An MPT must be designed—

(a) In accordance with the ASME Code and this subpart;

(b) With a maximum gross weight of 55,000 pounds;

(c) To hold a liquid cargo that has a vapor pressure of 43 pounds per square inch absolute (psia) or less at a temperature of 122 °F;

(d) With a minimum service temperature of 0 °F or higher;

(e) With a maximum allowable working pressure of not less than 20 pounds per square inch gauge (psig) but not more than 48 psig; and

(f) To withstand dynamic loading conditions applied simultaneously.

(a) The calculated stress in the tank under design conditions, including dynamic loading conditions applied simultaneously, must not exceed the allowable stress listed in Division 1 of section VIII of the ASME Code, for a design temperature of 122 °F.

(b) The calculated stress in the tank at test pressure must not exceed 75 percent of the minimum yield stress, 1 or 37.5 percent of the minimum tensile stress 1 of the material, whichever is less.

The calculated stress for the framework must be 80 percent or less of the minimum yield stress of the framework material under the dynamic loading conditions that are applied simultaneously.

(a) Except as allowed in paragraph (b) of this section, a tank with a diameter of—

(1) 6 feet or less must have a shell and head of 3/16 inch thickness or more; or

(2) More than 6 feet must have a shell and head of 1/4 inch thickness or more.

(b) If the tank has additional framework to guard against accidental puncturing of the tank, the shell and head thickness must be 1/8 inch or more.

(a) A tank without a vacuum breaker must be designed to withstand an external pressure of 7 1/2 psig or more.

(b) A tank with a vacuum breaker must be designed to withstand an external pressure of 3 psig or more.

The material for a tank must meet the requirements in Division 1 of section VIII of the ASME Code.

Each gasket and lining must be made of material that is—

(a) Chemically compatible with the product for which the tank is approved; and

(b) Resistant to deterioration from the product for which the tank is approved.

A tank must have a cross section design that is—

(a) Circular; or

(b) Other than circular and stress analyzed experimentally by the method contained in UG-101 of the ASME Code.

The base of an MPT must be as wide and as long as the tank.

If a tank is not completely supported by a framework, it must be supported by two or more external saddles, each of which extends to 120 degrees or more of the shell circumference.

An MPT must have an inspection opening that is designed in accordance with Division 1 of section VIII of the ASME Code.

Each pipe connection that is not a pressure relief device must be fitted with a manually operated stop valve or closure located as close to the tank as practicable.

If an MPT is designed with a filling or discharge connection in the bottom, the connection must be fitted with a bolted blank flange, threaded cap, or similar device to protect against leakage of the product, and a manually operated valve that is located—

(a) Inside the tank and operated outside the tank; or

(b) Outside the tank but as close to it as practicable.

Each valve and fitting must be protected from mechanical damage by—

(a) The tank;

(b) A tank saddle;

(c) The framework; or

(d) A guard.

Each filling and discharge valve must have a securing device to prevent unintentional opening.

A stop valve that operates by a screwed spindle must close in a clockwise direction.

Each MPT must have attached lifting fittings so that the tank remains horizontal and stable while being moved.

An MPT or its framework must have sufficient number of positive action securing devices, including hooks, lugs, or padeyes, to attach the unit to the vessel so that—

(a) The stress does not exceed the standard contained in § 64.15; and

(b) Additional lashing is not needed.

(a) An MPT with an internal capacity of more than 550 U.S. gallons must have one or more spring loaded relief valves. In addition, a rupture disc may be attached.

(b) An MPT with an internal capacity of 550 U.S. gallons or less must have a rupture disc or a spring loaded relief valve.

Each opening of a tank must be labeled to identify the function such as “suction”, “discharge”, “heating coil”.

Any part of a tank furnished by an outside supplier may not be used in a tank unless it bears—

(a) The Coast Guard symbol;

(b) The Marine Inspection Office identification letters;

(c) The word “part”;

(d) The manufacturer's name and serial number; and

(e) The design pressure.

(a) A corrosion-resistant metal plate containing the information in paragraph (b) of this section must be permanently attached to each MPT.

(b) Each information plate required in paragraph (a) of this section must bear the following information in legible letters 3/16 inch or more in height:

(1) Owner's name.

(2) Manufacturer's name.

(3) Date of manufacture.

(4) Serial number of tank.

(5) Maximum allowable working pressure in psig.

(6) Test pressure in psig.

(7) External-pressure rating in psig.

(8) Total capacity in gallons.

(9) Maximum net weight in long tons.

(10) Maximum gross weight in long tons.

(11) Percent ullage at 122 °F.

(12) Date of hydrostatic test.

A pressure relief device must be located on an MPT in a place that—

(a) Is the highest practical point of the tank; and

(b) Allows direct communication with the vapor space.