Dixon Bros Wins with Outstanding Cargo Tank Inspection, Maintenance

A recent Department of Transportation (DOT) audit determined that Dixon Bros Inc has one of the most thorough cargo tank testing and inspection programs. That was good news, but not totally surprising.

The Newcastle, Wyoming-based tank truck carrier has invested significant time and effort in its vehicle maintenance program, and tanks receive special emphasis. A team of eight mechanics uses state-of-the-art equipment to keep the fleet's 340 tank trailers in top shape in some of the most demanding operating conditions faced by a tank truck carrier.

"Prior to the DOT inspection, we were confident that we had a good maintenance program," says James H Dixon, vice-president of Dixon Bros Inc. "It confirmed what we already believed. The inspector said we would be well-served to do all of our testing in-house because it was more thorough and precise than what he had seen at some third-party shops. We took that as a pat on the back.

"We've always made maintenance a focal point, because it's good for business. Our objectives are to ensure that vehicles are available when needed and that shipments reach customers with little or no delay. Reliable service is one reason we've been so busy over the last couple of years. We expect to stay busy this year, also."

Above-Average Year Last year was an above-average year for Dixon Bros with revenues up 8% to 10%. Road construction was one reason, but the carrier also benefited from a dedicated 566-mile jet fuel haul that kept six Rocky Mountain doubles trains busy. The carrier hauled 13 million gallons of JP-8 from Newcastle to Salt Lake City, Utah, under the year-long government contract.

"We moved five loads a day with four sleeper teams and two solo drivers," says Jimmy Dixon, vice-president of equipment and maintenance. "We kept the maintenance shop open longer, and our mechanics put in extra time on Saturday and Sunday. They did what was necessary to keep the equipment running 24 hours a day."

Rigs also have been busy hauling ammonium nitrate to mining operations in Wyoming's Powder River Basin. Most of the shipments originate at a chemical plant in Cheyenne, Wyoming, but some are brought in from Salt Lake City and points in Canada.

"Mining customers account for about 35% of our business right now," James Dixon says. "A single cast blast at a mine site can take over a million pounds of ammonium nitrate. The charges are positioned to move the surface material from one area to another. It's an impressive sight when they set it off."

Steady Revenue Dixon Bros also hauls a full range of refined petroleum products, asphalt, propane, motor oil, cement, fly ash, lime, caustic, and sulfuric acid. "For years, our revenue curve looked like a bell, with the peak in the summer," Dixon says. "We got more aggressive with our sales, and we've pulled in a lot more work that keeps us busy throughout the year. We have more customers today that are active year around, but we're also hauling more propane and other heating fuels."

Trips average 180 miles, and rigs are rarely out overnight. Still, Dixon Bros operates in Wyoming, Idaho, Utah, Colorado, Kansas, Nebraska, Montana, North and South Dakota, Washington, and Oregon. Rigs also run into the Canadian provinces of British Columbia, Alberta, and Saskatchewan.

Vehicles are based at 10 terminals in Wyoming, North and South Dakota, Nebraska, and Montana. Small satellite terminals also are in Wyoming, Minnesota, and Montana. Satellite terminals generally have one or two rigs and are at a pipeline terminal or other shipper location.

All of the full-scale terminals have maintenance capabilities, but the only registered tank inspectors are at the main shop in Newcastle and the shop in Cheyenne. However, the two inspectors in Newcastle take the testing and inspection program to other terminals when necessary.

"We do as much testing and inspection as possible in Newcastle, and virtually all five-year testing is done there," says Wayne McDougall, Dixon trailer maintenance supervisor. "Our registered inspectors usually are out for parts of two weeks out of every month. They are gone several days to a full week at a time."

The cargo tank testing and inspection program is directed by Rod Dowding, testing supervisor. He and the other registered inspector in Newcastle handle the overwhelming majority of tank tests and inspections. The third registered inspector in Cheyenne focuses on the trailers based at that terminal, which is the largest in the Dixon Bros system.

For inspections at the other terminals, Dowding has a pickup truck that is outfitted with a full range of testing equipment, including a digital manometer from Micro Pneumatic Logic Inc, Ft Lauderdale, Florida. "It gives us a much more accurate reading than a standard manometer," he says. "We also have a number of test fittings from Werts Welding."

Thorough Procedures Regardless of where the tests and inspections are conducted, the procedures are the same. For instance, petroleum tanks are degassed 12 to 14 hours and then are checked with an explosion meter. Blowers are used to remove any lingering vapors. "We want a reading of zero before anyone enters a tank," McDougall says.

During the external visual inspection, mechanics check the emergency valve controls, paying particular attention to the cables. Mechanics look for leaks and check the grounding system, decals, and placards. The subframe is inspected for cracks, and loose components are tightened. The external visual inspection takes half an hour to an hour.

The internal visual inspection is more involved and takes approximately two hours per trailer. It would take even longer if Dixon Bros did its own thickness testing. "At this time, we're sending thickness testing to Express Trailer Service in Billings (Montana)," Jimmy Dixon says. "Our mechanics don't have the equipment or training right now. However, we'll probably start doing our own thickness testing in the next year or so."

Pressure and vacuum testing are done in-house. For MC306/DOT406 tanks, Dixon Bros follows the Environmental Protection Agency's Method 27 procedure. Pressure tests take at least 45 minutes per compartment, and vacuum tests run a minimum of 25 minutes. "The exact amount of time depends on whether repairs are needed," Dowding says.

