1305.9.3 Horizontal Offsets

Where it is necessary to make horizontal offsets in the supply piping and pipe shafts, such piping shall be enclosed in a sleeve of other piping of at least No. 10 standard Gage steel, two sizes larger than the supply piping and arranged to drain into the shaft. Horizontal piping offsets shall be further enclosed in construction having a 2-hour fire-resistance rating except that no such enclosure or pipe sleeve shall be required within the room containing the pump, tank, or equipment where such room is itself enclosed with construction and materials having at least a 2-hour fire-resistance rating.