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 TB 55-1900-201-45/1
moisture picked up from the atmosphere alone without any direct wetting may result in very faulty welds.
E-32. Edge Preparation. The preparation of the edge of the base metal before welding depends upon the thickness of
the plate and the design of the joint. The requirements are specified in Section 26 of the American Bureau of Shipping
Rules. The following are some points which require special attention:
a. Rough or irregular preparation of the edge should not be accepted.
b. The dimensions of the root opening should be within the specified tolerances. Excessive root face, insufficient
root gap, or insufficient bevel angle will result in poor penetration. Too wide a root gap will result in difficulty in making a
satisfactory root pass unless one face of the joint is first built up by welding or a backing strip is used. All of these defi-
ciencies are readily apparent if the fit-up is examined before the welding is commenced and all are correctable.
c. The surface to be welded should be clean and dry. This includes both the base metal and previous beads of
welding. A clean surface is one free of dirt, slag, oil, rust, scale, or paint.
E-33. Welding Sequence. In most repair work locked-in welding stresses cannot be avoided. However, they can be
minimized if some attention is given to working in accordance with a planned welding sequence. In general, this must be
left to a welding engineer. But, when major repairs are undertaken, the inspector should ascertain that a welding se-
quence has been prepared and he should check to see that it is followed on the job. Some of the fundamental consid-
erations in this regard are as follows:
a. It is poor practice to weld across an open butt. Proper Method of Butt Welding
Proper Method of Butt Welding
E-22
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