Awelding helmet is a piece ofpersonal protective equipment used by welders to protect the user from concentrated light and flying particles. Different welding processes need stronger lens shades with auto-darkening filters, while goggles suffice for others.OSHA andANSI regulate this technology, defining shades based on thetransmittance of light.

Welding helmets are most commonly used inarc welding processes such asshielded metal arc welding,gas tungsten arc welding, andgas metal arc welding. They are necessary to preventarc eye, a painful condition where thecornea is inflamed. Welding helmets can also preventretina burns, which can lead to a loss of vision. Both conditions are caused by unprotected exposure to the highly concentratedinfrared andultraviolet light emitted by the welding arc.^[1] Ultraviolet emissions from the welding arc can also damage uncovered skin (such as of the face and neck), causing asunburn-like condition in a relatively short period of welding. In addition to the radiation, gases or splashes can also be a hazard to the skin and the eyes.^[2]

All welding helmets are susceptible to damages such as cracks that can compromise the protection from ultraviolet and infrared rays. In addition to protecting the eyes, the helmet protects the face from hot metalsparks generated by the arc and from UV damage. When overhead welding, a leather skull cap and shoulder cover are used to prevent head and shoulder burns.^[3]

Most welding helmets include a window (visor) covered with a filter called a lens shade, through which the welder can see to work. The window may be made of tinted glass, tinted plastic, or a variable-density filter made from a pair ofpolarized lenses. Different lens shades are needed for different welding processes. For example,metal inert gas (MIG) andtungsten inert gas (TIG) welding are low-intensity processes, so a lighter lens shade will be preferred.

Welding goggles are protective eyewear that has dark shading, meant to protect eyes from the bright light produced byoxyfuel welding and allied processes, and also from sparks and debris.^[4] Open electrical arcs (as created byarc welding and other processes) generate much higher amounts of light andUV radiation, requiring the whole face to be protected; most welding goggles do not have a dark enough shade for arc welding.

The modern welding helmet used today was first introduced in 1937 by Willson Products.^[5] In 1981, Swedish manufacturer Hornell International (now owned by 3M^[6]) introduced an LCD electronic shutter that darkens automatically when sensors detect the bright welding arc,^[7] the Speedglas Auto-Darkening Filter. With such electronic auto-darkening helmets, the welder no longer has to get ready to weld and then nod their head to lower the helmet over their face. The advantage is that the welder does not need to adjust the position of welding helmet manually, which not only saves time but also reduces the risk of exposure to the harmful light generated by the welding process.

In the United States, the industry standard for welding helmets is ANSI Z87.1+, which specifies performance of a wide variety of eye protection devices. The standard requires that auto-darkening helmets provide full protection against both UV and IR even when they are not in the darkened state.^[7] The standard is voluntary, so buyers should confirm that the helmet is ANSI Z87.1 compliant (indicated by appropriate labeling).

United StatesOSHA requirements for welding helmets are derived from standards likeANSI Z49.1,Safety in Welding and Cutting, section 7 (Protection of Personnel)^[8] and ANSI Z89.1 (Safety Requirements for Industrial Head Protection).^[9] OSHA also recommends certain shade numbers based on the weld's type and current rating.^[10]

The 1967 edition of ANSI Z49.1.7.2.2.10 specifies that "all filter lenses and plates shall meet the test for transmission of radiant energy prescribed in paragraph 6.3.4.6 of theSafety Code for Head, Eye and Respiratory Protection, USA Standard Z2.1-1959".^[8]

As of 2023,OSHA's website provides standards for minimum protective shades under standard 1910.133 (Eye and face protection), section (a)(5):^[11]

As a rule of thumb, start with a shade that is too dark to see the weld zone. Then go to a lighter shade which gives sufficient view of the weld zone without going below the minimum. In oxyfuel gas welding or cutting where the torch produces a high yellow light, it is desirable to use a filter lens that absorbs the yellow or sodium line in the visible light of the (spectrum) operation.

Per ANSI Z87.1-2003,^[12]: 42 "shade numbers" are derived as such:

Shade Number,${\displaystyle S}$, is related toluminous transmittance${\displaystyle T_L}$ (expressed as a fraction, not as a percent) by the equation:

${\displaystyle S={\displaystyle \frac{7}{3}}lo{g}_{10}{\displaystyle \frac{1}{T_L}}+1}$^[12]

${\displaystyle T_L}$ is defined with respect to CIEIlluminant A (i.e a reference point for typical domesticincandescent lighting) and theCIE 1931Standard Colorimetric Observer.^[12]

The actual ANSI-specified shades are not specific numbers, but ranges; each has a designated maximum, minimum, and nominal transmittance value. Moreover, acceptable transmittance values forfar ultraviolet are far lower than those for the Illuminant A light ("shall be less than one tenth of the minimum allowable luminous transmittance").^[12]

While ANSI shades are ranges based on a specific illuminant, and do not directly convert into other measurements of transmittance, the following table gives a rough approximation (in terms ofneutral density filter numbers andf-stops).

• Jeffus, Larry (1999).Welding: Principles and Applications. Albany: Thomson Delmar.ISBN 0-8273-8240-5 .

• Helmets
• Welding safety
• Protective gear
• Functional masks

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