Page 252 - Buried Pipe Design

226 Chapter Four

Liner classification:
■ Class A: No liner
■ Class B: Polyester resin—nonreinforced
■ Class C: Epoxy resin—nonreinforced
■ Class D: Phenolic resin—nonreinforced
■ Class E: Polyester resin—reinforced
■ Class F: Epoxy resin—reinforced
■ Class G: Phenolic resin—reinforced
■ Class H: Thermoplastic resin liner (specify)
■ Class I: Furan resin liner—reinforced

ASTM D 2992 is the standard method for obtaining hydrostatic
design basis for reinforced thermosetting resin pipe and fittings. There
are two procedures:
1. Procedure A: cyclic strength. This procedure is based on pipe failure
at a minimum of 150 10 cycles at 25 cycles/min, 11.4 years.
6
2. Procedure B: static strength. This procedure is based on pipe fail-
ure at a minimum 100,000 h (11.4 years) of static pressure.

It is important to note that ASTM does not specify a service factor
for RTR pipe. Therefore, it is up to the design engineer to determine
the hydrostatic design basis to be used for a particular pipe. The prod-
uct designation code, the manufacturer’s product data, and ASTM
standards make it easy to determine what safety factor is being
employed at the recommended working pressure.
The hydrostatic design bases are listed in the applicable ASTM spec-
ifications. In the case of ASTM D 2996 for filament-wound RTR pipe,
the following hydrostatic design base categories are listed:

Cyclic test method Static test method
Designation Hoop stress, lb/in 2 Designation Hoop stress, lb/in 2
A 2,500 Q 5,000
B 3,150 R 6,300
C 4,000 S 8,000
D 5,000 T 10,000
E 6,300 U 12,500
F 8,000 W 16,000
G 10,000 X 20,000
H 12,000 Y 25,000
Z 31,500
Equation (4.3) can be utilized to calculate pressure ratings for RTR pipe.
An AWWA standard for glass-fiber-reinforced thermosetting resin
pressure pipe, AWWA C950, was first approved in 1981. It incorporates
information from the ASTM standards discussed above.