ssc-367 - Ship Structure Committee

the general quality of fabrication, also affect specifics such as
the rate of crack growth and corrosion.
The four primary fabrication parameters are:
●
Who is Doinq the Work? (i.e. personnel qualificat
on)
●
What are the Work Requirements? (i.e.,defining th(
program
●
When is the Work Done? (i.e., sequence/timingof activity)
●
How is the Work Done? (i.e., following the specifications)
Post-FabricationParameters
Both the design parameters and fabrication parameters directly
affect fatigue performance of a fabricated component, thereby
influencing the post-fabrication processes. The post-fabrication
processes discussed here are activities that enhance the fatigue
performance of the structure component.
The toe of the weld and the weld root often contain geometric
imperfections and high localized stresses and therefore they are
often the site of fatigue crack propagation. To enhance fatigue
performance,modificationof both the weld geometry and the residual
stress is recommended. The weld geometry can be improved by weld
toe grinding,which is often specifiedto obtain a smooth transition
from weld to the parent material. This process should improve
fatigue life locally both by removing small defects left at the toe
during welding and by reducing the stress concentrationat the weld
toe due to elimination of any notches. Weld toe remelting (by TIG
or plasma dressing) and the use of special electrodes for the final
pass at the toe can also improve fatigue performance.
Post-weld heat treatment (PWHT) is recommended to relieve residual
stresses introducedin welding thick sections,typically defined as
having a wall thickness in excess of 2.5 in (63 mm) in U.S. (less
3-5