One of the structural steel shapes is the tee. Tees can be supplied straight or curved. The smaller sizes are produced in steel mills; the larger sizes are produced by splitting beams longitudinally.
A customer who is seeking steel tees for use in machinery and equipment or for use in construction would typically contact either a steel mill (if the quantity was sufficient, e.g. a truckload) or a steel service center which would stock structural shapes and sell in smaller quantities (e.g. as few as one piece.)
Some steel service centers have equipment to split tees. Rotary shears, which work something like a can opener, split a beam into two tees. The beams are typically split in the middle of the web, but also can be cut with unequal stems. (What is left of the web is called the “stem.”) When the material is too thick for a rotary shear (above, say, about 7/16in), a cutting torch is used to split the tees.
With either method, when the beam is split residual stresses are released, and the resulting tees relax into a shape curved in one or two planes. The tees look like bananas and need to be straightened.
There are primarily two ways to straighten the tees: ramming and rolling. In the former case, a hydraulically powered ram pushes on the tee when the tee is held at two ends. By repeatedly applying pressure along the length of the curved tee, it can be straightened.
A quicker and more effective way to straighten tees is with a three-roll section bender (also called a “profile bender,” or an “angle roll.”). The curved steel tee is run through large rollers with smaller calibrating rollers until it is straight. The process is faster than ram straightening and provides superior quality. Mill tolerance for straightness of tees is 1/8in variation from straightness in ten feet. Ram bending can achieve this tolerance. With roll straightening, however, tolerances of 1/8in over 40 feet and longer can be achieved.
Most steel service centers do not operate section rollers and so it is common for them to send out tees to be split and straightened by companies who specialize in curving steel. Such companies also curve tees to a specified radius for customers. In some cases the “banana” tees can be fed into a section bender without previously being straightened. The tees can be rolled stem in, stem out, and stem up depending on the application. And tees as large as 18in can be curved these ways.