[Code of Federal Regulations]
[Title 49, Volume 2]
[Revised as of October 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 49CFR180.407]
[Page 1145-1152]
TITLE 49--TRANSPORTATION
CHAPTER I--PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION,
DEPARTMENT OF TRANSPORTATION
PART 180_CONTINUING QUALIFICATION AND MAINTENANCE OF PACKAGINGS--Table
of Contents
Subpart E_Qualification and Maintenance of Cargo Tanks
Sec. 180.407 Requirements for test and inspection of specification
cargo tanks.
(a) General. (1) A cargo tank constructed in accordance with a DOT
specification for which a test or inspection specified in this section
has become due, may not be filled and offered for transportation or
transported until the test or inspection has been successfully
completed. This paragraph does not apply to any cargo tank filled prior
to the test or inspection due date.
(2) Except during a pressure test, a cargo tank may not be subjected
to a pressure greater than its design pressure or MAWP.
(3) A person witnessing or performing a test or inspection specified
in this section must meet the minimum qualifications prescribed in Sec.
180.409.
(4) Each cargo tank must be evaluated in accordance with the
acceptable results of tests and inspections prescribed in Sec. 180.411.
(5) Each cargo tank which has successfully passed a test or
inspection specified in this section must be marked in accordance with
Sec. 180.415.
(6) A cargo tank which fails a prescribed test or inspection must:
(i) Be repaired and retested in accordance with Sec. 180.413; or
(ii) Be removed from hazardous materials service and the
specification plate removed, obliterated or covered in a secure manner.
(b) Conditions requiring test and inspection of cargo tanks. Without
regard to any other test or inspection requirements, a specification
cargo tank must be tested and inspected in accordance with this section
prior to further use if:
(1) The cargo tank shows evidence of dents, cuts, gouges, corroded
or abraded areas, leakage, or any other condition that might render it
unsafe for hazardous materials service. At a minimum, any area of a
cargo tank showing evidence of dents, cuts, digs, gouges, or corroded or
abraded areas must be thickness tested in accordance with the procedures
set forth in paragraphs (i)(2), (i)(3), (i)(5), and (i)(6) of this
section and evaluated in accordance with the criteria prescribed in
Sec. 180.411. Any signs of leakage must be repaired in accordance with
Sec. 180.413. The suitability of any repair affecting the structural
integrity of the cargo tank must be determined either by the testing
required in the applicable manufacturing specification or in paragraph
(g)(1)(iv) of this section.
(2) The cargo tank has sustained damage to an extent that may
adversely affect its lading retention capability. A damaged cargo tank
must be pressure tested in accordance with the procedures set forth in
paragraph (g) of this section.
(3) The cargo tank has been out of hazardous materials
transportation service for a period of one year or more. Each cargo tank
that has been out of hazardous materials transportation service for a
period of one year or more must be pressure tested in accordance with
Sec. 180.407(g) prior to further use.
(4) [Reserved]
(5) The Department so requires based on the existence of probable
cause that the cargo tank is in an unsafe operating condition.
[[Page 1146]]
(c) Periodic test and inspection. Each specification cargo tank must
be tested and inspected as specified in the following table by an
inspector meeting the qualifications in Sec. 180.409. The retest date
shall be determined from the specified interval identified in the
following table from the most recent inspection or the CTMV
certification date.
Compliance Dates--Inspections and Test Under Sec. 180.407(C)
------------------------------------------------------------------------
Date by which
Test or inspection (cargo tank first test must be Interval
specification, configuration, and completed (see period after
service) note 1) first test
------------------------------------------------------------------------
External Visual Inspection:
All cargo tanks designed to be September 1, 1991. 6 months.
loaded by vacuum with full
opening rear heads.
All other cargo tanks........... September 1, 1991. 1 year.
Internal Visual Inspection:
All insulated cargo tanks, September 1, 1991. 1 year.
except MC 330, MC 331, MC 338
(see Note 4).
All cargo tanks transporting September 1, 1991. 1 year.
lading corrosive to the tank.
All other cargo tanks, except MC September 1, 1995. 5 years.
338.
Lining Inspection:
All lined cargo tanks September 1, 1991. 1 year.
transporting lading corrosive
to the tank.
Leakage Test:
MC 330 and MC 331 cargo tanks in September 1, 1991. 2 years.
chlorine service.
