[Federal Register Volume 60, Number 65 (Wednesday, April 5, 1995)]
[Rules and Regulations]
[Pages 17398-17403]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-8349]




[[Page 17397]]

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Part III





Department of Transportation





_______________________________________________________________________



Research and Special Programs Administration



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49 CFR Parts 173, 178, and 180



Cargo Tanks; Miscellaneous Requirements; Revisions and Response to 
Petitions for Reconsideration; Final Rule

Federal Register / Vol. 60, No. 65 / Wednesday, April 5, 1995 / Rules 
and Regulations 
[[Page 17398]] 

DEPARTMENT OF TRANSPORTATION

Research and Special Programs Administration

49 CFR Parts 173, 178 and 180

[Docket No. HM-183C; Amdt. Nos. 173-240, 178-105 and 180-7]
RIN 2137-AC37


Cargo Tanks; Miscellaneous Requirements; Revisions and Response 
to Petitions for Reconsideration

AGENCY: Research and Special Programs Administration (RSPA), DOT.

ACTION: Final rule; response to petitions for reconsideration.

-----------------------------------------------------------------------

SUMMARY: This document amends a final rule published on November 3, 
1994, and concerns manufacture, qualification, and maintenance of DOT 
specification cargo tank motor vehicles. In response to petitions for 
reconsideration, RSPA is revising design loading requirements for MC 
331 cargo tank motor vehicles and making other minor editorial and 
technical changes for clarity. The changes made in this document are 
intended to ease certain regulatory requirements where there will be no 
adverse effect on safety.

DATES: Effective: May 22, 1995.
    Compliance date: Compliance with the regulations, as amended 
herein, is authorized as of April 5, 1995.

FOR FURTHER INFORMATION CONTACT: Ronald Kirkpatrick, telephone (202) 
366-4545, Office of Hazardous Materials Technology, or Jennifer Karim, 
(202) 366-4488, Office of Hazardous Materials Standards, Research and 
Special Programs Administration, U.S. Department of Transportation, 
Washington, DC 20590-0001.

SUPPLEMENTARY INFORMATION: On November 3, 1994, RSPA published in the 
Federal Register a final rule, under Docket No. HM-183C (59 FR 55162), 
amending certain requirements for the manufacture, qualification and 
maintenance of cargo tank motor vehicles. Changes were made to relax 
the requirements for structural integrity, accident damage protection, 
welding and design quality control procedures, and pressure relief 
based on comments from industry. Changes were also made to require 
facilities repairing cargo tanks stamped as meeting the American 
Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME 
Code) to have a Certificate of Authorization for use of an ``R'' stamp 
from the National Board of Boiler and Pressure Vessel Inspectors 
(National Board) Code .
    RSPA received five petitions for reconsideration of certain aspects 
of the final rule. These petitions were submitted by the Cargo Tank 
Manufacturers Association (CTMA), Cargo Tank Concepts, Ltd. (CTCL), 
Truck Trailer Manufacturers Association (TTMA), National Propane Gas 
Association (NPGA), and the Compressed Gas Association, Inc. (CGA).
    CTMA opposed several provisions adopted in the final rule. First, 
CTMA petitioned RSPA to reconsider its position on how the design 
stress calculations, in 49 CFR 178.345-3(c), should be applied to cargo 
tank loading conditions. Except for the loadings prescribed in 
paragraph (c)(i), CTMA stated:

    [T]he loads are extreme loads that will be experienced rarely if 
at all during the life of a cargo tank and [the] ASME Code allowable 
stresses should be based on the stress increase allowed for wind and 
seismic loads which are also experienced rarely if at all in the 
life of stationary vessels. Per UG-23 of the ASME Code, this 
increase is 20 percent. CTMA believes that the loads specified in 
building codes [are] applicable to pressure vessels in the same 
manner. Using ASME allowable stresses for these load conditions is 
too conservative since margins of safety are pyramided if rarely 
occurring extreme loads cannot be resisted by emergency stresses as 
recommended by CTMA.

