A longitudinal sequence in which weld passes are made in the direction opposite to the progress of welding. See STANDARD WELDING TERMS. See also Figure B-3.
The backstep sequence is a welding technique used to prevent accumulation of stresses and distortion by distributing deposited weld metal. This method consists of dividing the weld into short increments, and depends on depositing the weld metal in a direction opposite to the direction of progression. The welds may be made in the sequence shown in Figure B-3, or this sequence may be changed. For example, the welds may be made in the order of 1, 2, 3, 4, 5, 6, etc., or 1, 3, 5, 2, 4, 6, etc. The latter is an illustration of the skip backstep method, which is a combination of skip and back-step welding. In skip backstep welding the welds may be made in any convenient order. See BLOCK SEQUENCE, CASCADE SEQUENCE, CONTINUOUS SEQUENCE, CROSS SECTIONAL SEQUENCE, and LONGITUDINAL SEQUENCE.