All other cargo tanks except MC September 1, 1991. 1 year.
338.
Pressure Test:
(Hydrostatic or pneumatic) (See .................. ..............
Notes 2 and 3).
All cargo tanks which are September 1, 1991. 1 year.
insulated with no manhole or
insulated and lined, except MC
338.
All cargo tanks designed to be September 1, 1992. 2 years.
loaded by vacuum with full
opening rear heads.
MC 330 and MC 331 cargo tanks in September 1, 1992. 2 years.
chlorine service.
All other cargo tanks........... September 1, 1995. 5 years.
Thickness Test:
All unlined cargo tanks September 1, 1992. 2 years.
transporting material corrosive
to the tank, except MC 338.
------------------------------------------------------------------------
Note 1: If a cargo tank is subject to an applicable inspection or test
requirement under the regulations in effect on December 30, 1990, and
the due date (as specified by a requirement in effect on December 30,
1990) for completing the required inspection or test occurs before the
compliance date listed in table I, the earlier date applies.
Note 2: Pressure testing is not required for MC 330 and MC 331 cargo
tanks in dedicated sodium metal service.
Note 3: Pressure testing is not required for uninsulated lined cargo
tanks, with a design pressure or MAWP 15 psig or less, which receive
an external visual inspection and lining inspection at least once each
year.
Note 4: Insulated cargo tanks equipped with manholes or inspection
openings may perform either an internal visual inspection in
conjunction with the external visual inspection or a hydrostatic or
pneumatic pressure-test of the cargo tank.
(d) External visual inspection and testing. The following applies to
the external visual inspection and testing of cargo tanks:
(1) Where insulation precludes a complete external visual inspection
as required by paragraphs (d)(2) through (d)(6) of this section, the
cargo tank also must be given an internal visual inspection in
accordance with paragraph (e) of this section. If external visual
inspection is precluded because any part of the cargo tank wall is
externally lined, coated, or designed to prevent an external visual
inspection, those areas of the cargo tank must be internally inspected.
If internal visual inspection is precluded because the cargo tank is
lined, coated, or designed so as to prevent access for internal
inspection, the tank must be hydrostatically or pneumatically tested in
accordance with paragraph (g)(1)(iv) of this section. Those items able
to be externally inspected must be externally inspected and noted in the
inspection report.
(2) The external visual inspection and testing must include as a
minimum the following:
(i) The tank shell and heads must be inspected for corroded or
abraded areas, dents, distortions, defects in welds and any other
conditions, including leakage, that might render the tank unsafe for
transportation service;
(ii) The piping, valves, and gaskets must be carefully inspected for
corroded areas, defects in welds, and other conditions, including
leakage, that might render the tank unsafe for transportation service;
[[Page 1147]]
(iii) All devices for tightening manhole covers must be operative
and there must be no evidence of leakage at manhole covers or gaskets;
(iv) All emergency devices and valves including self-closing stop
valves, excess flow valves and remote closure devices must be free from
corrosion, distortion, erosion and any external damage that will prevent
safe operation. Remote closure devices and self-closing stop valves must
be functioned to demonstrate proper operation;
(v) Missing bolts, nuts and fusible links or elements must be
replaced, and loose bolts and nuts must be tightened;
(vi) All markings on the cargo tank required by parts 172, 178 and
180 of this subchapter must be legible;
(vii) [Reserved]
(viii) All major appurtenances and structural attachments on the
cargo tank including, but not limited to, suspension system attachments,
connecting structures, and those elements of the upper coupler (fifth
wheel) assembly that can be inspected without dismantling the upper
coupler (fifth wheel) assembly must be inspected for any corrosion or
damage which might prevent safe operation;
(ix) For cargo tanks transporting lading corrosive to the tank,
areas covered by the upper coupler (fifth wheel) assembly must be
inspected at least once in each two year period for corroded and abraded
areas, dents, distortions, defects in welds, and any other condition
that might render the tank unsafe for transportation service. The upper
coupler (fifth wheel) assembly must be removed from the cargo tank for
this inspection.
(3) All reclosing pressure relief valves must be externally
inspected for any corrosion or damage which might prevent safe
operation. All reclosing pressure relief valves on cargo tanks carrying
lading corrosive to the valve must be removed from the cargo tank for
inspection and testing. Each reclosing pressure relief valve required to
be removed and tested must open at the required set pressure and reseat
to a leak-tight condition at 90 percent of the set-to-discharge pressure
or the pressure prescribed for the applicable cargo tank specification.
