We have rolled and twisted the hard-way, helical flat bars known as strakes for use in preventing wind vortex shedding on towers, stacks and other tall round structures. The wind vortex shedding can cause damaging vibration in structures which the helical strakes dampen or eliminate.
Strakes can be attached to towers in multiple ways. Sometimes they are welded directly to the columns. At other times they need to be attached to a clip which is then welded to the column, as is the case in the stainless steel clip on the left side of the picture below.
One customer needed to allow for expansion of metal due to large fluctuations in temperature in his application. The solution was to design a clip which is two angles welded together. The strake was to be welded onto one angle while the other would be welded directly to the stack.
As part of these projects, we have occasionally formed the angles ourselves such as in the example on the right side of the photo. A small bent plate out of Corten was required with a hole punched to plug weld the strake to the stack. The tolerances were fairly tight, so the most cost effective route was determined to have blanks laser-cut from plate that we then formed into angles.
In a more recent design, we used our AngleMaster to cut over 190,000 clips from 2 x 2 x 1/4″ angle for our customer and package them per their needs.