ssc-367 - Ship Structure Committee

to the electrode position, so the strength improvements are
better than the improvementsobtained from TIG dressing.
Although overall weld profiling is considered desirable for
tubular intersections, rules and recommendations other than
API do not allow improvement in fatigue strength of a joint
unless weld profiling is accompanied by weld toe grinding.
Tliefatigue strength increaseof welded joints dueto weld toe
grinding in air is considered equally applicable to
catholicallyprotectedwelded joints in seawater. However, in
the absence of cathodic protection, a corrosive environment
helps to initiate fatigue cracks. Thus, without cathodic
protection, fatigue strength improvement due to weld toe
grinding cannot be justified.
The fatigue strength increaseinwelded joints dueto weld toe
grinding is basedon simple plate specimenstested in air and
in seawater (with and without cathodicprotection). However,
extensionof welded plate specimentest data to tubular joints
may not be correct. Hork carried out by Wylde et al
(Reference 9.6) indicates that additional research is
necessary because:
1) The corrosive effect of seawater appears to be greater
on tubular joints than on flat plates.
2) Cathodic protection appears to be less effective on
tubular joints than on flat plates.
Modification of Residual Stress Distribution
A wide range of residual stress techniques are available to
redistribute the fabrication stresses at a welded joint. If large
residual tensile stresses are present at a welded joint, the applied
stress cycle near the weld toe can remain wholly tensile. Thus,
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