The Effects of Testing Methodology on the Promoted Ignition-Combustion Behavior of Carbon Steel and 316L Stainless Steel in Oxygen Gas Mixtures

Abstract

Energy release from a substance with relatively low oxygen compatibility is a situation which could result in the ignition and combustion of more oxygen-compatible materials such as the structural metals used in gaseous oxygen systems. At the present time there are no standard ASTM test methods for testing metals ignition and combustion in gaseous oxygen over the range of pressures and purities required for the broad range of oxygen applications which may be encountered. Within recent years, there nas been an increase in the number of metals ignition-combustion studies which have been conducted at pressures in excess of 3.55 MPa. The studies have been conducted under both flowing and static conditions with different promoter systems. Some of the approaches might form the basis for standard ASTM test methods in metals ignition-combustion in gaseous oxygen. Discussion regarding the influence of various test variables which could affect selection of a standard test method does appear in the literature. This paper discusses experimental results obtained with caroon steel and AISI 316L stainless steel using three different apparatus for characterizing metal-oxygen ignition-combustion tendencies. One test method used a 100 mm diameter static chamber with hydrocarbon and wire promoter. The second test method was similar but the chamber was 8 times larger in volume. In contrast to these approaches the third method was a dynamic or flow tester in which tne gas mixtures were continuously flowed past the test specimen. The oxygen purities of the gas mixtures varied from 40 to 99.998% oxygen. Test data and methods were compared.