I hope this response is not too late. I just saw your post this morning.
I assume your question is: "What force should be applied to the pipe and its contents during a particular seismic event?"
If so, and if your project is located in the US or one of its commonwealths, then the answer to your question can be found in the 1997 Uniform Building Code, the new International Building Code, SBC, BOCA, or ASCE 7-98. Each of these documents specify minimum seismic lateral forces to be applied to structural and non-structural components. Each document contains relatively simple formulas for computing lateral force that is primarily dependent on the building or structure occupancy category and the seismic zone in which your building structure or non-building structure is geographically located.
You should inquire of your local building official to find out what design standards or building codes have been locally adopted or are alternatively approved for seismic design purposes. The 1997 UBC is generally adopted for use in the western US and BOCA and SBC are used in the east. Great Britain, Japan, and Australia each have their own seismic design standards as well. The new 2000 IBC is intended for use as a US national building design code. ASCE 7-98 is a design standard developed by the American Society of Civil Engineers and may or may not be accepted for use with respect to seismic forces by your local building official.
With respect to lateral wind forces, ASCE 7-98 is the basis of all US national building codes and design standards, including UBC, IBC, BOCA, SBC, etc. If your piping is exposed to the wind, then lateral wind forces must be calculated and the controlling force applied to the piping. This will determine the required strength of both the piping and its supports and connections for safe resistance to seismic and wind forces.