15-26-270 Tank cars – Piping systems.
   Tank cars shall be unloaded through piping systems which comply with the following requirements:
   Extra-heavy wrought steel pipe (ASTM Schedule 80) shall be used for all liquefied gas lines and no such pipe shall be larger than one and one-half inches nominal diameter. All joints shall be welded whenever possible. If flanges are required, they shall be of the 300-pound forged steel ammonia-type properly welded to the pipe with a continuous bead. Gaskets shall be of a material chemically resistant to the fluid in the line and suitable for the pressures and temperatures involved. Fittings shall be forged steel socket welding- type designed for temperatures and pressures to be encountered. Valves shall be of a type specifically designed and manufactured for the particular liquefied gas involved and shall be for a 300-pound minimum operating pressure. One valve shall be placed in the line near the car in an accessible position, and one valve shall be installed immediately before the line enters the building in which such gas is to be used. In addition, one valve shall be provided for each 200 feet of line, one and one-half inches in diameter or smaller. Where piping is exposed to variations in temperature, provisions shall be made for expansion of the piping and for the liquid in the line. One or more expansion loops shall be installed to provide for expansion of the pipe. The number of loops to be provided shall be calculated on the length of the line and extremes of temperature to which the line will be exposed. Adequate anchors shall be provided so that expansion will be in the directions desired. To provide for liquid expansion, one or more expansion chambers shall be installed depending on the length of line. The expansion chamber shall be in accordance with ASME standards for pressure vessels of a size approximately equal to a 150-pound gas cylinder. One such chamber shall be provided for each 500 feet of line of one and one-half inch pipe size or smaller. The expansion chambers shall be inverted over the line and enclosed in an insulated box maintained at a temperature in excess of the critical temperature of the gas involved, at the operating pressure used. The unloading line shall be connected to the car by a semiflexible gooseneck or helical pipe connection that is flanged at one or both ends for connecting and disconnecting. Flexible connections shall be adequately supported and protected against damage.
   Overhead lines shall be supported on steel, concrete columns or other noncombustible structures in a manner to conform with the code for pressure piping as approved by the American Society of Mechanical Engineers and American National Standards Institute. All horizontal lines and supporting structures shall have a minimum clearance of 23 feet over all roadways, over railroad rights-of-way and in other locations where they may be endangered by moving objects. In all other locations the minimum clearance between horizontal lines and supporting structures and the ground shall be 15 feet unless such lines are adequately protected from damage by a building of fire-resistive construction. All vertical and inclined risers at tank cars and at all other points where horizontal lines change from one elevation to another shall be protected by running them against the web of a wide flange beam weighing not less than 30 pounds per foot. In every case the web of the beam shall be between the pipe and the direction from which it might be struck. Such protective beams shall be supported and anchored so as to afford complete protection against damage to the pipeline.
   Underground lines shall be installed in an approved reinforced concrete trench, drained and with removable covers. In lieu of the concrete trench, where not feasible or desirable, the steel conductor pipe shall be protected in the ground by a pipe having pressure-tight joints, acting as a continuous sleeve, fabricated of a material which will not be deteriorated unduly by any chemicals in the soil in which it is located. The conductor pipe and sleeve shall be installed sufficiently deep in the ground to protect against damage from loading on the surface of the ground. The pipe sleeve shall be sealed to the conductor pipe at its ends outside of the ground either by welding the sleeve to the conductor pipe or by a pressure-tight lead-caulked joint.
   A pressure gauge shall be provided which will indicate pressure inside the sleeve in event of a leak in the conductor pipe. A compressed air pressure connection shall also be provided by which the sleeve can be tested for tightness. The vertical pipe from the flexible connection at the tank car to the ground shall be protected against damage by a steel beam as previously described.
   Welding procedures shall be qualified under the regulations of the latest edition of the American National Standard Code for Pressure Piping, ANSI B-31.1, and shall meet the approval of the fire commissioner. Certificates of each welder's qualifications shall be presented before any work is started.
(Coun. J. 12-9-92, p. 25465; Amend Coun. J. 2-7-96, p. 15616; Amend Coun. J. 5-18-16, p. 24131, § 148)