    As noted by RSPA in the preamble to the final rule (59 FR 55165), 
discussions have been ongoing for a number of years on how to combine 
the loadings in calculating the structural integrity requirements. The 
concept of separating structural loadings into two categories, normal 
operating loading and extreme dynamic loading, was proposed by several 
cargo tank motor vehicle designers at a public meeting in February 1994 
and more fully developed later. In normal operations, a cargo tank can 
be expected to routinely experience relatively low dynamic forces; 
these forces are to be considered to occur simultaneously. Under 
extreme dynamic loadings, the cargo tank experiences relatively high 
forces which occur rarely, if at all, during the life of a cargo tank; 
these forces are considered to act independently, one at a time. This 
approach has received wide acceptance and is the foundation for new 
recommended practices under development by a TTMA engineering 
committee.
    RSPA does not believe the calculations for ``stress increase'' 
referred to by CTMA necessarily apply to dynamic loads experienced 
either in normal operations or in extreme loading conditions 
experienced by cargo tank motor vehicles. Two provisions for increased 
allowable stresses are prescribed in the ASME Code, Section VIII, 
Division 1, UG-23. In paragraph (c) of UG-23, a factor of 1.5 is 
discussed for ``combined maximum primary membrane stress plus primary 
bending stress across the thickness.'' Evidently, the 20 percent factor 
referred to by CTMA is associated with the factor discussed in 
paragraph (d) for the ``combination of earthquake loading, or wind 
loading with other loadings in UG-22,'' with the stipulation that 
earthquake and wind loadings need not be considered to act 
simultaneously. RSPA believes the many years of experience accumulated 
by cargo tank motor vehicle manufacturers support the approach adopted 
in the final rule. The reference in the CTMA petition to other ``loads 
specified in building codes'' may or may not pertain to this matter. 
CTMA did not identify those codes and provided no information on 
whether or how they have any application to cargo tank structural 
integrity or accident damage protection. Therefore, CTMA's request is 
denied.
    Second, CTMA opposed the 2 ``g'' design load for rollover damage 
protection devices specified in Sec. 178.345-8(c)(1). CTMA stated that 
the loads on rollover devices, in the case of longitudinal sliding, 
would be limited by the coefficient of sliding friction of the metal 
rollover devices on the ground or pavement and, in the case of lateral 
rollover, would be limited even further by the lateral force leading to 
continued overturn of the tank. RSPA discussed commenters' requests to 
reduce the 2 ``g'' design load for rollover protection at length in the 
preamble of the final rule (59 FR 55166). RSPA recognizes that new 
designs may be necessary to gain significant benefits in safety.
    RSPA also recognizes that the amount of force currently imposed in 
the horizontal plane is a simplification of many potential variables 
which can come into play during an overturn accident. Many scenarios 
are possible: the impact surface may be smooth or rough, horizontal or 
sloping, as hard as concrete or as soft as sand or damp earth; the 
vehicle may roll over an obstacle such as a guard rail; the cargo tank 
may receive an impact over its entire length or on only a small part of 
its exposed surface; etc. CTMA's comments on use of the coefficient of 
sliding friction might be appropriate for overturn on a smooth, hard 
highway surface, but would impose relatively moderate loads in 
comparison to other rollover scenarios. Accident scenarios where the 
rollover damage protection devices plow through earth or strike 
[[Page 17399]] roadside obstacles impose much greater loadings on the 
devices. Therefore, CTMA's petition for a reduction in the safety 
performance of rollover damage protection is denied.
    Third, CTMA repeated its position that it is difficult to design 
rear-end protection devices in compliance with the loads prescribed in 
Sec. 178.345-8(d), particularly devices which are offset from the load 
path. CTMA repeated its belief previously expressed in comments that 
the intent of the regulation is for the loads to be transmitted to the 
tank structure and absorbed without exceeding the permitted stresses 
anywhere along the load path. CTMA offered no new information to 
