The welding operator and personnel in the welding area must be protected from the potential hazards of welding. These include radiation from the arc and hot spatter from a welding electrode. Arc radiation can very quickly cause damage to the eye if viewed directly without adequate eye protection. Even when viewed directly from a distance of 6 m (20 feet), the retina can be damaged in a few seconds. Damage to the skin does not occur as quickly, but if exposed for several minutes, arc radiation can cause painful burns similar to sunburn. The severity depends on the intensity of the arc and the distance from the arc.
Eye Protection. Eye protection consists of wearing a helmet with the correct filter lens when welding or using a hand shield with the correct filter when watching an arc. The filter lenses are available in several shades of darkness, numbered from 2 to 14 in a light-
to-dark sequence. Number 2 would be used for torch soldering; number 14 would be used for arc welding at currents of more than 250 to 500 amperes. Shade selection for a given application should start with a dark shade. If it is difficult to see, successively lighter shades should be tried until the operation is sufficiently visible for good control. In no c a m should a shade lower than number 7 be used for arc welding, and then only for arc current of less than 60 amperes. These lenses are designed to filter out harmful ultraviolet and infrared radiation from the arc.
Special radiation-sensitive helmet lenses are avail- able which are clear when no radiation is present, but darken within milliseconds when an arc is initiated. The lenses become clear again when the arc is extinguished.
In addition to the welder, other workers in the shop area should be protected with curtains or screens surrounding the weld areas. These curtains or screens may be opaque, or made of a translucent plastic which absorbs ultraviolet radiation. Portable curtains can be moved to a weld operation to completely shield it from other workers. Shielding should be provided to protect crane operators from arc flashes. Shop wall areas
should be painted with coating which provides a low reflectively for ultraviolet radiation. Paints or coatings formulated with titanium dioxide or zinc oxide have low reflectivity for ultraviolet radiation.
Protective Clothing
Sturdy shoes or boots and heavy clothing should be worn to protect the whole body from flying sparks, spatter, and radiation bums. Leather gloves should be worn to protect the hands and forearms. Woolen clothing is preferred to cotton because it is not as readily ignited. Leather aprons and leg shields are much better protection against hot droplets of metal than wool or cotton cloth. A leather jacket should be worn to cover
the upper body. Cuffless pants and covered pockets are recommended to avoid spark entrapment; the pants should be worn outside the shoes. A cap should be worn under the helmet to protect the hair or head from sparks.