---
kind: "section"
citation: "49 C.F.R. § 179.400-7"
title: "49"
number: "179.400-7"
heading: "Tank heads."
url: "https://uscodex.org/cfr/49/179.400-7"
---

# §179.400-7. Tank heads.

- (a) Tank heads of the inner tank and outer jacket must be flanged and dished, or ellipsoidal.
- (b) Flanged and dished heads must have—
  - (1) A main inside dish radius not greater than the outside diameter of the straight flange;
  - (2) An inside knuckle radius of not less than 6 percent of the outside diameter of the straight flange; and
  - (3) **An inside knuckle radius of at least three times the head thickness.**

## Notes

### Source

Source: Amdt. 179-32, 48 FR 27708, June 16, 1983, unless otherwise noted.

### 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.