---
kind: "section"
citation: "49 C.F.R. § 179.200-8"
title: "49"
number: "179.200-8"
heading: "Tank heads."
url: "https://uscodex.org/cfr/49/179.200-8"
---

# §179.200-8. Tank heads.

- (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](/cfr/49/179.200-6.md). Flanged and dished heads must have main inside radius not exceeding 10 feet, and inside knuckle radius must not be less than 3 3/4 inches for steel, alloy steel, or nickel tanks, and not less than 5 inches for aluminum alloy tanks.

## Notes

### Amendments

[Amdt. 179-10, 36 FR 21350, Nov. 6, 1971]

### Authority

Authority: 49 U.S.C. 5101-5128; 49 CFR 1.81 and 1.97.

### Source

Source: 29 FR 18995, Dec. 29, 1964, unless otherwise noted. Redesignated at 32 FR 5606, Apr. 5, 1967.

### Amendments

[Amdt. 179-10, 36 FR 21350, Nov. 6, 1971]