# Praxair Distribution, Inc. — Hazardous Materials Safety Interpretation

**Citation:** 12-0249  
**Type / status:** guidance / guidance  
**Agency:** Pipeline and Hazardous Materials Safety Administration  
**Effective:** Not stated  
**Published:** 2013-05-22

12-0249 response to Praxair Distribution, Inc. concerning 171.8, 172.406, 173.25.

## Document text

<<<PAGE 1>>>

U.S. Department of Transportation
Pipeline and Hazardous Materials
Safety Administration
MAY 2 2 2013
Mr. David B. Som1emann
Manager, Transport Regulations and Fleet Safety
Praxair Distribution Inc.
39 Old Ridgebury Road
Danbury, CT 06810-5113
Reference No.: 12-0249
Dear Mr. Sonnemann:
1200 New Jersey Ave, SE
Washington, D.C. 20590
This is in response to your November 06, 2012 email requesting clarification of the Hazardous
Materials Regulations (HMR; 49 CFR Parts 171-180). You ask several questions concerning the
definition of an overpack and marking and labeling requirements for cylinders in overpacks. Your
questions are paraphrased and answered below:
Q I) A I) You request clarification as to whether the packaging configuration in the photo provided
(Figure 1) is a unit load device. Figure 1 consists of a deck plate and one or more railings
to which cylinders are secured through the use of strapping. You believe this
configuration is not an overpack because (1) it is not an enclosure, (2) it meets the
definition of a freight container in § 17I.8 except for having a volume less than 64 cubic
feet and (3) it is intended primarily for containment of packages in unit form.
The answer to your question is no. The packaging configuration in your photo (Figure I)
does not meet the definition of a freight container or a unit load device. However, this
packaging configuration does meet the defining criteria for an overpack.
As defined in§ 171.8, a unit load device is "any type of freight container, aircraft
container, aircraft pallet with a net, or aircraft pallet with a net over an igloo." And a
fi·eight container means "a reusable container having a volume of 64 cubic feet or more,
designed and constructed to permit being lifted with its contents intact and intended
primarily for containment of [smaller] packages (in unit form) during transportation."
Since the packaging configuration in your photo (Figure 1) does not meet the definition of
a freight container, or any of the other package types described in the definition of unit
load device, this packaging configuration cannot be categorized as a unit load device.
In contrast, the definition for overpack in§ 171.8, provides several examples of overpacks.
One such example is "one or more packages placed or stacked onto a load board such as a
pallet and secured by strapping, shrink wrapping, stretch wrapping or other suitable
means." This definition corresponds with the packaging configuration described in your
letter.

<<<PAGE 2>>>

Q2) A2) Q3) A3) Q4) A4) You request clarification on the requirement to display the "OVERPACK" mark when an
overpack contains multiple packages with different specifications.
Section 173.25(a)(4) requires a shipper to mark the word "OVERPACK" on an overpack
when specification packagings are required if the specification markings on the inside
packages are not visible. Unlike the marking and labeling requirements in § 173.25(a)(2),
this provision does not exempt the overpack from being marked "OVERPACK" when a
marking representative of each inner package is visible; rather, the marking on every inner
package must be visible. However, since specification markings are unlikely to be visible
· on the innermost packagings within an overpack and there is no basis to distinguish the
requirements in§ 173.25(a)(2) and (a)(4), it is reasonable for the "OVERPACK" mark to
be required, unless specification markings representative of each type included in the
overpack are visible, as stated in Letter of Interpretation 10-0149. Therefore, PHMSA
anticipates addressing this requirement in a future rulemaking.
You request acknowledgement that the labels shown in your photo (Figure 2) are visible as
required by§ 173.25(a)(2).
The only visible label in Figure 2 is a neck ring label described in CGA Pamphlet C-7,
Appendix A. As provided by § 172.400a, a cylinder containing a Division 2.1, 2.2 or 2.3
material that is not overpacked is authorized to be marked in accordance with CGA
Pamphlet C-7, Appendix A without further DOT labeling. However, since the cylinders in
Figure 2 are overpacked that exception does not apply and a hazard warning label must be
applied to each cylinder.
Additionally, the overpack must display appropriate marks and labels for each hazardous
material contained in the overpack unless marks and labels representative of each
hazardous material in the overpack are visible, as required in§ 173.25(a)(2). The portions
of the cylinders shown in Figure 2 (i.e. the upper portions) do not display any visible
markings or labels, so markings and labels are required on the overpack. However, if
unobscured markings and labels, representing each hazardous material in the overpack, are
visible on the lower portions of the cylinders that are not depicted, that is acceptable. (See
49 C.F.R. Part 172, subparts D and E.)
You request acknowledgement that a protective mesh attachment shown in your photo
(Figure 3) is allowable for the purpose of safeguarding labels against abrasion and damage
during transport. You state that the labels are not obscured by markings or attachments
when using the protective mesh.
The mesh attachment pictured in the photo (Figure 3) you submitted does not appear to be
consistent with§ 172.406(f). The requirements for label visibility in § 172.406(f) specify
that labels "must be clearly visible and may not be obscured by markings or attachments."
The intent of this requirement is to ensure that hazard communication labels clearly
illustrate the hazards presented within the package, and that the view of the required label
is not obstructed by any additional markings or packaging accessories that may reduce the

