New 105-page paper features analysis gleaned from interviews at 19 sites around the country
Feb 1, 2010 12:00 PM, By Rick Weber
ATTENTION to detail is a key element in extending the service life of cargo tanks, according to “Guidelines for the Operation, Repair, Assembly, Testing, and Inspection of Hazardous Material Cargo Tanks,” a 105-page paper that was summarized at the NTTC Cargo Tank Maintenance Seminar.
“As you go about inspections, you want to make sure that the people who do these inspections know what they're looking for,” said Darrell Bowman of the Virginia Tech Transportation Institute (VTTI). “Then have in place some sort of quality control so the person can go back and certify that procedure. These are lessons learned from the industry itself. We consolidated that into a document that will be good for new fleets coming on board. Also, as you bring new people into the operation, you can give this to them and will give them overview.”
The paper was part of an 18-month project funded by FMCSA as a grant through the Virginia Department of Transportation (VDOT) and the Virginia Transportation Research Council, a partnership between VDOT and the University of Virginia.
There were two purposes: to identify factors that affect the service life of cargo tanks; and develop the document.
Researchers conducted interviews at 19 sites throughout the United States including eight fleets, two test and inspection facilities, two facilities that perform Wet Fluorescent Magnetic Particle Testing (WFMPT), three re-chassis facilities, two facilities that repair insulated tanks, and two mobile test and inspection facilities.
“A lot of places we went to did multiple types of operations, so we were able to capture even more information,” Bowman said. “We spent several days at some sites. We sat down with the head of maintenance or the administrator of the fleet or facility to understand operational factors that affect the bottom line. Then we did a group interview with the maintenance staff. We were able to hear some excellent examples of things that go on in shops or over the road that affect the service life of cargo tanks. We asked for written procedures, and some required a nondisclosure agreement. It allowed us to understand the industry as whole. No competitive information is in here. We tried to leave out anything that would cause a competitive disadvantage to the facilities.”
The data analysis included reviewing interview and focus group audio files to identify and document key sections (over 30 hours of audio recordings were reviewed), transcribing key sections of audio files (594 pages of transcripts were created), and organizing transcripts by source (company), with keyword searches for comments of interest.
The collected data was placed into eight factor categories:
Tank distortion/bulkhead reversal. He said it's caused by either excessive positive or negative pressure inside the cargo tank and typically is the result of loading and unloading procedures and valve failure. It could be because of improper modifications to a valve, overloading by volume over time, or inadequate operator training. Overloading is pumping with too much product or pumping out too quickly and overpowering the capacity of the vent. An operator may load the tank more quickly than the vent system can handle. The result is local straining of the shell or bulkhead at the juncture of the shell and bulkhead beyond the yield strength of the material.
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