support this position. The revised requirements were discussed in the 
preamble of the final rule (59 FR 55167). RSPA believes that the 
revised requirements for the DOT 400-series cargo tanks allow engineers 
more freedom in the design of rear-end protection, including approaches 
involving energy dissipation and dampening. Therefore, CTMA's petition 
is denied.
    Finally, CTMA commented on the suitability of applying ASME Code 
standards to the cargo tank industry while not recognizing other 
``alternative quality control program(s).'' This issue was fully 
discussed in the preamble of the final rule (59 FR 55162). In addition, 
this subject was addressed in previous notices and public meetings 
under Docket HM-183 extending over a period of nearly ten years. CTMA 
provided no additional data or information to support changing the 
final rule. Therefore, RSPA's position remains unchanged and 
requirements for using procedures established under the ASME Code and 
the National Board of Boiler and Pressure Vessel Inspectors (National 
Board) Code are retained, and CTMA's petition is denied.
    CTCL petitioned RSPA to reconsider amendments allowing a small 
release of certain types of ladings from the pressure relief system, in 
overturn accidents, before reclosing to a leak-tight position. CTCL 
stated that it has designed a vent which releases vapors instead of 
lading in an overturn accident situation, and that this information was 
not presented RSPA earlier because the technology had not yet been 
developed. RSPA welcomes the development by industry of improved valve 
designs. RSPA solicited information during the HM-183C rulemaking 
proceeding on the existence of reclosing pressure relief devices 
capable of reseating with no loss of lading and not subject to clogging 
and sticking during field service. However, RSPA believes CTCL has not 
provided sufficient information to support excluding the use of other 
valve designs at this time, and CTCL's petition is denied.
    TTMA petitioned RSPA to continue allowing a cargo tank manufacturer 
holding an ASME ``U'' stamp to make repairs to ASME stamped cargo 
tanks. TTMA stated that an ASME ``U'' stamp holder should not be 
required to obtain an ``R'' stamp from the National Board and there is 
no reason why the National Board cannot continue to inspect repairs 
made by a ``U'' stamp holder. Furthermore, the National Board 
Inspection Code allows repairs to be made on ASME stamped cargo tanks 
by a facility holding an ``R'' stamp or by a facility working within an 
individual governmental jurisdiction where that jurisdiction has issued 
authorization for the facility to perform repairs.
    RSPA explained in the preambles of the notice of proposed 
rulemaking (March 3, 1993; 58 FR 12316) and the final rule (59 FR 
55170) that the National Board has control over the quality of work 
performed by an ``R'' stamp holder. Jurisdictional authorization is 
recognized only within the governmental boundaries where the repair 
facility is located. This type of authorization may be appropriate for 
work performed on stationary vessels, but not for mobile systems such 
as cargo tank motor vehicles. RSPA believes it is essential to apply a 
nationally recognized consensus standard in a uniform manner regardless 
of jurisdiction. Therefore, the requirement that repairs on DOT 
specification cargo tanks certified to the ASME Code must be performed 
only by a facility holding a valid ``R'' stamp is retained and TTMA's 
petition is denied.
    CGA petitioned RSPA to remove the word ``internal'' in the first 
sentence in Sec. 178.338-11(c) specifying that each filling and 
discharge line for liquids must be provided with a remotely controlled 
internal self-closing stop valve. CGA pointed out that the word 
``internal'' did not appear in the provision in the notice of proposed 
rulemaking and that requiring internal valves would bring the cryogenic 
flammable lading industry to a standstill because of the inner tank/
outer jacket configuration of these cargo tanks. RSPA agrees. It was 
not RSPA's intent to require an ``internal'' self-closing valve on 
these tanks, but to broaden the requirement to include all flammable 
ladings. Therefore, the word ``internal'' is removed.
    NPGA asked RSPA to reconsider its decision in the final rule that a 
future rulemaking would address design loading requirements for MC 331 
specification cargo tanks. The preamble to the final rule (59 FR 55163) 
noted NPGA's recommendation for uniformity in design loading 