Pressure-relief vents are removed and tested on a fixture. If they malfunction, they are rebuilt or replaced. Hoods are pulled off the vapor recovery vents to ensure that they are performing as required.

A pressure-test fitting is attached to the outlet valve and is set for three times the maximum allowable working pressure. "This is where the digital manometer really pays off," Dowding says. "It's just like a water column but more accurate."

Propane trailer inspections are even more time-consuming. The process takes four days to a week per trailer and includes magnaflux and blacklight inspections.

While trailers are the primary focus of the Dixon Bros maintenance program, company-owned tractors receive routine service and preventive maintenance in-house. Extended warranties mean most major repairs are handled by the manufacturers.

Ninety-five of the 125 tractors in the fleet are company-owned. The remainder are supplied by owner-operators. "We gain flexibility with the owner-operators," James Dixon says.

The newest company tractors are Kenworth W900L and W900B conventionals. The only difference in the two is that the W900L has a hood that is 10 inches longer. Bothmodels are specified with a 244-inch wheelbase, and better than half have sleepers (50-inch).

"Driver acceptance of the Kenworth tractors is very good, and they especially like the long hoods," Jimmy Dixon says. "The W900-series is a good over-the-road tractor, and we find that it has a good resale value.

"We specify our tractors to handle the higher gross combination weights that are allowed in most of the western states. For instance, we can run as high as 123,000 pounds in Montana and 108,000 pounds in the Canadian provinces.

"The biggest challenge is to be able to comply with the varying requirements in the different states and provinces. Length is an even bigger issue than weight. In Montana and Wyoming, combinations can be 81 feet long. We're limited to 61 feet in western Canada and 68 feet in Washington."

High Horsepower For engines, the tractors have 525-horsepower Smart Torque II-series Cummins N14s with the Celect Plus system. Ten-speed transmissions are from Meritor, as are the 15" clutches and RT40-145A drivetandem with a 40,000-lb capacity. The tractors also have a WCAL True Track lift axle from Watson-Chalin.

To ensure reliable operation during the winter, the tractors are specified with 1500-watt block heaters, Webb fuel heaters, and oil pan heaters. The cold weather package for the cab includes extra insulation.

Cabs also have air-conditioning, National Cush-N-Aire air-ride seats, AM-FM radios, and Cobra CB radios. In addition to Cadec RoadRelay on-board computers, cabs are fitted with Abbott tachographs.

"The tachographs assist in driver log audits," Jimmy Dixon says. "They also help account for delays. That's important because we haul a lot of time-sensitive loads to road construction contractors. We don't use the tachographs for speed control because we get much more detailed reports from the various computer systems on the tractors and engines."

Other components include Meritor WABCO System Saver Twin air dryers, Spicer drivelines, Holland fifthwheels, Gunite slack adjusters, Meritor WABCO antilock braking, aluminum hubs, aluminum disc wheels, and Bridgestone steel-belted radial tires.

For product handling, the tractors have Chelsea PTOs and Blackmer compressors and pumps. Gardner Denver blowers are mounted on dry bulk trailers. Power for the compressors, pumps, and blowers comes from the tractor-mounted STAC hydraulic system.

"We've begun using the STAC hydraulic system, including the oil cooler, because it is as cost-effective as the system we used to build for ourselves," Jimmy Dixon says. "The STAC unit is efficient and compact."

Of the 340 trailers in the Dixon Bros fleet, 103 are MC306 or DOT406 units used to transport petroleum products. Most were built by Fruehauf. "Their trailers might be a little heavy, but they are rugged," Jimmy Dixon says. "That means less maintenance over the life of the tank, and the equipment has a good resale value. Fruehauf knows our needs, and they have taken very good care of us. They are open to our ideas and have done considerable special design work for us."

Most of the petroleum units run as doubles combinations. Lead trailer capacity ranges from 9,400 to 9,500 gallons, while pull trailers can carry 4,800 to 5,200 gallons. A few petroleum semi-trailers in the fleet can haul up to 11,000 gallons.

Tank hardware includes Tiona Betts domelids, Betts internal emergency valves, Betts vapor-recovery vents, Civacon and Emco Wheaton bottom-loading adapters, and Scully Intelli-Check overfill protection. Retained product monitors have been specified on the newest DOT406 trailers. Dixon Bros specifies either Pro-Par or Meritor axles and Pro-Par or Reyco Transpro spring suspensions. Running gear also includes Meritor S-cam brakes, Meritor WABCO antilock braking, and Alcoa aluminum wheels.

All 84 dry bulk trailers are from Fruehauf, and most of them are constructed of aluminum. Three sets of Rocky Mountain doubles are made of stainless steel and are used to transport ammonium nitrate emulsion. Lead semi-trailers range from 1,000 to 1,500 cubic feet, and pull trailers are 500 to 850 cubic feet. Hardware includes Milwaukee butterfly valves and Kunkle pressure-relief vents.

Stainless-steel chemical units consist of 6,500-gallon, two-compartment semi-trailers and 3,000-gallon, single-compartment pups. They are outfitted with Betts domelids and discharge valves and Girard pressure-relief vents.

Twenty-seven MC331 propane trailers are operated by Dixon Bros, the largest of which are quad-axle units that can carry 14,700 gallons of product. The newest trailers have Trinity barrels and were assembled by Bosselman Tank & Trailer Inc in Grand Island, Nebraska.

"We've got a fleet that gives us plenty of versatility," James Dixon says. "And we've got an outstanding maintenance program that keeps the fleet in top shape. It's been a winning combination for us."

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