Here is one that I got a few years ago off a gov. website.
Nominal
Pipe
size Suggested maximum span
Water Steam
Inches (ft) (m) (ft) (m)
1 7 2.1 9 2.7
2 10 3.0 13 4.0
3 12 3.7 15 4.6
4 14 4.3 17 5.2
6 17 5.2 21 6.4
8 19 5.8 24 7.3
12 23 7.0 30 9.1
16 27 8.2 35 10.7
20 30 9.1 39 11.9
24 32 9.8 42 12.8
Suggested maximum spacing between pipe supports for horizontal straight runs of standard and heavier pipe at maximum operating temperature of 750ººF (400ººC).
Does not apply where span calculations are made or where there are concentrated loads between supports, such as flanges, valves, specialties, etc.
The spacing is based on a fixed beam support with a bending stress not exceeding 2,300 psig (15.86 MPa) and insulated pipe filled with water or the equivalent weight of steel pipe for steam, gas, or air service, and the pitch of the line is such that a sag of 0.1 in. (2.5 mm) between supports is permissible