Page 288 - Buried Pipe Design

Rigid Pipe Products 259

TABLE 5.4 Standards for Clay Pipe
ASTM C 700 Clay pipe, vitrified, extra-strength, standard strength, and perforated
ASTM C 425 Compression joints for vitrified clay pipe and fittings
ASTM C 301 Clay pipe, vitrified (test methods)
ASTM C 12 Installing vitrified clay pipe lines
ASTM C 828 Low-pressure air test of vitrified clay pipe lines
Canadian Standards Association
CSA A60.1 Vitrified clay pipe
CSA A60.2 Methods of testing vitrified clay pipe
CSA A60.3 Vitrified clay pipe

TABLE 5.5 ASTM C 700 Clay Pipe Minimum Crushing Strengths (Three-Edge
Bearing Strength)
Nominal size, in Extra strength, lb/ft Nominal size, in Extra strength, lb/ft
3 2000 21 3850
4 2000 24 4400
6 2000 27 4700
8 2200 30 5000
10 2400 33 5500
12 2600 36 6000
15 2900 39 6600
18 3300 42 7000

During vitrification the clay fuses into a very hard, chemically sta-
ble compound. Vitrified clay is very corrosion- and abrasion-resistant.
Because of its inherent low strength, vitrified clay pipe is used for non-
pressure applications only. It is brittle and subject to impact damage;
therefore, special care in handling is a requirement.
Newer designs do not have extruded clay bells. Instead, a bell is
formed by helically winding continuous glass filaments and a ther-
mosetting resin to form a bell on a plain pipe end. A groove is molded
into the bell for a rubber gasket.
Clay pipe is generally available in sizes ranging from 4- to 36-in diam-
eter. However, it may be available in some locations in diameters up to
42 in. The strength is determined by the three-edge bearing test, varies
with diameter, and ranges from 2000 to 7000 lb/ft (Tables 5.4 and 5.5).

Example 5.4 A 15-in-diameter sanitary sewer line is to be installed 14 ft
deep. Native material, which is sand, will be used for final backfill. If the
trench width is 3.0 ft, what pipe and bedding classes should be selected?
(Note: This example was previously given as Example 3.1.)
1. Determine the earth load.

H 14
4.67 (from Fig. 2.2, C d 2.4)
B d 3