facilities located in Seismic Design Criteria C, D, E,
and F will be designed using the provisions in
6. All round air-handling ducts less than
28 inches (711mm) in diameter.
(3) All other piping.
All piping suspended by individual
hangers 12 inches (0.3m) or less in length from the
(a) Piping in Seismic Design Category A
top of pipe to the bottom of the support for the
structures is not required to have seismic restraint.
(b) Piping in Seismic Design Category B
All ducts suspended by hangers 12
structures that is not categorized as essential or
inches or less in length from the top of the duct to
hazardous is not required to have seismic restraints.
the bottom of the support for the hanger.
Seismic restraint provisions.
Piping in all other Seismic Design
Category structures that is not categorized as
restraints that are required for piping by Paragraphs
essential or hazardous is required to have seismic
restraints designed using the provisions in Paragraph
accordance with the following provisions.
Restraints may be omitted for the
The provisions of this
paragraph apply to the following:
1. Gas piping of less than 1-inch (25mm)
All risers and riser
Piping in boiler and mechanical
equipment rooms of less than 1 (32mm) inches
2. Horizontal pipe. All horizontal pipes
and attached valves.
For the seismic analysis of
horizontal pipes, the equivalent static force will be
3. All other piping of less than 2 inches
considered to act concurrently with the full dead load
(64mm) inside diameter.
of the pipe, including contents.
4. All electrical conduit of less than 2
All connections and
inches (64mm) inside diameter.
brackets for pipe will be designed to resist
concurrent dead and equivalent static forces. The
5. All rectangular air-handling ducts of
seismic forces will be determined from the
less than 6 square feet (0.6m2) in cross-sectional
appropriate provisions below.
Supports will be