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authorization by a motor carrier, authorize the use of limited numbers, and for limited times, of new tanks which fail to meet the requirements of this specification. In the event of such request for authorization, the carrier shall furnish those details concerning the design and construction of the tank as seem necessary for the determination of its ability safely to transport corrosive liquids. (Order 12, 18 F. R. 6782, Oct. 27, 1953)

$ 78.331–5 Marking of cargo tanks (a) Metal identification plate. On the right side, near the front, and in a place readily accessible for inspection, there shall be on every cargo tank a metal plate. This plate shall be permanently affixed by means of soldering, brazing, welding, or other suitable means; and upon it shall be marked by stamping, embossing, or other means of forming letters into or on the metal of the plate itself in the manner illustrated below, at least the information indicated. The plate shall not be so painted as to obscure the markings thereon.

Carrier's Serial Number.1
Manufacturer's Name.?
Date of Manufacture.”
ICC MC.
Maximum Working Pressure."
Material.
Lining."
Nominal Capacity

U. S. Gallons.' Density of Cargo, Maximum. Lb/Gallon..

(b) Test date markings. The date of the last test or retest required by

the regulations in this part shall be painted on the tank in letters not less than 114 inches high, in legible colors, immediately below the metal identification plates specified in paragraph (a) of this section,

(c) Certification by markings. The markings specified in paragraphs (a) and (b) of this section shall serve to certify that the information thereby set forth is correct. (Order 12, 18 F. R. 6782, Oct. 27, 1953)

$ 78.331-6 Times of retesting of cargo tanks. Every cargo tank used for the transportation of any corrosive liquid shall be tested or retested as follows:

(a) Tanks out of service one year of more. Every cargo tank which has been out of transportation service for a period of one year or more shall not be returned to or placed in such service until it shall have successfully fulfilled the requirements set forth under $ 78.331-7.

(b) Nonspecification tanks. Every cargo tank not complying with the requirements set forth in $ 78.331-2 (a) or $ 78.331-3 shall be tested at least once in every calendar year and shall successfully fulfill the requirements set forth under $ 78.331-7. No two such required tests shall be closer together than 6 months.

(c) Specification tanks. Every cargo tank complying with the requirements set forth in $ 78.331-2 (a) or $ 78.331-3 shall be tested at least once in every 5year period. If tested no oftener than once every 5 years, at least one such test shall be made in the last year of any such 5-year period. The time of reckoning of such testing of such cargo tanks shall be from the time of the last test made in accordance with the requirements set forth under $ 78.331-7.

(d) Novel cargo tanks. Every cargo tank which shall have been authorized by this Commission to transport corrosive liquids under the provisions of $ 78.331_4 shall be tested under requirements specifically set forth in the terms of such authorization.

(e) Testing following accidents. Every cargo tank capable of suitable repair following any accident in which a tank motor vehicle may have been involved shall be retested in accordance with the requirements set forth under $ 78.331-7

· Carriers are not required to number their tanks serially; any designation regularly used by the carrier to identify the tanks may be put in this space.

* In the event the identity of the tank manufacturer or the date of manufacture 18 not known and cannot be ascertained, the spaces indicated shall be marked "MAKE UNKNOWN" and/or "DATE OF MANUFACTURE UNKNOWN".

: Substitute "ICC SPEC-T-118", or "ICC 7.5-8-1", or "MC 310" or "NO SPECIFICATION", as appropriate. For MC 311 cargo tanks insert MC 311-IIS for steel tanks designed in accordance with Table II of § 78.331-8 (d); MC 311-IIIS for steel tanks designed in accordance with Table III of $ 78.331-8 (d) and MC 311-IVS for steel tanks designed in accordance with Table IV of $ 78.331–8 (d). For aluminum tanks substitute AL for S.

* This data required for MC 311 cargo tanks only.

if the cargo tank has itself been damaged in a manner likely to affect the safety of operation of the motor vehicle, or if the damage to the tank motor vehicle is such as to make the safety of the cargo tank uncertain.

(f) Special testing required by the Commission. Upon the showing of probable cause of the necessity for retest, the Commission may, in its discretion, cause any cargo tank to be retested in accordance with the requirements of $ 78.331-7 at any time. [Order 12, 18 F. R. 6782, Oct. 27, 1953)

$ 78.331-7 Method of testing-(a) Test for leaks; cargo tanks. Every cargo tank shall be tested by completely filling the tank and dome with water or other liquid having a similar viscosity, or with a corrosive liquid permitted to be transported in the cargo tank, the temperature of which shall not exceed 100° F. during the test, and applying a pressure of 142 times the design working pressure but not less than 3 pounds per square inch gauge. The pressure shall be gauged at the top of tank. The tank must hold the prescribed pressure for at least 10 minutes without failure, undue distortion, leakage or evidence of im. pending failure. All closures shall be in place while test is made.