(4) Ring stiffeners or other appurtenances, installed on cargo tanks
constructed of mild steel or high-strength, low-alloy steel, that create
air cavities adjacent to the tank shell that do not allow for external
visual inspection must be thickness tested in accordance with paragraphs
(i)(2) and (i)(3) of this section, at least once every 2 years. At least
four symmetrically distributed readings must be taken to establish an
average thickness for the ring stiffener or appurtenance. If any
thickness reading is less than the average thickness by more than 10%,
thickness testing in accordance with paragraphs (i)(2) and (i)(3) of
this section must be conducted from the inside of the cargo tank on the
area of the tank wall covered by the appurtenance or ring stiffener.
(5) Corroded or abraded areas of the cargo tank wall must be
thickness tested in accordance with the procedures set forth in
paragraphs (i)(2), (i)(3), (i)(5) and (i)(6) of this section.
(6) The gaskets on any full opening rear head must be:
(i) Visually inspected for cracks or splits caused by weather or
wear; and
(ii) Replaced if cuts or cracks which are likely to cause leakage,
or are of a depth one-half inch or more, are found.
(7) The inspector must record the results of the external visual
examination as specified in Sec. 180.417(b).
(e) Internal visual inspection. (1) When the cargo tank is not
equipped with a manhole or inspection opening, or the cargo tank design
precludes an internal inspection, the tank shall be hydrostatically or
pneumatically tested in accordance with 180.407(c) and (g).
(2) The internal visual inspection must include as a minimum the
following:
(i) The tank shell and heads must be inspected for corroded and
abraded areas, dents, distortions, defects in welds, and any other
condition that might render the tank unsafe for transportation service.
(ii) Tank liners must be inspected as specified in Sec. 180.407(f).
(3) Corroded or abraded areas of the cargo tank wall must be
thickness tested in accordance with paragraphs (i)(2), (i)(3), (i)(5)
and (i)(6) of this section.
[[Page 1148]]
(4) The inspector must record the results of the internal visual
inspection as specified in Sec. 180.417(b).
(f) Lining inspection. The integrity of the lining on all lined
cargo tanks, when lining is required by this subchapter, must be
verified at least once each year as follows:
(1) Rubber (elastomeric) lining must be tested for holes as follows:
(i) Equipment must consist of:
(A) A high frequency spark tester capable of producing sufficient
voltage to ensure proper calibration;
(B) A probe with an ``L'' shaped 2.4 mm (0.09 inch) diameter wire
with up to a 30.5 cm (12-inch) bottom leg (end bent to a 12.7 mm (0.5
inch) radius), or equally sensitive probe; and
(C) A steel calibration coupon 30.5 cm x 30.5 cm (12 inches x 12
inches) covered with the same material and thickness as that to be
tested. The material on the coupon shall have a test hole to the metal
substrate made by puncturing the material with a 22 gauge hypodermic
needle or comparable piercing tool.
(ii) The probe must be passed over the surface of the calibration
coupon in a constant uninterrupted manner until the hole is found. The
hole is detected by the white or light blue spark formed. (A sound
lining causes a dark blue or purple spark.) The voltage must be adjusted
to the lowest setting that will produce a minimum 12.7 mm (0.5 inch)
spark measured from the top of the lining to the probe. To assure that
the setting on the probe has not changed, the spark tester must be
calibrated periodically using the test calibration coupon, and the same
power source, probe, and cable length.
(iii) After calibration, the probe must be passed over the lining in
an uninterrupted stroke.
(iv) Holes that are found must be repaired using equipment and
procedures prescribed by the lining manufacturer or lining installer.
(2) Linings made of other than rubber (elastomeric material) must be
tested using equipment and procedures prescribed by the lining
manufacturer or lining installer.
(3) Degraded or defective areas of the cargo tank liner must be
removed and the cargo tank wall below the defect must be inspected.
Corroded areas of the tank wall must be thickness tested in accordance
with paragraphs (i)(2), (i)(3), (i)(5) and (i)(6) of this section.
(4) The inspector must record the results of the lining inspection
as specified in Sec. 180.417(b).
