Unit of competency details

Unit descriptor 

This unit of competency covers the preparation, positioning, fixing, and welding techniques associated with general trade level welding using gas tungsten arc welding (GTAW) equipment including the selection and set up of the equipment appropriate to both the material and the weld to be performed, carrying out the GTAW to prescribed standards, and examining for and correcting defects, in a range of welded fabrications.

Application of the unit 

This unit of competency applies to welds associated with heavy or light metal fabrications. Welds are fillet and butt welds in all positions on a range of ferrous and non-ferrous materials that may include carbon steel or stainless steel and aluminium. Weld quality would conform to Australian Standard 1554 General Purpose, American Bureau of Shipping (ABS), or equivalent.

This unit has been primarily developed to support Engineering Tradesperson - Fabrication apprenticeship training and the recognition of trade level skills in GTAW. It may also apply to other trade occupations requiring higher level GTAW welding skills.

Where manual thermal processes associated with preparation, pre-heat and/or post-heat are required, MEM05007C Perform manual heating and thermal cutting and/or MEM05008C Perform advanced manual thermal cutting, gouging and shaping should be considered for selection.

Band : A 

Unit Weight : 4 

Prerequisite units 

Path 1 

MEM05049B

Perform routine gas tungsten arc welding

MEM05051A

Select welding processes

MEM05052A

Apply safe welding practices

MEM12023A

Perform engineering measurements

MEM18001C

Use hand tools

MEM18002B

Use power tools/hand held operations

Employability skills 

This unit contains employability skills.

Elements describe the essential outcomes of a unit of competency.

Performance criteria describe the performance needed to demonstrate achievement of the element. Where bold italicised text is used, further information is detailed in the required skills and knowledge section and the range statement. Assessment of performance is to be consistent with the evidence guide.

ELEMENT 

PERFORMANCE CRITERIA 

1. Prepare materials for gas tungsten arc welding (GTAW)

1.1. Weld requirements are identified from specifications and/or drawings

1.2. Material is correctly prepared

1.3. Materials are assembled/aligned to specification, where required

2. Select welding equipment and consumables

2.1. Welding equipment and electrodes, accessories and consumables appropriate to the material are identified and selected

3. Assemble and set up welding equipment

3.1. Welding equipment is assembled and set up

4. Minimise and rectify distortion

4.1. Appropriate distortion prevention measures for weld and material type are selected and applied

4.2. Distortion is rectified

5. Weld to job specification using GTAW

5.1. Weld deposit is to specifications

5.2. Joints are cleaned to specifications

6. Ensure weld conformance

6.1. Defects are removed with minimum loss of sound metal using techniques and tools appropriate to the defect, material and process

6.2. Weld joints are visually inspected for conformance to specifications

7. Maintain weld records as required

7.1. Weld records are completed correctly

REQUIRED SKILLS AND KNOWLEDGE 

This section describes the skills and knowledge required for this unit.

Required skills 

Required skills include:

• identifying and interpreting welding specifications including appropriate standards e.g. Australian Standard 1554 General Purpose, American Bureau of Shipping (ABS) or equivalent
• selecting and using appropriate tools and equipment
• using a variety of welding machines and electrodes
• identifying and rectifying weld defects
• applying techniques for distortion prevention and rectification
• cleaning welds
• reading and interpreting information on sketches, written job instructions, specifications, standard operating procedures and engineering drawings
• recording routine information including routine weld records related to GTAW onto proformas and standard workplace forms
• following oral instructions
• measurement skills relating to joint preparation and GTAW

Required knowledge 

Required knowledge includes:

• correct welding machine, leads, hand pieces and electrodes
• material preparation
• joint preparations
• electrode classification
• causes of distortion for materials within the scope of this unit
• causes of defects and methods of rectification
• the relationships between amperage, electrode and material
• types of gases and their uses
• types of electrodes, current settings and high frequency voltage
• filler materials and consumables
• safe welding practices
• use and application of personal protective equipment for GTAW

EVIDENCE GUIDE 

The evidence guide provides advice on assessment and must be read in conjunction with the performance criteria, required skills and knowledge, range statement and the Assessment Guidelines for the Training Package.

