An Assessment of Health Hazards in Valves for Gaseous Oxygen Service: Sources and Preventive Measures

Abstract

Oxygen content in air is approximately 21% by volume. With many industrial uses, mainly in the manufacture of steel and chemicals, for metal cutting, welding ,hardening & scarfing, it is being transported as a non-liquefied gas at pressures of 138 bar (13800000 Pa) or above, also as a cryogenic fluid at pressures and temperatures below 13.8bar (1380000 Pa) & −146.5°C (126.65K). Commonly we found air separation plants produce ultra-pure oxygen (> 99.9% purity) via liquefaction of atmospheric air and separation of the oxygen by fractionation and thereby transported to the needy areas via pipelines. The research efforts directed towards technical assessment to establish the correlations between valve construction and turbulence and solving the complications in the transported ultra-pure oxygen gas in the pipelines and through mounted valves. Hence, it is necessary to study the performance, complexities and fire hazards associated with the valves transporting it and the preventive measures to avoid any catastrophic failure in ultra-pure gaseous oxygen services. The study was conducted on two isolation valves — each of ball and globe of relative size. It was realized that velocities of the ultrapure gaseous oxygen on the impingement sites inside the valve are beyond the safe limit as recommended by European Industrial Gas Association (EIGA) [4] and various other prominent industrial gas manufacturers. Moreover, globe valve gave relatively less turbulence and velocity at initial opening of the valve. The study revealed that majority of health hazards & accidents on industrial usage of ultra-pure gaseous oxygen media are the result of the inadequate awareness of the degreasing or cleaning and optimum material selection and construction of the valve and fittings on the industrial pipeline.