Year : 1984 | Volume
: 32 | Issue : 5 | Page : 347--349
Welding processes and ocular hazards and new protective devices
S Amrik Pabley, H Arthur Keeney
Department of Ophthalmology, University of Cal fornia-Davhs Davis California, USA
S Amrik Pabley
Department of Ophthalmology, University of California-Davis, Davis, California
|How to cite this article:|
Pabley S A, Keeney H A. Welding processes and ocular hazards and new protective devices.Indian J Ophthalmol 1984;32:347-349
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Pabley S A, Keeney H A. Welding processes and ocular hazards and new protective devices. Indian J Ophthalmol [serial online] 1984 [cited 2021 Sep 25 ];32:347-349
Available from: https://www.ijo.in/text.asp?1984/32/5/347/27508
There are over 60 different forms of welding but only 6 of them are generally used. Shielded metal arc or stick welding, gas metal arc welding and oxyacetylene welding are the most frequently used forms.
Stick welding shielded metal arc welding SMAW is the most commonly used welding process because of its high quality and rapid production for the cost involved. Gas metal arc welding technically abbreviated GMAW or MIG uses argon or carbon dioxide to shield the molten welded metal from the atmosphere ensuring a higher quality weld. Gas welding (oxyacetylene welding) is commonly used in maintenance welding of thin materials and is very popular because of its ease of performance and portability. We studied these above porcesses as well as less commonly used gas tungsten arc and carbon arc cutting.
There are nearly 500,000 welders in the United States and one-half percent of all Workmen's Compensation are welding related. Two-thirds of these welding related cases are ocular injuries. A study by Gupta and Singh of 520 welders from 7 factories linked welding to retinal damage manifested as visual functional defect. Approximately 75% of the welders had color vision deficiency which the authors felt was due to exposure to radiant energy.
Welding produces ultraviolet, visible and infrared radiation at damaging levels. These radiations and their secondary effects are responsible for the ocular hazards that are seen clinically. In general welding radiations of shorter wavelengths cause superficial comeal eye problems whereas welding radiations of longer wavelengths cause lenticular are retinal eye problems. The ocular hazards associated with welding include actinic keratitis (welder's flash), skin bums, foreign objects in the eye, electric shock, overheating and injuries resulting from explosion on fire.
The mainstay of ocular protection from welding arc radiation is filter placed within the welder's helmet. Historically these filters have been made of infrared obsorbing green glass. Recently a new polycarbonate reflective filter has been developed Our study compares these 2 filters.
Our main objective was to compare these 2 filters by measuring the temperatures attained by green glass welding filter plates and by newer polycarbonate reflective plates during various and actual welding processes.
MATERIALS AND METHODS
Our study was conducted in a local welding shop using experienced welders and procedures normally used in the industry. Standard 2X4.25-inch filter plates were used in shade numbers 5,10 and 12.
Two new welding helmets were used for each welding process. A green glass filter was mounted in one helmet and a polycarbonate reflective filter of the same shade number was used in the other. Thermocouples were attached to the back safety plates of each of these two helmets and the leads were connected to a strip chart recorder for continuous and simultaneous temperature monitoring during each of the welding processes studied.
Care was taken to duplicate the actual commercial welding conditions and to minimize thermal environmental interferences. Specifics of the materials and methods used are listed in the protocol sheet.
Measurement of temperatures with thermocouples securely mounted on the welding filter plate on the inner side of the helmet Welding filter plates mounted in the helmets without a back safety plate and a front plastic cover plate.
1. Date: 6/12/79 Time: 11:50 a.m.
2. Temperature: Dry bulb: 27.2°C Wet bulb: 21.1°C
3. Type of joint: Tee joint
4. Base metal: Mild steel Thickness : 3/8"
5. Process: Shielded metal-arc welding
(SMAW), also called arc/stick welding
6. Electrode: E7024
7. Current: 375 Amperes Voltage: 40AC
8. Polarity: AC
9. Shielding gas: None
10. Electrode diameter: 1 /4"
11. Arc length: Approximately 1/4 "
12. Welding machine mfr: Hobert model TR
13. Name of welder: Joseph M. Craft (Welding Instructor)
14. Measurements by: Amrik S. Pabley
15. Distance of air temperature probe & test filter plates from workpiece: 10"
16. Approximate angle of inclination of filter plates: 55°C from vertical
17. Distance of welder's helmet from workpiece: 14"
18. Helmet type: fibre-metal model no. 706-3
19. Welding filter plate shade number: 10
20. Green glass welding filter mfr: Gateway; avg. thickness 2.87mm 21.
21. Polycarbonate reflective welding filter mfr. gentex; avg thickness 2.4mm
22. Average thickness of front plastic cover plates: N/A
23. Average, thickness of back plastic safety plates: NA
24. Duration of experiment: 26.8 minutes
A Maximum temperature attained by the glass filter plate=86°C
B. Maximum temperature attained by polycarbonate reflective filterplate 42°C
C. Temperature difference between glass plate & polycarbonate plate 44°C
D. Percent increase in temperature above ambient in glass filter plate =216.2%
E. Percent increase in temperature above ambient in polycarbonate reflective filter plate=54.4%
F. Percent reduction in rise of temperature by using polycarbonate filter plate in place of glass filter plate= 161.8%
OBSERVATIONS AND DISCUSSION
In each process studied, green glass welding filters attained higher temperatures than the polycarbonate-reflective filters. Specifically in stick welding (SMAW), the most commonly used welding process, the filter temperature rose 216° above the ambient with the green glass plates and 54% with the polycarbonate reflective filter plates. This represents the four times the effectiveness in reducing rise in plate temperature. In other welding processes studied the reduction in temperature ranged from 10% in MIG welding to 30% in the carbon arc process.
Another observation was made on examining the 2 plates after the experiment.
The front of the glass filters showed extensive pitting caused by spatter, but the reflective polycarbonate filters showed no spatter marks.
Commonly used commercial welding processes are reviewed and ocular hazards associated with welding are discussed. Standard green glass welding filter and newer polycarbonate gold coated reflective filters are compared for their effectiveness in reducing thermal exposure to the eye(s) during various and actual welding processes used in a welding shop. Polycarbonate reflective filters are shown to substantially reduce the rise in temperature attained by the welding filter during the welding process without interfering with the welder's vision.
|1||Cary H.B., 1979. Modern Welding Technology, Prentice-Hall|
|2||Weymueller C.R, 1980. Welding Design and Fabrication 53(1): 138-139|
|3||Gupta M.N. and Singh H., 1978. Ocular Effects and Visual Performance in Welders, Report No. 27, Central labor Institute, Government of India.|
|4||Pabley AS. and Keeney A.H., 1982. Amer. J. of Ophthalmol 92: 77-84|