<<<PAGE 3>>>

effectiveness ofthe required hazard communication. As pictured, the mesh attachment in
the photo you provided reduces the effectiveness of the label to convey the hazards
represented within the package by partially obscuring the text on the markings and labels,
making them difficult to decipher.
I trust this satisfies your inquiry. Please contact us if we can be of further assistance.
~1:/11' .
Delmer Billings ~
Senior Regulatory Advisor
Standards and Rulemaking Division

<<<PAGE 4>>>

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Praxair Distribution Inc. /l-0 :Z L/j
39 Old Ridgebury Road
Danbury, CT 06810-5113
Tel (203) 837-2294
Fax (203) 837-2503
I. November 6, 2012
Pipeline and Hazardous Materials Safety Administration
US. Department of Transportation
1200 New Jersey Ave, SE
Washington, DC 20590
ATTN: Mr. Delmer Billings
Re: Request for Interpretation; Section §173.25
Dear Mr. Billings:
Praxair Distribution Inc. ("PDI'') hereby requests interpretation of various sections ofthe
Hazardous Materials Regulations (HMR) that define the term overpack and stipulate the
requirements for marking an overpack. In addition, PDI seeks clarification on the visibility of
labels affixed to a cylinder. The specific regulations and the interpretation for which PDI seeks
clarification are § 171. 8, § 1 73.25, and PHMSA Letter of Interpretation # 10-0 149.
PDI specifically requests clarification as to whether or not the transport device depicted in
Figure 1 is a unit load device as PDI believes. The device in Figure 1 consists of a deck plate
and one or more railings to which cylinders are secured and is used for more efficient
transport of cylinders.
Figure 1.

<<<PAGE 5>>>

Praxair Distribution, Inc. Request for Interpretation § 173.25 Page 2 of3
II. PDI believes that the transport device pictured in Figure 1 is a unit load device and not an
overpack because it is not an enclosure and meets the definition of the termfreight container
except for being smaller in volume than sixty-four (64) cubic feet. As defined in §171.8, a unit
load device is any type of freight container designed and constructed to permit being lifted with
its contents intact and intended primarily for containment of packages (in unit form) during
transportation. The device pictured in Figure 1, is intended primarily for containment of
packages (in unit form) during transportation and meets the other defining criteria as well. On
the basis that the transport device is a unit load device and not an overpack, section 173.25,
Authorized packagings and overpacks does not apply.
PDI requests clarification ofPHMSA's interpretation found in Letter oflnterpretation 10-
0149 requiring the "OVERPACK marking" unless the overpack contains multiple packages
with identical package specification marking provided package specification markings
representative of each package specification contained in the overpack are visible from the
outside. While this requirement is understood, it creates the unintended consequence
requiring marking of most overpacks containing multiple cylinders because cylinders
consolidated in an overpack typically have different package specification markings
This interpretation means that an overpack used to consolidate cylinders containing a gas of
the same proper shipping name and strapped to a wooden pallet may have to be marked
"OVERPACK" because the cylinders may be aluminum, steel, or nickel cylinders having
different package specification marking. Figure 2 illustrates a TC cylinder and a DOT
specification cylinder containing the same product.
III. Figure 2.
PDI seeks acknowledgement and clarification that labels shown in Figure 2 are visible as
required by § 173.25(a)(2) for cylinders provided with a mesh covering to protect labels and
marking and contained in an overpack. As shown in Figure 3 below, PDI applies protective
mesh over DOT required labels to guard against abrasion and other damage to labels while a
cylinder is in transportation. As shown in Figure 3, the labels affixed to the cylinder are
visible and not obscured by markings or attachments. In fact, words on the label and the
CGA C-7 marking are readable through the mesh.

<<<PAGE 6>>>

Praxair Distribution, Inc. Request for Interpretation § 173.25 Page 3 of3
figure 3.
On the basis of the information presented in items I, II, and III above, PDI hereby requests
PHMSA issue an interpretation and a further clarification to Letter of Interpretation 10-0149 to
address the three issues for defining PDI's transport device as a unit load device and answering
questions raised in items II and III of this letter.
Thank you, for your time cooperation in this matter.
Respectfully submitted,
David B. Sonnemann
Manager, Transport Regulations and Fleet Safety