(g) Pressure test. All components of the cargo tank wall, as defined
in Sec. 178.320(a) of this subchapter, must be pressure tested as
prescribed by this paragraph.
(1) Test Procedure--(i) As part of the pressure test, the inspector
must perform an external and internal visual inspection, except that on
an MC 338 cargo tank, or a cargo tank not equipped with a manhole or
inspection opening, an internal inspection is not required.
(ii) All self-closing pressure relief valves, including emergency
relief vents and normal vents, must be removed from the cargo tank for
inspection and testing.
(A) Each self-closing pressure relief valve that is an emergency
relief vent must open at the required set pressure and seat to a leak-
tight condition at 90 percent of the set-to-discharge pressure or the
pressure prescribed for the applicable cargo tank specification.
(B) Normal vents (1 psig vents) must be tested according to the
testing criteria established by the valve manufacturer.
(C) Self-closing pressure relief devices not tested or failing the
tests in this paragraph (g)(1)(ii) must be repaired or replaced.
(iii) Except for cargo tanks carrying lading corrosive to the tank,
areas covered by the upper coupler (fifth wheel) assembly must be
inspected for corroded and abraded areas, dents, distortions, defects in
welds, and any other condition that might render the tank unsafe for
transportation service. The upper coupler (fifth wheel) assembly must be
removed from the cargo tank for this inspection.
(iv) Each cargo tank must be tested hydrostatically or pneumatically
to the internal pressure specified in the following table. At no time
during the pressure test may a cargo tank be subject to pressures that
exceed those identified in the following table:
[[Page 1149]]
------------------------------------------------------------------------
Specification Test pressure
------------------------------------------------------------------------
MC 300, 301, 302, 303, 305, 306........... 20.7 kPa (3 psig) or design
pressure, whichever is
greater.
MC 304, 307............................... 275.8 kPa (40 psig) or 1.5
times the design pressure,
whichever is greater.
MC 310, 311, 312.......................... 20.7 kPa (3 psig) or 1.5
times the design pressure,
whichever is greater.
MC 330, 331............................... 1.5 times either the MAWP or
the re-rated pressure,
whichever is applicable.
MC 338.................................... 1.25 times either the MAWP
or the re-rated pressure,
whichever is applicable.
DOT 406................................... 34.5 kPa (5 psig) or 1.5
times the MAWP, whichever
is greater.
DOT 407................................... 275.8 kPa (40 psig) or 1.5
times the MAWP, whichever
is greater.
DOT 412................................... 1.5 times the MAWP.
------------------------------------------------------------------------
(v) [Reserved]
(vi) Each cargo tank of a multi-tank cargo tank motor vehicle must
be tested with the adjacent cargo tanks empty and at atmospheric
pressure.
(vii) All closures except pressure relief devices must be in place
during the test. All prescribed loading and unloading venting devices
rated at less than test pressure may be removed during the test. If
retained, the devices must be rendered inoperative by clamps, plugs, or
other equally effective restraining devices. Restraining devices may not
prevent detection of leaks or damage the venting devices and must be
removed immediately after the test is completed.
(viii) Hydrostatic test method. Each cargo tank, including its
domes, must be filled with water or other liquid having similar
viscosity, at a temperature not exceeding 100 [deg]F. The cargo tank
must then be pressurized to not less than the pressure specified in
paragraph (g)(1)(iv) of this section. The cargo tank, including its
closures, must hold the prescribed test pressure for at least 10 minutes
during which time it shall be inspected for leakage, bulging or any
other defect.
(ix) Pneumatic test method. Pneumatic testing may involve higher
risk than hydrostatic testing. Therefore, suitable safeguards must be
provided to protect personnel and facilities should failure occur during
the test. The cargo tank must be pressurized with air or an inert gas.
The pneumatic test pressure in the cargo tank must be reached by
gradually increasing the pressure to one-half of the test pressure.
Thereafter, the pressure must be increased in steps of approximately
one-tenth of the test pressure until the required test pressure has been
reached. The test pressure must be held for at least 5 minutes. The
pressure must then be reduced to the MAWP, which must be maintained
during the time the entire cargo tank surface is inspected. During the
inspection, a suitable method must be used for detecting the existence
of leaks. This method must consist either of coating the entire surface
of all joints under pressure with a solution of soap and water, or using
other equally sensitive methods.
