High-temperature hydrogen attack, accelerated by a fire incident

This article investigates the damage mechanism of a 2-in.outer diameter (OD)low-alloy Platformer furnace thermowell tubein a refinery. The thermowell tube that was connected to the outlet header failed after 4 mos in operation. The loss of primary containment releaseda mixture of hydrotreated hydrocarbons (naphtha) and hydrogen gases into the atmosphere, which combusted spontaneously within the fire box. The 4-in.OD furnace tubes have been fully re-tubed during the latest plant turnaroundwith upgraded metallurgy—T22[2.25 chromium (Cr)-1 molybdenum (Mo)]to T9(9Cr-1Mo)—because of creep and external sulfidation damages. Based on the laboratory metallurgical examination, it was observed that t