One of the most reliable non-destructive tests for detecting defects when inspecting tubes and piping is to use induced electrical currents, known commonly as Eddy Current Testing (ET).
Eddy Current testing is used to identify surface and sub-surface defects in conduct materials. This non-destructive testing method works on the principle of electromagnetism as a means of inspecting equipment that reveals damage, corrosion or cracking in tube nests.
INSPECTING TUBE NESTS USING EDDY CURRENTS
A wide range of thermal exchange equipment is used in processing plants in the chemical and petrochemical industries, as well as in power generating plants:
The criticality level of these items is normally very high and any failure they undergo usually incurs unscheduled downtime, with the financial consequences of lost production and other related costs.
Heat exchangers usually fail due to leakage from pipes in the tube nest, which can be caused by a multitude of factors, such as internal and/or external corrosion, erosion, mechanical impact, cracking under stress because of rust, or other reasons or failures in the expansion phase.
In order to monitor the integrity of these items and, more specifically, of the tube nest, SCI uses various NDT inspection techniques, although the general basis is the electromagnetic Eddy Current technique.
For this purpose, SCI Control & Inspección is proud to be able to count on the support of our technological partner from Germany, ec-works, a world leader with extensive expertise in this type of inspection service.
Therefore, depending on the type of material, characteristics of the pipe and type of defect to look for, SCI offers:
The results of the inspection are delivered in the form of colour-coded Tables and Graphs (Maps of the Flue Plate), which indicate approximate (% loss compared to nominal level of thickness) or exact (IRIS) remaining thickness in the pipes (i.e. whether there are any holes or cracks), so that the most appropriate mitigating or repair measures (plugging, re-tubing, partial or total sleeving, etc.) can be taken.
At SCI, we also offer advanced techniques for special cases, such as:
Inspection times (productivity) vary according to the technique used, the length and the state of cleanliness of the tubes or pipes, the means of access to the tube nest, the type of defects, etc.
As a guideline, the following productivity rates can be considered for 1 team on a 10-hour shift:
|NDT Technique||Productivity (Nº Tubes per 10-hour shift)|
|Conventional EC / PSEC EC||400 – 700|
|Remote Field EC||200 – 400|
|Rotating Ultrasound Probe (IRIS)||40 – 80|
|Ultra-Fast (Push / Puller) EC||2.500 – 3.500|
OTHER APPLICATIONS USING THE EDDY CURRENT TECHNIQUE
Inspection of surface and sub-surface cracking:
ADVANTAGES OF EDDY CURRENT TESTING
INDUSTRIAL SECTORS WHERE EDDY CURRENTS ARE APPLIED
At SCI, we have over 30 years’ demonstrable experience in Non-Destructive Testing and are specialised in the application of Eddy Current testing. We have suitably qualified personnel and appropriate technical equipment to solve our clients’ incidents and queries.
Tell us about your inspection requirements for heat exchanger tubes and we will try to offer you the most suitable solution.