Reformers made of modified HP-40 alloy (23Cr-35Ni) were used in the ammonia industry to produce hydrogen. One of the pipes in the reformer experienced failure. To understand the reason for such failure, the fractured section was characterized by SEM-EDS, creep tests, and polarization tests. The creep test indicated that the pipe failure was caused by overheating, which induced crack along the metal grain boundaries. The optical microscope images of the alloy revealed voids and micro-cracks in the fractured section. The increase in porosity due to diffusion of hydrogen gas shortened the time to rupture. EDS analysis detected high carbon content associated with the carbide phase in the fracture section. The carbide phase induced creep cracking in the alloy leading to the failure. The creep test confirmed that the material had experienced severe deformation from creep cracking.