Ultrasonic Examination (UE)

Not necessarily. Our research and testing of over 2,000,000 cylinders to date has found that we have rejected less than 1% of those tested. However, the cylinders that we do reject are those that for safety’s sake should be taken of UE of service.

In hydrotesting, leaking seals, operator interpretations, poor burette readings and human error can all reject cylinders that are still operational. In the FIBA UltraTest UE system, we remove improper testing and human error from the equation.

Yes, if the cylinder has previously been star and plus rated and meets the DOT and CFR requirements concerning lading and age, the star and plus can be placed on the cylinder.

Yes, FIBA received special permit (DOT SP-12607) in July 2001, which allows for the ultrasonic examination of certain 3AL cylinders in addition to 3A and 3AA cylinders authorized in 1993 under DOT SP-10922. FIBA’s new UE system has been designed to accommodate the software necessary to meet the rejection criteria currently required by the DOT for 3AL cylinders made of 6061 aluminum alloy.

When the cylinders are properly prepared by the cylinder owner, the UE operator can process over 25 cylinders per hour (i.e. 150-200 cylinders per day).

Yes, any company can enter into the Ultrasonic Examination business provided that the employees of that company are trained and certified by FIBA Ultra Test Division and registered with the DOT. This is necessary because UltraTest holds the special permit with the DOT and is therefore responsible for reporting the results of all tests. Additionally, some form of a cooperative agreement between FIBA Ultra Test and the retest company must be in place, which would make both companies responsible for the test results.

The primary if not the only, failure mode of cylinders that fail hydrotest is expansion directly correlated to thinning or excessive corrosion of cylinder walls. That method calculates wall thickness by indirect calculations based on permanent and elastic expansion. UE does this measurement directly and accurately.

If the fire was hot enough the plastic deformation and cracks so formed can be detected. If the cylinder has only been partially burned, and then repainted, the UE would probably miss it. However, if someone were trying to hide such an occurrence, they would be dealing in fraud. Someone dealing in fraud could also avoid the hydrotesting. UE is not a magic wand.

UE will detect points that go below minimum wall thickness from either an internal or external flaw. Most rejections due to arc burns are found during the mandatory visual examination based on CGA Standard C6. This test is not eliminated during FIBA Ultra Test’s UE testing, and from the position of the cylinder on the transport conveyor FIBA Ultra Test personnel can examine the cylinder better than during normal hydrotesting.

No. The latest rejection criteria invoked by the DOT addresses the potential for internal corrosion or pitting in certain wet gas cylinders. Cylinders that are suspect of internal corrosion and/or contaminants may be inspected internally, if desired.

No. But it is recommended that all cylinders containing such gases be emptied as a precaution. However, it is not necessary to empty the cylinder to perform UE.

No. If a cylinder is suspected of having been contaminated you must either test the gas for the suspected contaminant or pull the valve and examine the cylinder. You should not wait for the next requalification. Note that just because you need not devalve and internally inspect a cylinder for UE, nothing prevents you from doing such a procedure if your policy requires it. We highly recommend removal of any valves that are suspect to internal cylinder contamination.

Because of the design of 3A, 3AA and 3AL cylinders, the shoulder and bottom are low stress areas, with thicker material. The cylinder is examined from the transition area down through the knuckle radius.

No. Product would not have the same physical properties of the steel being tested, therefore the instant the sonic velocity changes, the system senses it has reached the end of the steel.

FIBA is the acknowledged leader in the use of ultrasonic technology to test cylinders. Since 1993, FIBA has installed over 40 systems across the country to test cylinders – no one else even approaches that number. Every U.S. major industrial gas company and many large retesters utilize FIBA’s UE systems to test cylinders or tubes. As stated before, FIBA’s UE systems have tested well over 2 million cylinders to date, far more than any other UE provider. FIBA is the preferred choice – without question!

An array of multiple, ultrasonic transducers are mounted in a customized shoe. The compressed gas cylinder is rotated on a supporting set of wheels, which rotate the cylinder and an encoder built into the mechanism, which positions the head and the transducers. As the system operates, the readings are taken as a function of rotation, not time. The readings are taken at specific intervals (helix) in a pattern that overlaps by 110%.

FIBA’s special permit is based upon measuring the wall thickness, area corrosion and line corrosion, rejecting any cylinder that has a wall section below the cylinder minimum wall thickness prescribed in the specifications for 3A, 3AA and 3AL cylinders. Many of these values are consolidated and listed in CGA C6. The system also employs sensors that are oriented at a 45o angle, which can detect cracks or pitting that may have the potential for infringing on the allowable wall thickness of the cylinder.

In the case of the Ultrasonic Examination system, the thickness is measured by one set of detectors that can detect variations of less than 0.002 inches from nominal. In addition, the remaining detectors, focused on the same spot, are bilateral and can detect aberrations (such as cracks and flaws) in the longitudinal, transverse and oblique directions.

Each detector has its own separate amplifier and data channel which records the results to the master computer system as unique values, not an average. (Some other UE systems, that depend on lateral arrays, record test results as an average, rather than as unique valves.) The computer is designed to sequence the data channel electronics between transmit and receive modes. This ensures an appropriate time delay between energizing the transducers and looking for echoes from those transducers. The design allows for over 2,000 pulses per second, but for practical purposes has been set to take a specified number of readings per inch based on the rotation of the encoder.

This system allows re-qualification of cylinders without having to remove the valve or remove the product. The test process does not violate any EPA regulations, which can be a concern when testing hydrostatically and disposal of the effluent is a consideration when flushing hydrotest water into local sewage systems.