Source: http://www.setonresourcecenter.com/49CFR/Docs/wcd0000b/wcd00b1d.asp
Timestamp: 2014-08-01 05:45:10
Document Index: 56334148

Matched Legal Cases: ['§ 178', '§ 178', 'art 180', 'arts 450', '§ 171', '§ 171', '§ 171', '§ 171', '§ 171', '§ 171', '§ 171', '§ 171', '§ 171', '§ 171', '§ 178', '§ 171']

178.274 Specifications for UN portable tanks.
(a) General. (1) Each UN portable tank must meet the requirements of this section. In addition to the requirements of this section, requirements specific to UN portable tanks used for liquid and solid hazardous materials, non-refrigerated liquefied gases and refrigerated liquefied gases are provided in §§ 178.275, 178.276 and 178.277, respectively. Requirements for approval, maintenance, inspection, testing and use are provided in § 178.273 and part 180, subpart G, of this subchapter. Any portable tank which meets the definition of a "container" within the terms of the International Convention for Safe Containers (CSC) must meet the requirements of the CSC as amended and 49 CFR parts 450 through 453 and must have a CSC safety approval plate.
(2) In recognition of scientific and technological advances, the technical requirements applicable to UN portable tanks may be varied if approved by the Associate Administrator and the portable tank is shown to provide a level of safety equal to or exceeding the requirements of this subchapter. Portable tanks approved to alternative technical requirements must be marked "Alternative Arrangement" as specified in paragraph (i) of this section.
(3) Definitions. The following definitions apply for the purposes of design and construction of UN portable tanks under this subpart:
Fine grain steel means steel which has a ferritic grain size of 6 or finer when determined in accordance with ASTM E 112-96 (see § 171.7 of this subchapter).
Mild steel means a steel with a guaranteed minimum tensile strength of 360 N/mm
2 to 440 N/mm
2 and a guaranteed minimum elongation at fracture as specified in paragraph (c)(10) of this section.
Offshore portable tank means a portable tank specially designed for repeated use in the transportation of hazardous materials to, from and between offshore facilities. An offshore portable tank is designed and constructed in accordance with the Guidelines for the Approval of Containers Handled in Open Seas specified in the IMDG Code (see § 171.7 of this subchapter).
Reference steel means a steel with a tensile strength of 370 N/mm
2 and an elongation at fracture of 27%.
(b) General design and construction requirements. (1) The design temperature range for the shell must be −40 °C to 50 °C (−40 °F to 122 °F) for hazardous materials transported under normal conditions of transportation, except for portable tanks used for refrigerated liquefied gases where the minimum design temperature must not be higher than the lowest (coldest) temperature (for example, service temperature) of the contents during filling, discharge or transportation. For hazardous materials handled under elevated temperature conditions, the design temperature must not be less than the maximum temperature of the hazardous material during filling, discharge or transportation. More severe design temperatures must be considered for portable tanks subjected to severe climatic conditions (for example, portable tanks transported in arctic regions). Shells must be designed and constructed in accordance with the requirements of the ASME Code, Section VIII, Division 1 (see § 171.7 of this subchapter), except as limited or modified in this subchapter. For portable tanks used for liquid or solid hazardous materials, a design code other than the ASME Code may be used if approved by the Associate Administrator. Portable tanks used for non-refrigerated and refrigerated liquified compressed gases require an ASME certification and U stamp. Shells must be made of metallic materials suitable for forming. Non-metallic materials may be used for the attachments and supports between the shell and jacket, provided their material properties at the minimum and maximum design temperatures are proven to be sufficient. For welded shells, only a material whose weldability has been fully demonstrated may be used. Welds must be of high quality and conform to a level of integrity at least equivalent to the welding requirements specified in Section VIII of the ASME Code for the welding of pressure vessels. When the manufacturing process or the materials make it necessary, the shells must be suitably heat-treated to guarantee adequate toughness in the weld and in the heat-affected zones. In choosing the material, the design temperature range must be taken into account with respect to risk of brittle fracture, stress corrosion cracking, resistance to impact, and suitability for the hazardous materials intended for transportation in the portable tank. When fine grain steel is used, the guaranteed value of the yield strength must be not more than 460 N/mm
2 and the guaranteed value of the upper limit of the tensile strength must be not more than 725 N/mm
2 according to the material specification. Aluminum may not be used as a construction material for the shells of portable tanks intended for the transport of non-refrigerated liquefied gases. For portable tanks intended for the transport of liquid or solid hazardous materials, aluminum may only be used as a construction material for portable tank shells if approved by the Associate Administrator. Portable tank materials must be suitable for the external environment where they will be transported, taking into account the determined design temperature range. Portable tanks shall be designed to withstand, without loss of contents, at least the internal pressure due to the contents and the static, dynamic and thermal loads during normal conditions of handling and transportation. The design must take into account the effects of fatigue, caused by repeated application of these loads through the expected life of the portable tank.