(b) Test for distortion or failure. Every cargo tank shall be tested by the pressures prescribed in paragraph (a) of this section and shall withstand such pressures without undue distortion or other indication of impending failure. If there is undue distortion, or if failure impends or occurs, the cargo tank shall not be returned to service unless a suitable repair is made. The suitability of the repair shall be determined by the same method of test.

(c) Test of heating system. After any interior heating system consisting of coil piping is installed, and before the tanks to which they are fitted are placed in service, the heating system shall be tested. Systems employing media such as steam or hot water under pressure for heating the contents of cargo tanks shall be tested with hydrostatic pressure and proved to be tight at 200 pounds per square inch gauge. Systems employing fiues for the heating of the contents of cargo tanks shall be suitably tested to insure against the leakage of the contents of the tanks either into the flues or into the atmosphere. (Order 12, 18 F. R. 6783, Oct. 27, 1953)

$ 78.331-8 Design requirements-(a) A. S. M. E. Code construction. Cargo tanks built of ferrous materials under this specification that are unloaded by pressure must be built of welded construction in accordance with the A. S. M. E. Code for Unfired Pressure Vessels, 1949, 1950, 1951, or 1952 editions-no revisions, but shall not have head, bulkhead, baffle or shell thicknesses less than that specified in paragraphs (c) and (d) of this section, nor shall the spacing of bulkheads, bafiles, or shell stiffeners exceed that specified in those sections.

(b) When divided into compartments. When the interior of the tank is divided into compartments, each compartment shall be designed, constructed, tested, and retested as a separate tank.

(c) Head, bulkhead and baffle thicknesses. Tanks built under this specification, that are not constructed in accordance with paragraph (a) of this section shall have head thicknesses conforming with those in the following tables:

TABLE 1-MINIMUM THICKNESS OF HEADS, BULKHEADS, AND BAFFLES (DISHED, CORRUGATED, REINFORCED OR

ROLLED)-FOR MILD, High TENSILE AND STAINLESS STEELS

Volume capacity of tank in gallons per inch of length

Weight of product at 60° F.

in pounds per gallon

10 or less

1

Less than 10. 10 to 13 Over 13 to 16.

10 gauge
8 gauge

Over 10 to 14

Over 14 to 18

Over 18

12 gauge
10 gauge
8 gauge

9 gauge.
36 inch.
44 inch

8 gauge.
44 inch.
44 inch.

36 inch

1 Wherever gauges are specified in this specification the references shall be to U. S. Standard gauge.

(d) Shell thickness. Tanks built under this specification, that are not constructed in accordance with paragraph (a) of this section, shall have shell thicknesses conforming with those in the following tables:

TABLE (I-FOR LIQUIDS LESS THAN 10 POUNDS PER GALLON Minimum shell thickness in United States Standard gauge and inches-For mild, high tensile and stainless steel

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TABLE III-FOR LIQUIDS OVER 10 TO 13 POUNDS PER GALLON (Minimum shell thickness in United States Standard gauge and inches-For mild, high tensile and stainless steel]

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TABLE IV-FOR LIQUIDS OVER 13 TO 16 POUNDS PER GALLON (Minimum shell thickness in United States Standard gauge and inches-For mild, high tensile and stainless steel)

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(e) Cargo tanks built of non-ferrous metals. Cargo tanks constructed of materials other than mild, high tensile or stainless steel shall have shell and head thicknesses designed in accordance with the following formula:

Thickness for materials other than steel-Steel thickness from tables X 3

3X 107 Modulus of elasticity of

material to be used.

(Order 12, 18 F. R. 6783, Oct. 27, 1953)

$ 78.331-9 Materials. Methods of design, fabrication, and construction for non-ferrous materials shall be such as to result in a cargo tank having properties at least equal to those of a ferrous cargo tank.

(a) A. S. M. E. Code materials. Cargo tanks required to comply with the A. S. M. E. Code for Unfired Pressure Vessels must be manufactured of materials authorized by the Code.

(b) Ferrous metal properties. Materials used in cargo tanks built to conform with the tables in $ 78.331-8 must have the following minimum physical properties: Yield point.--

25,000 lb. per sq. in. Ultimate strength.--- 45,000 lb. per sq. in. Minimum elongation, 20 percent.

2-inch sample.

