clamshell

Although it produces a nonuniform pressure drop across the die and thus causes nonuniform flow through the die lip, the distribution of the melt does not produce die distortion of clamshelling.

The additional handling that it would get by the canal would be: One dumping from the pockets into the canal barge, one clamshelling out of the canal barge, and one dumping onto the dock.

In the past, when a boat sank and was judged unfit for salvage, the Coast Guard 'clamshelled' it. That is, they broke it up in order to flatten it as much as possible so it wouldn't obstruct river traffic.

To avoid getting clamshelled, first check the seat pins, then climb in before you pin the canopy.