(2) When testing an insulated cargo tank, the insulation and
jacketing need not be removed unless it is otherwise impossible to reach
test pressure and maintain a condition of pressure equilibrium after
test pressure is reached, or the vacuum integrity cannot be maintained
in the insulation space. If an MC 338 cargo tank used for the
transportation of a flammable gas or oxygen, refrigerated liquid is
opened for any reason, the cleanliness must be verified prior to closure
using the procedures contained in Sec. 178.338-15 of this subchapter.
(3) Each MC 330 and MC 331 cargo tank constructed of quenched and
tempered steel in accordance with Part UHT in Section VIII of the ASME
Code (IBR, see Sec. 171.7 of this subchapter), or constructed of other
than quenched and tempered steel but without postweld heat treatment,
used for the transportation of anhydrous ammonia or any other hazardous
materials that may cause corrosion stress cracking, must be internally
inspected by the wet fluorescent magnetic particle method immediately
prior to and in conjunction with the performance of the pressure test
prescribed in this section. Each MC 330 and MC 331 cargo tank
constructed of quenched and tempered steel in accordance with Part UHT
in Section VIII of the ASME Code and used for the transportation of
liquefied petroleum gas must be internally inspected by the wet
fluorescent magnetic particle method immediately prior to and in
conjunction with the
[[Page 1150]]
performance of the pressure test prescribed in this section. The wet
fluorescent magnetic particle inspection must be in accordance with
Section V of the ASME Code and CGA Technical Bulletin TB-2 (IBR, see
Sec. 171.7 of this subchapter). This paragraph does not apply to cargo
tanks that do not have manholes. (See Sec. 180.417(c) for reporting
requirements.)
(4) All pressure bearing portions of a cargo tank heating system
employing a medium such as, but not limited to, steam or hot water for
heating the lading must be hydrostatically pressure tested at least once
every 5 years. The test pressure must be at least the maximum system
design operating pressure and must be maintained for five minutes. A
heating system employing flues for heating the lading must be tested to
ensure against lading leakage into the flues or into the atmosphere.
(5) Exceptions. (i) Pressure testing is not required for MC 330 and
MC 331 cargo tanks in dedicated sodium metal service.
(ii) Pressure testing is not required for uninsulated lined cargo
tanks, with a design pressure or MAWP of 15 psig or less, which receive
an external visual inspection and a lining inspection at least once each
year.
(6) Acceptance criteria. A cargo tank that leaks, fails to retain
test pressure or pneumatic inspection pressure, shows distortion,
excessive permanent expansion, or other evidence of weakness that might
render the cargo tank unsafe for transportation service, may not be
returned to service, except as follows: A cargo tank with a heating
system which does not hold pressure may remain in service as an unheated
cargo tank if:
(i) The heating system remains in place and is structurally sound
and no lading may leak into the heating system, and
(ii) The specification plate heating system information is changed
to indicate that the cargo tank has no working heating system.
(7) The inspector must record the results of the pressure test as
specified in Sec. 180.417(b).
(h) Leakage test. The following requirements apply to cargo tanks
requiring a leakage test:
(1) Each cargo tank must be tested for leaks in accordance with
paragraph (c) of this section. The leakage test must include testing
product piping with all valves and accessories in place and operative,
except that any venting devices set to discharge at less than the
leakage test pressure must be removed or rendered inoperative during the
test. All internal or external self-closing stop valves must be tested
for leak tightness. Each cargo tank of a multi-cargo tank motor vehicle
must be tested with adjacent cargo tanks empty and at atmospheric
pressure. Test pressure must be maintained for at least 5 minutes. Cargo
tanks in liquefied compressed gas service must be externally inspected
for leaks during the leakage test. Suitable safeguards must be provided
to protect personnel should a failure occur. Cargo tanks may be leakage
tested with hazardous materials contained in the cargo tank during the
test. Leakage test pressure must be no less than 80% of MAWP marked on
the specification plate except as follows:
(i) A cargo tank with an MAWP of 690 kPa (100 psig) or more may be
leakage tested at its maximum normal operating pressure provided it is
in dedicated service or services; or
(ii) An MC 330 or MC 331 cargo tank in dedicated liquified petroleum
gas service may be leakage tested at not less than 414 kPa (60 psig).