(c) Aluminum properties. Aluminum materials must have the following minimum physical properties:

Yield point.-

12,000 lb. per sq. in. Ultimate strength.--- 17,000 lb. per sq. in. Minimum elongation, 6 percent. 2-inch sample.

(d) Lining. Except as provided in paragraph (e) of this section, cargo tanks must be lined and the material used for lining each cargo tank subject to this specification shall be homogeneous, nonporous, imperforate when applied, not less elastic than the metal of the tank proper, and substantially immune to attack by the commodities to be transported therein. It shall be of substantially uniform thickness, and it shall be directly bonded or attached by other equally satisfactory means. Joints and seams in the lining shall be made by fusing the material together, or by other equally satisfactory means. The interior of the tank shall be free from scale, oxidation, moisture, and all foreign matter during the lining operation. (e) Conditions under which tanks need not be lined. Tanks need not be lined as provided in paragraph (d) of this section if:

(1) The material of the tank is substantially immune to attack by the materials to be transported therein.

(2) The material of the tank is thick enough to withstand 10 years' normal service without being reduced at any point to less thickness than that specified in $ 78.331-8 corresponding to its type, or

(3) The chemical reaction between the material of the tank and the commodity to be transported therein is such as to allow the tank to be properly pacified or neutralized. (Order 12, 18 F. R. 6784, Oct. 27, 1953)

$ 78.331-10 Joints. (a) All joints and seams formed in the manufacture of any cargo tank shall be made tight by welding, riveting, riveting and welding, brazing, or riveting and brazing, at the option of the motor carrier, subject to the limitation that any of the aforesaid methods are permissible only when any one of them or combination as used in the tank is not subject to adverse action by the nature of the corrosive liquid which is to be transported in such tank. (Order 12, 18 F. R. 6784, Oct. 27, 1953)

$ 78.331-11 Tank outlets-(a) No bottom outlets. Except as provided hereinafter, no cargo tanks, except those used for the shipments of sludge acid or alkaline corrosive liquids, shall have bottom discharge outlets; outlets leaving the cargo tank at or near the top but having the end of the outlet below the top liquid level shall not be considered as bottom outlets but such outlets must be equipped with a shut-off valve at the point of outlet from the cargo tank and a shut-off valve at the discharge end of the outlet and must not be moved with any of the contents in the outlet beyond the point where it leaves the cargo tank. The valve at the tank shall be protected against damage in the event of overturn. Cargo tanks used for the transportation of sludge acid and/or alkaline corrosive liquid may be equipped with bottom outlets when the products to be transported are too viscous to be unloaded through a dome connection or top outlet provided such bottom outlets are equipped with an effective and reliable shut-off valve located inside the

shell of the tank, tank compartment outlet, or sump if the sump is integral with the tank.

(b) Bottom wash-out chambers. Tanks may be equipped with bottom washout chambers. Bottom wash-out chambers shall be of metal not subject to rapid deterioration by the lading and shall be provided with a liquid-tight closure at its lower end. If used for loading or unloading, they shall be equipped with a valve or plug at the upper end.

(c) Bottom outlets. Bottom outlets shall be of metal not subject to rapid deterioration by the lading, and each shall be provided with a valve or plug at its upper end and a liquid-tight closure at its lower end. Every such valve or plug shall be such as to insure against unseating due to stresses or shocks incident to transportation.

(d) Shear section. Any outlet shall be provided with a shear section between each shut-off valve seat and draw-off valve which section will break under strain, unless the discharge piping is so arranged as to afford equivalent protection, and leave the shut-off valve seat intact in case of accident to the draw-off valve or piping. Heater coils, when installed, shall be so constructed that the breaking off of their external connections will not cause leakage of contents of tanks.

(e) Protection of valves. Draw-off valves and fittings of cargo tanks projecting beyond the frame, or if the vehicle be frameless, beyond the shell, shall be adequately protected in the event of a collision by steel bumpers or other equally effective devices. [Order 12, 18 F. R. 6784, Oct. 27, 1953, as amended by Order 27, 21 7611, Oct. 4, 1956)

$ 78.331-12 Venting, gauging, loading, and air inlet devises-(a) Safety vent. Each tank or compartmnet thereof must be equipped with suitable pressure relief devices as required by the Code, or shall be fitted with suitable rupture discs in the dome or manhole assemblies in lieu of mechanical pressure-relief valves. Such discs shall be designed to rupture at not to exceed 112 times the design working pressure.

(b) Gauging, loading and air inlet devices. Gauging, loading, and air-inlet devices, including their valves, shall be provided with adequate means for their

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