This can be found quickly using a web search. It is generally in the Section 15050 or 15060 Mechanical General Requirements specification for any project; the IMC also gives a pretty general maximum spacing.
Basic piping installation requirements are specified in Section 15050, "Basic Mechanical Materials and Methods."
Hanger spacing shall be as follows:
Horizontal:
Copper Piping Maximum Spacing
3/8" and under 4'-0"
1/2" through 3/4" 6'-0"
1" through 1-1/2" 8'-0"
2" and larger 10'-0"
Vertical: Copper piping shall be supported at 10 feet intervals maximum.
Round rods supporting the pipe hangers shall be of the following dimensions:
2" pipe and under 3/8" rod
2-1/2" to 3" pipe 1/2" rod