RSPA Works on MC306/DOT406 Wetlines Rule
Feb 1, 2000 12:00 PM, mbt staff
Several high-profile accidents, renewed pressure from the National Transportation Safety Board (NTSB), and some highly critical reports in the general media have shined a spotlight on cargo tank wetlines. At the request of the Secretary of Transportation, the Research and Special Programs Administration (RSPA) reportedly has developed a proposed rule that will prohibit wetlines.
The notice of proposed rulemaking reportedly was finished in late 1999 and was undergoing a thorough review at the Department of Transportation (DOT). It had not been published at the time this report went to press.
Representatives from RSPA and the tank truck industry discussed the wetlines issue during the 1999 Cargo Tank Maintenance Seminar that was held October 25-27 in Chicago, Illinois. The seminar was cosponsored by the National Tank Truck Carriers and the Truck Trailer Manufacturers Association.
While constrained in what he could say about a proposed rulemaking that is under development, RSPA's Ron Kirkpatrick confirmed that wetlines are being addressed by the agency, and any rulemaking will be published as a separate initiative. "It will not be included in another rulemaking, such as HM-213," he said.
Risk Assessment Phil Olson, also with RSPA, went into greater detail, basing his comments on a report that was issued by NTSB. He said that RSPA believes wetlines pose enough risk to justify consideration of corrective action. At the same time, the agency acknowledges that solutions that add weight or reduce productivity will be difficult to justify.
"RSPA has long been concerned about the potential for loss of life and injury due to the transportation of hazardous materials in cargo tank wetlines," he said. "When HM-183 was being developed, RSPA proposed eliminating wetlines. The final rules that took effect in 1990 prohibited carrying poisonous, corrosive, or oxidizer liquids in external piping unless that piping is protected by substantial guards.
"RSPA reluctantly agreed at that time to except gasoline and other flammable liquids from the final rule because of strong industry objections based on the cost impact of changes, the relatively low level of risk that could be demonstrated, and the fact that a system to empty wetlines after loading was not available. RSPA challenged industry to find ways to eliminate the risks in a cost-effective manner."
The report that is prompting the new rulemaking effort was published by NTSB in January 1999 and is the agency's latest effort to ban wetlines, primarily the exposed piping that contains product on a petroleum cargo tank. NTSB, which has no rulemaking authority of its own, has advocated a ban on wetlines for many years.
The NTSB report was incorporated into a RSPA risk/benefit-cost analysis that is entitled "Prohibiting Hazardous Material in External Piping of MC306/DOT406 Cargo Tank Motor Vehicles." This report forms the basis for the rulemaking.
RSPA and NTSB estimate that the number of fatalities attributable to accidents involving wetlines in gasoline transportation is 0.70 per year, and the number of major injuries is estimated at 0.52 per year. Total property damage is estimated at $800,000. The total value of wetline risk avoidance-including values for fatalities, injuries, and property damage-is estimated at $3 million per year.
Tanks Affected RSPA estimates that approximately 50,000 tank trailers would be affected by a wetline rule. These MC306 and DOT406 trailers are constructed of aluminum and have external piping that retains 30 to 50 gallons of product in each line.
These lines are vulnerable in a side impact by an automobile, according to the RSPA report. Clearance between the roadway and a cargo tank generally is two to four feet. An average automobile will typically underride the cargo tank in a collision from the side and can damage the external piping. Larger vehicles such as vans, sport utility vehicles, and other trucks pose more of a risk to the cargo tank itself in a side collision. Determining how often these accidents occur is difficult. RSPA admits that it has inadequate data, but it makes the following estimates:
Using a Hazardous Materials Information System database that contains 447 incidents involving the release of gasoline in a cargo tank motor vehicle accident for the period 1990 to 1997, RSPA has identified 47 accidents where wetlines appear to have been involved. Two deaths and three major injuries resulted, and five fires occurred. RSPA is using those numbers to claim that wetlines are involved in about 11% of all gasoline cargo tank motor vehicle accidents.
Two Systems RSPA claims that at least two systems show promise in eliminating risk from wetlines. One uses an on-board pumping or purging system to move product from the wetlines to a main tank compartment. The other adds a second set of loading lines that retain a smaller amount of product, thus reducing risk. RSPA admits that both systems add cost and weight.
The on-board pumping/purging system is from Cargo Tank Concepts, Brooklyn, New York. After loading is complete and the main cargo compartment valves have been closed, compressed air is introduced into the loading line under low pressure. Product from the loading pipe is pushed through a check valve into the tank compartment. The process takes about six minutes. Cost is roughly $5,000 for a typical petroleum trailer, and the system will add about 100 pounds.
The other option examined by RSPA is short lines. The arrangement was prepared by Weld-It Company, Los Angeles, California. The shortened loading lines were positioned to be in compliance with the American Petroleum Institute recommended practice for bottom loading and vapor recovery. Since placement is above the tank low point, a second set of lines is needed for unloading.
Retained product in each shortened loading line is only about a gallon, compared with 30 to 50 gallons in a traditional arrangement. Cost of the short-line arrangement is estimated at $350 per compartment. Added weight would be eight to 10 pounds per compartment. For instance, the cost for a five-compartment trailer would be around $1,750, and tare weight would increaseby about 50 pounds.
Cost Justification Olson acknowledges that RSPA may have difficulty with the cost justification for elimination of wetlines. The agency's best-case estimates are for a purging system priced at around $2,500 per new vehicle or short lines costing $1,400 per new vehicle. Retrofit costs for the purging system are estimated at $3,500 per vehicle, while the short-line retrofit would be about the same as for a new tank.
When it's all said and done, industrywide installation of the purging system would cost the tank truck industry approximately $125 million. Shortlines would have an industrywide cost of around $70 million. In addition, lost annual productivity due to higher tare weights is valued at approximately $1.08 million.
Bill Boyd, Heil Trailer International, said it is very likely that RSPA is being overly optimistic in its cost estimate. He suggested that new installations and retrofits could cost more than estimated. In addition, total elimination of wetlines in petroleum transports may not be feasible.
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