WELDING POSITIONS
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WELDING IMPERFECTION
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WELD DEFECTS
The strength of a weld depends on the :
- tools and filler used;
- their shapes;
- their arrangement on the piece to be welded;
- the manner in which it is done by the welder.
Weld, root and fusion faults are recognizable
requirements for good welding :
- complete melting of the joint edges;
- through-welding to the root of the joint;
- the correct degree of convexity on the top
Correctly executed weld
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If one or more of these requirements are not met,
there is a risk of weld defects.
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Imperfect shape
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undercut
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overlap
causes
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too hard rushing flame;
blowpipe is too large;
too slow rate of travel;
rod addition too small
Excessive reinforcement (excess weld metal)
(overfilled groove) (reinforced joint)
Causes :
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- speed travel is too slow;
- rod addition too large.
Excessive penetration ( excessive root convexity )
Causes :
- unsuitable edge preparation (gap too large,
face too small, included angle too large);
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- Slow speed of travel of blowpipe;
- Concentration of heat.
Root concavity Lack of penetration
Causes :
unsuitable edge preparation
( included angle too small,
gap too small, face too large ).
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Poor restart
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And so on !! Like :
Porosity
Burn through
Excessive spatter
Lack of fusion
Etc.
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Cacat las dan cara
Menghindarinya :
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QUALIFICATION OF WELDERS
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Welder Performance
Qualification (WPQ)
Standardized welder performance qualifications guarantee that the
dexterity-test of welders is done according to standardized
prescriptions and on standardized specimens under the same
conditions, independently from the field of application. When the
welder passes the welder performance qualification as per
standards, it shows that he has the necessary, minimum manual
skills for his operational assignment.
EN 287-1 applies for the qualification of a welder
EN 287-1
EN 287-1
111
BW W 11 B t ag PFS ss nb
Standard after which the WPQ has been passed
That mean :
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111
Abbreviation for the welding process -)- manual metal arc welding
Code for sheet metal
BW
Code for butt weld
W11
Material-group -> austenitic steel
Code for filler metal, basic coating
t09
Specimen-dimension: plate thickness 9 mm
PF
Code for welding-position: butt weld on sheet metal, uphill-position ss
Seam-execution: single-side
nb
Seam-execution: without backing
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WELDER CERTIFICATE
according to EN9606
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Welding Procedure Specifications (WPS)
The fabricator has to prepare welding prodedure specifications (WPS) in
agreement with the corresponding section of EN 288, and to guarantee
their correct application during the fabrication.
Before WPS to be applied by the company in particular job
within the project/job, should be approved first !
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STOP DULU AH.
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