Download 22906 Demonstrate and apply knowledge of welding low carbon steel

NZQA registered unit standard
22906 version 2
Page 1 of 4
Title
Demonstrate and apply knowledge of welding low carbon steel
Level
3
Purpose
Credits
3
This unit standard is for use in training of people whose work
involves welding of low carbon steel, using the Manual Metal
Arc (MMAW), Gas Metal Arc (GMAW), and Flux-Cored Arc
(FCAW) welding processes.
People credited with this unit standard are able to: demonstrate
knowledge of ferrous metals from a welding perspective, and of
the MMAW, GMAW, and FCAW processes for welding low
carbon steel; and weld low carbon steel.
Classification
Mechanical Engineering > Welding
Available grade
Achieved
Entry information
Recommended skills
and knowledge
Unit 21907, Demonstrate and apply knowledge of safe welding
procedures under supervision, or demonstrate equivalent
knowledge and skills.
Explanatory notes
1
This unit standard is concerned with welding at an introductory level, typically as
taught and assessed on apprenticeship courses. The credit value reflects the limited
practice time available on such courses. It is envisaged that apprentices would
continue to practice welding in the workplace until they reach the level of proficiency
required by industry standards. Unit standards 2671-2698 cover welding at industry
standard level.
2
References
AS/NZS 1554.1:2004 Structural steel welding – Welding of steel structures.
Health and Safety in Welding. Wellington: Department of Labour, 2006. Available
from http://www.osh.govt.nz/.
3
Definitions
FCAW – Flux Cored Arc Welding.
GMAW – Gas Metal Arc Welding, also referred to as Metal Inert Gas (MIG) welding.
MMAW – Manual Metal Arc Welding.
Low carbon steel is commonly referred to as mild steel.
Competenz
SSB Code 101571
 New Zealand Qualifications Authority 2017
NZQA registered unit standard
22906 version 2
Page 2 of 4
Safe working practice – refers to the practices established by Health and Safety in
Welding or equivalent codes of practice.
Welding procedure – refers to a written work instruction providing all the necessary
technical detail for a specific welding application.
Outcomes and evidence requirements
Outcome 1
Demonstrate knowledge of ferrous metals from a welding perspective.
Evidence requirements
1.1
The effects of welding on mechanical properties are explained for ferrous
metals.
Range
1.2
the explanation is limited to the general effects related to –
material composition, section thickness, welding heat input,
cooling rates.
Weldability of different ferrous metals is compared.
Range
ferrous metals – low carbon steel, structural steel, high strength
steel, grey cast iron.
1.3
Methods of applying preheat and controlling the cooling rate are described for
steel.
1.4
Weld faults in steel are identified, and remedial and preventative actions
described.
Range
faults include – cracks, lack of fusion, incomplete penetration,
porosity, undercut, incorrect weld shape and size.
Outcome 2
Demonstrate knowledge of the MMAW process for welding low carbon steel.
Evidence requirements
2.1
The features of the power source are described.
Range
features – constant current characteristic, current type (AC/DC),
rating, duty cycle, open circuit voltage, arc voltage, welding
current, arc starting aids.
2.2
The advantages and limitations of the MMAW process are explained.
2.3
Selection, handling, and storage requirements of welding consumables are
outlined.
Range
Competenz
SSB Code 101571
rutile electrodes, basic electrodes.
 New Zealand Qualifications Authority 2017
NZQA registered unit standard
22906 version 2
Page 3 of 4
Outcome 3
Demonstrate knowledge of the GMAW and FCAW processes for welding low carbon steel.
Evidence requirements
3.1
The features of the equipment are described.
Range
3.2
The advantages and limitations of GMAW and FCAW welding are identified.
Range
3.3
features – constant voltage characteristic, current type, rating, duty
cycle, voltage, synergic control, wire feed speed, welding current,
burn back control, welding gun set-up.
advantages and limitations include those related to the mode of
metal transfer used.
Selection, handling, and storage requirements of welding consumables are
outlined.
Range
consumables are limited to those commonly used to weld low
carbon steel – solid wire electrodes, gas-shielded rutile FCAW
electrodes, self-shielded FCAW electrodes; shielding gases.
Outcome 4
Weld low carbon steel.
Range
evidence is required of six welds consisting of one lap or tee fillet weld in the
horizontal-vertical position and one butt weld in the flat position for each of the
MMAW, GMAW, and FCAW processes, using steel plate or sections in the 3-10
mm thickness range.
Evidence requirements
4.1
Safe working practices are followed.
Range
practices include – use of personal protective equipment, checking
of equipment for faults, use of fume extraction equipment,
elimination of risk of fire or explosion, protection from arc radiation.
4.2
Metals are prepared and joined in accordance with given welding procedure.
4.3
Welds are assessed for imperfections and compared to the permissible levels in
AS/NZS 1554.1:2004.
Range
Competenz
SSB Code 101571
assessment is by visual examination and may include – breakover, nick break, bend testing.
 New Zealand Qualifications Authority 2017
NZQA registered unit standard
Planned review date
22906 version 2
Page 4 of 4
31 December 2014
Status information and last date for assessment for superseded versions
Process
Version Date
Last Date for Assessment
Registration
1
20 June 2006
N/A
Rollover and
Revision
2
17 September 2010
N/A
Accreditation and Moderation Action Plan (AMAP) reference
0013
This AMAP can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
Please note
Providers must be granted consent to assess against standards (accredited) by NZQA, or
an inter-institutional body with delegated authority for quality assurance, before they can
report credits from assessment against unit standards or deliver courses of study leading
to that assessment.
Industry Training Organisations must be granted consent to assess against standards by
NZQA before they can register credits from assessment against unit standards.
Providers and Industry Training Organisations, which have been granted consent and
which are assessing against unit standards must engage with the moderation system that
applies to those standards.
Consent requirements and an outline of the moderation system that applies to this
standard are outlined in the Accreditation and Moderation Action Plan (AMAP). The
AMAP also includes useful information about special requirements for organisations
wishing to develop education and training programmes, such as minimum qualifications for
tutors and assessors, and special resource requirements.
Comments on this unit standard
Please contact Competenz [email protected] if you wish to suggest
changes to the content of this unit standard.
Competenz
SSB Code 101571
 New Zealand Qualifications Authority 2017