Ultraviolet radiation in manual arc welding using covered electrodes

Abstract

Welding arc is the source of intensive flow of optic radiation in infrared, visible and ultraviolet (UV) ranges, among which the most severe UV-C radiation with a strong harmful effect on the human organs of vision and skin covering should be distinguished. The aim of this work consisted in complex investigation of integral characteristics of UV radiation covered-electrode in manual arc welding (MAW), with covered electrodes of different grades (MR-3, UONI-13/55, ANO-12, ANO-36) and types of coatings (rutile, basic, rutile-cellulose), designed for welding of carbon and low-alloyed steels. The intensity of UV-C and UV-A radiation was measured using dosimeter of optic radiation DAU-81 at the distances of 0.55-1.50 m from the spot of welding. It was established during analysis and statistic processing of measurement results that at this distance at, which usually welder and support personnel are staying during MAW, the integral intensity of UV-C radiation amounts to 0.7-5 W/m 2 , which 700-5000 times exceeds the standard value of 0.001 W/m 2 specified by the acting sanitary standards SN 4557-88 for workers with non-protected skin surfaces. Here the minimum distance, at which staying of the mentioned category of workers at direct visibility of welding place is admissible, amounts from 25 to 65 m (depending on the grade of electrode and value of welding current). Intensity of UV-C radiation depends, in the first turn, on the grade of applied electrodes but not on the type of their coating. It was shown that the intensity of UV radiation is inversely proportional to the square of distance from welding arc and greatly depends on welding current. The results of this work can be used in sanitary-hygienic certification of working stations of welders. 6 Ref., 4 Tables.

Designing a combined device for determining the place of arc discharge

“…There are three spectra of ultraviolet radiation: UV-A (315-400) nm, UV-B (280-315) nm, UV-C (200-280) nm. At the same time, the most rigid is UV-C, which has an intensity of radiation up to 5 W/m 2 at a current of 200 A, which is harmful to a person at a distance larger than 60 meters [13]. The welding arc discharge spectrum consists of 70 % ultraviolet, 15 % visible and 15 % infrared radiation.…”

“…Necessary much higher frequencies than 50Hz of industrial frequency. The electromagnetic spectrum of an electric welding arc has three resonance bands; their centers are at a frequency of 750 kHz, 3 MHz, and 20 MHz [13,14]. Absorbing pincers and vertically polarized antennas are used at a height of 3 m and at a distance of up to 10 m (GOST 11001-69) to control interferences of arc discharge for radio communications.…”