Tubing applications are usually defined as the inspection of ferromagnetic or non-ferromagnetic tubes in a variety of assets such as shell-and-tube heat exchangers, steam generators, boilers, coolers, and condensers.

The tubes in such assets are usually small in diameter and very numerous (some bundles can contain as few as five tubes, while others as many as 50 000). The tubes in this fixed equipment are sometimes straight, sometimes bent, sometimes twisted, which requires a vast array of probes to inspect the tubes from the inside.

Inspecting such tubes is common in the oil, gas, and petrochemical industry, as well as in the power generation and nuclear industries. Timing is usually critical, as shutting down for inspection is usually costly, but more so when the shutdowns are unplanned. Inspections must therefore be highly productive, considering the large amount of tubes to be inspected.

The most common defects that asset owners and inspection companies look for in tubes are inner and outer-diameter pitting and corrosion, longitudinal cracks, circumferential cracks (especially at the tubesheet), erosion, fretting, and metal loss. It’s usually important to find such defects before tubes begin leaking, because that causes pressure inside the equipment to drop, which leads to lower performance and even critical failure.

However, no single inspection technique is adequate for all tubing applications, all types of materials, and all defects. Eddy current testing (ECT) is commonly used to inspect non-ferromagnetic tubes, RFT and MFL are used to inspect carbon steel and other ferromagnetic tubes, while IRIS ultrasonic testing is perfect for metal loss measurements on both types of tubes.

Ferrous Tubing

Ferrous tubes are common in the shell-and-tube heat exchangers of the oil, gas, and petrochemical industry, among others, where inspection companies use RFT, NFT, MFL, and IRIS in various combinations to detect corrosion, pitting, cracking, and erosion in the tubes to maintain efficiency. The generally poor cleanliness of tubes means that probes must be durable, reliable, and have short lead times.

This is exactly what Eddyfi probes offer. And, when our standard probes don’t meet application requirements, we are fully equipped to custom-design and manufacture special probes.

Non-Ferrous Tubing

Non-ferrous metals, for example Inconel, are used to make tubes that are non-magnetic and offer a better resistance to corrosion and stress cracking. They are necessary in the power generation and nuclear industries due to the critical nature of the systems they are part of, such as steam generators in nuclear plants. They are also omnipresent in the balance of plants (BoP) of such industries.

Eddy currents are used in these industries because they are perfectly suited to inspecting non-ferrous alloys. Our high-performance probes are designed to offer excellent signals while being very durable. You can therefore inspect large number of tubes rapidly and precisely.

Suitability According to Material

Material/Tech ECT ECA IRIS RFT NFT NFA MFL PSEC
Non-ferromagnetic Tube

Yes

Yes

Yes

No

No

No

No

No

Finned tube

Yes

Yes

Yes

No

No

No

No

No

Low ferromagnetic Tube

No

No

Yes

Yes

Yes

Yes

Yes

Yes

Finned tube

No

No

Yes

Yes

Yes

Yes

Yes

Yes

Ferromagnetic Tube

No

No

Yes

Yes

Yes

Yes

Yes

Yes

Integral finned tube

No

No

Limited

Yes

Yes

Yes

Yes

Yes

Aluminum finned tube

No

No

Yes

No

Yes

Yes

Yes

Yes

Detection Capabilities According to Defect Type

Defect/Tech ECT ECA IRIS RFT NFT NFA MFL PSEC
ID pitting

Excellent

Excellent

Excellent

Acceptable, but limited

Acceptable, but limited

Excellent

Excellent

Excellent

OD pitting

Excellent

Excellent

Excellent

Acceptable, but limited

Not suitable 

Not suitable

Acceptable, but limited 

Acceptable, but limited 

Axial cracking

Acceptable, but limited

Excellent

Not suitable

Acceptable, but limited

Acceptable, but limited

Acceptable, but limited

Not suitable

Acceptable, but limited

Circumferential cracking

Acceptable, but limited

Excellent

Not suitable

Not suitable

Not suitable

Acceptable, but limited

Acceptable, but limited

Acceptable, but limited

ID corrosion

Excellent

Excellent

Excellent

Excellent

Excellent

Excellent

Excellent

Excellent

OD corrosion

Excellent

Excellent

Excellent

Excellent

Not suitable

Not suitable

Acceptable, but limited

Acceptable, but limited

At tubesheet

Acceptable, but limited

Excellent

Excellent

Acceptable, but limited

Not suitable

Not suitable

Acceptable, but limited

Acceptable, but limited

Excellent

Acceptable, but limited

Not suitable

Sizing Capabilities According to Defect Type

Defect/Tech ECT ECA IRIS RFT NFT NFA MFL PSEC
ID pitting

Good

Excellent

Excellent

Good

Not suitable

Excellent

Not suitable

Not suitable

OD pitting

Excellent

Excellent

Excellent

Good

Not suitable 

Not suitable

Not suitable 

Not suitable 

Axial cracking

Good

Excellent

Not suitable

Not suitable

Not suitable

Good

Not suitable

Not suitable

Circumferential cracking

Not suitable

Excellent

Not suitable

Not suitable

Not suitable

Good

Not suitable

Not suitable

ID corrosion

Good

Excellent

Excellent

Excellent

Not suitable

Excellent 

Not suitable

Not suitable

OD corrosion

Excellent

Excellent

Excellent

Excellent

Not suitable

Not suitable

Not suitable

Not suitable

At tubesheet

Good

Good

Excellent

Not suitable

Not suitable

Not suitable

Not suitable

Not suitable

Excellent

Good

Not suitable