Then they bolt the piece in place temporarily, check vertical and horizontal alignment with plumb bobs, laser equipment, transits, or levels and then bolt or weld it permanently in place. Reinforcing ironworkers set the bars in the forms that hold concrete, following blueprints that show the location, size, and number of reinforcing bars. They fasten the bars together by tying wire around them with pliers. When reinforcing floors, workers place blocks under the reinforcing bars to hold them off the deck. Although these materials usually arrive ready to use, ironworkers may occasionally have to cut the bars with metal shears or acetylene torches, bend them by hand or machine, or weld them with arc-welding equipment.
Some concrete is reinforced with welded wire fabric.
Workers cut and fit the fabric and, while a concrete crew places the concrete, ironworkers use hooked rods to position it properly in the concrete. As the pieces are hoisted into position, ironworkers bring them into position, make sure they fit correctly, and bolt, braze, or weld them for a secure fit. They also erect metal tanks used to store petroleum, water, or other fluids and assemble prefabricated metal buildings according to plans or specifications.