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 TB 55-1900-201-45/1
(3) After V-ing out, if a crack has a root opening too wide for closing with the first bead, do not draw the edge of
the plate together by means of a steamboat ratchet or other means preliminary to welding. Instead, build up the groove
with light beads until a groove of usual proportions is obtained or use a backing strip. Backing strips should be removed
followed by back side chipping and welding.
(4) Where the crack in the plating crosses stiffeners, framing or girders, the welds connecting these members to
the plating should be released. This should be done by burning through the weld for a distance of at least 6 inches on
each side of the crack before welding of the crack is commenced. In way of gunwale or hatch side assemblies, it may be
desirable to increase the length of release.
(5) If the crack extends into the framing member, it should be suitably prepared and welded. If the resulting butt
is welded after the plating or poor accessibility exists, the butt in the frame should be smoothly scalloped out adjacent to
the plating.
(6) Special care should be taken in the repair of surface cracks. Care should be taken that the defect is com-
pletely removed by grinding or other suitable means. In that such a procedure may easily mask cracks by the "peening"
effect, the use of a NDT method such as magnetic particle may be useful in detecting any remaining subsurface defect.
E-24. Replacement of and Work on Shell and Deck Plating.
a. The following precautions apply to repairs on alterations on both riveted and welded hulls:
(1) Sheer strake. The sheer strake, insofar as practicable, should be kept clear of welded fittings. Where there
is no alternative but to make attachments in this region, the attachment should be suitably faired with curved brackets, as
applicable, and at least 1500F preheat should be maintained during welding. However the use of preheat may ordinarily
be omitted if low hydrogen electrodes are used. The upper edge of the sheer strake should be fair and smooth, i.e., free
of notches, nicks, and cuts, weld craters, and any irregular edge burning. Because of the change in ship steel require-
ments which became effective at that time, the foregoing pre-cautions are particularly applicable to ships built prior to
1947.
(2) Stringer plate. Insofar as practicable the stringer plate should also be kept free of welded attachments.
(3) Welding of deck fittings. Where heavy deck fittings, such as chucks, bitts and cleats, are to be welded to the
strength deck, pre-heat of at least 150 should be employed during welding or low hydrogen electrodes should be used.
F
Such heavy fittings should only be installed in accordance with approved plans. Ends of deck fittings should be kept well
clear of deck butts and seams. When a number of fittings are installed on deck, positioning them
E-15
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