The Client had installed four pressure vessels at the Woodinville location that needed to be rerated and re-certified to a lower operating temperature. The pressure vessels are identified as V9, V10, V11 and V12 with National Board numbers of 2899, 3746, 3733 and 2900, respectively. Current lower end operating temperature limitation is approximately -20F; Americold asked TAI to provide the lowest temperature rating for normal operation without conducting impact testing.

Scope requirements were as follows:
1) field data collection: information and/or dimensions on all four vessels;
2) provide an external visual inspection and UT thickness survey and also develop a detailed sketch of each vessel with specific dimensional information on the nozzles and their location; and
3) provide the engineering calculations needed for the re-rating.

Project Management/Coordinator: For this work, TAI provided a project coordinator to act as a central point of contact for the Client to schedule work and provide deliverables and results as applicable. The coordinator scheduled TAI internal services and resources and communicated with the Washington State Authorized Inspector, as needed.

Field Data Collection & Inspection:
TAI’s inspector worked with the Client’s local representative to collect the field data for the four vessels for API 510 external inspection and thickness readings. The TAI inspector also visited the site to obtain information needed develop vessel configuration drawings. The information that was obtained included the requirements to match the U- 1A forms and UT information needed to support the rerating calculations for each vessel. A minimum of 15 UT readings were taken from each vessel. The inspector developed an inspection report for each of the subject vessels.

Design & Engineering Analysis:
TAI prepared calculations to verify that the current vessels’ conditions complied with ASME section VIII for pressure vessel design and operation and prepared calculations for the lowest available MDMT without impact testing. The calculations were prepared in accordance with the 2013 edition of the ASME Boiler & Pressure Vessel Code, Section VIII, Division 1, Part UCS-66. Finally, TAI provided an outline configuration drawing for each vessel from the field dimensions obtained and the materials of construction confirmed during the site visit.