Figure 3-18. Portable power grinder
e. Descalers. Descalers are electric or pneumatic hammers with multiple-needle heads. The
needles are interchangeable with a chisel-like unit. This tool is good for cleaning hard-to-get-at areas on
metal surfaces, such as grooves, corners, crevices, rivets, protruding nuts or bolts, and gratings. The
descaler operates with a reciprocating action and hammers the surface clean with wear-resistant alloy
needles. This tool weighs approximately 4 1/2 pounds and is 14 to 20 inches long. When using this
tool, you should wear goggles and a face shield or a hood.
f. Portable abrasive blasters.
(1) Use portable abrasive blasters (Figure 3-19) to remove paint from metal or masonry
surfaces and corrosion from metal surfaces. Blasting is a very effective method of removing traffic
markings from concrete paving.
(2) Abrasive-blasting equipment is simple to operate. In fact, only 8 to 16 hours of operating
time is required to acquire a basic knowledge of abrasive-blasting techniques. However, simple though
the operation may be, each equipment type has its own peculiarities. Because of this, you should closely
follow the operating instructions of the specific equipment to prevent damage to the equipment or to the
material being cleaned.
(3) The abrasive blaster is operated by compressed air. The air pressure bombards the
surface with the abrasive (sand, grit, split shot, or glass beads) at a high velocity. If the compressed air
is furnished by a portable compressor, you must follow the manual for operating this particular