requirements for all DOT specification cargo tanks. In its petitions, 
NPGA asked RSPA to extend, until March 1, 1997, the compliance date for 
construction of MC 331 cargo tank motor vehicles conforming to the 
structural integrity requirements contained in Sec. 178.337-3. It also 
urged RSPA to make resolution of stress analysis a priority project.
    RSPA has reviewed the report previously submitted by NPGA and found 
that NPGA's proposed loadings for the MC 331 cargo tank are very 
similar to the loadings adopted for the DOT 400-series cargo tanks. 
This supports NPGA's position that cargo tank motor vehicles encounter 
similar loadings regardless of whether the cargo tank is used to 
transport a liquid or gas lading. Therefore, for greater consistency, 
RSPA is amending the structural integrity requirements in Sec. 178.337-
3 by adopting the same loadings as specified for the DOT 400-series 
cargo tank specifications. In view of this change, a new paragraph (f) 
is added in Sec. 178.23 to provide for a MC 331 specification cargo 
tank conforming to the structural integrity requirements contained in 
Sec. 178.337-3 or to the corresponding requirements in effect at the 
time of manufacture. However, the material thickness may not be less 
than that required by the ASME Code.
    Based on comments received from CGA that design loadings specified 
for MC 338 cargo tanks should not be revised for consistency with the 
MC 331 specification, RSPA is not making any change to Sec. 178.338-3. 
CGA has advised it is developing a document to provide additional 
guidance to its members on the design and construction of MC 338 cargo 
tanks.
    The amendment to Sec. 178.337-3 eliminates any need for a delay in 
the compliance date for construction of MC 331 cargo tank motor 
vehicles conforming to the structural integrity requirements, and this 
part of NPGA's petition is denied.
    Additionally, CGA petitioned RSPA to allow modifications on 
cryogenic cargo tanks originally authorized by exemption prior to 
introduction of the MC 338 specification. In accordance with 
Sec. 180.405(d), such cargo tanks must be marked ``DOT MC 338-E'' 
followed by the exemption number. CGA contends that modifications such 
as adding a manhole may require removal of the outer jacket and 
installation of a new shell course to the inner vessel; only local 
reinforcement of the inner vessel was required 
[[Page 17400]] previously. After further consideration, RSPA agrees 
with CGA. In establishing the MC 338 specification, the final rule 
(June 16, 1983; 48 FR 27674) stated ``[T]his grandfathering of existing 
tanks is necessary to avoid potential severe economic consequences to 
some exemption holders and can be justified from a safety point of view 
because of the thorough technical review involved in the exemption 
process, notwithstanding the fact that certain aspects of certain 
exemptions may differ from this final rule.'' Nothing in subsequent 
rulemakings has changed this premise. Therefore, in this final rule, in 
Sec. 180.413, in paragraph (d)(3), the introductory text is revised, 
and a new paragraph (v) is added to allow MC 338 cargo tanks authorized 
under Sec. 180.405(d) to be structurally modified provided that no 
reduction in structural integrity is incurred and that any modification 
is in accordance with the ASME Code or with the MC 338 specification.
    Finally, RSPA has made the following editorial revisions for 
clarity: In Sec. 178.345-3, in paragraphs (c)(1)(iii)(B) and 
(c)(2)(iii)(B), in the second sentence, the wording ``horizontal pivot 
of the tractor'' is revised to read ``horizontal pivot of the truck 
tractor''. In Sec. 178.345-14, in paragraph (b)(3), the wording ``Tank 
MAWP'' is revised to read ``Tank maximum allowable working pressure 
(MAWP)''. In Sec. 180.403, a sentence is added to the definition of 
modification. In Sec. 180.405, in paragraph (h)(2), reference to 40 CFR 
60.601 is deleted. In Sec. 180.407, in the table in paragraph (c), 
under the subheading ``Thickness Test'' in the first column, the 
wording ``in corrosive service, except'' is revised to read 
``transporting lading corrosive to the tank, except''; and paragraphs 
(d)(1) (i) and (ii) are revised to remove duplicative language. In 
Sec. 180.413, paragraphs (b)(6) and (d)(10) are revised to clarify that 
a repair or modification affecting the structural integrity of a 
pressure cargo tank, with respect to pressure, must be determined by 
testing required by the specification or by Sec. 180.407(g)(1)(iv).

