Frequently
Asked
Questions (FAQs)
The
most frequently asked
questions about
VR Potable
Water
Tank and
In-Ground
Reservoir Inspections
1. Does the reservoir/tank owner need to do anything in
preparation
. . for the inspection?
NO! As opposed to dry or diver inspections, there is no
preparation required by the reservoir/tank owner for a Tank
Rover inspection. Unlike diver inspections, the tank stays
on-line and full of water. You do not need to isolate the
tank, which means no valve turning, pumping or loss of pressure.
There is no need for follow-up bacteria testing or disinfecting.
2. Is there any possibility of water contamination by the
ROV?
NO! The Tank Rover unit is constructed of inert high-density
plastics.
Even the critical thruster bearing seals have been
filled with a food grade glycerin. The unit is disinfected
before every inspection in accordance with AWWA C652 using
a 200ppm+ chlorine solution on all components that enter
the water. Unlike with divers there is no concern over medical
records or discharged breathing air into the water.
3. How much detail can be viewed through the video camera?
The Tank Rover is equipped with a 12:1 macro zoom video
camera, which allows the inspector to zoom in and clearly
view surface features as small as 1/32 inch. The power wire-cleaning
tool cleans off all surface debris, corrosion products and
failed coating, permitting the inspector to see pits, cracks
and weld corrosion.
4. Can still photographs be provided of the internal inspection?
YES! ScanTron is able to digitally capture any individual
frame of the color video and print those frames in high quality
full color. The stills are equal to a 35mm camera photo and
are provided in the written report. A full explanation of
the inspection video is included.
5. Has the ROV inspection ever been directly compared with
dry and
. . diver inspections?
YES! The level of detail and surface coverage of the Tank
Rover was equal to the diver method, but the Tank Rover caused
much less turbidity than the diver. There is no danger to
human life because the ROV can stay immersed for several
hours.
6. Can the ROV view larger sections of the internal surfaces?
YES! When tanks are dark due to surface staining they absorb
light.
When the tanks are dark they are difficult for both
the divers and ROVs to get wide shots. The Tank Rover carries
three high intensity halogen lamps as opposed to one or two
normally carried by divers. This extra light allows for better
wide views even in the darkest tanks. The Tank Rover is equipped
with a 1-lux camera that can operate in natural light.
7. How does the ROV inspector assess metal loss and pitting?
The Tank Rover is equipped with a powerful wire brush-cleaning
tool for removing surface corrosion. This device can fully
expose all metal pits and weld defects. The inspector can
use a pit gauge to accurately evaluate the size and depth
of these pits. Ultrasonic method of inspection is also used.
8. Can sediment depth be measured?
YES! We simply attach a ruler that is viewed by the video
camera and the Tank Rover
in the sediment for a measurement. As well,
the
type of sediment can be determined by its
color, for example: manganese, lime,
and floc).
9. What are the qualifications of the ROV inspector?
Our personnel are all highly qualified tank inspectors.
Qualifications include various methods of inspection. They
have the support backing of a chief inspector that has NACE
coating inspector qualifications and over
12 years of tank
inspection experience. The background of our inspections
includes protective coatings inspection, catholic protection
systems
non-destructive metal testing, and paint sampling
and tank erection.
10. Can the ROV operator inspect the tank floor?
The Tank Rover camera rotates
down 120 degrees, allowing for direct inspection of the tank floor. If
the floor has
sediment on it we can use a crawler mounted pump vacuum
system with “pan-and-tilt” video system to safely remove
bottom sediment and inspect the bottom.
11. Are there any tests called for in the AWWA D101 Tank
Inspection
. .
. Procedure that cannot be performed with
the ROV?
The Tank Rover can perform all
of the critical inspection elements required in the AWWA standard. Ultrasonic
thickness
measurements and other testing can be performed. Adhesion
testing is per ASTM 3359 and is
not performed by the ROV
because we do not recommend damaging the interior coatings.
Divers cannot perform this test in accordance with the
ASTM procedure. We do not do this test because we never recommend
spot prep and top coatings on the interior. Adhesion measurements
are done to assess a coating’s ability to accept
additional costs of paint.
This is routinely done on the
exterior but
never done on the interior.
12. Other tasks using ROV that may be possible.
Anything the client requires, we will confirm the feasibility
of
performing (example: retrieval, sampling, testing, etc.).
1-877-757-1537
info@scantronrobotics.com
