ALGOR FEA HELPS SHAVE 15,000 LBS FROM HUGE BUTTERFLY VALVE

The following story ran in the November 9, 1992 issue of Design News Magazine. It is reprinted here with permission.

Imagine a butterfly valve so big you can walk through it while carrying someone!

That was what NASA's Lewis Research Center asked engineers at Enpro Systems to do when they gave them the contract to design and build an isolation valve for a vacuum chamber. But the real challenge in this project was the next requirement: Keep the weight of the valve to 50,000 lbs.

Enpro's initial AutoCAD design of the 156-inch valve weighed in at 67,500 lbs, based on the weight of the components. To trim that design down, Enpro turned to Algor finite element analysis (FEA) software.

Engineer Richard Biel imported the AutoCAD design into Algor FEA software, produced a solid model, and then meshed it. He originally made a brick element model, then discarded it and made a plate element model. The brick and plate elements gave virtually the same results, he says.

A light-shaded rendering of the butterfly valve model created by Richard Biel of Enpro Systems.

Biel had to contend with two key design issues:

• Because of the end-use application, the valve stems had to be rotated 30-degrees from the horizontal, which made classical calculations impractical.
• The elastomeric seal had to operate without external energizing, which meant deflections of the rubber seal were critical.

Result: After 13 iterations in about three weeks, Biel redesigned the entire valve component-by-component, including treating the 13 foot diameter, eight-inch-thick disk as a structural member. He got the valve weight down to 52,000 lbs, a 22% weight reduction.

"The software made it easy to do the analysis and design," he says. "I had hardly used it at all before, but now I use it quite a bit."

Enpro, which manufactures pressure vessels and specialty valves for petrochemical plants, refineries and high-temperature flow lines, delivered the valve last summer. NASA will use the valve in its testing program for high altitude jet and rocket engines.

Copyright ?1993 Algor, Inc. All rights reserved.