A welding helmet is a type of personal protective equipment used in performing certain types of welding to protect the eyes, face, and neck from flash burn, sparks, infrared and ultraviolet light, and intense heat. The modern welding helmet used today was first introduced in 1937 by Willson Products.[1]
Welding helmets are most commonly used in arc welding processes such as shielded metal arc welding, gas tungsten arc welding, and gas metal arc welding. They are necessary to prevent arc eye, a painful condition where the cornea is inflamed. Welding helmets can also prevent retina burns, which can lead to a loss of vision. Both conditions are caused by unprotected exposure to the highly concentrated infrared and ultraviolet rays emitted by the welding arc.[2] Ultraviolet emissions from the welding arc can also damage uncovered skin, causing a sunburn-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.[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 of polarized lenses. Different lens shades are needed for different welding processes. For example, metal inert gas (MIG) and tungsten inert gas (TIG) welding are low-intensity processes, so a lighter lens shade will be preferred.
United States OSHA requirements for welding helmets are derived from standards like ANSI Z49.1, Safety in Welding and Cutting, section 7 (Protection of Personnel)[4] and ANSI Z89.1 (Safety Requirements for Industrial Head Protection).[5]
The shade of lens that is suitable depends on the current rating of the weld. In the United States, OSHA recommends DIN shade numbers as shown in the following table:
Weld Current (Amperes)
Shade Number
50–60
10
60–160
11
160–200
12
200–240
13
> 240
14
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 the Safety Code for Head, Eye and Respiratory Protection, USA Standard Z2.1-1959".[4]
As of 2023, OSHA's website provides standards for minimum protective shades under standard 1910.133 (Eye and face protection), section (a)(5), and says: "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."[6]
Safety
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 metal sparks 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.[7]
Goggles
Oxyfuel welding goggles
Welding goggles are protective eyewear that has dark shading, meant to protect eyes from the bright light produced by oxyfuel welding and allied processes, and also from sparks and debris.[8] Open electrical arcs (as created by arc welding and other processes) generate much higher amounts of light and UV radiation, requiring the whole face to be protected; most welding goggles do not have a dark enough shade for arc welding.
Auto-darkening filters
Speedglas welding helmet.
In 1981, Swedish manufacturer Hornell International (now owned by 3M[9]) introduced an LCD electronic shutter that darkens automatically when sensors detect the bright welding arc,[10] 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.
ANSI standards
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.[10] The standard is voluntary, so buyers should confirm that the helmet is ANSI Z87.1 compliant (indicated by appropriate labeling).
Shades
Per ANSI Z87.1-2003,[11]:42 "shade numbers" are derived as such:
Shade Number, , is related to luminous transmittance (expressed as a fraction, not as a percent) by the equation:
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 for far ultraviolet are far lower than those for the Illuminant A light ("shall be less than one tenth of the minimum allowable luminous transmittance").[11]
Transmittance values
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 of neutral density filter numbers and f-stops).
Notation
Lens area opening, as fraction of the complete lens
Note: Hoya, B+W, Cokin use code ND2 or ND2x, etc.; Lee, Tiffen use code 0.3ND, etc.; Leica uses code 1×, 4×, 8×, etc.[12]
Note: ND 3.8 is the correct value for solar CCD exposure without risk of electronic damage.[citation needed]
Note: ND 5.0 is the minimum for direct eye solar observation without damage of retina. A further check must be performed for the particular filter used, checking on the spectrogram that also UV and IR are mitigated with the same value.[citation needed]
Ultraviolet (UV) light is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs, Cherenkov radiation, and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights.
Electromagnetic radiation can be classified into two types: ionizing radiation and non-ionizing radiation, based on the capability of a single photon with more than 10 eV energy to ionize atoms or break chemical bonds. Extreme ultraviolet and higher frequencies, such as X-rays or gamma rays are ionizing, and these pose their own special hazards: see radiation poisoning. The field strength of electromagnetic radiation is measured in volts per meter (V/m).
Personal protective equipment (PPE) is protective clothing, helmets, goggles, or other garments or equipment designed to protect the wearer's body from injury or infection. The hazards addressed by protective equipment include physical, electrical, heat, chemical, biohazards, and airborne particulate matter. Protective equipment may be worn for job-related occupational safety and health purposes, as well as for sports and other recreational activities. Protective clothing is applied to traditional categories of clothing, and protective gear applies to items such as pads, guards, shields, or masks, and others. PPE suits can be similar in appearance to a cleanroom suit.
Sunglasses or sun glasses are a form of protective eyewear designed primarily to prevent bright sunlight and high-energy visible light from damaging or discomforting the eyes. They can sometimes also function as a visual aid, as variously termed spectacles or glasses exist, featuring lenses that are colored, polarized or darkened. In the early 20th century, they were also known as sun cheaters.
A welder is a person or equipment that fuses materials together. The term welder refers to the operator, the machine is referred to as the welding power supply. The materials to be joined can be metals or varieties of plastic or polymer. Welders typically have to have good dexterity and attention to detail, as well as technical knowledge about the materials being joined and best practices in the field.
Photokeratitis or ultraviolet keratitis is a painful eye condition caused by exposure of insufficiently protected eyes to the ultraviolet (UV) rays from either natural or artificial sources. Photokeratitis is akin to a sunburn of the cornea and conjunctiva.
