Page 332 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

SITE UTILITY SYSTEMS

6.54 CHAPTER SIX

FIGURE 6.32 Earth load on pipe in trench. (Courtesy: ANSI 21.1.)

Discussion:
1. The surface load factor is the weight transmitted to the pipe from a truck on a road
passing over the pipe. Tables have been prepared for both one truck and two trucks pass-
ing over the pipe simultaneously. The proper chart should be consulted based on road
construction and number of trucks. Refer to Table 6.10 (one truck on flexible pavement,
Table 6.11 (two trucks on flexible pavement), or Table 6.12 (one or two trucks on rigid
pavement).
2. The reduction factor allows for the fact that adjacent portions of pipe that are not directly
under the load assist in carrying some portion of the live load. Refer to Table 6.13.
3. Wheel load is the actual weight of the truck and its cargo on a wheel passing over the
pipe. Refer to Table 6.14. The H-20 loading is most commonly used.
4. Impact factor is a dynamic load caused by a moving object. Refer to Table 6.15 to deter-
mine the factor based on depth of burial.
5. Table 6.16 gives the outside diameter of pipe, based on pipe size and material.

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