[Code of Federal Regulations] [Title 49, Volume 2] [Revised as of October 1, 2004] From the U.S. Government Printing Office via GPO Access [CITE: 49CFR179.103-1] [Page 1032] TITLE 49--TRANSPORTATION CHAPTER I--RESEARCH AND SPECIAL PROGRAMS ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PART 179_SPECIFICATIONS FOR TANK CARS--Table of Contents Subpart C_Specifications for Pressure Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120) Sec. 179.103-1 Type. (a) Tanks built under this section may be of any approved cross section. (b) Any portion of the tank shell not circular in cross section shall have walls of such thickness and be so reinforced that the stresses in the walls caused by a given internal pressure are no greater than the circumferential stresses which would exist under the same internal pressure in the wall of a tank of circular cross section designed in accordance with paragraphs Sec. 179.100-6 (a) and (b), but in no case shall the wall thickness be less than that specified in Sec. 179.101. (c) [Reserved] (d) Valves and fittings need not be mounted on the manway cover. (e) One opening may be provided in each head for use in purging the tank interior. [29 FR 18995, Dec. 29, 1964. Redesignated at 32 FR 5606, Apr. 5, 1967, and amended by Amdt. 179-50, 60 FR 49077, Sept. 21, 1995]