(a) All external tank heads must be an ellipsoid of revolution in which the major axis must equal the diameter of the shell and the minor axis must be one-half the major axis.
(b) Internal compartment tank heads may be 2:1 ellipsoidal, 3:1 ellipsoidal, or flanged and dished to thicknesses as specified in § 179.200-6. Flanged and dished heads must have main inside radius not exceeding 10 feet, and inside knuckle radius must not be less than 33/4 inches for steel, alloy steel, or nickel tanks, and not less than 5 inches for aluminum alloy tanks.
[Amdt. 179-10, 36 FR 21350, Nov. 6, 1971]
Title 49 published on 2014-10-01
no entries appear in the Federal Register after this date.
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