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6-3 High-Density Items

6-3.1 General

High-density items are solid objects whose weight is comparatively high for their volume. Examples include tools, hardware, machine and auto parts, and other metal or heavy items (but not books).

A mailing of high-density items weighing between 15 and 35 pounds is usually machinable on Postal Service mail processing equipment if the contents exert no more than 60 pounds of pressure per square foot (0.4167 pound per square inch) on the smallest side of the container.

A container packed with high-density items often becomes damaged for two reasons:

• The blocking, bracing, or cushioning inside the container is inadequate to prevent shifting of the items.

• The container, the closure, or the reinforcement outside the container is insufficient to withstand normal mail processing.

6-3.2 High-Density Items up to 20 Pounds

6-3.2.1 Packing

A mailing of high-density items weighing up to 20 pounds must be packed in at least a 200-pound test fiberboard box or an equivalent wood, metal, or plastic container. A hard nonfiberboard container should be prepared so that its coefficient of friction is similar to that of a domestic-class fiberboard box of the same size and weight.

Internal blocking and bracing must be used as required (methods include interior containers, cut forms, partitions, dunnage, and liners). The mailing container must maintain its integrity without damage to its contents if dropped once from a height of 3 feet on its smallest side onto a solid surface.

6-3.2.2 Closing

The mailing container must be securely closed with staples, heat sealing, adhesive, or tape. A container without inner packing or a container with loose material should be reinforced with reinforced paper or plastic tape, pressure-sensitive filament tape, or firmly applied nonmetallic banding.

6-3.3 High-Density Items From 20 to 45 Pounds

6-3.3.1 Packing

A mailing of high-density items weighing from 20 to 45 pounds must be packed in at least a 200-pound test fiberboard box or an equivalent wood, metal, or plastic container. A hard nonfiberboard container must be prepared so that its coefficient of friction is similar to that of a domestic-class fiberboard box of the same size and weight.

Internal blocking and bracing must be used as required (methods include interior containers, cut forms, partitions, dunnage, and liners). The mailing container must maintain its integrity without damage to its contents if dropped once from a height of 3 feet on its smallest side onto a solid surface.

6-3.3.2 Closing

The mailing container must be securely closed with staples, heat sealing, adhesive, or tape. A container without inner packing or a container with loose material should be reinforced with pressure-sensitive filament tape or firmly applied nonmetallic banding.

6-3.4 High-Density Items From 45 to 70 Pounds

6-3.4.1 Packing

A mailing of high-density items weighing from 45 to 70 pounds must be packed in at least a 275-pound test fiberboard box or an equivalent wood, metal, or plastic container. A hard nonfiberboard container must be prepared so that its coefficient of friction is similar to that of a domestic-class fiberboard box of the same size and weight.

Internal blocking and bracing must be used as required (methods include interior containers, cut forms, partitions, dunnage, and liners). The mailing container must maintain its integrity without damage to its contents if dropped once from a height of 3 feet on its smallest side onto a solid surface.

6-3.4.2 Closing

The mailing container must be securely closed with staples, heat sealing, adhesive, or tape. A container without inner packing or a container with loose material should be reinforced with pressure-sensitive filament tape or tight nonmetallic banding.