Failure and Residual Life Analysis of Service Exposed Hydrogen Reformer Tubes
•February 21, 2026
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Why It Matters
Understanding these failure modes enables operators to extend tube lifespan, reduce unplanned outages, and protect costly hydrogen production assets.
Key Takeaways
- •Creep rupture initiates at dendritic boundaries, causing microcracks
- •Overheating from burner misalignment accelerates tube failure
- •Nb and Zr alloying extend creep life of reformer steels
- •Nondestructive testing essential for early detection of voids
- •Designed service life ~100,000 hours often exceeded in practice
Pulse Analysis
Hydrogen reformer tubes are the workhorses of steam‑reforming facilities, converting natural gas into hydrogen for petrochemical, steel, and fertilizer sectors. Constructed from high‑temperature alloys such as HK40, HP40, HP40mod, and Paralloy H39WM, these centrifugally cast tubes endure temperatures near 1,000 °C and pressures up to 30 kg cm⁻². Recent alloy innovations introduce niobium and zirconium to improve thermal stability and creep resistance, aiming to meet the API‑recommended 100,000‑hour design life.
In practice, tubes frequently fail well before their intended lifespan due to two dominant mechanisms. Creep rupture begins at dendritic grain boundaries, where voids coalesce into microcracks that propagate through the wall thickness. Simultaneously, burner misalignment can cause localized flame impingement, raising surface temperatures and accelerating oxidation and creep damage. Cyclic thermal and mechanical loads from unexpected shutdowns further exacerbate carbide cracking. Detecting these internal defects requires sophisticated nondestructive evaluation techniques, such as ultrasonic phased‑array or eddy‑current testing, to identify voids before catastrophic rupture.
The implications for the hydrogen economy are significant. Early detection and accurate residual‑life assessment can prevent costly plant shutdowns and extend the operational window of existing assets. Moreover, the study underscores the value of continued alloy development—particularly Nb and Zr additions—to push creep limits beyond current thresholds. Integrating predictive maintenance platforms with real‑time monitoring will be essential for scaling hydrogen production while maintaining reliability and safety.
Failure and Residual Life Analysis of Service Exposed Hydrogen Reformer Tubes
By Devana Sankara Rao, Research Assistant Manager at Indian Oil Research & Development Centre; Dr. S. P. Singh, Mechanical Engineer at Indian Oil Research & Development Centre; and Mahendra Pal, General Manager – Applied Metallurgy at Indian Oil Research & Development Centre
Published in the November/December 2025 issue of Inspectioneering Journal
Introduction and Background
Hydrogen production is an essential requirement in industries like oil and gas, petrochemicals, iron and steel production, and fertilizer plants. Steam reforming of natural gas is one of the most widely used processes (48 % of current hydrogen production) to produce hydrogen gas in these industries through reformer tubes [1, 2]. These reformer tubes are manufactured using the centrifugal casting method of heat‑resistant steels. The metallurgy used in reformer tubes is HK40 (25Cr20Ni), HP40 (25Cr35Ni), HP40mod (25Cr35NiNb), and Paralloy H39WM (25Cr35NiZrTi), which have resistance to high‑temperature oxidation and creep damage [3]. Nowadays, new alloying elements Nb and Zr are added to enhance their thermal stability and increase the creep life of the material [4, 5].
These centrifugally cast tubes generally contain an austenitic matrix in which dendritic grains are positioned on the outer surface, followed by equiaxed grains formed at the final stage of solidification on the inner surface of the tube. These tubes are designed for around 100,000 hours of operation as per API recommended practice [6].
During hydrogen production, these reformer tubes are exposed to severe working conditions such as temperatures in the range of 970–1,000 °C and pressure in the range of 20–30 kg cm⁻² [7]. Frequently, premature failure of these tubes and sudden plant shutdown are unavoidable because of these conditions. Several damage mechanisms predominantly cause tube failures, such as creep rupture—one of the most prominent. In creep rupture, damage starts at about one‑third of the wall thickness in the form of voids on dendritic boundaries. As creep damage progresses, the dendritic boundaries show an alignment of voids that convert to microcracks/fissures; thus, the damage initiates inside the tube material. Specialized nondestructive testing is required for damage assessment.
Localized overheating is another major cause of premature failure due to misalignment of burners, which leads to direct flame impingement on the tubes [8]. Cyclic mechanical and thermal loading caused by unexpected shutdowns also leads to microstructural damages such as creep voids and carbide cracks [9, 10].
Experimental Methods
The details of the working and design conditions of the tube sample used for failure and residual‑life analysis are given in Table 1. For this study, two sections of the same tube were examined: the bottom portion (failed region) and the top portion (unfailed region). A detailed investigation was carried out on the tube sample to determine the root cause of the failure and to assess the serviceability of the heater.
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