(iii) An operator of a specification MC 330 or MC 331 cargo tank,
and a nonspecification cargo tank authorized under Sec. 173.315(k) of
this subchapter, equipped with a meter may check leak tightness of the
internal self-closing stop valve by conducting a meter creep test. (See
appendix B to this part.)
(iv) An MC 330 or MC 331 cargo tank in dedicated service for
anhydrous ammonia may be leakage tested at not less than 414 kPa (60
psig).
(v) A non-specification cargo tank required by Sec. 173.8(d) of
this subchapter to be leakage tested, must be leakage tested at not less
than 16.6 kPa (2.4 psig), or as specified in paragraph (h)(2) of this
section.
(2) Cargo tanks used to transport petroleum distillate fuels that
are equipped with vapor collection equipment may be leak tested in
accordance
[[Page 1151]]
with the Environmental Protection Agency's ``Method 27--Determination of
Vapor Tightness of Gasoline Delivery Tank Using Pressure-Vacuum Test,''
as set forth in Appendix A to 40 CFR part 60. Test methods and
procedures and maximum allowable pressure and vacuum changes are in 40
CFR 63.425(e)(1). The hydrostatic test alternative, using liquid in
Environmental Protection Agency's ``Method 27--Determination of Vapor
Tightness of Gasoline Delivery Tank Using Pressure-Vacuum Test,'' may
not be used to satisfy the leak testing requirements of this paragraph.
The test must be conducted using air.
(3) A cargo tank that fails to retain leakage test pressure may not
be returned to service as a specification cargo tank, except under
conditions specified in Sec. 180.411(d).
(4) After July 1, 2000, Registered Inspectors of specification MC
330 and MC 331 cargo tanks, and nonspecification cargo tanks authorized
under Sec. 173.315(k) of this subchapter must visually inspect the
delivery hose assembly and piping system while the assembly is under
leakage test pressure utilizing the rejection criteria listed in Sec.
180.416(g). Delivery hose assemblies not permanently attached to the
cargo tank motor vehicle may be inspected separately from the cargo tank
motor vehicle. In addition to a written record of the inspection
prepared in accordance with Sec. 180.417(b), the Registered Inspector
conducting the test must note the hose identification number, the date
of the test, and the condition of the hose assembly and piping system
tested.
(5) The inspector must record the results of the leakage test as
specified in Sec. 180.417(b).
(i) Thickness testing. (1) The shell and head thickness of all
unlined cargo tanks used for the transportation of materials corrosive
to the tank must be measured at least once every 2 years, except that
cargo tanks measuring less than the sum of the minimum prescribed
thickness, plus one-fifth of the original corrosion allowance, must be
tested annually.
(2) Measurements must be made using a device capable of accurately
measuring thickness to within 0.002 of an inch.
(3) Any person performing thickness testing must be trained in the
proper use of the thickness testing device used in accordance with the
manufacturer's instruction.
(4) Thickness testing must be performed in the following areas of
the cargo tank wall, as a minimum:
(i) Areas of the tank shell and heads and shell and head area around
any piping that retains lading;
(ii) Areas of high shell stress such as the bottom center of the
tank;
(iii) Areas near openings;
(iv) Areas around weld joints;
(v) Areas around shell reinforcements;
(vi) Areas around appurtenance attachments;
(vii) Areas near upper coupler (fifth wheel) assembly attachments;
(viii) Areas near suspension system attachments and connecting
structures;
(ix) Known thin areas in the tank shell and nominal liquid level
lines; and
(x) Connecting structures joining multiple cargo tanks of carbon
steel in a self-supporting cargo tank motor vehicle.
(5) Minimum thicknesses for MC 300, MC 301, MC 302, MC 303, MC 304,
MC 305, MC 306, MC 307, MC 310, MC 311, and MC 312 cargo tanks are
determined based on the definition of minimum thickness found in Sec.
178.320(a) of this subchapter. The following Tables I and II identify
the ``In-Service Minimum Thickness'' values to be used to determine the
minimum thickness for the referenced cargo tanks. The column headed
``Minimum Manufactured Thickness'' indicates the minimum values required
for new construction of DOT 400 series cargo tanks, found in Tables I
and II of Sec. Sec. 178.346-2, 178.347-2, and 178.348-2 of this
subchapter. In-Service Minimum Thicknesses for MC 300, MC 301, MC 302,
MC 303, MC 304, MC 305, MC 306, MC 307, MC 310, MC 311, and MC 312 cargo
tanks are based on 90 percent of the manufactured thickness specified in
the DOT specification, rounded to three places.
