maintenance ac tanks - · pdf file · 2013-08-06asphalt storage tanks produced by...

Heatec asphalt tanksMaintenance

Publication No. 9-04-147 Revised 9-21-04

SCOPEThis document provides information on maintenance of asphalt storage tanks produced by Heatec. It applies to tanks that incorporate heating coils and to tanks that include optional equipment such as mixers, gauge boards and radar level sensors. The information applies to both vertical and horizontal tanks, although vertical tanks are featured (Fig. 1).

OTHER PUBLICATIONS We refer to other publications for additional information on components used on Heatec tanks. You should obtain those publications and follow their recommendations where ap-plicable.

In most cases those publications are included in the packet of documents furnished with your tanks. You can also find all of the Heatec Tec-Notes and other Heatec documents on the Heatec web site www.heatec.com. Likewise, you can find publications published by manufacturers of various compo-nents on their web sites.

Following is a list of publications that contain information you may need in addition to this document:

• How to prevent leaks in pipe joints at HMA plants. Heatec Tec-Note 6-04-126

• Setting Honeywell controllers used with Heatec vertical asphalt tanks. Heatec Tec-Note 5-04-120

• Recalibrating UE controllers. Heatec News, April and May 2003

• Resun valves—Sealant Injection Equipment and Recommended Maintenance Procedures: www.rmenergy.com.

• Resun valves—sealant specifications

• OSHA regulations:

Subpart J—General Environmental Controls29 CFR PART 1910.146—Permit-Required Confined Space29 CFR PART 1910.147—The control of hazardous energy (lockout/tagout)

Subpart H—Hazardous Materials9 CFR PART 1910.119(k)—Hot Work Permit

Subpart Q—Welding, Cutting and Brazing29 CFR PART 1910.252—General Requirements

SAFETYIn order for you to safely work on asphalt tanks you must adhere strictly to OSHA regulations that apply to working at heights, working in confined spaces and performing hot work. These regulations are listed above.

PROPER MAINTENANCE IS ESSENTIALYou should not overlook the need to perform periodic main-tenance on asphalt tanks. Failure to properly maintain an asphalt tank can cause any or all of the following things to happen:

• Asphalt may overflow when the tank is being filled

• Operators may unintentionally run out of asphalt

• The tank may collapse or rupture

• The heating coils may coke over and reduce heat transfer

• Operators may get false level indications from gauge boards and/or radar

Proper maintenance is preventive maintenance—not fixing problems after they occur. On plants that shut down for the winter or for annual maintenance, certain maintenance work should be done before the plant is put back into operation. Likewise, after the plant is back in operation, certain tasks should be done on a regular basis (at least monthly).

TEMPERATURE CONTROL SYSTEMThe temperature control system consists of a controller (Fig. 1), an actuator (Fig. 2), a 3-way valve (Fig. 3, and a ther-mometer (Fig. 4).

The 3-way valve has two positions. In one position it diverts hot oil through the heating coils of the asphalt tank. In its other position it bypasses the hot oil so that it does not flow through the heating coils.

HEATEC TEC-NOTE

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Figure 1. Heatec vertical asphalt tank.

TANK INCLUDES OPTIONALCOMPONENTS

BULLS EYE

MIXING BAFFLE

MANHOLE WITH BOLT-ON COVER

MANHOLE WITH HINGED COVER

HEATING COILS

CAGED LADDER

ALUMINUM SKIN

HANDRAILS

MIXER SHAFT WITH IMPELLERS

OVERFLOW PIPE

DIAL THERMOMETER

CAPILLARY BULB

HIGH-LEVEL PROXIMITY SWITCH

FLOAT FOR PROXIMITY SWITCH

FILL PIPE

VENT/OVERFLOW PIPE

VENT CONDENSERRADAR SENSOR UNIT

GAUGE BOARD EMPTY-LEVEL SWITCH

GAUGE BOARD

GAUGE BOARD FULL-LEVEL SWITCH

FLOAT FOR GAUGE BOARD

P-TRAP

UE CONTROLLER

APOLLO ACTUATOR

1/4” SHELL

MIXER GEAR BOX

3-WAY HOT-OIL VALVE

6” INSULATION

Revised 9-8-04

The valve (Fig. 4) is electrically-pow-ered by an Apollo actuator (Fig. 5), and has two positions. Each position cor-responds to one of the two positions of the actuator. The actuator is controlled by a UE controller (Fig. 2), which has a capillary tube (Fig. 5) that senses the temperature of asphalt. The controller activates the actuator, which rotates the valve to divert hot oil to the coils when the temperature of the asphalt is lower than the set point of the controller.

