Asphalt Plant Daily Reports

by
Cliff Mansfield

Record keeping. We all hate the task but it’s important in a well run business. Without it we wouldn’t be able to track expenses, or payroll, or our most important asset: profits. While most of us tend to think of offices when we think of record keeping, there’s another place where it is useful. The asphalt plant.

Daily asphalt plant reports provide information not always readily available to management, like fuel consumption, oil percentages and plant ‘idle’ time. They also provide an inventory record of oil and fuel in case the plant operator isn’t available to ask.

A plant report is also a powerful tool to the alert operator. It can indicate problems with the burner, or with the asphalt oil delivery system. For example: On June 8th a Boeing drum plant belonging to Continental Paving produced 2970 tons of hot mix. In doing so it burned 4455 gallons of diesel for a rate of 1.5 gallons per ton. Cold feed samples indicate a moisture content of 5.4%. The fuel rate seems high to the operator, so he goes back through his plant reports to May when he first fired the plant after its winter maintenance regimen. On May 10th he produced 2125 tons of hot mix, burning 2550 gallons of fuel for a yield of 1.2 gallons per ton. A glance at the report indicates cold feed moisture was 5.9%. It’s now obvious to the operator that something has changed and he needs to be looking into it. A check of fuel filters on the burner reveals a partially plugged filter which caused a drop in fuel pressure resulting in a higher burner setting to yield the same amount of heat, thus higher fuel consumption. The plugging happened so gradually that the operator never noticed the progressively higher settings he was using on the burner controls. Without the plant reports to reference he might have soldiered onward, blissfully unaware that he was wasting .3 tenths of a gallon of burner fuel per ton. At $3.70 per gallon that equals $1.11 per ton wasted. That’s a total of $2,358.75 for the day.

Daily plant reports can also point out problems in oil content. Let’s use a StanSteel, RM-80 batch plant as an example. On August 12th, the second day of a major state contract, All State Paving received the results from state sample #4, sublot 1. As its predecessor did, the sample shows an oil content of 6.7%, a tenth of a percent out of spec and in penalty territory. The previous day’s samples indicated a range of 6.3% to 6.5%. Since the target value was 6.1% the plant operator reduced the batch menu oil content by .3%, expecting a 6.0% on his next test. When this didn’t happen, he fell back of the traditional asphalt plant operator’s defense: The state got a couple of inaccurate tests or the nuke gauge is faulty.

In the example above, an investigation later revealed that the oil content listed by the state was correct. This particular plant uses an external oil weigh pot. The problem was traced to a build-up of asphalt/aggregate in the hole under the oil distribution bar where it enters the pug mill. The material restricted the downward movement of the scales as they loaded up, causing the scale outputs to indicate a weight lighter than reality. This forced an excessive amount of oil to be loaded in order to satisfy the batching computer’s demand for a set weight.

Since this condition did not occur overnight, it is a fair assumption that if the operator had kept daily records of oil consumption he would have noticed that his tank stickings were indicating a progressively higher yield than his plant’s computer was requesting.

In both of the examples cited a daily plant report proves to be a valuable asset in operations. While the actual amount of dollars saved by a plant report program can be hard to estimate and likely varies from plant to plant, few people would argue that the potential is great.

The plant report can also contain other useful information, like venturi pressure drop, water pressure and gallons per minute for the wet systems. Baghouse data can be substituted where needed. Plant reject and mix wasted can also be tracked. By including a section for operator comments, plant down time can also be recorded. If the plant’s temperature ‘chart recorder’ disk is included a very accurate picture of daily operations emerges.

Figure 1 illustrates a typical plant report form for a drum mix plant with dual AC tanks and a wet wash, venturi system. It is set-up for a 2.5 inch Viking oil pump which moves .23 gallons per revolution. It also utilizes a fuel ‘flow-meter’ instead of tank measurements to track burner fuel. These parameters can be modified easily to fit a company’s particular set-up.

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FIGURE 1

BATCH PLANT DAILY REPORT

DATE:__/__/__                                                                                                           SCALE TONS:_______
DAY: ________                                                                                                               WEATHER:_________
                                                                                                                                                 _________________
CONTRACT#:________                                                                            CUMULATIVE TONS:______

ASPHALT INVENTORY                                                                              BURNER FUEL METER

Start: Tank 1 _____tons                                                                                                    End: _____
           Tank 2 _____tons                                                                                                   Start:_____
              Total _____tons                                                                                                   Used:_____gals
End: Tank 1 _____tons                                                                                              Gals/ton:_____
          Tank 2 _____tons
             Total _____tons                                                                                 BELT SCALE TOTALIZER
Start Total: _____tons                                                                                                        End: _____
Total Deliv: _____tons                                                                                                      Start:_____
                                                                                                                                     -__%H2O:_____
Combined Oil:_____tons                                                                                                  Total:_____dry tons
ENDING TOTAL:_____tons
Amount Used:_____tons                                                                                            Dry Tons:_____
Percent by Total:_____%                                                                                     +Asph Tons:_____
                                                                                                                                  =Tons Made:_____
                                                                                                                                    -Scale Tons:_____
                                                                                                                               =Tons Wasted:_____

                                                                             OIL DELIVERIES

                                                        Ticket Number                          Tons of Oil
                                                        1 __________                           __________
                                                        2 __________                           __________
                                                        3 __________                           __________
                                                        4 __________                           __________

                                                                                  Total Received________tons

               Plant Hours:______                                                                                 Loader Hours:______

Operator Comments:_____________________________________________________________
_______________________________________________________________________________
Signed:____________________________

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FIGURE 2

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As can be seen, these forms are not hard to generate. Modifying one to fit your company’s needs is just a matter of a few minutes on your computer. Since converting most HMA facilities to the metric system requires expensive modifications to ratio and batching computers, and existing plant owners aren’t likely to rush to spend unwarranted funds on such things, these forms use Imperial measurements. Feel free to convert them as needed.

Once the form has been finalized to fit a particular company, it can be sent off to the printer. A hard copy with two carbons is a good choice. One copy is for the main office, one for the plant superintendent and the hard copy stays at the asphalt plant. In some states asphalt plants are required to provide asphalt tank measurements and mix produced tonnages to the plant inspectors at the end of each day. For this purpose a third carbon can be added, with inappropriate data like fuel consumption and operator comments blanked out. A word of caution: Only provide the information required. It’s amazing how unnecessary and poorly understood data in uneducated hands can sometimes come back to haunt you.

For additional information on this subject or help with any problems encountered contact Cliff Mansfield, Call 541-352-7942, 7:30am to 9:00pm Pacific Standard Time.

Email me- cmconsulting@hotmail.com