Creating Close Tolerance Curved Steel Tees

Steel tees, especially larger tees, are produced by splitting a steel beam and then straightening or curving the two resultant tees to the required specifications. At times these specifications can require close tolerance work.
For example, WT12 x 27.5 steel tees were required to be rolled stem-out to an inside radius of 53ft 0.187in with 44ft 4in of outside arc and left untrimmed (with some extra material—for grip or pickup– at each end to be trimmed to length by the customer.)

The splitting tolerance was +/-1/8in; the rolling tolerance was +/-1/8in on the rise over 10ft. (Tighter than the 1/8 over 5ft AISC tolerance for straighness.) Beyond these tolerances, what was critical to the application was consistency of the outside radius measured at the tip of the stem and that the tees be as equal as possible.

Measuring the radius of a stem-out steel tee at the tip of the stem precluded using a chord and rise measurement. (The inside radius, of course, could be measured that way.) A special checking fixture was manufactured with an inside radius to match the specifications. The stem-out tee could then be set against the checking fixture to verify the dimensions. This fixture in fact mimicked the application of the curved tees: they are to be welded to the inside radius of curved plate. If the tees did not match up to the plate, the welders would have serious problems.

Other measures were taken to ensure accuracy and consistency. Special arrangements were made with the steel supplier to improve consistency in the height of the beams. The beams were checked before they were split into tees for any variation in height.


Measuring Consistency in the Height of the Beams Before Splitting and Rolling

Great care was taken to guarantee that the beams were split right down the center.

Beams Split Down the Center to Make Two Equal Tees

And then the rolling was done to the precise specifications and checked on the fixture.

Tees Rolled to Close Tolerances

Inspectors from the equipment manufacturer who will use these tees checked the first four rolled tees and approved proceeding with production.  As production proceeded, continuous checking was done to guarantee the required quality.


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