Stainless Steel Welding Fumes Research Articles

Application of X-ray photoelectron spectroscopy to the analysis of stainless-steel welding aerosols

Aerosol particles (“fume”) from manual metal arc welding of stainless steel with E316L-16 electrodes were analysed by X-ray photoelectron spectroscopy. The inherent complexity of the particles required the use of a wide range of experimental techniques. These included IR spectrophotometry, TGA/DTA, XRF, XRD, AAS and electron microprobe analysis. The surface of the fume particles comprised ≈ 50 at% NaF and KF, ≈ 8 at.% soluble (probably K) chromate, ≈ 30 at% SiO 2 and several at.% transition-metal oxides, hydroxides or silicates. The fluorides and chromates were removed by washing to reveal a surface which was predominantly SiO 2 (≈ 60 at%) with the remainder comprising of transition-metal oxides, silicates and fluorides. Approximately 6 at% F remained on the surface of the water-washed particles, presumably as transition-metal fluoro-complexes. The water-soluble fraction of the fume contained K + , Na + , F − and CrO 2− 4 ions in the mole ratio 5:5:4:3. When aerosol particles are deposited in lung tissues, water-soluble constituents would be expected to dissolve rapidly. In view of the suspected carcinogenicity of stainless steel welding fume, a bio-medical study of the combined effects of F − and CrO 2− 4 ions on lung tissue is warranted.

Application of X-ray photoelectron spectroscopy to the analysis of stainless-steel welding aerosols

Aerosol particles (“fume”) from manual metal arc welding of stainless steel with E316L-16 electrodes were analysed by X-ray photoelectron spectroscopy. The inherent complexity of the particles required the use of a wide range of experimental techniques. These included IR spectrophotometry, TGA/DTA, XRF, XRD, AAS and electron microprobe analysis. The surface of the fume particles comprised ≈ 50 at% NaF and KF, ≈ 8 at.% soluble (probably K) chromate, ≈ 30 at% SiO 2 and several at.% transition-metal oxides, hydroxides or silicates. The fluorides and chromates were removed by washing to reveal a surface which was predominantly SiO 2 (≈ 60 at%) with the remainder comprising of transition-metal oxides, silicates and fluorides. Approximately 6 at% F remained on the surface of the water-washed particles, presumably as transition-metal fluoro-complexes. The water-soluble fraction of the fume contained K +, Na +, F − and CrO 2− 4 ions in the mole ratio 5:5:4:3. When aerosol particles are deposited in lung tissues, water-soluble constituents would be expected to dissolve rapidly. In view of the suspected carcinogenicity of stainless steel welding fume, a bio-medical study of the combined effects of F − and CrO 2− 4 ions on lung tissue is warranted.

Urine chromium as an estimator of air exposure to stainless steel welding fumes.

Welding stainless steel with covered electrodes, also called manual metal arc welding, generates hexavalent airborne chromium. Chromium concentrations in air and post-shift urine samples, collected the same arbitrarily chosen working day, showed a linear relationship. Since post-shift urine samples reflect chromium concentrations of both current and previous stainless steel welding fume exposure, individual urine measurements are suggested as approximate although not exact estimators of current exposure. This study evaluates the practical importance of such measurements by means of confidence limits and tests of validity.

Detection by replica plating of false revertant colonies induced in the Salmonella-mammalian microsome assay by hexavalent chromium.

The replica plating method as developed by Lederberg has been used to differentiate between "true" and "false" histidine-requiring revertant bacterial colonies which develop on minimal agar plates in the Ames test. Strains of S. typhimurium LT2, TA 100, when exposed to either sodium dichromate or the fumes from the welding of stainless steel, develop colonies whose apparent numbers are directly in proportion to the Cr(VI) content per plate in both cases, over a wide dose range. Replica impressions of the resulting colonies were transferred to Vogel Bonner minimal agar plates and incubated for 48 hr at 37 degrees C. It was then observed that considerable numbers of "false" revertant colonies were obtained at those Cr(VI) doses which resulted in a pronounced toxic effect, albeit with an acceptable level of the bacterial background lawn. No morphological distinction between "true" and "false" revertant colonies could be made. Although it would appear that at low doses (i.e., low toxicity) the true mutagenicity of stainless steel welding fumes can be completely accounted for by the presence of Cr(VI), the dose range over which the mutagenicity assay is reliable cannot be estimated from examination of the background lawn or from an estimate of the degree of survival of the treated cultures. Thus there is raised a serious question concerning the reliability of quantitative data published in bacterial mutagenicity testing where replica testing of the histidine requirement of the resulting "revertant" colonies is not routinely made. It is suggested that the replica technique can easily be developed as a simple and useful tool for the control of histidine requirement and ampicillin resistance in routine mutagenicity testing.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromium and nickel aerosols in stainless steel manufacturing, grinding and welding

