Tank Floor Inspection Methods in Belgium | MFL, Manual UT and Robotic UT
Compare MFL floor scanning, manual UT and robotic in-service UT for Belgium storage tank integrity programs and shutdown planning.
PetroBot Technologies ·
For Belgium tank integrity teams, the right method depends on whether the immediate need is screening, prove-up or in-service decision support.
Key takeaways
- MFL is fast full-floor screening, but indications normally need UT prove-up.
- Manual UT gives accurate point readings, but coverage is limited and requires entry into a cleaned tank.
- Robotic in-service UT increases measurement density without draining or gas-freeing the tank, subject to suitability limits.
- The strongest inspection strategy combines methods instead of treating them as direct substitutes.
The three methods answer different questions
A method comparison should start with the question being asked. If the goal is to screen a clean open floor quickly, MFL is efficient. If the goal is to confirm exact remaining thickness at a known point, UT is the reference method. If the goal is to collect current floor evidence before a shutdown decision, robotic in-service UT can be the most useful option.
Confusing those roles creates poor expectations. A fast screening technique is not the same as a thickness measurement. A precise point reading is not the same as broad coverage. A robotic survey is not a guarantee that every inaccessible area has been measured.
| Method | Strength | Limitation | Best use |
|---|---|---|---|
| MFL floor scan | Fast screening of large clean plate areas. | Requires out-of-service cleaned tank and UT confirmation. | Open-tank full-floor screening. |
| Manual UT | Accurate remaining-thickness reading at the measured point. | Sparse coverage and confined-space entry burden. | Prove-up, repair verification and targeted checks. |
| Robotic in-service UT | Current UT data while tank remains operating. | Depends on access, product and internal geometry. | Shutdown prioritization and repeatable trend surveys. |
MFL floor scanning
Magnetic flux leakage scanners magnetize the floor plate and detect flux leakage caused by metal loss. They can cover large areas quickly once the tank is empty, cleaned and prepared. MFL is particularly useful for screening because it can flag suspect areas that deserve closer evaluation.
The limitation is that MFL is not a direct remaining-thickness measurement in the way UT is. Indications are influenced by plate condition, geometry, calibration and corrosion profile. Good programs therefore use MFL to find candidates and UT to confirm thickness and repair decisions.
Manual UT measurement
Manual UT gives a local thickness reading at the point where the probe is coupled to the plate. It is accurate, familiar to inspectors and valuable for confirming indications, qualifying repairs and documenting acceptance readings. It remains essential in many tank-floor programs.
Its weakness is coverage. Manual UT on a floor is slow, and every reading requires an inspector inside a tank that has been opened, cleaned, ventilated and tested. That makes it expensive to use manual UT as the only source of broad floor-condition evidence.
Robotic in-service UT crawlers
Robotic UT crawlers bring the probe to the bottom plate while product remains in the tank. Planned survey paths can collect many more readings than a sparse manual grid, and each reading can be associated with a location for repeat surveys. That makes the method valuable for corrosion trending and tank ranking.
The method still has practical limits. The inspection team must confirm access openings, product compatibility, sludge, obstructions, floor features, hazardous-area requirements and the inspection objective. Robotic UT should be scoped as an engineering inspection method, not as a generic gadget deployment.
- Useful for pre-shutdown floor condition evidence
- Supports repeatable measurement campaigns
- Reduces the need to enter the tank for the survey
- Requires suitability review before mobilization
How to combine methods
A practical integrity program uses each method where it is strongest. Robotic UT can collect current in-service evidence and guide the outage plan. MFL can screen the opened floor efficiently. Manual UT can prove up MFL indications, verify repairs and capture acceptance readings. Together, the methods reduce blind spots.
The decision should be driven by the tank's risk profile, product, inspection history, outage cost and the data needed for the next engineering decision. The cheapest method is the one that produces enough trustworthy evidence at the right time, not necessarily the method with the lowest daily rate.
Frequently asked questions
Is MFL better than UT for tank floors?
They solve different problems. MFL is a fast screening method for open cleaned tanks, while UT gives thickness readings at measured points. Most programs use MFL to find indications and UT to confirm them.
Why use robotic UT if a tank will eventually be opened?
Robotic UT can provide current data before the outage, helping teams decide which tanks to open first and where to focus cleaning, verification and repair planning.
Can robotic UT inspect every tank floor?
No. Suitability depends on access, product, temperature, sludge, obstructions, floor design and hazardous-area requirements.
Next step
Share tank details for a Belgium tank-floor inspection method review.
ITIS Rover - In-Service Tank Inspection Robot