Hydrogen reforming (HR) in refinery produces hydrogen, which is used to remove sulphur in hydroprocessing plants to make environment friendly fuels. Reformer is a heart of any HR, which converts methane gas into hydrogen using steam at high temperature in presence of catalyst.

High Nickel-Chromium alloys and alloy 800H is commonly used material for reformer tubes and pigtails which operates at very high temperature. Under high temperature conditions, the material must be resistant against creep, oxidation and carburization being these are the most active damage mechanisms.

In this paper, an incidence of alloy 800H reformer pigtail failure has been described, which is in service since last 49 years and operating at 1450F (788C). This paper investigates the failure mechanism and discusses several destructive and non-destructive testing performed on the pigtail sample to identify root cause and to minimize future production downtime with reliable integrity. Detailed analysis confirmed the pigtail sample suffered from combination of creep, stress relaxation cracking, internal carburization & external oxidation on account of extended design life.