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Interpretation Response #02-0159 ([HMT Associates, L.L.] [E. A. Altemos])

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

Interpretation Response Details

Response Publish Date:

Company Name: HMT Associates, L.L.

Individual Name: E. A. Altemos

Location State: VA Country: US

View the Interpretation Document

Response text:

Aug 20, 2002

Mr. E. A. Altemos                 Reference No. 02-0159
HMT Associates, L.L.C.
603; King Street
Suite 300
Alexandria, VA 22314-3105

Dear Mr. Altemos:

This responds to your letter requesting a determination that an article, i.e., a valve for internal combustion engines (e.g., automobile or aircraft engines) containing a small quantity of sodium or potassium sodium alloy encapsulated and sealed within the valve cavity by welding, is not subject to the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180).  You provided information, as follows:

The valves vary in size, the largest is approximately five (5) inches in length.  The outside appearance of the valves are similar to other internal combustion engine intake or exhaust valves.  However, to aid in transferring heat down the stem and away from the head -- which is directly exposed to the high temperatures attained in the engine cylinder during operation -- a small quantity of sodium or potassium sodium alloy is contained in a cavity inside the valve.  The maximum quantity of material contained in the valve cavity is 1.6 grams, and the cavity is not filled to more than 65% of its volume, allowing room for expansion of the material under all operating conditions to which the valve would be subjected in an operating engine.

The valves are inspected by performing non-destructive testing to ensure that they are free of defects that could cause failure of the valve and release of its contents.  The minimum melting temperature of the steel used in the valves is 2,500°F, and the filled valves are subjected to heat treatment at temperatures ranging from a minimum of 830F to a maximum of 2,050°F, without failure or release of contents.  Valves are designed, and some are tested, to ensure that they do not fail or leak when subjected to lateral bending loads that induce stress levels in walls of the cavity of approximately 50,000 psi.  The valves may be expected to retain their contents when subjected to mechanical shocks or crushing if involved in transport or handling accidents.

Based on the information provided, it is our determination that 1.6 grains or less of sodium or potassium sodium alloy encapsulated and sealed by welding within a valve for an internal combustion engine is in a quantity and form that does not pose a hazard in transportation and, therefore, these articles are not subject to the HMR.  This determination does not apply to valves containing more than 1.6 grams of sodium or potassium sodium alloy, which must be shipped in conformance with all applicable requirements of the HMR.

I hope this satisfies your inquiry.  If we can be of further assistance, please contact us.


Edward T. Mazzullo
Director, Office of Hazardous
Materials Standards


Regulation Sections

Section Subject
172.101 Purpose and use of hazardous materials table