University:
California State University, Northridge
Course:
PHYS 466 | Experimental Physics IV
Academic year:

2008
Views:

467

Pages:

8
Author:

Alejandro Callahan

Welding Hazards Introduction Welding fuses metal parts together z Hot process, generates toxic gases, fumes and physical hazards z It is a common process, encountered in many situations z 2 Welding Hazards 1 Learn About Welding Hazards and Processes SMA, MIG, TIG, and other processes z Fumes and gases that are generated z 3 Shielded Metal Arc Welding Manual metal arc welding z Cellulosic electrodes z Rutile electrodes z Basic electrodes z Video z 4 Welding Hazards 2 Gas Metal Arc Carbon dioxide z High UV z Little slag z Mechanized z 5 Gas Tungsten Arc Tungsten Inert Gas (TIG) z Tungsten electrode, filler metal z Helium or argon shield z Ozone and NOx z z http://www.youtube.com/watch?v=X9LGKKrncas&feature=related 6 Welding Hazards 3 Submerged Arc Welding Continuous fed, in flux powder z Reduced UV and fume z HF may be generated z 7 Flux Core Arc Welding Metal surrounds flux core z May be a shielding gas used z 8 Welding Hazards 4 Plasma Arc Welding 30,000 C (ionize argon). z Transfer metal ions. z Noise (115 dB), ozone (8.3 ppm), NO2 (9.6 ppm), metal fume. z 9 Soldering and Brazing Lower temperature operations. z Soldering less than 450 C. z Brazing above 450 C. z Oxyacetylene process uses oxygen and acetylene. MAPP gas is methylacetylenepropadiene. Flame up to 3200 C. z Soldering low hazard. z Brazing potentially high fume exposure. z 10 Welding Hazards 5 Respiratory Hazards z Metal fumes – – – – z Stainless 18 % Cr, 10 % Ni Steel may have lead Mild steel, low alloy steel: no Cr Metal coatings Gases generated – Ozone from UV z z GTA, GMA on Al Oxyacetylene cutting 11 Air Concentrations Generated z Fume Generation rate – – – – – z SMA 300 – 800 mg/min GMA 200 – 500 mg/min Flux core 900 – 1300 mg/min GTA 3 – 7 mg/min Oxyacetylene cut 200 – 700 mg/min Particle size < 1 um – Concentration up to 30 mg/m3 12 Welding Hazards 6 Acute Respiratory Hazards z Metal fume fever – Zinc oxide, polymers, other metals z Pneumonitis – Alveolar damage – Phosgene, ozone, cadmium, NOx, phosphine, manganese 13 Chronic Respiratory Hazards z Arc welders pneumoconiosis. – Iron oxide exposure. – Shadows on x-ray. – Unknown physiologic damage. z Lung cancer. – IARC classifies welding as possibly carcinogenic to humans. 14 Welding Hazards 7 Safety Hazards High current z Fire and explosion z PPE Required z 15 Welding Hazards 8

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