A. Al-Meshari

Creep of outlet pigtail tubes of steam reformer and grain size effect on Creep of an Incoloy 800H material

Abstract During the inspection of a scheduled turnaround of one of the Steam Reformers in a Methanol Plant, a diameter increase was observed on the outlet pigtail tubes. Original dimension of the outlet pigtail tubes is; 1¼ × 0.2 inch wall thickness & Sch. 80 (42.2 mm OD). The material of the tubes was Incoloy 800H. The outlet pigtail tubes of the steam reformer are connected to a manifold header which used to transport the process fluid. It was requested to conduct a failure analysis on damages in the outlet pigtail tubes that occurred in the form of a diametral expansion. The failure analysis study is described in details and the mechanism of the diametral expansion damage is identified. The grain size effect of different increases in the strain of the tube OD was studied to correlate its effect on the material’s creep. It was also concluded that the tertiary creep phase (instable behaviour) starts around 7% increase in the strain of the tube OD. The 7% is set as the creep limit and the criterion of end-of-safe life.

Failure Analysis of Reformer Tubes

This paper presents a failure analysis performed to investigate cracking observed in reformer tubes. Thorough investigation showed that the tubes failed by thermal shock. No signs of advanced creep failure could be observed near the ruptures or across the microstructure. Also, no material-related abnormalities were observed in the tube microstructure. The reformer tube material is suitable for the application, and there is no need for metallurgy upgrade. It is recommended that reformer operating, start-up and shut down procedures be followed to ensure safe and sustainable operation. The condition of un-replaced tubes that had been exposed to the extreme thermal cycles has to be frequently monitored.

Failure Analysis of Furnace Tube

This article describes the findings of a detailed investigation into the frequent failure of ethylene furnace radiant tubes at a petrochemical plant. Thorough analyses including visual and stereoscopic examination, metallography, chemical analysis, and hardness testing show that the tube failure is attributed to creep accelerated by heavy carburization and uneven heating. The inability of the alloy to form a re-healing protective oxide scale led to accelerated carburization and nitridation. Possible factors that could adversely affect the scale protectiveness are discussed.

Metal Dusting of Process Gas Heater Convection Tubes

Abstract An investigation was conducted into a failure of convection section tubes in a process gas heater in a steel-making company. Thorough study using various characterisation techniques showed that the failure of the tubes, which were made of low-alloyed steel ASTM A335 P22, was attributed to metal dusting. The attack was accelerated because of the use of incompatible tube material for the intended operating conditions. Moreover, thermal fatigue cracks were discovered on the tube surfaces. Such cracks might have been caused by the high number of plant start-ups and shutdowns. Failure contributing factors and recommendations to avoid similar failure are discussed in this article.

Failure Analysis of Turboexpander

AbstractThis article describes an investigation into a failure of a turboexpander wheel driving a compressor. Some of the wheel blades were completely cracked and detached, while others had cracks of varying lengths running parallel to the root of the blade. Detailed failure investigation using different characterization techniques such as visual examination, chemical analysis, fractography, metallography, SEM/EDX, hardness testing, modal impact testing, and FEA showed that the cracks and fractures in the turboexpander wheel were caused by fatigue which progressed from multiple origins on concave blade side surfaces, near the hub. The fatigue performance of the turboexpander wheel was degraded significantly by the presence of the anodized layer on the wheel surface. Corrective measures to avoid similar failures are suggested and discussed.

Cracking Investigation of Vaporizer Tubes

This article describes the results of an investigation into failures of washing phenol vaporizer tubes. Thorough analyses including visual examination, chemical testing, fractography, metallography, heat treatment, and hardness testing have shown that the vaporizer tube failure is attributed to intergranular corrosion. The failure contributing factors are identified and elucidated.

Failure Analysis of a Pressure Transmitter Line

A pressure transmitter pipe in a PVC plant failed during shutdown. An investigation was performed in order to determine the failure mechanism. Investigation methods included visual examination, optical and scanning electron microscope analysis, chemical analysis of the material, and microhardness test. It was concluded that the pipe cracking is attributed to chloride SCC.