Applies to the painting of metal structures which exceed 2 stories in height. Includes metal skeleton frameworks of buildings exceeding 2 stories, smokestacks, cross country power line towers, radio towers, television towers, aircraft, aircraft beacon towers and observation towers. Also includes painting of metal bridges, viaducts, railroad overpasses, trestles and elevated highways. Includes shop operations. Does not apply to painting the exterior or interior of buildings made of wood, concrete, stone or a combination thereof. Refer to code 5474 for the painting of metal storage tanks, fire escapes, staircases, balconies, shutters, window frames or sashes.