Robert Zawierucha

Promoted Ignition Behavior of Engineering Alloys in High-Pressure Oxygen

Promoted ignition describes a situation in which a substance with relatively low compatibility with oxygen ignites and supports the combustion of a more oxygen-compatible material. As a consequence, this mechanism could lead to significant component damage in a high-pressure oxygen system. Current cleaning specifications and normal engineering review procedures to a large extent preclude or minimize the possibility of oxygen incompatible substances in an oxygen system. Nevertheless, it is important for an oxygen system design engineer to be aware of the combustion resistance of potential oxygen system structural alloys as a result of a promoted ignition scenario. The trend towards higher oxygen usage pressures reinforces this requirement. Aluminum, cuprous, ferrous, nickel, and to a lesser extent, cobalt-based alloys are encountered in high-pressure oxygen systems. In this study, the promoted ignition resistance of over 40 engineering alloys from these systems were evaluated in gaseous oxygen at pressures up to 38.6 MPa using hydrocarbon and hydrocarbon-iron promoters. Burn rate data were obtained for selected alloy-oxygen pressure combinations. A ranking of alloys is proposed that is based on resistance to ignition, self-extinguishing of burning, effect of oxygen pressure, and upward combustion rates. This ranking will assist qualified technical personnel in materials selection for high-pressure oxygen services.

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

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. Witnin 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 oasis 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 the 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.

Promoted ignition-combustion behavior of precipitation hardened engineering alloys

Promoted ignition and more recently promoted combustion are terms which have been used to describe a situation where a substance with low oxygen compatibility ignites and supports the combustion of a more combustion resistant material. Previous papers as well as a companion paper by the authors have reported on the investigation of this phenomenon as it related to carbon steels, 316L stainless steel and a number of significant engineering alloys. Within oxygen systems there are a number of engineering alloys which receive precipitation hardening heat treatments in order to develop desired mechanical properties. Although flammability data on some of these alloys have been reported in the literature, the effect of heat treatment on flammability tendencies has not received much attention. Metallurgical processes such as solution heat treatment and precipitation hardening may affect the distribution and relative proportions of metallic and intermetallic phases thereby influencing mechanical and in some cases physical properties. Several recent papers have suggested that metallurgical processes should receive more attention in flammability studies. The alloys selected for investigation in this study were 17-4PH stainless steel and Inconel® 718. Both alloys may be strengthened via precipitation hardening processes. Promoted ignition-combustion tests of these alloys in both the solution annealed and precipitation hardened conditions were conducted in flowing and static (fixed volume) testers using the rod configuration used in the joint ASTM-CGA-NASA program. The flammability tests were conducted in oxygen-nitrogen gas mixtures with oxygen purities ranging from approximately 40% to 99.7% at pressures of 0.79MPa to 34.6MPa.

Promoted ignition-combustion behavior of selected hastelloys in oxygen gas mixtures

Promoted ignition and more recently promoted combustion are terms which have been used to describe a situation where a substance with low oxygen compatibility ignites and supports the combustion of a more ignition resistant material. Previous papers by Union Carbide have reported on the investigation of this phenomenon as it related to carbon steel, 316L stainless steel, aluminum-bronze, Carpenter® 20 Cb-3, Incoloy® 65, Inconel® 625 and Haynes® 25. In this paper, additional data will be presented on the promoted ignition-combustion behavior of various Hastelloy® type materials, which are significant engineering alloys that may be encountered in or considered for gaseous oxygen applications in severe environments. In this investigation, alloys have been evaluated via both flowing and static (fixed volume) approaches using the rod configuration used in the joint ASTM-CGA-NASA program. Static tests have been conducted in a vessel of the same volume as the apparatus used by NASA in the joint ASTM-CGA-NASA test program conducted at WSTF and also in a larger 6.0 liter vessel. Oxygen-nitrogen gas mixtures with purities ranging from approximately 40% to 99.7% at pressures of 3.55 MPa to 34.6 MPa were used in the comparative studies of five Hastelloy® compositions. As an adjunct to this investigation, neural network techniques were utilized in the analysis of the data. Neural network analysis is an artificial intelligence technique which mimics the human brain. The data generated in this investigation and other work was incorporated into a predictive tool.

Promoted Ignition - Combustion Behavior of Selected Engineering Alloys In Oxygen Gas Mixtures

Promoted ignition and more recently promoted combustion are terms which have been used to describe a situation where a substance with low oxygen compatibility ignites and supports the combustion of a more ignition resistant material. A companion paper described the investigation of this phenomenon as it related to carbon steel and 316L stainless steel. In this paper, additional data will be presented on the promoted ignition-combustion behavior of other engineering alloys which may be encountered in or considered for gaseous oxygen applications. Although a number of papers in recent years have dealt with metal ignition-combustion studies in gaseous oxygen, a standard ASTM test to cover this phenomenon does not currently exist. Due to the range in pressure and purity requirements in oxygen applications, answers to the following issues are needed: (1) applicability of flowing vs. static (fixed) volume approaches, (2) significance of the test volume in static tests, (3) promoter selection, (4) oxygen purity, and (5) test methods for reduced pressures. In this investigation, alloys have been evaluated via both flowing and static (fixed volume) approaches using the rod configuration used in the joint ASTM-CGA-NASA program. Static tests have been conducted in a vessel of the same volume as the apparatus used by NASA in the joint ASTM-CGA-NASA test program conducted at WSTF and also in a larger 6.0 liter vessel. Oxygen-nitrogen gas mixtures with purities ranging from approximately 40% to 99.7% at pressures of 0.79 MPa to 34.6 MPa were used in the comparative studies of five alloys from the austenitic stainless steel, aluminum-bronze, cobalt and nickel families.

Accelerating rate calorimeter studies of metal oxide interactions with hydrocarbons in high-pressure oxygen

The presence of metals and metal oxides decreases the autogenous ignition temperature (AIT) of hydrocarbons in the presence of high-pressure oxygen. In this study, the accelerating rate calorimeter (ARC), which can detectself-heating reactions as low as 0.03°C/ minute, was used to study the interaction of selected metal oxides with a hydrocarbon oil in high-pressure oxygen at pressures up to 10.3 MPa. Hydrocarbon oil-metal oxide mixtures demonstrated self-heating reactions below the AIT of the hydrocarbon oil. Effects on peak self-heating rates and the temperatures at which self-heating occurred were also noted.

Utilization of high-pressure oxygen in enhanced oil recovery

Oil production methods are classified as primary, secondary, or tertiary processes. Each of these may recover approximately 15% of the available oil in a reservoir. Oxygen fireflooding is a tertiary oil recovery process that uses in-situ combustion to recover heavy oil. Oxygen injection pressures of approximately 6.9 and 20.7 MPa, respectively, are being used in Alberta and Texas to recover heavy oil. This is an application in which the effects of both corrosion and materials flammability have to be considered. Surface and downhole components associated with oil recovery may be relatively complex and have evolved to meet the specific needs of the industry. Materials, systems, and operating considerations that affect the design of surface and downhole equipment for oxygen firefloods will be discussed.