(i) Compatible with the hazardous materials intended to be transported; or (ii) Properly passivated or neutralized by chemical reaction, if applicable; or
(c) Design criteria. (1) Portable tanks and their fastenings must, under the maximum permissible loads and maximum permissible working pressures, be capable of absorbing the following separately applied static forces (for calculation purposes, acceleration due to gravity (g) =9.81m/s
(5) For shells of portable tanks used for liquefied compressed gases, the shell must consist of a circular cross section. Shells must be of a design capable of being stress-analysed mathematically or experimentally by resistance strain gauges as specified in UG-101, Section VIII of the ASME Code (see § 171.7 of this subchapter), or other methods approved by the Associate Administrator.
Re = yield strength in N/mm2, or 0.2% proof strength or, for austenitic steels, 1% proof strength;
Rm = minimum tensile strength in N/mm
(11) For the purpose of determining actual values for materials for sheet metal, the axis of the tensile test specimen must be at right angles (transversely) to the direction of rolling. The permanent elongation at fracture must be measured on test specimens of rectangular cross sections in accordance with ISO 6892 (see § 171.7 of this subchapter), using a 50 mm gauge length.
(d) Minimum shell thickness. (1) The minimum shell thickness must be the greatest thickness of the following:
(ii) the minimum thickness determined in accordance with Section VIII of the ASME Code (see § 171.7 of this subchapter) or other approved pressure vessel code; or
(3) When additional protection against shell damage is provided in the case of portable tanks used for liquid and solid hazardous materials requiring test pressures less than 2.65 bar (265.0 kPa), subject to certain limitations specified in the UN Recommendations (see § 171.7 of this subchapter), the Associate Administrator may approve a reduced minimum shell thickness.
(e) Service equipment. (1) Service equipment must be arranged so that it is protected against the risk of mechanical damage by external forces during handling and transportation. When the connections between the frame and the shell allow relative movement between the sub-assemblies, the equipment must be fastened to allow such movement without risk of damage to any working part. The external discharge fittings (pipe sockets, shut-off devices) and the internal stop-valve and its seating must be protected against mechanical damage by external forces (for example, by using shear sections). Each internal self-closing stop-valve must be protected by a shear section or sacrificial device located outboard of the valve. The shear section or sacrificial device must break at no more than 70% of the load that would cause failure of the internal self-closing stop valve. The filling and discharge devices (including flanges or threaded plugs) and any protective caps must be capable of being secured against unintended opening.
(f) Pressure relief devices. -- (1) Marking of pressure relief devices. Every pressure relief device must be clearly and permanently marked with the following:
(v) the rated flow capacity of the device in standard cubic meters of air per second (m
3/s)determined according to ISO 4126-1 (see § 171.7 of this subchapter); and
(vi) when practicable, the device must show the manufacturer's name and product number.
(2) Connections to pressure relief devices. Connections to pressure relief devices must be of sufficient size to enable the required discharge to pass unrestricted to the safety device. No stop-valve may be installed between the shell and the pressure relief devices except where duplicate devices are provided for maintenance or other reasons and the stop-valves serving the devices actually in use are locked open or the stop-valves are interlocked so that at least one of the devices is always in use. There must be no obstruction in an opening leading to a vent or pressure relief device which might restrict or cut-off the flow from the shell to that device. Vents or pipes from the pressure relief device outlets, when used, must deliver the relieved vapor or liquid to the atmosphere in conditions of minimum back-pressure on the relieving devices.