A hard hat is a type of helmet predominantly used in workplace environments such as industrial or construction sites to protect the head from injury due to falling objects, impact with other objects, debris, rain, and electric shock. Suspension bands inside the helmet spread the helmet's weight and the force of any impact over the top of the head. A suspension also provides space of approximately 30 mm between the helmet's shell and the wearer's head, so that if an object strikes the shell, the impact is less likely to be transmitted directly to the skull. Some helmet shells have a mid-line reinforcement ridge to improve impact resistance. The rock climbing helmet fulfills a very similar role in a different context and has a very similar design.
Arc welding is a welding process that is used to join metal to metal by using electricity to create enough heat to melt metal, and the melted metals, when cool, result in a binding of the metals. It is a type of welding that uses a welding power supply to create an electric arc between a metal stick ("electrode") and the base material to melt the metals at the point of contact. Arc welding power supplies can deliver either direct (DC) or alternating (AC) current to the work, while consumable or non-consumable electrodes are used.
In photography and cinematography, a filter is a camera accessory consisting of an optical filter that can be inserted into the optical path. The filter can be of a square or oblong shape and mounted in a holder accessory, or, more commonly, a glass or plastic disk in a metal or plastic ring frame, which can be screwed into the front of or clipped onto the camera lens.
An optical filter is a device that selectively transmits light of different wavelengths, usually implemented as a glass plane or plastic device in the optical path, which are either dyed in the bulk or have interference coatings. The optical properties of filters are completely described by their frequency response, which specifies how the magnitude and phase of each frequency component of an incoming signal is modified by the filter.
Laser radiation safety is the safe design, use and implementation of lasers to minimize the risk of laser accidents, especially those involving eye injuries. Since even relatively small amounts of laser light can lead to permanent eye injuries, the sale and usage of lasers is typically subject to government regulations.
Gas tungsten arc welding is an arc welding process that uses a non-consumable tungsten electrode to produce the weld. The weld area and electrode are protected from oxidation or other atmospheric contamination by an inert shielding gas. A filler metal is normally used, though some welds, known as 'autogenous welds', or 'fusion welds' do not require it. A constant-current welding power supply produces electrical energy, which is conducted across the arc through a column of highly ionized gas and metal vapors known as a plasma.
Eye protection is protective gear for the eyes, and sometimes face, designed to reduce the risk of injury. Examples of risks requiring eye protection can include: impact from particles or debris, light or radiation, wind blast, heat, sea spray or impact from some type of ball or puck used in sports.
In photography and optics, a neutral-density filter, or ND filter, is a filter that reduces or modifies the intensity of all wavelengths, or colors, of light equally, giving no changes in hue of color rendition. It can be a colorless (clear) or grey filter, and is denoted by Wratten number 96. The purpose of a standard photographic neutral-density filter is to reduce the amount of light entering the lens. Doing so allows the photographer to select combinations of aperture, exposure time and sensor sensitivity that would otherwise produce overexposed pictures. This is done to achieve effects such as a shallower depth of field or motion blur of a subject in a wider range of situations and atmospheric conditions.
A face shield, an item of personal protective equipment (PPE), aims to protect the wearer's entire face from hazards such as flying objects and road debris, chemical splashes, or potentially infectious materials. Depending on the type used, a face shield may protect its wearer from a physical hazard, chemical splashes, or biological hazards.
A photochromic lens is an optical lens that darkens on exposure to light of sufficiently high frequency, most commonly ultraviolet (UV) radiation. In the absence of activating light, the lenses return to their clear state. Photochromic lenses may be made of polycarbonate, or another plastic. Glass lenses use visible light to darken. They are principally used in glasses that are dark in bright sunlight, but clear, or more rarely, lightly tinted in low ambient light conditions. They darken significantly within about a minute of exposure to bright light and take somewhat longer to clear. A range of clear and dark transmittances is available.
Ultraviolet photography is a photographic process of recording images by using radiation from the ultraviolet (UV) spectrum only. Images taken with ultraviolet radiation serve a number of scientific, medical or artistic purposes. Images may reveal deterioration of art works or structures not apparent under light. Diagnostic medical images may be used to detect certain skin disorders or as evidence of injury. Some animals, particularly insects, use ultraviolet wavelengths for vision; ultraviolet photography can help investigate the markings of plants that attract insects, while invisible to the unaided human eye. Ultraviolet photography of archaeological sites may reveal artifacts or traffic patterns not otherwise visible.
A biosafety cabinet (BSC)—also called a biological safety cabinet or microbiological safety cabinet—is an enclosed, ventilated laboratory workspace for safely working with materials contaminated with pathogens requiring a defined biosafety level. Several different types of BSC exist, differentiated by the degree of biocontainment they provide. BSCs first became commercially available in 1950.
Ballistic eyewear is a form of glasses or goggles that protect from small projectiles and fragments. For the U.S. military, choices are listed on the Authorized Protective Eyewear List (APEL). Ballistic eyewear including examples that meet APEL requirements are commercially available for anyone who wishes to buy it. The history of protective eyewear goes back to 1880 and extends through to World War I and the present. There are three standards that are currently used to test the effectiveness of ballistic eyewear. These include a U.S. civilian standard, a U.S. military standard (MIL-PRF-31013), and a European standard.
The Authorized Protective Eyewear List (APEL) is a list of protective eyewear tested and approved by the U.S. Military for use by its soldiers. The APEL includes spectacles and goggles optimized for different situations.
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