Rulemaking Analyses and Notices

1. Executive Order 12866 and DOT Regulatory Policies and Procedures

    This final rule is not considered a significant regulatory action 
under section 3(f) of Executive Order 12866 and was not reviewed by the 
Office of Management and Budget. The rule is not considered significant 
under the Regulatory Policies and Procedures of the Department of 
Transportation (44 FR 11034). This amendment imposes no new 
requirements on affected persons. The final regulatory evaluation for 
the November 1994 final rule is available for review in the docket. 
Changes in this final rule did not warrant revision of the regulatory 
evaluation.

2. Executive Order 12612

    This final rule has been analyzed in accordance with the principles 
and criteria contained in Executive Order 12612 (``Federalism''). 
Federal law expressly preempts State, local, and Indian tribe 
requirements applicable to the transportation of hazardous material 
that cover certain subjects and are not ``substantively the same'' as 
the Federal requirements. 49 U.S.C. 5125(b)(1). These covered subjects 
are:
    (A) The designation, description, and classification of hazardous 
material;
    (B) The packing, repacking, handling, labeling, marking, and 
placarding of hazardous material;
    (C) The preparation, execution, and use of shipping documents 
related to hazardous material and requirements respecting the number, 
contents, and placement of those documents;
    (D) The written notification, recording, and reporting of the 
unintentional release in transportation of hazardous material; or
    (E) The design, manufacturing, fabricating, marking, maintenance, 
reconditioning, repairing, or testing of a packaging or a container 
which is represented, marked, certified, or sold as qualified for use 
in transporting hazardous material.
    This final rule addresses the design, manufacturing, and certain 
other requirements for packages represented as qualified for use in the 
transportation of hazardous material. Therefore, this final rule 
preempts State, local, or Indian tribe requirements that are not 
``substantively the same'' as Federal requirements on these subjects. 
Section 5125(b)(2) of Title 49 U.S.C. provides that when DOT issues a 
regulation concerning any of the covered subjects after November 16, 
1990, DOT must determine and publish in the Federal Register the 
effective date of Federal preemption. The effective date may not be 
earlier that the 90th day following the date of issuance of the final 
rule and no later than two years after the date of issuance. RSPA has 
determined that the effective date of Federal preemption of this final 
rule will be July 5, 1995.
    Because RSPA lacks discretion in this area, preparation of a 
federalism assessment is not warranted.

3. Regulatory Flexibility Act

    I certify that this final rule will not have a significant economic 
impact on a substantial number of small entities. This rule applies to 
manufacturers, shippers, carriers, and owners of cargo tanks, some of 
which are small entities. There are no direct or indirect adverse 
economic impacts for small units of government, businesses, or other 
organizations.

4. Paperwork Reduction Act

    This amendment imposes no changes to the information collection and 
recordkeeping requirements contained in the June 12, 1989 final rule, 
which were approved by the Office of Management and Budget (OMB) under 
the provisions of 44 U.S.C. chapter 35 and assigned control number 
2137-0014.

5. Regulation Identifier Number (RIN)

    A regulation identifier number (RIN) is assigned to each regulatory 
action listed in the Unified Agenda of Federal Regulations. The 
Regulatory Information Service Center publishes the Unified Agenda in 
April and October of each year. The RIN number contained in the heading 
of this document can be used to cross-reference this action with the 
Unified Agenda.

List of Subjects

49 CFR Part 173

    Hazardous materials transportation, Packaging and containers, 
Radioactive materials, Reporting and recordkeeping requirements, 
Uranium.

49 CFR Part 178

    Hazardous materials transportation, Motor vehicles safety, 
Packaging and containers, Reporting and recordkeeping requirements.

49 CFR Part 180

    Hazardous materials transportation, Motor carriers, Motor vehicle 
safety, Packaging and containers, Reporting and recordkeeping 
requirements.

    In consideration of the foregoing, title 49, chapter I of the Code 
of Federal Regulations, is amended as set forth below:

PART 173--SHIPPERS--GENERAL REQUIREMENTS FOR SHIPMENTS AND 
PACKAGINGS

    1. The authority citation for part 173 continues to read as 
follows:

    Authority: 49 U.S.C. 5101-5127, 49 CFR 1.53.

    2. In Sec. 173.23, a new paragraph (f) is added to read as follows:


Sec. 173.23  Previously authorized packaging.

* * * * * [[Page 17401]] 
    (f) An MC 331 cargo tank motor vehicle must conform to structural 
integrity requirements in Sec. 178.337-3 or to corresponding 
requirements in effect at the time of manufacture.

PART 178--SPECIFICATIONS FOR PACKAGINGS

    3. The authority citation for part 178 continues to read as 
follows:

    Authority: 49 U.S.C. 5101-5127, 49 CFR 1.53.

    4. In Sec. 178.337-3, paragraph (c) is revised to read as follows:


Sec. 178.337-3  Structural integrity.

