Number and nature of tests
85.  Tensile and bending tests shall be made from the tubes made from each charge in the following proportions:
(a)tubes up to and including 4 inches in diameter: 1 in 40 or part thereof;
(b)tubes above 4 inches up to and including 5 inches in diameter: 1 in 10 or part thereof;
(c)tubes above 5 inches up to and including 7 inches in diameter: 1 in 6 or part thereof; and
(d)tubes above 7 inches in diameter: 1 in 4 or part thereof.