Client
Ammonia plant operator
Asset type
Ammonia synthesis converter
Location
Trinidad
Client challenge
During a planned turnaround, the client identified significant High Temperature Hydrogen Attack (HTHA) cracking on the ammonia converter pressure boundary welds. This posed a significant problem, as the indications found were rejectable by code, compromising safe and reliable operation. As a result, the client decided to perform ASME/National Board coded repairs.
How we helped
Vysus worked alongside the client and ASME repair organisation to ensure that a repair strategy was developed in accordance with relevant codes and regulations. Vysus provided repair QC oversight as well as 24/7 quality control, using our repair quality inspectors and ASME engineers, to ensure all works were performed in accordance with the approved repair plan.
In addition, we performed
multiple engineering evaluations to assist the decision making and repair
process, namely, buckling assessments, fitness for service crack evaluations
and preparation of risk-based inspection plans.
The repair consisted of
complete excavation of two circumferential welds (5” thick) and rewelding same,
including the use of hydrogen bakeouts, post weld heat treatment and advanced
NDEs. This required following a stringent process, within stipulated parameters
to be successfully completed without flaws. Onsite repair QC oversight and the engineering
studies helped to ensure this with appropriate communication and technical advice
to client personnel and the ASME repair organisation.
Powerful results
Repairs were carried out successfully in accordance with the repair strategy under the guidance and oversight of Vysus’ ASME engineers and repair quality inspectors. The vessel was subsequently R-Stamped by the ASME repair organisation, indicating a successful repair and that the vessel was fit for continued service. The plant subsequently resumed operation successfully using an RBI monitoring plan developed by Vysus, and further assurances via fitness for service. The successful repair of the ammonia converter also alleviated the need for the client to immediately procure a new reactor - which would have taken years to construct - resulting in large cost savings.
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