WOOD PIPE FOR CONVEYING IRRIGATION WATER. 7 



length; that the end of the stave shall be cut square, and shall be fitted with 

 a saw kerf for the insertion of a metal tongue; in depth the saw kerf shall 

 be one-sixteenth of an inch less than half the width of the tongue, and its po- 

 sition must be the same in all staves. 



BANDS. 



For bands, the usual specifications require soft steel of ultimate 

 tensile strength equal to 55,000 to 65,000 pounds per square inch; 

 elastic limit not less than one-half the ultimate tensile strength; 

 elongation in 8 inches not less than 25 per cent, and the bands are 

 required to stand bending, cold, 180° around a diameter equal to 

 that of the specimen tested, without fracture on either side. Such 

 steel is similar in quality to that used for steam boilers. 



It is usual to specify that bands shall be provided with not less 

 than 5 inches of cold-rolled thread or have upset ends; the idea being 

 to insure as great strength in the threaded portion as in the body 

 of the band. Each threaded end should be supplied with a standard 

 hexagonal nut three-sixteenths of an inch thicker than the diameter 

 of the band, and a plate washer of proper diameter and standard 

 thickness. 



In determining the size of bands many engineers have used a 

 formula developed by the late A. L. Adams. 1 Four is the usual 

 factor of safety. Bands less than three-eighths of an inch in diame- 

 ter are not used. The following table prepared by Mr. Adams shows 

 minimum sizes of pipe for which bands of several sizes are applicable. 



Minimum sizes of pipe for which specified bands are applicable. 



Size of 

 band. 



S equals 

 J ulti- 

 mate 

 tensile 



strength. 



Band 

 pressure 



per 

 square 



inch. 



E equals 

 band 



pressure 



per 



linear 



inch. 



Least 

 external 

 radius of 



pipe. 



Band 

 pressure 



per 

 square 



inch. 



E equals 

 band 



pressure 



per 



linear 



inch. 



Least 

 external 

 radius of 



pipe. 



Inch. 



A 



Pounds. 

 1,650 

 2.250 

 2,950 

 3.725 

 4,000 

 6,600 



Pounds. 

 650 

 650 

 650 

 650 

 650 

 650 



Pounds. 

 122 

 142 

 163 

 183 

 203 

 244 



Inches. 

 13.5 

 15.8 

 18.1 

 20.4 

 22.6 

 27.0 



Pounds. 

 750 

 750 

 750 

 750 

 750 

 750 



Pounds. 

 140 

 164 

 187 

 211 

 234 

 281 



Inches. 

 11.8 

 13.7 

 15.7 

 17.65 

 19.6 

 23.5 



The particular style of band to use, one piece or two piece, oval 

 head or square head, depends upon the size of the pipe, etc. Stand- 

 ard patterns of each, as made by one of the leading manufacturers, 

 with weights and dimensions, are given as follows . 



1 Trans. Amer. Soc. Civ. Engin., 41 (1899), p. 27. 



