DOT 55

[Roy Parker <RoyAParker@compuserve.com>]

                    DOT SPECIFICATION 55
                  49 CFR 178.250 (Deleted)
178.250   Specification 55: metal encased, lead or uranium
    metal-shielded, radioactive materials container.
178.250-1 Compliance
    (a)   Required in all details.
178.250-2 Requirements for design and construction.
    (a)   Lead or uranium metal shield to be encased in mild
          steel or equally fire resistant metal of minimum
          wall thickness as follows:
          (1)  One-eight inch (1/8") thick for not more than
               6 inches of lead or uranium metal (see
               Note 1).
          (2)  One-fourth inch (1/4") thick for more than
               6 inches of lead or uranium (see Note 1).
              
               Note 1: Thickness of lead to be measured from
                       outer  edge   of  source   cavity  to
                       nearest  point   on  outer  container
                       wall.
    
    (b)   Lead or uranium metal shield to be completely
          encased so that molten lead or uranium metal will
          not flow away or lose its shielding efficiency if
          involved in a fire.  The shield must be supported
          in the outer container in such manner that it
          cannot change position under any ordinary
          conditions.  Parts of the shield must be so
          designed that radiation cannot be "beamed" at
          point where sections join (offset design
          required).
    (c)   Containers weighing more than 500 pounds must be
          fitted with skids or otherwise designed so that
          excessive weight will be prevented on small areas
          of car or truck floors.
    (d)   Containers weighing more than 500 pounds must be
          provided with hooks, handles, skids, or other
          devices to facilitate handling.
    (e)   Containers must be of such size and design as are
          necessary to reduce the radiation from the
          container to within the limits prescribed in
          173.393 of this chapter.
    (f)   Containers constructed with tubing for drainage
          purpose must have the opening exterior to the
          shipping container plugged or capped.  Drain lines
          must be plugged or capped with a material which
          will have a melt-point at or below that of lead,
          for example, lead, hard rubber or plastic.
178.250-3 Welding and brazing.
    (a)   When used to join parts of the container must in a
          workmanlike manner and shall provide a joint
          efficiency of not less than 85 percent.  The
          melting point of brazing material must be in
          excess of 1,000 degrees F.
178.250-4 Closures.
    (a)   Closures must be by positive fastening device
          capable of withstanding sever impacts without
          failure.
    (b)   Lead or uranium metal shielding forming part of
          closing device must be completely encased in mild
          steel or equally fire-resistant metal.
    (c)   Closure must be of off-set design where inserted
          into other parts of the container.
    (d)   A means must be provided on the closure to
          accommodate a seal of a type that must be
          destroyed if container is opened for any purpose.
178-250-5 Marking.
    (a)   Marking on each container in an unobstructed area,
          by embossing or die-stamping on the container, or
          on a metal plate attached to the container by
          welding or brazing, in letter and figures at least
          1/4" in height, as follows:
          (1) DOT-55 *** [stars to be replaced by the tare
               weight of the container (for example:
               DOT-55 850)].  These marks shall be
               understood to certify that the container
               complies with all specification requirements.
          (2)  The words "RADIOACTIVE MATERIAL."
          (3)  Name or symbol (letters) of maker or user
               assuming responsibility for compliance with
               specification requirements; this must be
               recorded with the Bureau of Explosives.


Roy A. Parker, Ph.D.
E-Mail: 70472.711@compuserve.com
Tel: 225-924-1473 - Note new area code
Fax: 225-924-4269 - Note new area code
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