48 DEPARTMENT BULLETIN 1216, L T . S. PEPT. OF AGRICULTURE 
4. The sand used shall be clean and dry and shall be such as will pass a No. 4 
screen. 
5. The top bearing frame shall not be allowed to come in contact with the pipe 
nor with the top bearing plate. The upper surface of the sand in the top 
bearing shall be struck level with a straight edge, and shall be covered with a 
rigid top bearing plate, with lower surface a true plane, made of heavy timbers 
or other rigid material, capable of distributing the test load uniformly without 
appreciable bending. The test load shall be applied at the exact center of this 
top bearing plate, or in such manner as to produce uniform deflection through- 
out the full length of the pipe. For this purpose, a spherical bearing is pre- 
ferred, but two rollers at right angles may be used. The test may be made 
without the ues of a testing machine, by piling weights directly on a platform 
resting on the top bearing plate, provided, however, that the weights shall be 
•Sond 
.7;, Sand± {/ vi 
Bedding of Barrel 
Bedding of Socket 
r*d. 
Bedding of Barrel 
" 1 1 ' ' L - j t 4-1 ^ h i 1 1 m m ^ ir 1 Tm . -j--'-' '-■ — '-*■* 
■Side View 
Upper Bearing Frame 
Side View 
Fig. 17. — Arrangement for sand-bearing test of bell-and- Fig. 18. — Arrangement for 
spigol sand-bearing test of pipe 
without bell and spigot 
piled symmetrically about a vertical line through the center of the pipe, and 
that the platform shall not be allowed to touch the top bearing frame. 
6. The frames of the top an<3 bottom bearings shall be made of timbers so 
heavy as to avoid appreciable bending by the side pressure of sand. The interior 
surfaces of the frames shall be dressed. No frame shall come in contact with 
the pipe during the test. A strip of cloth may, if desired, be attached to the 
inside of the upper frame on each side, along the lower edge, to prevent the 
escape of sand between the frame and the pipe. 
7. Any prime mover or hand power which will apply the load at a uniform 
rate of "about 2,000 pounds per minute, or in increments of not more than 100 
pounds, at the same rate, may be used in making the test. The testing machine 
shall be substantial and rigid throughout, so that the distribution of the load 
will not be affected appreciably by the deformation or yielding of any part. The 
