A single leaking tube can take a heat exchanger, boiler or condenser out of service. Eddy current and remote field testing examine tubes from the inside, one after another, and show where wall is being lost and which tubes need plugging or replacing before they fail.
- Finds
- Wall loss, pitting, cracking, erosion, support-plate and baffle-cut damage
- Typical use
- Boilers, heat exchangers, air coolers, feedwater heaters, surface condensers, absorbers
What tube inspection finds
- General wall loss from corrosion and erosion
- Pitting
- Cracking
- Wear and damage at support plates and baffle cuts
Choosing the technique
The right technique depends on the tube material and the damage mechanism you expect, and we will help you choose it. Eddy current testing with an internal probe suits nonferromagnetic tubes, such as copper alloys, austenitic stainless steel and titanium. Remote field testing suits ferromagnetic tubes, such as carbon steel, where conventional eddy current cannot see through the wall. Remote field testing is among the fastest tube inspection methods available.
Data can be analyzed on site for immediate results, or remotely to reduce cost on large projects. For eddy current inspection of structure, fastener holes and material sorting, see eddy current testing.
Where it’s used
- Heat exchangers and air coolers
- Boilers and feedwater heaters
- Surface condensers and absorbers
- Power generation, nuclear, chemical and petrochemical plants
Codes and standards
- ASTM E690, in-situ electromagnetic (eddy current) examination of nonmagnetic heat exchanger tubes
- ASTM E2096/E2096M, in-situ examination of ferromagnetic heat exchanger tubes using remote field testing
- ASME Boiler and Pressure Vessel Code, Section V, Article 8, eddy current examination of tubular products
- The owner’s plugging and acceptance criteria
Who does the work
Every Midgard technician who performs eddy current and remote field testing holds current certification in that method, issued under a written practice. For most industrial work the written practice follows ASNT’s SNT-TC-1A; for aerospace and defense work it follows NAS410. A Responsible Level III oversees the program: approving procedures and technique sheets, examining and certifying technicians, and answering the technical questions that come up on the job.
If your contract calls for a different scheme, such as ANSI/ASNT CP-189 or NAVSEA requirements, tell us when you ask for a quote.
Training in eddy current and remote field testing
Midgard also trains in eddy current and remote field testing, along with all the other major methods. Instruction is given at Level I, II and III by certified Level III instructors, to SNT-TC-1A, CP-189, NAS410, NAVSEA or whichever code you certify to, with general, specific and practical examinations at your facility or ours. It suits new hires working toward first certification as well as technicians due for re-examination. See training and certification, or ask about a class.
Common questions
What is the difference between eddy current and remote field testing for tubes?
Both pass a probe through the tube. Conventional eddy current works well on nonferromagnetic tubes such as copper alloys, stainless steel and titanium. Remote field testing is designed for ferromagnetic tubes such as carbon steel, where conventional eddy current cannot penetrate the wall.
How should tubes be prepared for inspection?
The probe has to pass freely, so scale, deposits and debris are removed beforehand, usually by hydro-blasting or brushing. We will tell you the cleanliness the technique needs when we plan the job.
What does a tube inspection report show?
A tubesheet map showing each tube examined, the indications found with their type, location along the tube and estimated wall loss or depth, and the tubes that meet your criteria for plugging or further examination.
When is tube inspection usually done?
During a scheduled outage or turnaround, when the bundle is open and the tubes are clean. Planning it into scheduled downtime finds problems that can be repaired on plan, before they force an unscheduled shutdown.
Tell us the equipment, the tube material, size and count, the damage you expect, and your outage dates. Call 1-844-MIDGARD, email contact@midgardscientific.com, or use the contact page.