Gas 2024 Issue

Steam methane reformer tube lifecycle improvement best practices

Reformer tube life assessment can be done via online monitoring, non-destructive testing, and tube harvesting with historical operating, monitoring, and inspection data

Richard D Roberts and Grant Jacobson Becht

S team methane reformers (SMRs) are an integral asset operated globally within methanol, hydrogen, ammo- nia, and direct reduced iron (DRI) plants. Providing plant owners/operators with the ability to extend tube life within the steam reformer is essential in maximising the use of an owner’s capital investment. Most of the tube’s material content is made up of nickel, ultimately driving the overall economics of fabrication. The cost of purchasing and install- ing a single reformer tube can be upwards of USD 25,000. However, in today’s highly competitive markets, the effect of unplanned downtime in reducing the plant on-stream factor is far greater than the installed cost of a single reformer tube. It is essential that plant engineers have access to highly accurate online monitoring and inspection data, allowing them to better manage the reformer tubes and, where cir- cumstances allow, extend the tube life expectancy beyond the typical prescribed life expectancy. One hundred thou- sand operating hours is a typical design life guideline prac- tice used by furnace design engineers. Today, plant owners and tube manufacturers have

QC screening at the tube manufacturing facility. Internal inspection methods tend to be preferred as they allow the tubes to be stacked on top of one another in the hori- zontal orientation, thus requiring a small footprint within the facility. External methods require tubes to be spread out to allow for adequate space around the exterior, thus requiring a much larger space to carry out the inspections. Both approaches often apply one or more of the previously described NDT methods. Conducting QA/QC inspections prior to the tubes being shipped from the manufacturer’s facility allows necessary repairs to be made in advance of shipping and often tight installation deadlines. Flaws such as dimensional over-bor- ing, machine gouges, and excessive weld-root penetration are damages that may reduce tube life downstream if not addressed prior to placing into service. Data collected as part of the QA/QC inspection can also be archived as ‘baseline’ data and applied during future rou- tine inspections. Even tubes fabricated well within design tolerances naturally contain variations within the internal

become accustomed to inspecting tubes with the latest technologies, even before they ship from the tube fabrication facility. This proactive approach enables quick detection and quantifi - cation of manufacturing flaws, enabling repairs to be made if necessary. Additionally, this early inspection approach provides plant owners with ‘baseline’ inspection data for future use over the life of the tube. Tube inspection instrumentation technolo- gies often apply non-destructive testing (NDT) methods such as laser profilometry (LT), eddy current (ET), ultrasound (UT), radiography (RT), and electromagnetic acoustic transducer (EMAT). Each method has its strengths and weaknesses. Therefore, some instruments have coupled two or more NDT methods to maximise the accuracy of test result outputs and inspec- tion area coverage. QA/QC and ‘baseline’ inspections Both internal and external inspection approaches (see Figure 1 ) can be utilised to facilitate QA/

bore dimension. Precise bore dimensions can be obtained and documented during this exercise. Future routine inspections can leverage these dimensional data rather than applying design values. This approach ultimately produces much more precise creep strain monitoring over the life of the tube, which directly impacts the accuracy of remaining life assessment calculations.

Figure 1 Internal and external inspection methods

Gas 2024