IRIS Inspection for Lube Oil Cooler for Compressor

I would just install shut-off valves on either side of the coil, with an additional valve on the inside of each valve for nitrogen gas injection...then you could isolate the cooler and perform pressure test....

What about the IRIS which required water as test medium, can be done with using this shut-off valves?

IRIS - Definition by AcronymFinder

https://www.intertek.com/non-destructive-testing/internal-rotary-inspection-system/

..."What are the limitations of iris inspection?

However, tube inspection with IRIS has the following limitations: Heat exchanger tubes must be flooded with filtered water making the inspection setup complex and difficult to use. It is sensitive to ID / OD deposits and fins, which are not defects. It is unable to detect cracking."...

Well in some cases the IRIS testing is required by code or liability risk assessment, or just deemed necessary by the AHJ....The pressures involved or oil toxicity are likely to be a determining factor...IMO pressure testing at appropriate intervals and at sufficient pressures along with an automated alarm system that could detect pressure loss in oil circuit and shut the system down would be adequate, but not having all the details involved here, I can't say with certainty....

The service life of the tubing should have been predetermined by the design engineer, and replacement intervals should be designated...a lot of times the service life is dependent on the maintenance and chemical treatment, or other factors that cause wear on the tubing, this should be factored into the service life estimate and the tubing be replaced with adequate safety margins...there is also the criticality to consider, what would be the results of a catastrophic failure of this system....it all comes down to dollars and sense...

<...maintenance activities...>

• How far away is the original equipment manufacturer [OEM]'s operation and maintenance manual? What does it say on the topic?
• How was it done on previous occasions and how far away is the procedure against which the <...inspection on the tubes...> was carried out?
• What does the OEM say over the phone?
• What improvements can be made to the maintenance regime at the facility that would render the above information readily available in time for the next occasion that it will be carried out?
• Etc.