Composition, morphology and solubility of chromium and nickel in fumes from stainless steel manufacturing, based on ferrochrome, and in dusts from grinding of stainless steel, were studied. The results were compared with corresponding analyses of stainless steel welding fumes. In fumes from the melting of ferrochrome and stainless steel, as well as in dusts from the grinding of stainless steel, chromium is only slightly oxidized to the hexavalent state. Therefore, chromates are present in very low concentrations in contrast to manual metal arc welding fumes where chromium is oxidized to CrO3 and reacts with alkali oxides (K2O, CaO) to form respective chromates. Nickel occurs in fumes from stainless steel manufacturing mainly as metallic alloyed element in the iron matrix or in small amounts as oxide (NiO). In stainless steel welding fumes, separate nickel oxide particles have been found. Airborne particles originating from the melt are typically round and possibly covered by a slag layer.

Monitoring personnel exposure to stainless steel welding fumes in confined spaces at a petrochemical plant

This paper documents exposure to stainless steel welding fumes at a petrochemical plant. The situation evaluated may be separated into three categories: 1) evaluation of background concentration levels in a maintenance shop (area monitoring), 2) evaluation of personnel exposures during open air welding in a maintenance shop (personal monitoring), 3) evaluation of personnel exposures in confined space welding (personal monitoring). Thirty-five area samples and seventy-six personal samples were collected and analyzed for chromium (VI), total chromium, nickel, iron, copper, and total particulates. The background concentrations in the maintenance shop were found to be far below those felt to be harmful. Personnel exposures found in the maintenance shop during open air welding were also low, especially when compared to current OSHA permissible exposure levels. Contaminant levels found during confined space welding, as in distillation towers, were considered excessive. After several possible solutions to the problem were considered, it was decided to implement a mandatory air-line respirator program for all employees entering confined spaces during stainless steel welding operations.

Occupational asthma due to stainless steel welding fumes

Seven patients with respiratory symptoms after welding were examined. Five had occupational asthma caused by fumes from manual metal are stainless steel welding. The detailed clinical results of two patients with repeated challenge tests are reported. One patient was nonatopic and had earlier had contact dermatitis due to chromium. He experienced a non-immediate type of asthmatic reaction after welding stainless steel. The other patient was atopic and showed an immediate-type reaction. Both reactions were repeated in the second provocation test after about 2 years. In addition both disodium cromoglycate and beclomethasone pretreatments inhibited the reaction of the two patients, but a placebo medication did not. A remarkable amount of chromium and nickel are detected in the fumes released during stainless steel welding but not in the fumes from mild steel welding, with which all provocation tests were negative. The chromium or the nickel in welding fumes might be the aetiological factor of the reaction.

Measurement of chromium VI and chromium III in stainless steel welding fumes with electrom spectroscopy for chemical analysis and neutron activation analysis.

Electron Spectroscopy for Chemical Analysis (ESCA) was explored as a means of studying the oxidation state of chromium in SMAC (coated electrode) stainless steel welding fume collected on Nucleopore filters in the laboratory. Chromuim VI and III (as a percent of the total chromium) obtained from ESCA analysis was applied to results from Neutron Activation Analysis (NAA) to yield an average of 69 microgram chromium VI per sample. Diphenylcarbazide/atomic absorption (DPC/AA) results are reported for samples submitted to an industrial laboratory. Possible chemical species and solubility of chromium VI in stainless steel fumes is discussed in light of analogy between the SMAC process and the manufacturing process for chromates.

Identification of stainless steel welding fume particulates in human lung and environmental samples using electron probe miciroanalysis

Open lung biopsy specimens from two welders and air samples from their workplace environments were examined with the electron probe microanalyzer. X-ray analysis showed that the majority of particles found in the lung tissue from both workers and in the air samples to be composed of varying amounts of iron, chromium, manganese and nickel, the major components of some types of stainless steel. Based upon these analyses, it was concluded that the majority of the particles in both biopsy specimens were a result of the workplace environment.