* * * * *
    (c) Shell design. Shell stresses resulting from static or dynamic 
loadings, or combinations thereof, are not uniform throughout the cargo 
tank motor vehicle. The vertical, longitudinal, and lateral normal 
operating loadings can occur simultaneously and must be combined. The 
vertical, longitudinal and lateral extreme dynamic loadings occur 
separately and need not be combined.
    (1) Normal operating loadings. The following procedure addresses 
stress in the tank shell resulting from normal operating loadings. The 
effective stress (the maximum principal stress at any point) must be 
determined by the following formula:

    S = 0.5(S<INF>y + S<INF>x) <plus-minus> [0.25(S<INF>y - 
S<INF>x)<SUP>2 + S<INF>s<SUP>2]<SUP>0.5

Where:

(i) S = effective stress at any given point under the combination of 
static and normal operating loadings that can occur at the same time, 
in psi.
(ii) S<INF>y = circumferential stress generated by the MAWP and 
external pressure, when applicable, plus static head, in psi.
(iii) S<INF>x = The following net longitudinal stress generated by the 
following static and normal operating loading conditions, in psi:

    (A) The longitudinal stresses resulting from the MAWP and external 
pressure, when applicable, plus static head, in combination with the 
bending stress generated by the static weight of the fully loaded cargo 
tank, all structural elements, equipment and appurtenances supported by 
the cargo tank wall;
    (B) The tensile or compressive stress resulting from normal 
operating longitudinal acceleration or deceleration. In each case, the 
forces applied must be 0.35 times the vertical reaction at the 
suspension assembly, applied at the road surface, and as transmitted to 
the cargo tank wall through the suspension assembly of a trailer during 
deceleration; or the horizontal pivot of the truck tractor or converter 
dolly fifth wheel, or the drawbar hinge on the fixed dolly during 
acceleration; or anchoring and support members of a truck during 
acceleration and deceleration, as applicable. The vertical reaction 
must be calculated based on the static weight of the fully loaded cargo 
tank, all structural elements, equipment and appurtenances supported by 
the cargo tank wall. The following loadings must be included:
    (1) The axial load generated by a decelerative force;
    (2) The bending moment generated by a decelerative force;
    (3) The axial load generated by an accelerative force; and
    (4) The bending moment generated by an accelerative force; and
    (C) The tensile or compressive stress generated by the bending 
moment resulting from normal operating vertical accelerative force 
equal to 0.35 times the vertical reaction at the suspension assembly of 
a trailer; or the horizontal pivot of the upper coupler (fifth wheel) 
or turntable; or anchoring and support members of a truck, as 
applicable. The vertical reaction must be calculated based on the 
static weight of the fully loaded cargo tank, all structural elements, 
equipment and appurtenances supported by the cargo tank wall.

(iv) S<INF>s = The following shear stresses generated by the following 
static and normal operating loading conditions, in psi:

    (A) The static shear stress resulting from the vertical reaction at 
the suspension assembly of a trailer, and the horizontal pivot of the 
upper coupler (fifth wheel) or turntable; or anchoring and support 
members of a truck, as applicable. The vertical reaction must be 
calculated based on the static weight of the fully loaded cargo tank, 
all structural elements, equipment and appurtenances supported by the 
cargo tank wall;
    (B) The vertical shear stress generated by a normal operating 
accelerative force equal to 0.35 times the vertical reaction at the 
suspension assembly of a trailer; or the horizontal pivot of the upper 
coupler (fifth wheel) or turntable; or anchoring and support members of 
a truck, as applicable. The vertical reaction must be calculated based 
on the static weight of the fully loaded cargo tank, all structural 
elements, equipment and appurtenances supported by the cargo tank wall;
    (C) The lateral shear stress generated by a normal operating 
lateral accelerative force equal to 0.2 times the vertical reaction at 
each suspension assembly of a trailer, applied at the road surface, and 
as transmitted to the cargo tank wall through the suspension assembly 
of a trailer, and the horizontal pivot of the upper coupler (fifth 
wheel) or turntable; or anchoring and support members of a truck, as 
applicable. The vertical reaction must be calculated based on the 
static weight of the fully loaded cargo tank, all structural elements, 
equipment and appurtenances supported by the cargo tank wall; and
    (D) The torsional shear stress generated by the same lateral forces 
as described in paragraph (c)(1)(iv)(C) of this section.
    (2) Extreme dynamic loadings. The following procedure addresses 
stress in the tank shell resulting from extreme dynamic loadings. The 
effective stress (the maximum principal stress at any point) must be 
determined by the following formula:

