on a vertical seam, either uphill or downhill.
Overhead Welding – Welding performed from the underside of the joint.
Welding Joints – Configurations of two or more pieces of metal joined together by welding.
Butt Joint – Two pieces of metal joined edge-to-edge in the same plane.
Lap Joint – Two pieces of metal overlapping each other, welded along the edge.
Tee Joint – One piece of metal joined perpendicular to another, forming a ‘T’ shape.

Differentiation

For pupils who are struggling, the teacher will provide simplified diagrams and offer more one-on-one guidance during the practical setup. Advanced learners will be encouraged to research more complex welding positions or specialized joint designs and present their findings to the class.

Note for teachers using this lesson plan

Safety is paramount in Metal Work. Ensure all safety protocols are strictly followed during demonstrations and any practical attempts by pupils. Emphasize the correct use of personal protective equipment (PPE) at all times. If a full practical session is not feasible within this lesson’s duration, focus on thorough explanation and demonstration, scheduling extended practical practice for a dedicated workshop period. Encourage pupils to draw and label the positions and joints in their notes for better retention.