(By J. F. Partridge, Trans. A. S. C. E., Vol. 82, page 461) ───────────┬───────────┬───────────┬───────────┬───────────┬─────────── │ Stave │Stock Size │ Size of │ Top Width │Spacing of │Thickness, │of Lumber, │ Band, │of Staves, │ Bands for Diameter, │ Standard, │ Inches │ Inches │ Standard, │ 100 Feet Inches │ Inches │ │ │ Inches │ Head ───────────┼───────────┼───────────┼───────────┼───────────┼─────────── 12│ 1⅜ │ 2 × 4 │ ⅜ │ 3.56 │ 6.38 18│ 1–7/16 │ 2 × 4 │ 7/16 │ 3.66 │ 5.76 24│ 1–7/16 │ 2 × 4 │ 7/16 │ 3.70 │ 4.34 30│ 1½ │ 2 × 6 │ ½ │ 5.48 │ 4.53 36│ 1–9/16 │ 2 × 6 │ ½ │ 5.62 │ 3.77 42│ 1⅝ │ 2 × 6 │ ½ │ 5.51 │ 3.23 │ 1⅝ │ 2 × 6 │ ½ or ⅝ │ 5.60 │ 2.84 or 48│ │ │ │ │ 4.41 60│ 2½ │ 3 × 6 │ ⅝ │ 5.56 │ 3.54 │ 3½ │ 4 × 6 │ ⅝ or ¾ │ 5.69 │ 2.95 or 72│ │ │ │ │ 4.24 84│ 3½ │ 4 × 6 │ ¾ │ 5.65 │ 3.63 120│ 3⅝ │ 4 × 6 │ ¾ │ 5.68 │ 2.54 │ 3⅝ │ 4 × 6 │ ¾ or ⅞ │ 5.64 │ 2.12 or 144│ │ │ │ │ 2.89 ───────────┴───────────┴───────────┴───────────┴───────────┴─────────── CHAPTER IX DESIGN OF THE SEWER RING =99. Stresses in Buried Pipe.=—The stresses which sewer pipe should be designed to resist are: internal bursting pressure, for sewers flowing under pressure; stresses due to handling, for precast pipe; temperature stresses; and external loads. The latter is by far the most important and frequently is the only stress considered in design. The thickness of a pipe to resist internal stress should be (_PR_)⁄_f__{_t_}, in which _P_ = the intensity of internal pressure; _R_ = the radius of the inside of the pipe, and _f__{_t_} = the unit-strength of the material in tension The derivation of this expression is simple. The stresses due to handling cannot be computed and are cared for by a thickness of material dictated by experience. These thicknesses are given for vitrified clay and cement pipe in the specifications in the preceding chapter. Temperature stresses are not allowed for in the design of the pipe ring, but allowance must be made for them in long rigid pipe lines exposed to wide variations in temperature. Such a condition seldom exists in sewerage works.