[[Page 1152]]
TABLE I--IN-SERVICE MINIMUM THICKNESS FOR MC 300, MC 303, MC 304, MC
306, MC 307, MC 310, MC 311, AND MC 312 SPECIFICATION CARGO TANKS
CONSTRUCTED OF STEEL AND STEEL ALLOYS
------------------------------------------------------------------------
In-
Nominal service
Minimum manufactured thickness (US gauge or decimal minimum
inches) equivalent thickness
for reference
(inches) (inches)
------------------------------------------------------------------------
19............................................... 0.0418 0.038
18............................................... 0.0478 0.043
17............................................... 0.0538 0.048
16............................................... 0.0598 0.054
15............................................... 0.0673 0.061
14............................................... 0.0747 0.067
13............................................... 0.0897 0.081
12............................................... 0.1046 0.094
11............................................... 0.1196 0.108
10............................................... 0.1345 0.121
9................................................ 0.1495 0.135
8................................................ 0.1644 0.148
7................................................ 0.1793 0.161
3/16............................................. 0.1875 0.169
1/4.............................................. 0.2500 0.225
5/16............................................. 0.3125 0.281
3/8.............................................. 0.3750 0.338
------------------------------------------------------------------------
TABLE II--IN-SERVICE MINIMUM THICKNESS FOR MC 301, MC 302, MC 304, MC
305, MC 306, MC 307, MC 311, AND MC 312 SPECIFICATION CARGO TANKS
CONSTRUCTED OF ALUMINUM AND ALUMINUM ALLOYS
------------------------------------------------------------------------
In-
service
Minimum manufactured thickness minimum
thickness
(inches)
------------------------------------------------------------------------
0.078........................................................ 0.070
0.087........................................................ 0.078
0.096........................................................ 0.086
0.109........................................................ 0.098
0.130........................................................ 0.117
0.141........................................................ 0.127
0.151........................................................ 0.136
0.172........................................................ 0.155
0.173........................................................ 0.156
0.194........................................................ 0.175
0.216........................................................ 0.194
0.237........................................................ 0.213
0.270........................................................ 0.243
0.360........................................................ 0.324
0.450........................................................ 0.405
0.540........................................................ 0.486
------------------------------------------------------------------------
(6) An owner of a cargo tank that no longer conforms to the minimum
thickness prescribed for the design as manufactured may use the cargo
tank to transport authorized materials at reduced maximum weight of
lading or reduced maximum working pressure, or combinations thereof,
provided the following conditions are met:
(i) A Design Certifying Engineer must certify that the cargo tank
design and thickness are appropriate for the reduced loading conditions
by issuance of a revised manufacturer's certificate, and
(ii) The cargo tank motor vehicle's nameplate must reflect the
revised service limits.
(7) An owner of a cargo tank that no longer conforms with the
minimum thickness prescribed for the specification may not return the
cargo tank to hazardous materials service. The tank's specification
plate must be removed, obliterated or covered in a secure manner.
(8) The inspector must record the results of the thickness test as
specified in Sec. 180.417(b).
(9) For MC 331 cargo tanks constructed before October 1, 2003,
minimum thickness shall be determined by the thickness indicated on the
U1A form minus any corrosion allowance. For MC 331 cargo tanks
constructed after October 1, 2003, the minimum thickness will be the
value indicated on the specification plate. If no corrosion allowance is
indicated on the U1A form then the thickness of the tank shall be the
thickness of the material of construction indicated on the UIA form with
no corrosion allowance.
(10) For 400-series cargo tanks, minimum thickness is calculated
according to tables in each applicable section of this subchapter for
that specification: Sec. 178.346-2 for DOT 406 cargo tanks, Sec.
178.347-2 for DOT 407 cargo tanks, and Sec. 178.348-2 for DOT 412 cargo
tanks.
[Amdt. 180-2, 54 FR 25032, June 12, 1989]
Editorial Note: For Federal Register citations affecting Sec.
180.407, see the List of CFR Sections Affected which appears in the
Finding Aids section of the printed volume and on GPO Access.