229.31—Main reservoir tests.

D = (.6PR/S-0.6P)
Where:
D = extreme depth of telltale holes in inches but in no case less than one-sixteenth inch;
P = certified working pressure in pounds per square inch;
S = one-fifth of the minimum specified tensile strength of the material in pounds per square inch; and
R = inside radius of the reservoir in inches.
One row of holes shall be drilled lengthwise of the reservoir on a line intersecting the drain opening. A reservoir so drilled does not have to meet the requirements of paragraphs (a) and (b) of this section, except the requirement for a pneumatic or hydrostatic test before it is placed in use. Whenever any such telltale hole shall have penetrated the interior of any reservoir, the reservoir shall be permanently withdrawn from service. A reservoir now in use may be drilled in lieu of the tests provided for by paragraphs (a) and (b) of this section, but shall receive a hydrostatic test before it is returned to use or may receive a pneumatic test if conducted by the manufacturer in an appropriately safe environment.
[45 FR 21109, Mar. 31, 1980, as amended at 71 FR 61857, Oct. 19, 2006]