Corrosion is rarely uniform — it hides where you're least likely to probe, so a healthy reading isn't the same as a healthy pipe.
Adapted for the web from the original post of 30 August 2026.
Picture one pipe section. 9.6 mm where the probe sat. 6.1 mm at the invert, a hundred millimetres away. Both readings are correct. The gauge was not asked the right question.
So the measurement plan matters as much as the instrument. Grid the location instead of taking a spot, bias toward six o'clock on anything wet, and record where every reading was taken — so next year gives you a trend rather than a fresh opinion.
Most survey reports I get handed have the readings and not the map. Numbers without positions are just a nice-looking PDF.
I have seen lines where last year's readings couldn't be put back on the same spot. Without the map you're not trending the line — you're starting over every year. A survey is only as useful as the next one that can repeat it.
A thickness reading tells you about the material under the probe. A thickness survey tells you about the line. Only one supports a decision about remaining life.
Were your last survey's reading locations recorded well enough to measure the same points again?
Fixed-scope and fixed-price, quoted in writing before work begins.
OMNIX carries out ultrasonic thickness surveys on plant piping — gridded, located and recorded. If your last one was spot readings with no positions noted, a re-survey gives you something you can trend. Every finding is located and photographed, and readings are set against minimum wall thickness in a fitness-for-service note. The same wall-thickness and corrosion-mapping work covers pressure vessels, boiler drums, steam headers, centrifuge bowls and fabricated structures, checked against the relevant Indian Standards. Which of them apply depends on your equipment and its duty.
A thickness reading tells you about the material under the probe. A thickness survey tells you about the line.
Short notes on machines, steam, fire systems and NDT — each first posted on LinkedIn.
Tell us your unit name, location and the equipment or premises concerned. A thirty-minute walkthrough at your plant — travel included within Visakhapatnam city limits, quoted in advance for outstation sites.
