Rolled Steel Half Cylinder

[curvyrace]

I am working on the design of a vacuum vessel that is 41" high and oval in cross section. The end radii are 5.75" with a 13" wide mid section. So the ovsl is 24.5" overall length and 11.5" wide. The material is 1/4" thick steel, but haven't settled on the grade yet. We have made many of these towers out of schedule 10 pipe before with no issues, but this is the first oval one. I have had a couple of rolling houses quote the end sections but the pricing is coming back very high, about $750 per part. I designed the end sections as pure half cylinders with no flats at either end. Am I missing something here that is driving the cost up or are rolled steel sections just that expensive? I asked for quotes on 1 and 5 pcs. I can understand 1 pc being very expensive but would expect 5 to be considerably less than $750 each. Thanks for any advice you can offer.

 

[JStephen]

Check with the supplier and see what's going on. You may be hitting a size range that is too small for their normal rolling machinery and they're figuring to press it in a press brake.
Can you use pipe and split it lengthwise?
Can the people forming it, form it with one or both straight sides attached and save a weld?