Repair means any welding on a cargo tank wall done to return a cargo tank or a cargo tank motor vehicle to its original design and construction specification, or to a condition prescribed for a later equivalent specification in effect at the time of the repair. Excluded from this category are the following:
(1) A change to motor vehicle equipment such as lights, truck or tractor power train components, steering and brake systems, and suspension parts, and changes to appurtenances, such as fender attachments, lighting brackets, ladder brackets; and
(2) Replacement of components such as valves, vents, and fittings with a component of a similar design and of the same size.
(3) Replacement of an appurtenance by welding to a mounting pad.
49 CFR § 180.403
In addition to the definitions contained in 171.8, 178.320 and 178.345-1 of this subchapter, the following definitions apply to this subpart: