 This third and final video segment of chip seal application shows some of the problems and pitfalls that may occur during the operation. It's based on a presentation developed by the Oklahoma Department of Transportation. Improper equipment maintenance or operation causes most chip sealing problems. A major failure in any key piece of equipment would usually halt the entire process. The most serious problems are likely to occur at the asphalt storage facility. Overheated flues, a half filled booster pump, or return lines containing oil pockets can cause explosions resulting in severe damage and injury. Premature opening of the valve during distributor loading can produce an unexpected surge of hot oil, creating a big mess and maybe severe burns. A full distributor tank does not eliminate all danger when firing the burners. Faulty plumbing is likely to give the operator a surprise. Telltale vapors, drips, and frost build-ups all indicate leaks in the propane burner systems. A poorly maintained spray bar with a heavy build-up of cured binder usually leads to partially clogged nozzles and, consequently, an irregular fan pattern. Improper nozzle settings may compound the problem and result in a seriously uneven binder application. If a distributor in this condition is used on the job, several problems will occur with the binder. First, when a clogged spray bar applies binder under normal pressure, the oil flow will be insufficient and the fan profile will be poor. If, on the other hand, the pressure is increased beyond the recommended 206 kPa to compensate for the restricted flow, the high pressure can cause emulsion oil to break upon impact with the road surface, separating the water from the asphalt and ruining the qualities of the binder. The higher pressure also makes the oil spatter excessively, propelling droplets over the entire width of the adjacent lane, where tires of oncoming traffic will pick it up. But the most serious consequence of this problem is when the oil spatters onto a freshly chipped lane where it lies free to be picked up and tracked by tires. Another cause of surface oil is grass and debris that stick to binder-coated distributor parts and then drop into the spray path to be covered by oil. This debris often protrudes through the surface after the chip application. The worst spray bar problem is revealed by this trail of binder. A serious leak in the distributor's plumbing with the bar under pressure leaves a thick pool of oil on the pavement. When the binder is applied, this concentration of oil will not be apparent. But when the chipper covers the pool with aggregate, the problem rises to the surface as the first wheel passes over it. The chips are pressed down and the oil seeps through. Subsequent tires and rolling equipment pick it up and track it. A problem not related to equipment maintenance arises when the wind distorts the spray fans. Gusts of wind and extreme cases can totally interrupt the uniformity of the binder coat. So be careful in windy weather and watch out for drafts caused by big trucks. This line of puddles left by a leaking spray bar is typical of the many distributor-related problems that can profoundly affect job quality. Since most serious problems of chip sealing involve the binder oil in some way, it stands to reason that a well-maintained and operated distributor can keep these problems to a minimum. The chip spreader, like all the other equipment, should be checked each morning for operational readiness and safety. But even then, problems can still occur. If one of the gate's jams in a closed position, it shuts off a small portion of the chip fall, as is clearly shown by the opening in the chip fall in a corresponding strip of exposed binder on the surface. If a vehicle tire gets into the oil, the problem is seriously compounded. A gate can also jam in an open position, spelling excess chips onto the roadway. While this problem does not threaten the job quality, it must be corrected before the operation continues. Another chipping problem occurs when the dump truck bed is raised to transfer aggregate into the chipper's hopper. If the volume control guards are worn or missing, the aggregate will spill over the sides and accumulate in little piles on the surface. This same overflow can happen when the chipper is in motion, although here the spill is less apparent since the chips are dispersed along the roadway. The aggregate lost over a period of time can be considerable. Also, these little chip piles can cause trouble for the trucks and rollers. Big spills, on the other hand, can happen if the chipper and dump truck disengage during spreading. While this machine's hitch is designed to prevent disengagement, many chippers have a simple hook that doesn't completely surround the steel rod connection of the truck. Should the chipper operator fail to verify the connection, the entire load could be dumped when the chipper pulls away. Disengagement can also occur when the machines are in motion, by raising the truck bed too high or running over chip piles. In either case, if the rear of the truck is lifted high enough to clear the chipper hitch, the load ends up on the roadway. The chip fall should be continuously monitored, not only for excessive chips, but for thin spots. If the road coverage is poor, it's likely that the spreader box or screens have become clogged with sand or debris. Here's a safety point. Operators of heavy equipment aren't normally required to wear a safety vest because the equipment is more visible to drivers than is the vest. But it's hazardous for the operator to dismount his machinery and set foot on the roadway. Improper equipment operation is responsible for many problems, nearly all related to the fresh binder. A careless broom operator may do more harm than good when trying to clean the road shoulder too near to the distributor, especially if the wind is blowing in the wrong direction. The broom operator may also contaminate the fresh chips by rolling his tires in the oil and getting the broom too deep into the binder strip. This throws oil-covered rocks back onto the chipped surface to be picked up and thrown by vehicle tires. Every effort should be made to avoid contact with the exposed binder strip, especially when driving onto the freshly chipped surface. The consequences will speak for themselves. Finally, tire contact with the freshly chipped surface must always be handled with care. Any twisting, spinning, or sliding of the tires will roll the chips over and expose the oil. Often both the rock and the oil are removed, requiring difficult manual repairs. Once you've developed an eye for problems that can happen during chip seal application, the clues are generally easy to spot. Sometimes we may be our own worst enemy because the first wheels to touch the freshly chipped surface are those of our own equipment. The key to a successful chip seal job lies in proper procedure, crew awareness, and attention to detail. For more information and help with your chip seal operations, contact your state's Technology Transfer Center.