Advanced NDT
IRIS ultrasonic tube inspection
IRIS (internal rotary inspection system) is an ultrasonic immersion technique for tubes. A probe is pulled through a water-filled tube while a spinning mirror sweeps the beam around the full circumference, giving a direct wall-thickness measurement at every point. Because it measures thickness rather than inferring it from an electromagnetic signal, IRIS is the usual way to verify and size wall loss found by faster screening methods.
How IRIS works
The tube is flooded with water as the couplant. A centring device keeps the probe on the tube axis while a turbine-driven mirror reflects the beam onto the tube wall, so the instrument records an outer-surface and inner-surface echo around the circumference. The result is a B-scan and C-scan of the tube that shows where the wall is thin, whether the loss is on the inside or outside, and how deep the deepest pit goes.
Tubes must be cleaned to bare metal first; scale and deposits scatter the beam. Cleaning is usually the controlling item in the schedule, so it is planned with the shutdown team before inspection starts.
IRIS alongside eddy current and RFT
IRIS is slower than eddy current, remote field or near field testing, so many programmes screen the full bundle electromagnetically and use IRIS on a sample and on every tube the screening flags. IRIS works on ferrous and non-ferrous tubes alike and gives the measured thickness that a remaining-life or plugging decision needs.
What to plan for
- Tube cleanliness: hydro-blasting or mechanical cleaning to bare metal.
- Tube bends, very small bores and heavy internal deposits limit coverage.
- A reference tube of the same material and size, with machined flaws, for setup and verification.
How we deliver it
IRIS tube inspection is carried out to a written procedure approved for the scope, naming the code and edition, the equipment and calibration, the coverage and the acceptance criteria. The procedure and each technician’s certification are submitted for the client’s review before mobilisation.
Work is planned and supervised by ASNT Level III personnel; our founder holds ASNT NDT Level III in UT, RT, MT, PT and VT. Reports state the coverage achieved and any limitations, so the engineer reading them knows what was examined and what was not, and any reportable finding is raised the same day.
Governing codes and standards
- Written procedure qualified on a reference tube with known flaws
- API 572 (inspection practices for pressure vessels, including exchangers)
- API 573 (inspection of fired boilers and heaters)
- API 579-1/ASME FFS-1 (fitness-for-service, when wall loss is assessed)
What you receive
- Tube-sheet map colour-coded by remaining wall
- Minimum measured wall and loss location (ID/OD) per tube
- Plugging recommendations against the client criteria
- Raw data retained for the next inspection comparison
Industries served
- Refining and petrochemical
- Power generation (boilers, feedwater heaters)
- Chemical processing
- Fertiliser and gas processing
Frequently asked questions
Is IRIS or eddy current better for heat exchanger tubes?
They answer different questions. Eddy current and RFT screen a whole bundle quickly; IRIS measures actual wall thickness and is used to size and confirm what screening finds. Most programmes use both.
Why do tubes need cleaning before IRIS?
IRIS sends ultrasound through water onto the tube wall. Scale and deposits scatter the beam, so the tube must be cleaned to bare metal for a reliable thickness reading.
Talk to an inspection engineer
Send the equipment list or drawings, the inspection you need and your timing. Quotes are prepared for each scope and region.
Request a QuoteRequest an inspection quote (RFQ)
Tell us the asset, the method, where it is, the governing code, your dates, the size of the job and the report you need. We reply with questions or a quote. Affordable, accessible, fully customizable — no published pricing.
Or email the same details to info@atlantisndt.com. Mobilisation: North America; confirm your location in your RFQ.
Speak to an ASNT NDT Level III
Atlantis NDT provides ASNT Level III consulting, NDT training to ASNT SNT-TC-1A, inspection management software and independent report validation. Request a free consultation and we will return a tailored quote — affordable, accessible and fully customizable to your programme.