Standard for chemical vapor recovery should be in place by middle of year
Feb 1, 2002 12:00 PM, By Charles E Wilson
A STANDARDIZED approach to chemical vapor recovery on cargo tanks is on a fast track and should be in place by the middle of this year. A draft recommended practice (RP) should be approved during the Truck Trailer Manufacturers Association (TTMA) annual meeting April 17 to 21.
Significant progress toward final approval of this RP came during a special meeting October 29, 2001, in Chicago, Illinois. The meeting brought together representatives from the tank truck, chemical manufacturing, and cargo tank fabrication and design sectors. They spent the day reviewing draft number seven of the proposed RP. Changes agreed on during that meeting were incorporated into what is now designated as draft number eight.
The objective of the proposed RP is to cover 80% of the chemical products that are transported in stainless steel cargo tanks, according to John Cannon, Brenner Tank Trailer Inc. He led a point-by-point review of the TTMA draft RP during the special meeting, which was convened by TTMA, National Tank Truck Carriers (NTTC), and the American Chemistry Council (ACC).
Members of the TTMA cargo tank engineering committee met October 31 to finalize draft number eight. They recommended that the draft RP be sent out to the full TTMA membership for a ballot vote before the end of 2001. This would be followed by a final vote at the annual meeting in April 2002.
The meetings in Chicago followed three years of industry effort, prompted by Environmental Protection Agency (EPA) plans to mandate nationwide vapor recovery requirements for volatile organic compounds (VOCs). The EPA push seems to have stalled, but companies involved in chemical hauling believe it is important to be proactive and move ahead.
“We don't know what is going to happen with the EPA's proposed rule on VOCs,” said Cliff Harvison, NTTC president. “In the wake of the September 11 terrorist attacks, all non-security issues have been preempted in Washington DC. This situation could continue for the next year and a half.
“However, individual states such as Texas have moved ahead with their own rules. Chemical vapor recovery requirements are spreading across this country. It's to our benefit to have an industry standard regardless of whether chemical vapor recovery is a federal or state mandate.”
The strongest call for standardization in chemical vapor recovery is coming from operators of tank truck fleets. The chemical industry is decidedly less enthusiastic. Just a handful of chemical company representatives attended the Chicago meeting, and no one from ACC was on hand to speak on behalf of the whole industry.
The chemical industry has resisted calls for standardized chemical vapor recovery from the outset, and the result has been chaos and lost efficiency for tank truck carriers. “Even hauling just for DuPont, we don't have uniformity from one plant to another,” said Orville White, Sentinel Transportation LLC, a wholly owned carrier subsidiary of DuPont.
He voiced strong support for vapor recovery on chemical trailers, saying it should be viewed as much as a safety issue as an environmental factor. “We want to keep people off the tops of our tank trailers to limit the potential for falls,” White said. “We've used vapor recovery as a component in closed-loop loading and unloading since 1994.”
Lack of standardized vapor recovery means that each chemical plant may have a different system and configuration. As a result, tank truck drivers must carry an assortment of fittings, not just for the loading rack but for the delivery location as well. If the right fitting isn't on board, the driver must return to the terminal for the right equipment or jury-rig an alternative. The potential for operator error is intensified by the lack of standardization, and training is more complicated.
The petroleum industry provides a clear example of what can be obtained in the chemical industry through standardization. Faced with an EPA mandate for vapor recovery in the 1960s, refiners realized that they needed a uniform system that would enable any tank truck carrier to serve any petroleum facility. The refiners saw standardization as a way of maintaining productivity and keeping costs down. Today, the standard developed by the American Petroleum Institute is a worldwide standard.
Proponents of the chemical vapor recovery standard hope to achieve similar success. Cargo tank vapor recovery hardware already is being manufactured in accordance with the proposed recommended practice by Betts Industries Inc, Fort Vale Inc, and Girard Equipment Inc.
Changes made in RP draft number eight provide the chemical manufacturing and transport sectors with a standardized vapor recovery system that can meet the vast majority of needs.
The RP will focus on new DOT407 and DOT412 cargo tanks. Those attending the Chicago meeting agreed that MC307 and MC312 cargo tanks should be addressed separately, possible through a technical bulletin.
“Spill dams and related components on new stainless steel tank trailers already meet the basic dimensions required for the three vapor recovery systems now on the market,” Cannon said. “Retrofit will always be somewhat of an art form. You have to custom fit the system to the equipment.
“On some existing trailers, we may need to raise the overturn protection to accommodate the vapor recovery hardware. This may pose a problem for overhead clearance at some loading racks.”
Probably the biggest change is that most of the optional provisions were deleted in RP draft number eight. This won't stop anyone from using a different configuration, but it should encourage uniformity in most cases.
The typical configuration will consist of vapor recovery fittings in the spill dam area and at the rear of the trailer at ground level. The top fitting is for use at chemical plant loading racks, and the bottom fitting is for use during offloading. A separate vapor line is recommended for each compartment on a multi-compartment trailer. Manifolding is discouraged.
The valves will be constructed of stainless steel and can be designed for either hydraulic or pneumatic operation. Quick disconnects for the hydraulic lines are a good idea but won't be part of the RP, according to Cannon.
The pressure required to actuate the valve should not exceed 275 psi, and a pressure gauge should be mounted in the spill dam so operators can monitor pressure. The overall height of the vapor valve should not exceed 8.5 inches when closed.
Vapor valves will be required to have a positive means of showing open and shut status. If possible, the indicator should be visible within a reasonable distance from the side of the cargo tank. If the indicator cannot be made visible, some other means of notification should be used.
Valves must be designed to be fully disassembled for cleaning. There was concern at the Chicago meeting that few wash rack workers understand how to clean chemical vapor vents, and the racks lack procedures. This is an issue that still must be addressed.
The chemical vapor relief vent in the draft RP should cost around $1,000 for a new-build single-compartment trailer. The cost of retrofitting vapor vents on older trailers will be higher.
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