The UE controller has either two or three pointers. The black pointer always indicates the temperature of the asphalt inside the tank. The red pointer enables the operator to set a temperature or set point, which is the desired temperature for the asphalt.

The green pointer is only on control-lers for asphalt tanks that have mixers. This pointer is used to set the asphalt temperature at which you want the mixer to shut off. This pointer should be set to shut off the mixer at tempera-tures of 300 degrees F (minimum) to avoid overloading or damaging the mixer from asphalt that has thickened or begun to solidify.

To check the green pointer for proper operation, make sure the asphalt is at least 300 degrees F. Set green pointer lower than black pointer and turn on mixer. The mixer should operate normally. With mixer running, reset the green pointer higher than black pointer. The mixer should shut off and the mixer alarm should sound. After test, reset all controls to their normal condition.

The capillary bulb of the UE control-ler is installed in a pipe called a “dry well.” A conventional dial thermometer (Fig. 5) is also installed in a dry well next to the one where the capillary tube is installed. The dial thermometer is for backup so you can double-check the temperature indications of the UE controller.

Incidentally, a dry well is a pipe welded into the wall of the asphalt tank. It protrudes into the liquid asphalt, but is capped so that no asphalt enters the pipe (hence the name “dry well”). The other end of the pipe protrudes out of

Figure 2. UE controller for hot oil.

Figure 3. Apollo valve actuator.

Figure 4. Hot oil valve.

the tank. The capillary temperature sensing bulb of the temperature control-ler is installed in the external end the pipe. The pipe is partially filled with heat transfer oil to ensure efficient transfer of heat from the liquid asphalt inside the tank to the sensing bulb. The same is true for the dial thermometer.

You should periodically remove both the capillary bulb and the dial ther-mometer to make sure that the pipe is partially filled with heat transfer oil. Without the heat transfer oil in the dry well, these devices will not respond reliably or consistently. Do not over tighten the fittings that secure the bulb and dial thermometer. On dial ther-mometers, do not grip face of dial for tightening. Instead, use a wrench on the hex fitting.

To check for proper operation of the temperature control system first check that the temperature pointer of the UE controller is within 5 degrees of the dial thermometer. If not, you may need to either replace the dial thermometer or recalibrate the UE controller. Please refer to applicable Heatec documents on recalibrating UE controllers listed above.

If the power-operated valve is presently diverting hot oil to heat the tank, reset the set point on the UE controller to a temperature lower than the current temperature. The valve should respond by shutting off hot oil to the tank.

If the power-operated valve is not pres-ently diverting hot oil to heat the tank, reset the set point on the UE control-ler to a temperature higher than the current temperature. The valve should respond by diverting hot oil to heat the tank.

Reset all controls to their normal condi-tion.

Figure 5. Capillary bulb and dial thermometer.

AUTOMATIC SHUTOFF CONTROLSAutomatic shutoff controls are electrical controls that auto-matically shutoff unloading pumps that fill the tank with as-phalt. This prevents overflowing the tank with liquid asphalt.

These controls also shut off hot oil to the tank in case the liquid level falls below the top of the heating coils. This prevents coking the heating coils in the bottom of the tank. Coking forms a layer of hardened asphalt on the coil surfaces thereby insulating the coils and reducing their ability to transfer heat.

It is very important to make sure these controls are function-ing properly at seasonal startup and each month that the plant is in operation. These controls are discussed in other parts of this document.

HIGH LEVEL FLOAT SWITCHMost asphalt tanks—both vertical and horizontal—have a high-level proximity switch on top of the tank (Fig. 6). The switch is activated by a pipe connected to a float inside the tank (Fig. 7). The pipe protrudes through a sleeve in top of the tank. When the tank is being filled and reaches its “full” level, the pipe on the float extends until it is close to the proximity switch. The switch has a magnetic sensor activated by close proximity of the metal pipe. When activated the switch opens the circuit that controls the asphalt unloading pump and shuts off the pump to prevent overflowing the tank.

A common problem is for residues from asphalt fumes to build up on the outer surfaces of the float pipe and the inner surfaces of the sleeve it travels through. The residues can cause the float to stick and become unreliable.

To remedy a sticking problem, clean the float pipe and the sleeve it travels through. From the top of the tank pull the float pipe out as far as possible and remove all residues that you can reach. Use a brush or rag soaked with a solvent. Also work some of the solvent into the sleeve.

Two people are needed to check the proximity switch for proper operation. One person should be on top of the tank next to the switch (Fig. 6). The other person should be at the controls of the asphalt unloading pump (Fig. 15). Make sure the pump controls are set for the tank you are testing. Also make sure that the tank fill valve is open.

Now, make sure the end of the float pipe is below the prox-imity switch so it cannot activate the switch. Momentarily switch on the pump. The pump should operate.

Now, pull up the pipe on the float until the end of the pipe is next to the proximity switch without actually touching the switch. Switch on the pump again. The pump should not op-erate. Moreover, this should set off an alarm horn and cause a red light to come on at the controls of the unloading pump.

Because the float pipe intentionally has extra clearance in its sleeve, be sure to wiggle the pipe around to make sure it keeps the pump shutoff in all possible positions while the

pipe is extended. If necessary, adjust the proximity switch in its mounting bracket to achieve proper operation.

Reset all controls to their normal condition.

Figure 6. High-level proximity switch and float pipe protruding through sleeve in top of tank.

Figure 7. Float for high-level proximity switch.

GAUGE BOARDGauge boards are optional on asphalt tanks (Fig. 1). They indicate the asphalt level inside the tank. Gauge boards are simple, reliable devices, but they do require a little mainte-nance to prevent problems that could adversely affect reli-ability. The red “bulls eye” should run up and down the scale smoothly as the tank is filled and as asphalt is used. However, there is a problem if it hangs or if you find slack in its run-ning cable. Not only could this result in unreliable level indi-cations, but could cause shutoff problems as explained later.

Problems with gauge boards are usually limited to build-up of asphalt on the cable that supports the bulls eye. Conse-quently, the cable can’t run freely through the P-trap on top of the tank (Fig. 8). The solution is to manually pull out as much of the cable as you can and clean the asphalt from it.

Another problem is that the cable may slip off of one or more of the pulleys and wedge to one side of the pulley. This will bind the cable. The remedy is to remove the covers from the P-trap and reset the cable around the pulley.

Another problem that can cause the bulls eye to hang is mis-alignment at one or more joints of the scale where the seg-ments of the scale are fitted together. The bulls eye can hang on a misaligned edge as it passes over the joint. The remedy is to realign the edges of the joints.

A liquid seal pulley support (better known as the “P-trap”) is on top of the tank. The cable that supports the bulls eye travels through the P-trap and over pulleys inside the P-trap. The P-trap allows the cable to travel through the top of the tank while preventing asphalt fumes from escaping the tank. It contains oil that prevents the fumes from escaping. Oil in the P-trap should be checked monthly. A plug in the side of the P-trap can be removed in order to put oil in the lower sec-tion of the P-trap.

The P-trap contains three pulleys that guide the cable through the P-trap. After cleaning the support cable be sure to check that the pulleys are turning freely. You should be able to determine this by pulling down on the bulls eye causing the cable to manually raise the float. You should not encounter any unusual resistance in cable travel except for the effort needed to raise the float inside the tank. Unusual resistance may indicate that one or more of the pulleys is not turning freely. In that case, remove covers from the pulleys and make sure they are not distorted or damaged.

Figure 8. Support cable for float on gauge board passes through P-trap shown here. Remove plug on side of P-trap to add oil.

Figure 9. Float for gauge board is supported by single cable and is guided by two other cables, one on each side.

GAUGE BOARD SHUTOFF CONTROLSThe gauge board has a switch mounted externally near the bottom of the gauge board for a preset “full” level (Fig. 11). When the tank is being filled, the red target (“bulls eye”) travels down the gauge board and actuates the switch. Conse-quently, it causes the unloading pump to shut off.

The gauge board also has a switch mounted externally near the top of the gauge board for a preset “empty” level (Fig. 10). When asphalt is being used, the “bulls eye” travels up the gauge board and actuates the switch. When the switch is actuated it causes the power-actuated valve to rotate so as to bypass the hot oil, thereby shutting off heat to the tank. This is done to prevent coking the coils.

Asphalt residues can build up on the cable that supports the bulls eye, causing the cable to stick so the bulls eye cannot travel freely. Thus, the bulls eye may not engage the switches that shut off the unloading pump tank or the hot oil. The remedy is to manually pull out as much of the cable as you can and clean the asphalt from it.

It is helpful to use two people to check both gauge board shut off functions. Tie a rope about 50 feet long to the bulls eye so you can pull it down while standing on the ground.

When checking for proper high level control, one person should be at the unloading pump controls (Fig. 15). The other person should be on the ground holding the rope that is tied to the bulls eye of the gauge board. Make sure the pump controls are set for the tank you are testing. Also make sure that the tank fill valve is open. Momentarily turn the unload-ing pump on. It should operate. Pull the bulls eye down until it actuates the high level switch at the bottom of the gauge board (Fig. 11). Turn the unloading pump on again. The pump should not operate. Moreover, this should set off an alarm horn and cause a red light to come on at the controls of the unloading pump.

When checking for proper low level control, one person should be at the power-actuated hot oil valve controls (Fig. 3 and 4). Reset the UL temperature controller to a set point higher than the current temperature of the asphalt and make sure the power-operated hot oil valve is diverting hot oil so as to heat the tank coils.

The other person should be on top of the tank and should manually actuate the low level switch at the top of the gauge board (Fig. 10). The power-actuated valve should rotate so as to bypass the hot oil, thereby shutting off heat to the tank.


Figure 10. Switch at top of gauge board is for preset “empty” level.

Figure 11. Switch at bottom of gauge board is for preset “full” level.

RADARRadar level sensors are optional on asphalt tanks and serve the same purpose as optional gauge boards (Fig. 12). Most HMA plants use one or the other. The antenna on a radar unit requires cleaning periodically (Fig. 13). Vapors from the liquid asphalt tend to leave thin deposits on the antenna over a period of time. These deposits can build up and decrease the sensitivity of the radar. Consequently, the radar may not provide accurate indications of asphalt level in the tank.

To clean the antenna, simply unbolt the radar unit from the top of the tank and pull the unit out of the tank with wires attached. But before pulling the unit out, take special note of the position of the small hole drilled in the side of the radar body. This hole should face towards the center of the tank and is the position it was in when the unit was calibrated. Clean the antenna with a rag soaked with solvent and rein-stall the unit. Make sure that the drilled hole faces the exact same way it was before the unit was removed. Otherwise, the unit will not work properly.

Cleaning the antenna once a month during the operating season should be adequate. However, any time you encoun-ter false level indications, the first thing to do is to clean the antenna. Your experience may indicate that it needs cleaning more often than once a month.

Aside from keeping the antenna clean, your radar unit should not require any other routine maintenance. However, if you ever need to replace the radar unit with a new one and the new one has not been set up for your specific tank, you will need to do that. Please refer to Heatec Tec-Note applicable to setting up your radar unit.

RADAR SHUTOFF CONTROLS When the tank is being filled, the radar senses when the asphalt reaches a preset “full” level. Consequently, it causes the unloading pump to shut off.

The radar also senses when the asphalt has reached a preset “empty” level. The radar reacts to the preset empty level by closing the temperature control valve that supplies hot oil to the tank coils. This prevents coking the coils.

If asphalt residues have coated the antenna of the radar unit, the radar unit may fail to shut off the unloading pump when the tank is full. Or it may fail to shut off the hot oil when the tank is empty. The remedy is to clean the antenna as de-scribed previously.

If cleaning the antenna does not remedy the problem, the radar unit may not be properly programmed. Please refer to the Heatec Tec-Note applicable to setting up your radar unit.

You can check both of these functions controlled by the radar by temporarily changing its Honeywell controller (Fig. 14) as described below. The applicable Heatec Tec-Note previously listed provides information for setting Honeywell controllers used with Heatec vertical asphalt tanks.

Figure 12. Vega radar sensor unit

Figure 13. Antenna of radar unit needs to be cleaned regularly to ensure reliable level indications. Unit should be removed from tank for access to clean the antenna.

HOLE FOR ORIENTATION

It is helpful to use two people to check both radar shutoff functions. When checking for proper high level control, one person should be at the Honeywell controller. The other person should be at the controls of the asphalt unloading switch (Fig. 15). Make sure the pump controls are set for the tank you are testing. Also make sure that the tank fill valve is open.

Take note of the actual asphalt level indicated by the Honeywell controller. If the tank is less than full, momen-

tarily turn on the unloading pump. The pump should operate. Then reset ALARM A2S1VA on the Honeywell controller to a value for any level below the actual level. Turn on the unloading pump again. It should not operate. Moreover, this should set off an alarm horn and cause a red light to come on at the controls of the unloading pump. Reset all controls to their normal condition.

When checking for proper low level control, one person should be at the Honeywell controller (Fig. 14). The other person should be at the power-actuated temperature control valve on the side of the tank (Fig. 3 and 4).

Take note of the actual asphalt level indicated by the control-ler. Reset the UL temperature controller to a set point higher than the current temperature of the asphalt and make sure the power-operated hot oil valve is diverting hot oil so as to heat the tank coils. Then reset ALARM A1S1VA on the Honeywell controller to a value for any level above the actual level. The power-actuated valve should rotate so as to bypass the hot oil, thereby shutting off heat to the tank.


NOTE: In normal operation the radar shuts off the unload-ing pump before the proximity switch is activated. Thus, if the proximity switch shuts off the unloading pump it means

that the radar is not working properly.

So every time you fill the tank pay special attention to whether the indicator light for high float level comes on. If it does come on, this indicates that the radar failed to shutoff the unloading pump and the shutoff was achieved only by the backup system.

TANK VENT/OVERFLOW PIPEProper maintenance of the vent/overflow pipe is crucial to safe operation of the tank. Failure to maintain this pipe could lead to either rupturing or collapsing the tank.

A 4-inch pipe installed inside the tank serves as a vent/over-flow pipe (Fig. 1). Both ends are open. Its top end is posi-tioned just below the inside top head of the tank. Its bottom end turns outboard just above the heating coils, goes through the side of the tank and turns down. It ends several inches above the ground and is painted red for easy identification (Fig. 16).

It is extremely important to make sure that this pipe never gets stopped up or restricted in any way. If this pipe ever be-comes restricted or stopped up, pumping asphalt into the tank leaves no way for air displaced by the incoming asphalt to escape. Consequently, air pressure inside the tank could build up and rupture the tank with disastrous consequences.

Conversely, pumping asphalt from the tank that has a stopped up vent could reduce the pressure inside the tank creating somewhat of a vacuum. Consequently, the reduced pressure could cause the walls of the tank to collapse.

Figure 15. Controls for unloading pump.

Figure 14. Honeywell controller used with radar unit..

Fumes from asphalt inside the tank sometimes have a ten-dency to build up a residue in the pipe, especially near the bottom end of the pipe where the pipe turns and comes out of the tank.

One clue to a clogged vent is the sound of air escaping the bottom end of the pipe when the tank is being filled with asphalt. A strong, steady stream of air escaping from an unclogged pipe as the tank is filled has a distinct sound. It is usually a good indication that the vent is clear. But if you de-tect changes in the usual sound or flow of air from the vent, it may be clogged or partially so.

You may be able to unclog the pipe without opening the tank or going inside the tank. If you suspect the vent may be clogged, remove the red elbow and short piece of red pipe from the bottom of the tank. Make sure these two items are clear of any obstructions. Then check the vent pipe still pro-truding from the tank and its elbow just inside the tank. You may need to use a short rod to prod the elbow to determine if it is okay.

