FLOOD06195 - Laserfiche WebLink

Home Browse Search

40 1.20 TECHNIQUES OF WATER-RESOURCES INVESTIGATIONS ~ ... 0,04 ~ I,<~////n Om Darb-- -41-", ~" " " " " 'I 0.10 w w borfj Figure 22.-Variatlon of the: discharge coefficient with entrance beveling, types 1, 2, and 3 flow in box or pipe culverts set flush with vertical headwall. variation. Therefore, use a 0 of 0.95 for all sizes of machine tongue-and-groove concrete pipe without regard to (h,-z)ID for flow types 1, 2, and 3. BeIlmouthed precast concrete pipe is considered to be in this category; therefore use a 0 of 0,95 for it, too, According to one manufacturer of corru- gated-metal pipe, the pipe actually has a beveled rather than a rounded edge. The bevel has an average w (fig. 22) of 0.30 inch (0.025 fl.) with a bevel angle of 670. If the entrance appears to be rounded rather than beveled, the rounding may vary with the gage of the metal, but it will average very nearly 0.80 inch (0.067 fl.) for the weights of metal ordinarily used. Occasionally a culvert with a beaded or rolled entrance will be found. The radius of rounding of the bead generally is about 3/8 inch (0.031 fl.). Always make exact measure- ments in the field. The following list shows values of riD and wiD for various sizes of standard riveted corrugated-metal pipe. D (Inches) I 'ID "'ID 24 . -I 0.031 0.0125 I 36 .021 .0083 '~ 48 i-<',OI".' .0062 60 .0050 72 .010 .0042 Because of the longer pitch in multi plate pipe construction, the entrance is most likely to be considered beveled. The value of w will average about 1.2 inches and 8 about 520. Always measure in the field these factors or the data required to compute them. ~ ~ ''-(' - e -- .