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 TB 55-1900-201-45/1
E-35.
Welding Defects.
a. Particular attention is called to weld deficiencies which can occur if correct procedures are not followed. These
weld deficiencies can and do lend to cracking of the main hull girder of the vessel and are about the most effective crack
initiators known. The destructive potential of the deficiencies often lies dormant for protracted periods while awaiting the
necessary conditions of temperature and/or service stress magnitude to trigger a crack which instantaneously progagates
into a serious hull failure. Such failures can occur under fairly moderate stresses, arising from sea action or from cargo
distribution alone, on a cold winter day.
(1) Sub-surface weld defects in butts and seams which include interpass weld bead cracks, slag inclusion, in-
complete penetration and lack of fusion must be avoided.
(2) Slugged welds. Slugged welds involve laying welding rods, cable, bolts or other extraneous material in a
welding groove and then welding over it. Such a procedure obviously creates a serious cavity in the heart of the weld
which is not detectable from surface appearance. Supervisors and workmen who have been well in- formed as to the
critical nature of such a condition are the best protection against slugged welds. Welders turning out very high footage
would have their welding subjected to radiographic examination as a precaution against "slugging."
(3) Caulking of leaky or cracked welds. Caulking or peen- ing in no way reduces the crack initiating properties of
a defective weld nor does it reduce the liability of an existing crack to prop- agate further. Such an operation only serves
to "conceal" and there- by "build" into the vessel a potential source of serious structural failure. Accordingly, all peening
or caulking of leaky or cracked ship welds should be prohibited. Leaky or cracked welds should be chipped out and re-
welded.
(4) Square corners. Welding into or around square corners, such as can occur in the installation of insert and
doubler plates, should not be permitted for attachments to shell, strength decks or tank tops. Such square corners should
be rounded to a 3 inch minimum radius. Corners of openings should be rounded to the largest practicable radius, gener-
ally not less than 1/8 the trans- verse dimension but not ordinarily more than 24 inches. Cuts should be made either by
guided burning or should be ground to a fair smooth contour. An exception to this is the welding of an entire plate sec-
tion. Generally, the corners are not rounded but the seams in the adjacent plates are released as shown in the following
sketch to minimize locked-in stresses and then rewelded in suitable sequence. Holes drilled as shown prior to releasing
the adjacent plate will minimize the likelihood of cracks occurring at the ends of the slots.
E-25
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