Inspection of tank

AIM Control Inspection techniques have been widely used in the Oil field Inspection Industry for over a quarter of a century for the examination of pipe, tubing and casing both new and used.

In order to understand how this particular application of AIM Control Inspection works it is necessary to understand the basic principles of the technique. Everybody is familiar with the ability of a magnet to “stick” to a carbon steel plate. This is due to the fact that magnetic lines of force (flux) much prefer to travel in the carbon steel plate than in the surrounding air. In fact this flux is very reluctant to travel in air unless it is forced to do so by the lack of another suitable medium.

For the purposes of this particular application a magnetic bridge is used to introduce as near a saturation of flux as is possible in the inspection material between the poles of the bridge.

Any significant reduction in the thickness of the plate will result in some of the magnetic flux being forced into the air around the area of reduction.

Sensors which can detect these flux leakages are placed between the poles of the bridge, our MFL equipment can detect in real time these material losses and help the inspector to identify the critic zones in the tank floor for a UT inspection.

The ultrasonic prove up necessary must be carried out by personnel who are adequately trained and qualified.

It must be remembered that this is not just “thickness measurement” but rather corrosion evaluation and the technician must have a full understanding of the technique that should be applied.

This is not a subject that we can cover within the limits of this paper. It will, however, be the subject of the next in a series of papers regarding the NDT of Storage Tanks.

Tank Inspection of AIM Control Inspection Group offers a complete line of NDE services and engineering evaluations per API Standard 653, API Standard 570, API Standard 510, STI Standard SP001, and AWWA D100. Our certified inspectors and engineers work as a team to provide quality, comprehensive inspections.

  ·     Inspection of tanks

We perform comprehensive tank inspections, which meet, or exceed, the requirements established in API 653 or STI SP001. The personnel used to perform this inspection are certified individuals and have been further trained by AIM Control Inspection Group.

We offer the latest in NDE equipment for tank inspection including the Magnetic Flux Leakage (MFL) Floorscanners, the Motorized MFL Mini Scanner and MFL Manual Scanner for inspection adjacent to the corner welds and under steam coils and internal piping, ultrasonic thickness, magnetic particle, vacuum box testing and helium leak testing, ACFM and other NDE techniques. 

  ·     Scanner for Bottoms with Thick Reinforced Liners

AIM Control Inspection Group provides the latest innovation in tank bottom inspection, SLOFEC (Saturation Low Frequency Eddy Current). The SLOFEC scanner is designed to inspect tank bottoms with reinforced coatings up to 0.300 inch thick. The scanner uses a combination of electro-magnetic and eddy current technologies to inspect through thick coatings. SLOFEC can – detect corrosion as well as locate the corrosion (soil side or product side) on the plates. This system also has the capability to quantify the remaining plate thickness resulting from soil side metal loss. This method of testing disturbs a minimum amount of coating.

  ·     Engineering Services

Our engineering services include evaluations per AWWA, API Standard 653, API Standard 510 and API 570 based on data gathered from the field inspections and evaluated using information recommended by codes or standards. A few of the evaluations we provide are: settlement evaluations, corrosion rate calculations, safe fill height calculations, seismic evaluation, brittle fracture evaluations, maximum working pressure and other evaluations referenced in the standards. Other engineering services include fitness for service evaluations and inspections per various state environmental regulations. We also perform specialized evaluations such as out-of-roundness surveys and verticality evaluations.

  ·     Helium Mass Spectrometer Leak Testing

Helium leak testing has proven to be a very effective method for the detection of leaks in many petrochemical applications, including tank bottoms, roof pontoons, roof drain systems and heat exchangers.

   ·     Automated Ultrasonic Crawler

AIM Control Inspection Group offers an automated crawler for performing ultrasonic line scans. The system is highly effective for providing continuous ultrasonic thickness data on tank shells and storage spheres.

   ·     Alternating Current Field Measurement (ACFM) Inspection

ACFM is a non-contacting technique to detect and size surface breaking crack-like defects through coatings up to a thickness of 0.200 inch.  We have used this method to detect crack-like defects in tank shell-to- bottom welds, tank bottom lap welds, sumps, nozzle and appurtenance welds and Stress Corrosion Cracking (SCC) in ethanol service.  Surface preparation is reduced compared to other NDE techniques.

  ·     Piping Inspection

Our piping inspection program includes MFL PipeScan services, which provides near 100% inspection coverage for above ground un-insulated straight runs of piping and vessels up to 0.750 inch wall thickness. Our API 570 inspections and engineering evaluations provide NDE data, visual inspection, and engineering assessments that include maximum working pressure (MAWP) and remaining service life calculations.

  ·     Low Pressure Storage Spheres/Pressure Vessels

Our vessel inspection program includes a full line of NDE inspection services for low-pressure storage spheres, pressure vessels and bullet tanks including a staff of experienced API 510 inspectors. Our services include an automated ultrasonic crawler and MFL wallscan.

  ·     NDE Services

AIM Control Inspection Group offers a full line of NDE services, including ultrasonic thickness, magnetic particle testing, liquid penetrant, visual and other NDE methods. Our inspectors are certified per ASNT SNT TC-1-A (Level I, II, and III) for ultrasonic, magnetic particle, liquid penetrant, visual, and other NDE methods.

  ·     Cleaning and Inspection Services

AIM Control Inspection Group can provide the combined service of tank cleaning and inspection.  In response to many customer requests, AIM Control Inspection Group has successfully teamed up with other key vendors to provide complete cleaning and inspection services with just one phone call/purchase order. This provides quicker tank turn-around, reduces internal project management and coordinates costs and insures no added mobilization cost for any additional cleaning to accommodate the inspection process. Additionally, all key vendors are evaluated thoroughly to insure all client qualification requirements are met and are in place.