Problem:

What is the recommended Seismic support spacing?

Solution:

MSS SP-127-2001 (Bracing for piping Systems Seismic - Wind - Dynamic) recommends a lateral seismic support every 40ft and longitudinal support every 80ft. 

But just note this guideline tends to be conservative and over predict number and size of seismic supports.

See Also

"Static Earthquake" Load Case

Bentley AutoPIPE