MANHOLESVertical asphalt tanks normally have two manholes, one on top of the tank and another in the side of the tank, close to the ground. The manhole on top of the tank is a hinged cover plate that is secured with a quick-release locking lever (Fig. 17). The one at the bottom of the tank is secured with a cover plate and that is bolted into place. The manhole on top of the tank can be opened while there is liquid in the tank. However, the opening should only be used for looking inside the tank. It is not an entrance way and no ladder is provided. Anyone looking inside the tank while it contains liquid as-phalt should keep their face well above the opening.

Maintenance of this manhole consists of two checks. First, check the locking lever to make sure it is functional and free of damage. Second, check the gasket inside the cover plate to make sure it is not damaged and that it completely seals the opening so that no fumes escape when the cover plate is closed and the lever is locked in place (Fig. 18). You can be sure that the cover plate is not sealed if you find a lot of residue around the manhole.

The manhole near the bottom of the tank is sealed with a large steel cover that is bolted into place. Never remove this cover while there is hot asphalt inside the tank. After the tank has been emptied and is cold, this manhole can be used to enter the tank for maintenance or repair. All of the safety requirements set forth in OSHA regulations should be strictly followed before anyone enters the tank. A new gasket should be installed when the cover plate is re-installed.

Horizontal asphalt tanks normally have one manhole for each compartment. They have hinged cover plates with locking levers, the same as those on top of vertical tanks. Each open-ing should only be used for looking inside the tank when the tank compartment contains liquid asphalt. Again, anyone looking inside a tank compartment while it contains liquid

Figure 16. Overflow pipe at bottom of tank.

Figure 17. Manhole on top of tank with hinged cover plate and quick-release locking lever.

Figure 18. Gasket on manhole cover plate should provide air-tight seal.

asphalt should keep their face well above the opening. After all tank compartments have been emptied and are cold the manholes can be used to enter the compartments for main-tenance or repair. All of the safety requirements set forth in OSHA regulations should be strictly followed before anyone enters the tank.

Maintenance of the manholes on horizontal tanks is the same as for those on top of vertical tanks as described above.

MIXER GEAR BOXMixers are optional on asphalt tanks and are used mainly for blending PMACs (polymer modified asphalt cement). Heatec currently uses Dodge gear boxes from Rockwell Automation.

The mixer has a gear box that is filled with lubricant. The lubricant should be periodically checked and replaced ac-cording to the manufacturers instructions.

A vent is shipped loose with each new mixer gear box. You should install the vent in place of the non-vented plug after the tank is erected and before the mixer is put into service (Fig. 19) . The vent prevents a build-up of pressure inside the gear box housing while the mixer is in operation.

The manufacturer of Dodge gear boxes currently recom-mends use of ISO 220 EP type mineral oil. The manufacturer recommends replacing it—depending on operating condi-

Figure 19. Mixer gear box. Install vent when tank is erected. Remove it to add lubricant. Plug on side is used to check lubricant level.

tions— after 3 years of operation or 10,000 hours of opera-tion whichever comes first.

The manufacturer provides other essential information about the gear box. This information is furnished with each new gear box. You should always follow the manufacturers rec-ommendations, which are subject to change and may differ from the recommendations cited above. You may damage the bearings and gears inside the mixer gear box if you operate it without proper lubrication.

You should check the gear box for proper operation and lubrication at the start of the operating season and once a month during operation.

A plug is located in the housing of the gear box so that the level of lubricant in the gear box can be checked (Fig. 19). Do not check lubricant level while gear box is running. Re-move this plug temporarily to make sure the level of lubri-cant is approximately the same height as the hole from which you removed the plug. If not, add lubricant until it begins to spill out of the hole. Be sure to replace the plug. When you check for proper lubrication you should also check mount-ing bolts of the mixer gear box to make sure they have not vibrated loose from operation.

To check for proper operation, open the manhole on top of the tank and operate the mixer. Visually observe that the shaft is rotating.

VENT LUBRICANT LEVEL PLUG

LUBRICATIONIt is not unusual for plant operators to overlook the need to lubricate certain parts of an asphalt tank. Tanks have a number of parts that need lubrication. And their lubrication is very important.

