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 TB 55-1900-201-45/1
provides for radiographic or equivalent inspection of hull joints at important locations. Since any joints in the hull, in-
cluding the upper decks within approximately at least the middle half length may be regarded as important, this rule is
considered to provide a basis for requiring random spot checking of hull welding by means of radiographic or ultrasonic
techniques. Such spot checking should be accomplished to the extent determined necessary by experience in checking
welding in the yard concerned. Yards should keep a record of the work performed by each welder. Any welder found to
be deliberately slugging welds should be disqualified and may be subject to criminal prosecution.
c. When welds are checked by a non-destructive testing method, such as radiography, the question often arises as
to the proper standard to apply for a rejection or acceptance criterion. Slugged welds, of course, give a gross defect in-
dication and there is no question as to the non-suitability of such a weld. Other welding defects such as slag inclusions,
porosity and subsurface cracks re- quire some judgment as to what constitutes an unacceptable weld. There is no simple
answer. In some cases, such as a main strength highly stressed joint, a very rigid standard would be proper. In other
cases, an evaluation of the design and the type of stress applied might indicate a large margin of safety exists and the
acceptance criteria can safely be set lower. The following information sources offer guidance:
SSC-177 "Guide for Interpretation of NDT of Welds in
Ship Hull Structures" prepared by the Ship
Structures Committee
IIW Pamphlet "Radiographs of Welds"
ABS Circular No. 145, Guide for the Radiographic
Inspection of Welds
ABS Circular No. 40, Magnetic Particle Inspection
SSC-177 applies only to hull welding and therefore the requirements are not as stringent as for
pressure vessels.
SECTION VI. Riveting
E-36. General. The renewal of deck and shell plating is best accomplished from an overall structural viewpoint by re-
placement in kind, (i.e.) riveted replacements in riveted hulls to avoid hard spots or points of high stress concentration in
an otherwise less restrained hull structure. However, riveting is becoming increasingly difficult and costly. Hence, it be-
comes necessary to make welded repairs to riveted ships. Extensive experience and tests indicate that the steel in the'
existing riveted ships may be more sensitive to brittle fracture initiation and propagation, when welded, than is shipbuild-
ing steel presently being supplied under American Bureau of Shipping requirements for Classes B or C hull steel. Be-
cause of this, the use
E-27
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