1625-0062 Stat/Authority

§ 64.9

46 CFR Ch. I (10–1–11 Edition)

working pressure is used in the calculation of the minimum thickness of each
element of the tank, excluding the allowance for corrosion and the thickness for loadings other than pressure,
as provided for in the ASME Code.
(e) Test pressure means a hydrostatic
pressure of at least one and one-half
times the maximum allowable working
pressure.
(f) Dynamic loading conditions means
the following:
(1) A loading in the vertical down direction equal to 2 times the weight of
the tank and the heaviest product carried.
(2) A loading in the transverse direction equal to the weight of the tank
and the heaviest product carried.
(3) A loading in the longitudinal direction equal to the weight of the tank
and the heaviest product carried.
(g) Owner means the person, corporation, company, partnership, or organization in which is vested the ownership, dominion, or title of a portable
tank.
[CGD 73–172, 39 FR 22950, June 25, 1974, as
amended by CGD 84–043, 55 FR 37409, Sept. 11,
1990]

§ 64.9 Maintenance, repair, and alteration of MPTs.
(a) Each MPT must be maintained in
accordance with the approved plans,
this part, and subpart 98.30 of this
chapter.
(b) Repair of an MPT is authorized,
provided that each repair is in accordance with the approved plans.
(c) No MPT may be altered, except
with the written approval of the Commanding Officer, U.S. Coast Guard Marine Safety Center.
(d) After each welded repair or alteration, an MPT must be hydrostatically
pressure-tested in accordance with
paragraph (a) of § 64.83 of this part.
[CGD 84–043, 55 FR 37409, Sept. 11, 1990]

wreier-aviles on DSK3TPTVN1PROD with CFR

Subpart B—Standards for an MPT
§ 64.11 Design of MPTs.
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.
[CGD 84–043, 55 FR 37410, Sept. 11, 1990; 55 FR
40755, Oct. 4, 1990]

§ 64.13

Allowable stress; tank.

(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.
[CGD 73–172, 39 FR 22950, June 25, 1974, as
amended by CGD 84–043, 55 FR 37410, Sept. 11,
1990]

§ 64.15

Allowable stress; framework.

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.
§ 64.17

Minimum tank thickness.

(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.
1 Listed in Division 1 of section VIII of the
ASME Code.

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