Hydrogen reforming (HR) in refinery produces hydrogen, which is used to remove sulphur in hydro-processing 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.
In Jan2023, during reformer shutdown; one of the reformer inspections revealed cracks at hot collector and pigtail. Most of the cracks were on the surface and some of the cracks were through. Pigtail sample was removed, and it was taken for failure investigation to confirm the failure root cause. The reformer pigtail has served 49 years, which is more than four times of the design creep life (100,000 hours - 11.4 years).
This paper describes pigtail root cause failure investigation along with work performed to maintain reformer integrity till next planned shutdown.
Hydrogen Plant at BAPCO is a part of the Low Sulphur Fuel Oil Complex. It is a conventional steam methane reforming hydrogen plant. The plant supplies hydrogen to Hydro-desulphurisation Unit for diesel hydrotreating.
