04 welding sequence
DESCRIPTION
csc sdasdTRANSCRIPT
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Welding sequence
Welding course
MarineTypewritten textMATERI SOSIALISASI DAN PELATIHAN WELDING INSPECTORBAGI MAHASISWA TEKNIK SISTEM PERKAPALANTAHUN 2013
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Learning objectives
After this lesson, you will be able to:
- easier observe if wrong welding sequences are used.
- evaluate welding sequences of some common welded connections.
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Version Slide 306 April 2010
Useful information
Information on NB and repairs regarding welding, minimum weld length and other limitations are to be found in
the IACS Guide No.47 SHIPBUILDING AND REPAIR QUALITY STANDARD
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Version Slide 406 April 2010
Why welding sequences?
Why should we consider the welding sequences?
Welding creates stresses in the structure and shrinkage occur.
Use of correct welding sequences may decrease the stress level in the structure.
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Version Slide 506 April 2010
Stress levels
You may have seen what happens when you are welding two plates together.
Use of back step technique give smaller distortions.
Welding straighton gives a lotof distortions.
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Version Slide 606 April 2010
Welding of erection joints
Deck, double-bottom, bottom and skin may be welded in the above mentioned sequences.
Welding sequences are used in order to transfer the high stress peaks in the structure to a free end.
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Version Slide 706 April 2010
1. Completely fill up weld no.1
2. Continue with the vertical no.2and finish it before welding thehorizontal part of joint no.2
3. Clean the joint in the crosses4. Weld joint no.3 starts at least
150mm away from the crossingweld.
This will prevent increased stress levels in the weld.
Erroneous Openings - Welding sequences
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Version Slide 806 April 2010
Inserts
Shrinkage of the weld will open up the joint at the opposite side
Since the insert plate has moved with free ends, the welds are without high stress levels.
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Version Slide 906 April 2010
Inserts of sheets
First weld the ends of the sheet from centre to the edge.
Then weld the full length.
Back step technique may prevent the stress level to increase too much.
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Version Slide 1006 April 2010
Welding of Block Joints
Which one to be welded first?1. Butt weld of sections
2. Butt weld of stiffener
and finally
3. Fillet weld of stiffener
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Version Slide 1106 April 2010
Conclusion
Correct welding sequences helpto avoid distortions.
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Version Slide 1206 April 2010