Interpretation Response #03-0304 ([Mr. Thomas Lee Bartlett])

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date: 04/21/2004

Company Name:

Individual Name: Mr. Thomas Lee Bartlett

Location State: TX Country: US

View the Interpretation Document

Response text:

Apr 21, 2004

Mr. Thomas Lee Bartlett                 Reference No. 03-0304
Attorney at Law
402 Main at Preston
Suite 3 North
Houston, TX 77002

Dear Mr. Bartlett:

This is in response to your letter requesting clarification concerning requirements under the Hazardous Materials Regulations (HMR), 49 CFR Parts 171-180, applicable to DOT Specification cargo tank motor vehicles.  You state that your request concerns an MC-312 cargo tank offloading 32% hydrochloric acid from the top of the cargo tank using pressure above 15 psig.  A PVC manual product ball valve located in the discharge piping on top of the cargo tank failed.  This cargo tank was manufactured in 1994 with the outlet nozzle blanked off for the customer to install the dip pipe, valve and piping.  I am answering your questions in the order as they appear in your letter.

Ql.       In 1994, were polyvinyl chloride (PVC) valves authorized on MC-312 cargo tank motor vehicles?

Al.        In 1994, a PVC (non-metallic) manually operated ball valve located in the product discharge could be used on an MC 312 cargo tank motor vehicle provided the material was capable of withstanding the pressures specified in the MC 312 specification.  The MC 312 specification was last published in The 1990 edition of the HMR, although new cargo tank constructions were authorized to be marked and certified to the MC 312 specification until October 31, 1995 (See current § 180.405(c)(1)). The applicable requirements in the 1990 49 CFR, at § 178-340-8(d) (3), state in part:

Strength of piping, fittings, hose and hose couplings: Hose, piping and fittings for tanks to be unloaded by pressure shall be designed for a bursting pressure of at least 100 p.s.i.g. and not less than four times the pressure to which, in any instance, it may be subjected in service by the action, of any vehicle mounted pump or other device (not including safety relief valves), the action of which may be to subject certain portions of the tank piping and hose to pressures greater than the design pressure of the tank.

Q2.      Are MC-412 cargo tank motor vehicles authorized to use PVC valves?

A2.      Yes. Section 178.345-9(h) authorizes the use of a non­metallic pipe, valve or connection line that is not as strong and heat resistant as the cargo tank material only when the attachment is located outside of the lading retention system.

Q3.       In January 2001, was a PVC valve installed as a replacement on an MC-312 cargo tank motor vehicle authorized?

A3.       Yes (see A2).

Q4.        In 2002, was a remote closure device required on an MC-312 cargo tank motor vehicle that was  unloaded from the top using air pressure?

A4.  Yes, see § 180.405(f) (1).

Sincerely,

Hattie L. Mitchell
Chief, Regulatory Review and Reinvention
Office of Hazardous Materials Standards

180.405, 180.07

Regulation Sections