Page 251 - Buried Pipe Design

Design of Pressure Pipes 225

appropriate action to eliminate it. Vacuum relief values may be neces-
sary. Also, a stiffer pipe may be required (see the section “Wall buck-
ling” in Chap. 3).

Temperature and longitudinal stresses. Welded steel lines are subject to
high-temperature induced and other longitudinal stresses. Expansion
joints and/or closure welds will reduce these stresses and may be
required. AWWA M11 and AWWA C206 make specific recommenda-
tions concerning expansion joint and closure welds.

Fiber-reinforced plastic. Reinforced thermosetting resin pipes are
widely used in the industrial market, but have gained very little
acceptance in the U.S. public works market. Aside from the rein-
forcing aspect, such as fiberglass, the primary difference in these
materials lies in the fact that thermosetting resins cannot be melted
and reformed whereas thermoplastic resin can. Members of the ther-
mosetting plastic family include epoxy, polyester, and phenolic
resins.
ASTM D 2996 is the standard specification for filament-wound rein-
forced thermosetting resin pipe. ASTM D 2997 is a standard specifica-
tion for centrifugally cast reinforced thermosetting resin pipe. Within
these standards, there are pipe designation codes and definitions.
ASTM D 2310 is the standard classification for machine-made rein-
forced thermosetting resin (RTR) pipe. This standard contains a com-
plete definition of the various class and types of RTR pipes. It includes
the following:

Manufacturing process:
■ Type 1: Filament wound
■ Type 2: Centrifugally cast
■ Type 3: Pressure-laminated
Resin used:
■ Grade 1: Glass-fiber-reinforced—epoxy
■ Grade 2: Glass-fiber-reinforced—polyester
■ Grade 3: Glass-fiber-reinforced—phenolic
■ Grade 4: Asbestos-reinforced—polyester
■ Grade 5: Asbestos-reinforced—epoxy
■ Grade 6: Asbestos-reinforced—phenolic
■ Grade 7: Glass-fiber-reinforced furan resin pipe—RTRP furan
■ Grade 8: Glass-fiber-reinforced epoxy resin mortar pipe—RPMP
epoxy
■ Grade 9: Glass-fiber-reinforced polyester resin mortar pipe—RPMP
polyester