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Section §173.115: Class 2, Divisions 2.1, 2.2, and 2.3-Definitions

Below are the available interpretations and guidance for the given section. To return to the list of parts, use the Parts link above. If you do not see any guidance or interpretation information below, that means there is none available for the given part/section. Return to the search page to browse additional regulations sections.

PHMSA has published several Frequently Asked Questions (FAQ) documents on regulatory topics. Please review our FAQ documents below:

Additionally PHMSA has Hazardous Materials FAQs based on letters of interpretation on the following topics:

This section of the website provides the ability to find regulations information including regulations parts, content of sections, and interpretations for regulations sections. Below is a list of parts, identified by the part number and subject. To browse sections by part, click on the subject link below. You will be taken to the eCFR website to view sections for a part.

A written regulatory interpretation, response to a question, or an opinion concerning a pipeline safety issue may be obtained by submitting a written request to the Office of Pipeline Safety (PHP–30), PHMSA, U.S. Department of Transportation, 1200 New Jersey Avenue SE., Washington, DC 20590–0001 or at the email address: In addition to email address, the requestor must include his or her return address and should also include a daytime telephone number. Requests should be submitted at least 120 days before the time the requestor needs a response.

Note: electronic submission is provided as alternative to the 49 CFR Part 190.11(b) mail-in requirement.

The regulations text of the section can be found on the eCFR website. To view the regulations text, use the link below. For assistance, please send an email to

View section 173.115 on the ECFR website

Interpretation Responses

Ref ID Date Company Name Individual Name Response Document
23-0096 Airborne Labs International, Inc. Aniyah Volpe View
21-0033 Hunter Aviation International, Inc. John Lusa View
19-0045 Maryland Department of Environment Michael Polinski View
19-0038 The Chemours Company Randolph Martin View
18-0054 Gayston Corporation Dave Schmitz View
18-0031 The Chemours Company Mr. Randolph Martin View
17-0115 C.H.&I Technologies, Inc. Eric WIlliams View
07-0143 PerkinElmer Optoelectronics Mr. David Harmon View
11-0287 USA Shooting Mr. Robert K. Mitchell View
12-0183 Bureau of Explosives, TTC, Inc Mr. Paul Draper View
11-0169 Duke Energy Corporation Mr. Charles Denny View
10-0012 Detector Electronics Corporation Mr. Jon Varner View
98-0186 Exxel/Atmos, Inc. Mr. John A. Del Grosso View
98-0518 Wastewater, Soil & Gas Analysis Inc. Dr. Kuldeep Verma View
08-0237 OxLife LLC Mr. Stuart H. Bassine View
15-0234 GBLTSC Inc. an ENCISO Industries Co. Mr. Oscar Enciso View
09-0264 Kelly Aerospace Mr. Mark Mertes View
08-0239 Thermo Fisher Scientific Customer Channels Group Mr. Gene Sanders View
11-0046 Chart Industries Mr. Dan Bricker View
04-0053 Inogen Inc Mr. Robert S. Fary View
11-0006 Stolt Tank Containers Mr. John Cario View
04-0093 Sovereign Specialty Chemicals Mr. Kevin W. Johnston View
06-0180 HMT Associates, L.L.C Mr. E.A. Altemos  View
09-0242 DGD Inc. Mr. Luis Lopez View
09-0223 Hydrotest Tech. Mr. David A. Wright View
11-0052 Honeywell Inc. Ms. Claire Matlon View
05-0215 SeQual Technologies, Inc. Ms. Pamela J. Jackson View
11-0088 Honeywell International, Inc. Ms. Carrie Wayne View
10-0055 MidAmerican Energy Holdings Company Mr. Douglas E. Lunstra View
15-0044 Northern Air Cargo Mr. Mark Smith View
08-0266 International Biophysics Corporation (IBC) Mr. William R. Wilkinson View