Customer Support Ruling
Letter and Flat Tray Strapping Specifications
This Customer Support Ruling provides guidelines on the specifications for strapping used on letter and flat trays.
The Domestic Mail Manual provides that generally each sleeved letter tray must be secured with one plastic strap placed tightly around the length of the tray without crushing the tray or sleeve. For flat trays, each covered tray must be secured with two plastic straps placed tightly around the width of the tray (the shorter dimension).
Plastic strapping should have a minimum tensile breaking strength of 70 pounds. Other plastic material may be used for strapping if it has a minimum tensile breaking strength of 70 pounds with an elongation before yield of less than 20 percent. Strapping should be applied to have a minimum tension of ten pounds. Strapping of any color is acceptable as long as it does not interfere with label visibility.
Sealing of the strapping may be accomplished by melting the ends together using heat or friction, using a non-corrosive plastic buckle or seal, tying a knot, or using self-locking straps. The seal of the strapping should have a minimum breaking strength of 60 pounds. Metal buckles or seals must not be used to secure the ends of strapping material placed around letter or flat trays.
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