4. Application – Compliance of coating thickness inside tanks
ECHOMETER 1076 TC: New Transducer for Hot Surfaces
The new wall thickness transducer DSE 8.3/15- PB 5 HT
from KARL DEUTSCH comprises a delay line made
from special plastics. This material combines essential
properties for this application, like high heat insulation,
low sound attenuation and small temperature effects.
The transducer can be used with the ECHOMETER 1076
TC and copes easily temperatures of 150 °C,
even with prolonged contact. In a measuring range of 2 mm to 25 mm (at a sound velocity of 5920 m/s)
the wall thickness can be measured stable and
reproducible.
Measuring the wall thickness on hot surfaces is always
difficult, since the oscillator material in the transducer is
sensitive to high temperatures. In extreme cases,
this may result in the complete failure of the transducer.
Even though the oscillator element of a wall thickness
transducer generally are mechanically protected by a
delay line of some millimetres length, however, due to
the lack of sufficient heat insulation properties of the
delay line it is not protected by heat induced damage.
Furthermore, in regular delay line materials the
temperature effects are too large to ensure stable
measurements. Materials with a low heat conductivity
typically have high sound attenuation properties, thus
they are not suitable. This, for examples, permits use
of the probe in all cases where the residual wall
thickness of pipes containing hot media needs to be
determined without shutting down operation.
Helmut Fischer Launch their new Fischerscope UMP Range
FISCHERSCOPE® UMP 20, 40, 100 & 150.With their exchangeable probes,
the ultrasonic gauges of the UMP series are ideal for measuring wall thickness
in all aspects of corrosion protection. Whether in the chemical or the
transport industry, the handy UMP gauges measure the thickness of metal
parts quickly and reliably. There is a device suited to every budget – from
entry level models to high-precision instruments.
Features • Dual-element probes for reliable results even on rough, corroded
surfaces • Range from 0.5-500mm • Zero-point adjustment for reliable
measurements even after frequent use and/or at fluctuating temperatures
• 2-point calibration function
• Comes with probe DKS-537 (5 MHz UMP 20, 40, 100), DLK-1025 (10 MHz UMP 150); & many other probes also available, Application & High Temp.
• Graphic display
• Multi-language menu
• Good life, 2 AA batteries
• Robust, IP54-rated housing
FISCHERSCOPE ST200
The FISCHERSCOPE® ST200 is Fischer’s first automatic scratch-test system for characterizing hard material layers. Easily check the adhesion and cohesive strength of layers ≥1 μm thick. The instrument is ideal for use in development, quality assurance, incoming goods control and production monitoring.
Features
Diverse measurement modes with progressive, constant or incrementally increasing test force. Measure according to the following norms: ASTM C1624, ISO 20502 & DIN EN 1071-3. Force control for measuring on curved surfaces. Three analysis methods: optical microscopy, friction force, acoustic emission. Intuitive user interface – only a brief familiarization is required to use the instrument. Fast measurements with motorized XY-stage and Z-axis. Easy creation of test reports
Applications
Testing how well thin coatings adhere to their substrates
Automated measurements with high sample throughput
Complying with regulations concerning coating thickness inside storage tanks
Anticorrosion coatings on the interior of storage tanks are critical when storing many types of products, whether saltwater or freshwater, gasoline, ballast, foamy liquids, or diesel. Typically, regulations are in place to ensure that the right coating is used. Quality inspection of the coating is an essential part of compliance with the regulations.
Although there are many such regulations, the Petrobras standard, N-1201:2008 – “Anticorrosion Coatings for the
Interior of Storage Tanks”, is a good example.
A multinational company headquartered in Brazil, Petrobras uses the above-mentioned standard wherever it has
operations. This standard is in the public domain and can be accessed online from their database; it regulates all
painting processes applied to storage tanks, from surface preparation, to painting and coating, through to final
inspection.
The Petrobras standard N-1201:2008 prescribes the following coating types and coating thicknesses for the different products to be stored, as listed in Table 1:
4.2.1 Coating Type 1
4.2.1.1 Primer: one layer of epoxy-zinc phosphate paint: 100 μm
4.2.1.2 Top protective coating: two layers of non-solvent epoxy paint:
50μm minimum thickness per layer.
4.2.2 Coating Type 2: one layer of zinc-ethyl-silicate paint: 75 μm
4.2.3 Coating Type 3: one layer of non-solvent epoxy resin, cured with
polyamine and embedded with ceramic or fibreglass: 800 μm
Once they are applied, the coatings need to be inspected – a tricky job, because this is done in place!
The enormous tank still smells sharply of noxious paint fumes as a technician wearing bulky protective gear
and a headlamp (perhaps the only source of light) is lowered into the slippery vessel to measure the coating
thickness at a number of positions. And, since a normal handheld gauge with integrated probe will not work,
as the tank geometry does not permit it in some spots, an external probe is necessary.
FISCHER developed the MP0x-FP products for just such applications performed under difficult conditions. While
other thickness gauges on the market require the use of both hands (one to hold the instrument and the
other for the probe), the wristband accessory is indispensable when the task itself requires some juggling.
Another very practical advantage of the MP0R-FP series is that calibration can be done outside the tank using
FISCHER calibration accessories to maximise accuracy. This procedure only needs a piece of the original tank
material, thus to avoid that the entire calibration procedure has to be performed directly in the tank.
Besides the unmatched accuracy & repeatability of the MP0R-FP series from FISCHER, extra features like the optional wristband or the easy calibration process make these coating thickness gauges the ideal choice for checking compliance with regulations like the Petrobras standard;
N-1201:2008.
For more information on the MP0R-FP series, please contact KK&S INSTRUMENTS
