# TANKCON — Hazardous Materials Safety Interpretation

- **operation:** document
- **citation:** 98-0569
- **title:** TANKCON — Hazardous Materials Safety Interpretation
- **source type:** guidance
- **agency:** Pipeline and Hazardous Materials Safety Administration
- **status:** guidance
- **official:** true
- **published on:** 1998-05-08
- **effective on:** Not available
- **summary:** 98-0569 response to TANKCON concerning 178.345.
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- **source url:** https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/1998/980569.pdf
**body:**

<<<PAGE 1>>>

of Transportation
U.S.Department
400 Seventh Street. S.W
Special Programs
Research and
Washington, D.C.
20590
Administration
MAY
8 1998
Mr. Al Chatillon, P. Eng.
TANKCON
4250 Marcel Lacasse,
Boisbriand, Que. J7H 1N3
Dear Mr. Chatillon:
This is in response to your letter concerning the location of pressure relief devices specified in 49
CFR 178.345-10(c). You state that your understanding is that a cargo tank designed with all
inlets/outlets in the rear, but with the pressure relief vent in the top of the manhole cover, would
comply with § 178.345-10(c) even if the vent is not in the center of the tank.
Section 178.345-10(c) provides specific requirements for the location of relief devices and
several examples on where relief can be located. It states "Each pressure relief device must
communicate with the vapor space above the lading as near as practicable to the center of the
vapor space." This requirement applies regardless of vehicle orientation. Therefore, the
configuration you suggest would not meet the requirements of the Hazardous Materials
Regulations unless the manhole cover is located as near practicable to the center of the vapor
space.
If you need further assistance, please contact us.
Sincerely,
Thorns I. Allan
Thomas G. Allan
Senior Transportation Regulations Specialists
Office of Hazardous Materials Standards

<<<PAGE 2>>>

02/24/98
18:32
84376208
TANKCONFRP
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Kaim
STANKCON
File 178.345-10
DAp'
ebruary 24th, 1998
-fice of Hazardous Materials
5. Department of Transport
Standards
ashington, DC.
1590
*ention: Mr. E. Mazzulla,
Interpretation of 178.345-10 c) Location of relief devices
lowing my conversation with Mr. P. Olsen concerning an
erstanding, could please confirm this position.
erpretation of Section 178.345-10 c) you will find here in our
• 're of the tank.
ser section 178.345-10 c) the pressure relief device must be
:ontact with
the vapor. space and
as close as practible to top
i stion: If the tank is designed with all the inlets/outlets in
the rear and the vent is located in the top of the
contact with
location would comply with section 178.345-10 c) even
the vapor space and consequently this
if it is not located in the centre of the tank.
files.
agree with the above statement? If so please confirm for
WE
-ank you in advance for your cooperation.
Ya
Truly,
A1 -
in ita
Chatillon, F.Eng.
•
:T.
4250
arcel Locasse, Boisbriand, Qué. J7H 1N3 • Tél: (514) 435-5483 • Fox: (514) 437-6208
4:.
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