the center section of five specimens of finished conduit, each approximately 15 inchs (380mm) long, are to be crushed between two flat, square steel plates having rounded edges and measuring 6inches (150mm) on each side moving toward one another at the rate of 1/2 ±1/8 inch/minute (10.0±2.5mm/minute) until the overall diameter of the conduit is reduced to one-half its original value. The load required to crush any specimen of the conduit to half of its original overall diameter shall be at leat as great as the value indicated in table 11.1