Failure analysis of catalytic steam reformer tubes

Abstract

Purpose

To determine if the interim use of liquid waste as a fuel in a catalytic steam reformer unit had any deleterious effect on the long‐term life of the reformer tubes.

Design/methodology/approach

Standard metallographic techniques were used to prepare representative samples obtained from various sections of the reformer tubes for metallurgical evaluation. Microstructural characterization was carried out in a scanning electron microscope equipped with an energy dispersive X‐ray spectrometer. Imaging and elemental analysis was used for the identification of the alloy material, corrosion products and other microstructural features.

Findings

Hydrogen was produced in a catalytic steam reformer by cracking methane using natural gas as a fuel. Corrosion of reformer tubes occurred when natural gas fuel was replaced with a liquid waste. Use of liquid fuel waste accelerated the rate of oxidation at the outer tube surface. However, foreign species from the fuel were not transported into the tube material. The heat‐resistant steel casting used for this application was susceptible to precipitation of Si‐stabilized Ni‐Nb Laves phase, thus reducing rupture life of the component. Voids at grain boundaries indicative of creep damage were observed.

Practical implications

Although, the interim use of liquid waste fuel appeared not to have damaged the tubes, it was concluded that the expected service life of the tubes may not be realized because of the susceptibility of the material to precipitation of Laves phase. An Fe‐base superalloy UNS N08810 or UNS N08811 was recommended as a replacement material for this application.

Originality/value

This paper provides an account of a failure analysis study. It identifies incorrect materials selection for a particular application and suggests better alternative along with its justification. The information is deemed useful for plant designers and engineers working in the related industry.

Citation

Tawancy, H.M., Ul‐Hamid, A., Mohammed, A.I. and Abbas, N.M. (2005), "Failure analysis of catalytic steam reformer tubes", Anti-Corrosion Methods and Materials, Vol. 52 No. 6, pp. 337-344. https://doi.org/10.1108/00035590510624677