Industrial gas companies operate and maintain hydrogen production facilities. Pressure swing adsorption (PSA) exists as the primary method of product purification in most large-scale hydrogen production facilities. The maintenance and inspection of PSA equipment is critical to the overall reliability and safe operation of the facility. Mechanical integrity of the vessels, piping, and piping components is crucial to ensure that this equipment is fit for service.
This publication is an industry-wide guideline for in-service mechanical integrity of PSA units and is intended to contribute to the operational safety and reliability of these units. This publication is not intended to address the details of design and installation of PSA vessels and piping.
This publication applies to PSA units with reformer syngas, refinery off-gas, and other hydrogen containing off-gases. This publication is focused on the parts of the PSA that are subjected to pressure cycles, although some consideration is given to the noncyclic portions of the PSA system.
The publication is part of the programme to develop Globally Harmonised publications amongst Regional Gas Associations.
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Table of Contents
1 Introduction 2 Scope and purpose 3 Definitions Publication terminology Technical definitions 4 Description of pressure swing adsorption systems General Pressure swing adsorption system limit Adsorbents Cyclic service versus noncyclic service Feedgas considerations 5 General safety considerations Purging equipment and piping Impact of adsorbents on purging of vessel Other maintenance considerations 6 General mechanical design and fabrication considerations Vessel design and fabrication considerations Pressure swing adsorption piping design considerations 7 Failure mechanisms and contributing factors Mechanical fatigue Hydrogen embrittlement Corrosion 8 Inspection techniques Online actions Offline inspection 9 Fitness for service considerations Inspection and maintenance history Determination of fitness for service 10 Repair considerations 11 References Appendix A - Fitness for service work flow (Normative) Appendix B - Examples of fitness for service work flow (Informative) Table 1 Summary of NDE methods Figure 1 PSA system schematic Figure 2 Potential areas for fatigue failure of a PSA vessel Figure 3 Weld surface profile example (dimensions in inches) Figure 4 UT scan coverage plan example Figure 5 Pressure vessels in cyclic service