WELDING 4

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QA/QC OF WELDING
Welding Inspector
Welding Inspector not required to be a welder
Welding Inspector should posses some specific working knowledge
of welding and other related subjects
The presence of welding inspector during welding are almost going
to reduce the number of weld defects.

2. 1 2
Duties of Welding Inspector
The main Duties of welding inspector is to ensure that all the
welding and associated actions are carried out in accordance
with the welding specification
A welding inspector should be able to find relevant information,
Interpret the information, understand and apply the information
Duties of welding Inspector
Before Welding
During Welding
After Welding

3. 1 3
Welding Inspector Equipments
Steel Rule
Flexible tape measure
Temperature measuring devices
Bevel angle gauge
Root gap gauge
Fillet weld gauge
Voltmeter
Ammeter
Polarity indicator
Hi/Lo depth gauge
Contour Gauge
Light source
Magnifying Glass
Marking pens

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QA/QC OF WELDING
The welding procedure shows all the approved values of variables
involved with the production welding
The contents of the welding procedure must be approved QA/QC
To qualify this procedure, A weld is made in accordance with
the requirements of this procedure. This test is known as Procedure
Qualification Test
The weld is NDT inspected and Mechanical tested to ensure that
all the welding variables used are compatible and can produce a
sound
weld
The test details and the NDT & mechanical testing reports are
recorded. This is called Procedure Qualification Record ( PQR )

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Welding Variables
Welding Process
Joint Design
Welding Position
Joint cleaning and tack welding
Welding technique
Back Gauging
Backing
Filler Metal
Flux
Shielding Gas
Electric parameters
Travel speed
Wire feed
Preheat & inter pass temperature
Post weld heat treatment

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Any change in essential variable needs the procedure to be
re -written and re-qualified
A welding inspector should be present throughout procedure
qualification test
Welder Qualification Test ( WQT )
Welder Qualification Test is carried out to ensure the welder is
able to produce a sound weld that meets the requirements of
relevant welding procedure.
If a change was proposed outside the a specified limitation,
a new welder qualification would have to be made
A welding inspector should be present throughout W Q T

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In normal circumstances only one test weld is permitted
Defects acceptance tolerance for welder approval may be
More strict than production welders
Usually visual examination and NDT ( RT,MPI or DPI)
On WQT welds. In some cases bend test ,Macro tests are
recommended

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Heat Treatment
Post weld heat treatment ( PWHT )
PWHT is usually carried out for the purpose of stress release and
Produce certain properties in the weld
The control points of the PWHT are
Heating rate
Temperature attained
Time through which this temperature retained
Cooling method
Cooling rate

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Common methods used for PWHT
Annealing
Normalizing
Hardening / quenching
Tempering
Hydrogen Release
Stress relieving

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Common methods used for PWHT
Annealing
Normalizing
Hardening / quenching
Tempering
Hydrogen Release
Stress relieving