Overview of assessment 

A person who demonstrates competency in this unit must be able to prepare materials, select and set up the welding equipment, carry out the GTAW welding and examine for and correct defects, in a range of welding activities associated with GTAW. Competency in this unit cannot be awarded until all prerequisites have been satisfied.

Critical aspects for assessment and evidence required to demonstrate competency in this unit 

Assessors must be satisfied that the candidate can competently and consistently apply the skills covered in this unit of competency in new and different workplace situations and contexts. Critical aspects of assessment and evidence include:

• following all safety procedures to protect self, other workers and members of the public
• identifying and interpreting specifications for GTAW including Australian Standard 1554 General Purpose
• interpreting welding specifications including standard welding symbols used to show weld procedure
• selecting appropriate weld preparation methods for material and position of welds.
• preparing materials, setting up of jigs, fixtures, clamps,etc. and joint preparation including bevelling
• consistently welding different ferrous and non-ferrous materials to AS 1554 General Purpose or equivalent
• identifying defects as described in the range statement across a range of welded materials
• rectifying defects.

Context of and specific resources for assessment 

Welding to AS 1554 General Purpose or equivalent requires both theoretical knowledge and high practical skills. The assessment process must be designed to identify consistent performance to standard and specification across a range of materials and positions. The assessment must also identify a level of workplace performance in terms of defect rate and weld failure rates. It is recommended that assessment involve demonstrations of competency under both workshop and site conditions. This means that the ideal assessment environment is either on the job or a combination of both on and off the job.

The competencies covered by this unit may be demonstrated by an individual working alone or as part of a team. The assessment environment should not disadvantage the candidate.

Method of assessment 

Typically an Engineering Tradesperson - Fabrication and other tradespersons engaged in welding are required to exercise GTAW skills and techniques across a range of jobs and specifications.

A single assessment event is not appropriate. On the job assessment should be included as part of the assessment process wherever possible. Where assessment occurs off the job, judgement must consider evidence of the candidate's performance in a productive work environment that includes a sufficient range of appropriate tasks and materials to cover the scope of application for this unit.

Assessors should gather a range of evidence that is valid, sufficient, current and authentic. Evidence can be gathered through a variety of ways including direct observation, supervisor's reports, project work, samples and questioning. Questioning techniques should not require language, literacy and numeracy skills beyond those required in this unit of competency.

The candidate must have access to all tools, equipment, materials and documentation required. The candidate must be permitted to refer to any relevant workplace procedures, product and manufacturing specifications, codes, standards, manuals and reference materials.

Guidance information for assessment 

This unit could be assessed in conjunction with any other units addressing the safety, quality, communication, materials handling, recording and reporting associated with welding using GTAW process or other units requiring the exercise of the skills and knowledge covered by this unit.

Assessors must be satisfied that the candidate can competently and consistently perform all elements of the unit as specified by the criteria, including required knowledge, and be capable of applying the competency in new and different situations and contexts.

RANGE STATEMENT 

The range statement relates to the unit of competency as a whole. It allows for different work environments and situations that may affect performance. Bold italicised wording, if used in the performance criteria, is detailed below. Essential operating conditions that may be present with training and assessment (depending on the work situation, needs of the candidate, accessibility of the item, and local industry and regional contexts) may also be included.

Prepared 

Prepared may include:

• pre-heating
• setting up of jigs, fixtures and clamps
• joint preparation (e.g. bevelling)

Welds 

Welds include fillet and butt welds carried out in all positions

Materials 

Materials may include ferrous and non-ferrous materials including carbon steel,stainless steel, aluminium and other materials suitable for GTAW welding

Welding equipment 

Welding equipment may include AC or DC welding machines

Distortion prevention measures 

Distortion prevention measures may include:

• pre-heating
• setting up of jigs, fixtures and clamps

Rectified 

Rectified may include:

• oxy acetylene and air arc equipment
• grinding devices

Defects 

Defects may include:

• porosity
• slag inclusions
• discontinuities
• lack of penetration
• undercut

Unit sector 

Co-requisite units 

Competency field 

Fabrication