§179.16. Tank-head puncture-resistance systems. — Inbound Citations

(4) AAR Specifications for Design, Fabrication and Construction of Freight Cars, Volume 1, 1988, into § 179.16.

(3) The following tank cars must have a tank-head puncture-resistance system that conforms to the requirements in § 179.16 of this subchapter, or to the corresponding requirements in effect at the time of installation:

(iii) Except as provided in paragraph (b)(3)(iv) of this section, those tank cars specified in paragraphs (b)(3)(i) and (ii) of this section not requiring a tank-head puncture resistance system prior to July 1, 1996, must have a tank-head puncture resistance system installed no later than July 1, 2006.

(iv) Class DOT 105A tank cars built prior to September 1, 1981, having a tank capacity less than 70 kl (18,500 gallons), and used to transport a Division 2.1 (flammable gas) material, must have a tank-head puncture-resistant system installed no later than July 1, 2001.

(d) The DOT-117R specification tank car must have a tank head puncture resistance system in conformance with § 179.16(c). The full height head shields must have a minimum thickness of 1/2 inch.

The DOT-117 specification tank car must have a tank head puncture resistance system in conformance with § 179.16(c). The full height head shields must have a minimum thickness of 1/2 inch.

(1) The minimum wall thickness, after forming, of the outer jacket shell may not be less than 7/16 inch. The minimum wall thickness, after forming, of the outer jacket heads may not be less than 1/2 inch and they must be made from steel specified in § 179.16(c).

(2) [Reserved]

(3) The annular space is to be evacuated, and the cylindrical portion of the outer jacket between heads, or between stiffening rings if used, must be designed to withstand an external pressure of 37.5 psig (critical collapsing pressure), as determined by the following formula: