Fitting Bends To Your Needs

Published: February 15, 2021
by Charles Busada
Two stacked clear bends on top of each other

This week we had a challenge. A customer ordered a specialty bend with 4 inch ID on a 20” Outside Radius. The bend was to have an extended tangent on one side of 15” and a short tangent of 1.125”.

The customer wanted to put the bend directly into a chute for their pneumatic conveyance of paper cups. The problem with thermoplastics’ bends, however, is that they are produced by heating. Packing materials can vary, but some kind of out-of-roundness is inevitable in the arc.

Secondly, thermoplastics’ bends do not have a “hard tangent,” rather, they transition from arc to tangent. So, the customer was having a difficult time in sleeving directly on the short tangent.

The solution was simply to increase the bend radius enough to get a 4” tangent while maintaining the offset. This provided about two inches of a true tangent and the connection to the chute was easy.

In the picture above, we see the tighter radius bend on top of the 18” OSR bend. The solution was quite simple, but again, we are reminded that thermoplastics’ bends are not to be confused with metal bends. The different processes may require different designs.

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