<<<PAGE 7>>>

U.S. Department of Transportation
Pipeline and Hazardous Materials
Safety Administration
1200 New Jersey Ave, SE
Washington, D.C. 20590
SEP 3 2010
Mr. Mike Ritchie
Hazardous Materials Specialist
Minnesota Department of Transportation
395 John Ireland Boulevard, Mail Stop 460
St. Paul, MN 55155
Ref. No. 10-0149
Dear Mr. Ritchie:
This responds to your July 16,2010 letter requesting clarification ofthe overpack marking and
labeling requirements under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-
180). Specifically. you ask if clear shrink wrapped pallets must be marked on the outside with
the required package markings (e.g., proper shipping name, identification number, orientation
arrows, and "OVERPACK") when the markings on individual packages are not visible because
of the package configuration, but markings and labels representative of each hazardous material
are visible from the outside of the overpack. Your areas of concern are restated and answered as
follows:
Labels and Proper Shipping Name/Identification Number Markings
Section 173.25(a)(2) requires the overpack to be marked with the proper shipping name and
identification number, and labeled for each hazardous material contained therein, unless
markings and labels representative of each hazardous material in the overpack are visible. For
example, an overpack need not be marked and labeled ifthe markings (i.e., proper shipping
name and identification number) and labels on an individual package inside the overpack are not
visible but the same markings (i.e., proper shipping name and identification number) and labels
representative of that package are clearly visible from the outside on another package contained
in that overpack.
Orientation Arrow Marking
Section 173.25{a)(3) requires an overpack containing packages subject to the orientation arrow
marking requirements of§ 172.312 to be marked with orientation arrows on two opposite
vertical sides of the overpack. This requirement is in addition to the orientation arrows
displayed on the individual packages.
-~~------~----~

<<<PAGE 8>>>

"OVERPACK" Marking
Section 173.25(a)(4) requires an overpack to be marked "OVERPACK" when specification
packagings are required, unless specification markings on the inside packages are visible. The
"OVERPACK" marking is not required if the overpack contains multiple packages with
identical package specification markings provided package specification markings
representative of each package specification contained in the overpack are visible from the
outside.
I hope this information is helpful. If you have further questions, please contact this office.
Sincerely,
BenSupko
Acting Chief, Standards Development
Office of Hazardous Materials Standards

<<<PAGE 9>>>

Drakeford, Carolyn (PHMSA)
From:
Sent:
To:
Subject:
Betts, Charles (PHMSA)
Friday, July 16, 2010 2:56PM
Drakeford, Carolyn {PHMSA)
FW: Marking of overpacks
oeh er1 taab
~ 1/3·:25 l73.312.
0 verpuc l<.s
lO- Dt'-IC(
Please log this in as a new request for interpretation.
Thanks,
Charles
From: Ritchie, Mike (DOT} [mailto:Michaei.Ritchie@state.mn.us]
Sent: Friday, July 16, 2010 2:29 PM
To: Betts, Charles (PHMSA)
Subject: Marking of overpacks
July 16, 2010
Charles Betts
Chief, Standards Development
Office of Hazardous Materials Standards
US DOT/ PHMSA
1200 New Jersey Avenue
Washington, DC 20590
Re: Marking, labeling and Display of Package Specifications on Overpacks
Dear Mr. Betts,
49 CFR 173.25 requires overpacks to be marked with the proper shipping name and identification number, and
the authorized labels, for each hazardous material contained in the overpack, unless those labels and marks
are visible on the packages. Paragraph (a) {4) of that section requires the overpack to be marked with the
word OVERPACK when the hazardous material is required to be in specification packaging unless the
specification markings on the inside packages are visible.
The most common type of overpack our safety investigators encounter while doing Hazardous Materials
Package Inspection Program (HMPIP) inspections are shrink wrapped pallets. Many are not marked
OVERPACK. These pallets often contain different types of packages, for example drums and boxes on the same
pallet, and may contain several different hazardous materials. labels and marking on packages loaded in the
center of the pallet are not visible because they are covered by packages on the edge or top of the pallet.
Many non-bulk packages display the required hazmat marking and labels on a different surface than the
printed or embossed specification marking required by §178.3.
Question: If an overpack contains packages requiring specification marks, must all specification marks on each
package be visible or is a representative sample of each different specification mark acceptable?
1

<<<PAGE 10>>>

Question: If packages displaying orientation arrows as required in §172.312 are in an overpack, and those
orientation arrows are visible on the packages on two opposite sides of the overpack, must additional
orientation arrows be added the outside of the overpack to comply with §173.25 {a) (3)?
Yours truly,
Michael Ritchie
Hazardous Materials Specialist
Minnesota Department of Transportation
Office of Freight & Commercial Vehicle Operations
395 John Ireland Boulevard, Mail Stop 460
St. Paul, MN 55155-1899
(651) 366-3697
2

## Provenance

- Official: Yes
- Source: <https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/2012/120249.pdf>
- Source ID: `phmsa`
- SHA-256: `c23001c5f7bfe771a74b9e760e16f7f6bb46b4a2e74563d30f7217e77877ac5d`
- Retrieved: 2026-08-20T00:59:31.977Z
- Exported: 2026-08-23T23:35:42.018Z
- Document slug: `phmsa-interpretation-12-0249`

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