S = 0.5(S<INF>y + S<INF>x) <plus-minus> [0.25(S<INF>y - S<INF>x)<SUP>2 
+ S<INF>s<SUP>2]<SUP>0.5

Where:

(i) S = effective stress at any given point under a combination of 
static and extreme dynamic loadings that can occur at the same time, in 
psi.
(ii) S<INF>y = circumferential stress generated by MAWP and external 
pressure, when applicable, plus static head, in psi.
(iii) S<INF>x = the following net longitudinal stress generated by the 
following static and extreme dynamic loading conditions, in psi:

    (A) The longitudinal stresses resulting from the MAWP and external 
pressure, when applicable, plus static head, in combination with the 
bending stress generated by the static weight of the fully loaded cargo 
tank, all structural elements, equipment and appurtenances supported by 
the tank wall;
    (B) The tensile or compressive stress resulting from extreme 
longitudinal acceleration or deceleration. In each case the forces 
applied must be 0.7 times the vertical reaction at the suspension 
assembly, applied at the road surface, and as transmitted to the cargo 
tank wall through the suspension assembly of a trailer during 
deceleration; or the horizontal pivot of the truck tractor or converter 
dolly fifth wheel, or the drawbar hinge on the fixed dolly during 
acceleration; or the anchoring and support members of a truck during 
acceleration and deceleration, as applicable. The vertical reaction 
must be calculated based on the static weight of the fully loaded cargo 
tank, all structural elements, equipment and appurtenances supported by 
the cargo tank wall. The following loadings must be included: 
[[Page 17402]] 
    (1) The axial load generated by a decelerative force;
    (2) The bending moment generated by a decelerative force;
    (3) The axial load generated by an accelerative force; and
    (4) The bending moment generated by an accelerative force; and
    (C) The tensile or compressive stress generated by the bending 
moment resulting from an extreme vertical accelerative force equal to 
0.7 times the vertical reaction at the suspension assembly of a 
trailer, and the horizontal pivot of the upper coupler (fifth wheel) or 
turntable; or the anchoring and support members of a truck, as 
applicable. The vertical reaction must be calculated based on the 
static weight of the fully loaded cargo tank, all structural elements, 
equipment and appurtenances supported by the cargo tank wall.

(iv) S<INF>s = The following shear stresses generated by static and 
extreme dynamic loading conditions, in psi:

    (A) The static shear stress resulting from the vertical reaction at 
the suspension assembly of a trailer, and the horizontal pivot of the 
upper coupler (fifth wheel) or turntable; or anchoring and support 
members of a truck, as applicable. The vertical reaction must be 
calculated based on the static weight of the fully loaded cargo tank, 
all structural elements, equipment and appurtenances supported by the 
cargo tank wall;
    (B) The vertical shear stress generated by an extreme vertical 
accelerative force equal to 0.7 times the vertical reaction at the 
suspension assembly of a trailer, and the horizontal pivot of the upper 
coupler (fifth wheel) or turntable; or anchoring and support members of 
a truck, as applicable. The vertical reaction must be calculated based 
on the static weight of the fully loaded cargo tank, all structural 
elements, equipment and appurtenances supported by the cargo tank wall;
    (C) The lateral shear stress generated by an extreme lateral 
accelerative force equal to 0.4 times the vertical reaction at the 
suspension assembly of a trailer, applied at the road surface, and as 
transmitted to the cargo tank wall through the suspension assembly of a 
trailer, and the horizontal pivot of the upper coupler (fifth wheel) or 
turntable; or anchoring and support members of a truck, as applicable. 
The vertical reaction must be calculated based on the static weight of 
the fully loaded cargo tank, all structural elements, equipment and 
appurtenances supported by the cargo tank wall; and
    (D) The torsional shear stress generated by the same lateral forces 
as described in paragraph (c)(2)(iv)(C) of this section.
* * * * *


Sec. 178.338-11  [Amended]

    5. In Sec. 178.338-11, in paragraph (c) introductory text, in the 
first sentence, the wording ``remotely controlled internal self-closing 
stop valve'' is revised to read ``remotely controlled self-closing 
shut-off valve''.


Sec. 178.345-3  [Amended]

    6. In Sec. 178.345-3, in paragraphs (c)(1)(iii)(B) and 
(c)(2)(iii)(B), in the second sentence, the wording ``horizontal pivot 
of the tractor'' is revised to read ``horizontal pivot of the truck 
tractor''.


Sec. 178.345-14  [Amended]

    7. In Sec. 178.345-14, in paragraph (b)(3), the wording ``Tank 
(MAWP)'' is revised to read ``Tank maximum allowable working pressure 
(MAWP)''.

PART 180--CONTINUING QUALIFICATION AND MAINTENANCE OF PACKAGINGS

    8. The authority citation for part 180 continues to read as 
follows:

    Authority: 49 U.S.C. 5101-5127, 49 CFR 1.53.

    9. In Sec. 180.403, the introductory text in the definition for 
``modification'' is revised to read as follows:


Sec. 180.403  Definitions.

* * * * *
    Modification means any change to the original design and 
construction of a cargo tank or a cargo tank motor vehicle which 
affects its structural integrity or lading retention capability. Any 
modification which involves welding on the cargo tank wall also must 
meet all requirements for ``Repair'' as defined in this section. * * *
* * * * *


Sec. 180.405  [Amended]

    10. In Sec. 180.407, in paragraph (h)(2), in the second sentence, 
the reference ``40 CFR 60.501 and 60.601'' is revised to read ``40 CFR 
60.501''.
    11. In Sec. 180.407, paragraphs (d)(1)(i) and (ii) are revised to 
read as follows:


Sec. 180.407  Requirements for test and inspection of specification 
cargo tanks.

* * * * *
    (d) * * *
    (1) * * *
    (i) Visual inspection is precluded by internal lining or coating, 
or
    (ii) The cargo tank is not equipped with a manhole or inspection 
opening.
* * * * *


Sec. 180.407  [Amended]

    11a. In addition, in Sec. 180.407, in the table in paragraph (c), 
under the subheading ``Thickness Test'' in the first column, the 
wording ``in corrosive service, except'' is revised to read 
``transporting material corrosive to the tank, except''.
    12. In Sec. 180.413, paragraphs (b)(6), ((d)(3) introductory text 
and (d)(10) are revised, and a new paragraph (d)(3)(v) is added to read 
as follows:


Sec. 180.413  Repair, modification, stretching, or rebarrelling of 
cargo tanks.

* * * * *
    (b) * * *
    (6) The suitability of any repair affecting the structural 
integrity of the cargo tank must be determined by the testing required 
either in the applicable manufacturing specification, or in 
Sec. 180.407(g)(1)(iv).
* * * * *
    (d) * * *
    (3) Except as provided in paragraph (d)(3)(v) in this section, all 
new material and equipment, and equipment affected by modification, 
stretching or rebarrelling must meet the requirements of the 
specification in effect at the time such work is performed, and must 
meet the applicable structural integrity requirements (Secs. 178.337-3, 
178.338-3, or 178.345-3 of this subchapter). The work must conform to 
the requirements of the applicable specification as follows:
* * * * *
    (v) For Specification MC 338 cargo tanks, the provisions of 
specification MC 338. However, structural modifications to MC 338 cargo 
tanks authorized under Sec. 180.405(d) may conform to applicable 
provisions of the ASME Code instead of specification MC 338, provided 
the structural integrity of the modified cargo tank is at least 
equivalent to that of the original cargo tank.
* * * * *
    (10) The suitability of any modification affecting the structural 
integrity of the cargo tank, with respect to pressure, must be 
determined by the testing required either in the applicable 
manufacturing specification, or in Sec. 180.407(g)(1)(iv).
* * * * *


Sec. 180.413  [Amended]

    13. In addition, in Sec. 180.413, the following changes are made:
    a. In paragraph (d)(3)(iii), at the end of the paragraph, the word 
``and'' is removed.
    b. In paragraph (d)(3)(iv), at the end of the paragraph, the period 
is removed and ``; and'' is added in its place.

    [[Page 17403]] Issued in Washington, DC on March 30, 1995, under 
authority delegated in 49 CFR Part 1.
Ana Sol Gutierrez,
Deputy Administrator, Research and Special Programs Administration.
[FR Doc. 95-8349 Filed 4-4-95; 8:45 am]
BILLING CODE 4910-60-P