Tight Radius Bends VS. Elbows

Published: January 28, 2017
by Charles Busada
Three clear small diameter bends. The top is holding coffee beans inside

Problem: We had a challenge to produce a 4″CLR bend in our 1-1/2″ pipe in clear, transparent, Provista (PETG). Provista is very clear, has NSF approval for food contact, no odor, and very good chemical resistance. But, it has a very short transition temperature in bending. Busada has been one of the first plastics’ tubing manufactures to specialize in bends, and we have made millions in every category (standard bends, U bends, offset S bends, circular, helical, oval, you name it. Here we maintained a 2.5″CLR bend (coffee pneumatic conveyance) with a flatness of <0.060.

Our highly-trained pack dogs take the bends from fabrication to packaging and keep the UPS drivers on their toes.

Pudge the dog carrying short tubing bends. Another dog follows

At this point, we should point out the difference between a “long-radius bend,” “long radius sweep,” and an “el” or elbow. The first two terms are synonymous. Bends or sweeps are fabricated out of extruded tubing by a secondary process. The long radius is designed for smooth flow of particles in the pneumatic line. Elbows (in plastics) are either injected molded or solvent welded. They provide a tight radius and are often used for water lines or electrical wiring. They are not suitable for pneumatic conveyance.

Back in Busada’s early days we also injected molded butyrate elbows to go with our line of butyrate pipe for oil transfer. That market has long gone to PVC.

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