(3) Location of pressure relief devices. (i) Each pressure relief device inlet must be situated on top of the shell in a position as near the longitudinal and transverse center of the shell as reasonably practicable. All pressure relief device inlets must, under maximum filling conditions, be situated in the vapor space of the shell and the devices must be so arranged as to ensure that any escaping vapor is not restricted in any manner. For flammable hazardous materials, the escaping vapor must be directed away from the shell in such a manner that it cannot impinge upon the shell. For refrigerated liquefied gases, the escaping vapor must be directed away from the tank and in such a manner that it cannot impinge upon the tank. Protective devices which deflect the flow of vapor are permissible provided the required relief-device capacity is not reduced.
(g) Gauging devices. Unless a portable tank is intended to be filled by weight, it must be equipped with one or more gauging devices. Glass level-gauges and gauges made of other fragile material, which are in direct communication with the contents of the tank are prohibited. A connection for a vacuum gauge must be provided in the jacket of a vacuum-insulated portable tank.
(h) Portable tank supports, frameworks, lifting and tie-down attachments. (1) Portable tanks must be designed and constructed with a support structure to provide a secure base during transport. The forces and safety factors specified in paragraphs (c)(1) and (c)(2) of this section, respectively, must be taken into account in this aspect of the design. Skids, frameworks, cradles or other similar structures are acceptable.
(iv) Protection of the shell against damage from impact or overturning by use of an ISO frame in accordance with ISO 1496-3 (see § 171.7 of this subchapter); and
(i) Marking. (1) Every portable tank must be fitted with a corrosion resistant metal plate permanently attached to the portable tank in a conspicuous place and readily accessible for inspection. When the plate cannot be permanently attached to the shell, the shell must be marked with at least the information required by Section VIII of the ASME Code (see § 171.7 of this subchapter). At a minimum, the following information must be marked on the plate by stamping or by any other equivalent method:
Alternative Arrangements (see § 178.247(a)(2)) "AA"
Month____Year____
Either "thermally insulated" or "vacuum insulated"____.
(3) If a portable tank is designed and approved for open seas operations, such as offshore oil exploration, in accordance with the IMDG Code, the words "OFFSHORE PORTABLE TANK" must be marked on the identification plate.
(j) Initial inspection and test. The initial inspection and test of a portable tank must include the following:
(6) A UN portable tank that meets the definition of "container" in the CSC (see 49 CFR 450.3(a)(2)) must be subjected to an impact test using a prototype representing each design type. The prototype portable tank must be shown to be capable of absorbing the forces resulting from an impact not less than 4 times (4 g) the maximum permissable gross mass of the fully loaded portable tank at a duration typical of the mechanical shocks experienced in rail transportation. A listing of standards describing methods acceptable for performing the impact test are provided in the UN Recommendations (see § 171.7 of this subchapter). UN portable tanks used for the dedicated transportation of "Helium, refrigerated liquid," UN1963 and "Hydrogen, refrigerated liquid," UN1966 that are marked "NOT FOR RAIL TRANSPORT" in letters of a minimum height of 20 cm (8 inches) on at least two sides of the portable tank are excepted from the 4 g impact test.
(i) Longitudinal inertia. The portable tank loaded to its maximum gross weight must be positioned with its longitudinal axis vertical. It shall be held in this position for five minutes by support at the lower end of the base structure providing vertical and lateral restraint and by support at the upper end of the base structure providing lateral restraint only.
(ii) Lateral inertia. The portable tank loaded to its maximum gross weight must be positioned for five minutes with its transverse axis vertical. It shall be held in this position for five minutes by support at the lower side of the base structure providing vertical and lateral restraint and by support at the upper side of the base structure providing lateral restraint only.
[66 FR 33440, June 21, 2001, as amended at 67 FR 15744, Apr. 3, 2002]