Ultrasonic tightness control of underground tanks

Throughout Europe and beyond, the problem of soil pollution has become a priority.

For some time now the majority of countries have created a legislative framework for this, aiming to identify and assess risks connected with historical soil pollution and avoid any new pollution. In view of possible pollution of soils or groundwater, the storage of vehicle fuels, heating oil or dangerous liquids in underground tanks is more and more subject to strict operating conditions. Rigorous, periodical tank leak-tightness monitoring is imposed in order to guarantee incident-free operation.

The aim is to be able to identify any leak rapidly so as to limit all risk of pollution as far as possible. In the event of major leaks it may be necessary subsequently to clean up the surrounding sub-soil, which usually leads to relatively costly treatments and work.

The controller is rendered liable through the services provided.

So it is easy to understand that the risk of a wrong diagnosis renders the controller liable when a tank is downgraded or approved. The latest SDT TankTEST system was designed with this technician's responsibility in mind.

The SDT 170 MTT is the most reliable, the most comprehensive and the most accurate available for checking the tightness of underground flammable liquid tanks and their associated pipe work by introducing a vacuum and listening to the ultrasounds. With the SDT's "Graphs & Measurements" software for the automatic creation of authenticated reports all data and test measurements are stored in the detector. They can be transferred to a PC. They provide evidence of testing, measurement readings and graphics and archiving of the performances.

Stengths

5 reasons to HEAR MORE with the SDT TankTEST ultrasonic method.

Ecological

In the event of a leak, no fuel is spilled in the ground during the test. The pollution is not worsened by the liquid (heating oil or water) under pressure being spilled in the ground (pressurizing method). There is no use of filling water having to be cleaned after the test.

Fast

The ultrasound technique does not require draining/filling of the tank and waiting time, so there is no down time (hydraulic method). It allows you to check the tank and its filler and bleeding pipes in a single operation and without dismantling the panel of the manhole.

Precise

The SDT TankTEST method detects even the smallest of perforations or "mini faults" not yet causing a leak. It allows you to locate the tightness problem, either on the tank itself, or around the manhole cover, or on the pipes or on their connections.

Reliable

The test can be carried out whatever the height of the liquid (max. 2 meters) except if the tank is 100 % full. The SDT TankTEST is not influenced by temperature, humidity or the angle of the tank. It is just as effective in dry environments as in wet.

Easy to use

The equipment is ergonomic and the check can easily be carried out by anyone who has received technical or practical training from the manufacturer or the latter’s representative.

In addition to the time gains linked to the set-up, the SDT TankTEST offers the benefits of robust equipment for work "in the field" and is able to perform thousands of checks. The Ni-Cd power pack provides total freedom of movement (8 to 10 hours autonomy).

A widely recognized and approved method.

The SDT TankTEST for testing underground tanks was developed by SDT.

Belgian accreditation

The SDT TankTEST method has been tested and approved since 1995 by various authorities, including AIB Vinçotte and Lloyd's Register in Antwerp. It meets the criteria of Walloon Government decrees of 3 July 1997 and 30 November 2000. It has also been approved by the Ministry for the Flemish Community (Aminal, number AMV/30.06.95/1 and Vlarem edition II, paragraphs 5.17.2.8 and 6.5.7.2).

French accreditation

In 1998, Cetim in Senlis tested the ultrasonic SDT TankTEST method on behalf of the French Ministry for Town and Country Planning and the Environment; it was approved. Compared with the hydraulic method (pressurizing the tank after filling it with water), the SDT TankTEST has been recognized as being more sensitive in its detection, easier to implement, faster and more economical.

US accreditation

The SDT TankTEST method has been tested successfully by Ken Wilcox Ass., an American company licensed by the EPA, the only organization in the world to have defined the minimum level of sensitivity to be met by a technique destined for use in the American market.

A unique experience in this domain

SDT International has participated directly or indirectly in the testing of several thousand tanks in Belgium and numerous other countries. The company employs a team of technicians and specialists with solid experience in this kind of service.

The SDT 170 MTT is a complete ultrasonic system for the tightness control of underground tanks and their associated pipe work, by introducing a vacuum in the tank and listening to the ultrasounds.

This method is much more sensitive to detection than any common pressure tightness control one. It highlights all tightness imperfections in a perceptible (translated audio signal that is representative of detected flaw, audible through provided headphones) and measurable (digital display in dBµV) way.

The SDT 170 MTT detector includes the SDT “Graphs & Measurements” software for automatic creation of authenticated reports. All data and test measurements are stored in the detector. They can be transferred to PC providing total traceability of performed tank tests:

• evidence of testing
• measurement readings and graphics
• archiving of the performances
• creation of authenticated reports with personalization of the company page headers, with all the identification details of the test and comments and with graphics and table showing sensor readings.

The memory capacity of the detector corresponds to 20 hours of measurement-taking, i.e. 72,000 measurements as the device makes one measurement per second during the recording phase (tank tightness testing on data recording mode). The battery pack allows 8 to 10 hours of autonomy (without backlighting) which can be multiplied using spare batteries.

Measurement unit

Internal ultrasonic sensor

Interface box

External ultrasonic sensors

Flexible sensor
Headphones

Battery pack

Battery charger

Non-ex-proof vacuum pump

Ex-proof vacuum pump

The unit contains :

• Storage case SDT 170
• SDT 170 MTT ultrasonic receiver with battery, blue rubber protection and user manual
• Precision indicator accessories (threaded tip, rubber tip, 2 tubes)
• Noise isolating headphones
• Battery loader for SDT 170 ultrasonic receiver
• Shoulder strap for SDT 170 ultrasonic receiver
• One RS 232 C cable and “Graphs & Measurements” software for data transfer from SDT 170 MTT to PC delivered on a CD Rom.
• Interface (Switchbox)
• Tube of water-finding paste
• Storage case for ultrasonic sensors
• Two ultrasonic watertight sensors (explosionproof and impervious to hydrocarbons)
• Camlock and mechanical bush
• One flexible ultrasonic sensor allowing checking the tightness of the connections, of the manhole, etc.
• Vacuum pump (specific for tank testing), suction hose and drain hose

For tanks containing flammable and/or explosive liquids, the pump, hoses and precision indicator accessories are replaced by the following explosion-proof equipment:

• ATEX certified explosion-proof vacuum pump
• Explosion-proof suction and drain hoses (5m) in antistatic rubber
• Precision indicator accessories in metal (antistatic)