Session: DA-21-01 Design and Analysis of Hydrogen Pressure Equipment - 1

Paper Number: 107766

107766 - Life Management of Pressure Swing Adsorbers 

Pressure cycles in a hydrogen environment can seriously affect the fatigue life of pressure swing adsorbers (PSAs).  PSAs are typically designed for a 20 to 30-year life and by the time the intended design life is approaching, many operators are challenged with making a deci­sion as to whether they need to purchase new vessels or explore whether or not life extension is a viable option.

In many cases, towards the end of design life or during midlife (50-60% of design life), operators elect to con­duct a life extension study that includes a Level 3 Fitness for Service assessment and Finite Element Analysis (FEA) to evaluate the areas of high stress where fatigue cracks might initiate. The outcome from the FEA is used to develop an inspection strategy. In most cases, it will show that the areas of high stress are around the inlet and outlet nozzles. However, most PSA vessels are well fabricated with nozzles or manways having integral reinforcement and blended nozzle welds, making these areas less susceptible to crack initiation.

In thre authors' experience, the real integrity concern is weld peaking in the long seams and/or weld misalign­ment, and this will not be highlighted by an FEA made from design drawings. Other potential crack locations are at internal attachment welds, for example, where the inlet screen is welded to the bottom head. These loca­tions have also been known to develop fatigue cracks in the past and need to be considered when developing an inspection plan for these vessels.

The work described in this paper highlights how it is pos­sible to operate PSAs beyond design life by developing inspec­tion plan based on a fracture mechanics approach and basing the underlying FEA stress analysis on laser scan data to capture the level of weld peaking in the long seam welds.

Presenting Author: Trevor Seipp Becht

Presenting Author Biography: Trevor Seipp is former Chair of the ASME PVP Division, Chair of the PVP2020 Conference, and current Chair of the PVP Division Senate Operations Committee.

Authors:

Annette Karstensen Becht
Trevor Seipp Becht
Chithranjan Nadarajah Becht