Oil in the P-trap of the gauge board and lubricant in the mixer gear box have already been discussed. In addition to those parts, you especially need to lubricate hot oil valves and asphalt valves on the tank. Moreover, you should lubri-cate these valves on all the asphalt piping and hot oil piping. Be sure to apply some grease to the locking lever on the manhole—its hinges and its latch joints.

Some operators may not be aware that valves really do need to be lubricated and that they do indeed have lubrication fit-tings (Fig. 20). The fittings are button-head fittings and have flat ends, unlike conventional fittings that most everyone rec-ognizes. The lubrication opening is often obscured by paint, which may be the reason they are commonly overlooked. Be sure to scrape the paint from the end of the fitting to ensure that your grease gun can easily inject the lubrication.

R&M Energy Systems is the manufacturer of Resun valves used on Heatec products. They provide servicing instructions entitled Sealant Injection Equipment and Recommended Maintenance Procedures. These instructions can be down-loaded from R&M Energy Systems. We normally provide a copy of these instructions with all Heatec products that use Resun valves.

You should follow Resun’s instructions for lubricating and maintaining valves on your Heatec products. They recom-mend a number of lubricants (sealants) suitable for various applications. Resun 101 and Resun 104 sealants (lubricants) are well-suited for valves on Heatec products.

LEAKING PIPE JOINTSLeakage at bolted joints of hot oil and asphalt piping are common problems. Most leakage problems stem from mis-alignment of the joints when they were originally installed (Fig. 21 and 22). Pipe installers often try to correct misalign-ment problems by using unusually thick gaskets and over-tightening nuts on the flange bolts. Sometimes they even resort to using two gaskets in an effort to stop a leaking joint. Unfortunately, these unorthodox fixes don’t last very long and the leaking returns after awhile.

If you are experiencing leaking pipe joints, please refer to Heatec Tec-Note: How to prevent leaks in pipe joints at HMA plants.

Figure 20. Resun valve with button-head fitting for lubrication. You may need to scrape paint from top of fitting to ensure that lubricant will be injected into body of valve.

Figure 21. Flanges properly positioned before bolting.

Figure 22. Flanges have unacceptable alignment.

LADDERS AND HANDRAILSLadders and handrails are important safety provisions (Fig. 1). Check them regularly to make sure they are secure and in good condition. Moreover, make sure they are not bent or damaged from contact with other objects. Also make sure they are not weakened from rust, especially at joints where they are welded. None of their bolts, nuts or other parts should be loose or missing.

INSULATIONPeriodically check the exterior of asphalt tanks to ensure the skin and insulation are not damaged. Damaged skin may lead to loss of insulation and unnecessary heat loss. Moreover, damaged skin may allow water to soak the insulation result-ing in unwanted rusting in addition to heat loss.

Damaged skin and insulation should be repaired with new materials.

CLEAN OUT OF TANKThe interior of asphalt tanks (Fig. 23) may need to be cleaned out after they have been used for a couple of years or more. Although cleaning out a tank may be tedious work, it can definitely be worthwhile.

In normal use asphalt can build up a coating inside the tank. Heavy buildup on heating coils—especially those with fins—can significantly reduce their effectiveness to heat the liquid asphalt. Massive buildups on other interior parts can reduce the usable volume of the tank. And it is not uncommon for built-up materials to form large clumps that can beak loose and block vents or clog pumps.

Cleaning out an asphalt tank requires emptying the tank completely and waiting until it is cold. All of the safety requirements set forth in OSHA regulations should be strictly followed before anyone enters the tank.

Cleaning may require using hammers, chisels, scrapers, wire brushes and shovels. It is not necessary to clean down to bare metal. Just try to get rid of the large pieces and the heavy deposits. Take care not to damage the heating coils when cleaning them. Wear hearing protectors.

© 2004 Heatec, Inc.Heatec, Inc. 5200 Wilson Road Chattanooga, Tennessee 37410 www.heatec.com (423) 821-5200 (800) 235-5200 Fax (423) 821-7673

Figure 23. When cleaning out a tank, take care not to damage components inside the tank—especially the coils and their fins.

ASPHALT TANK MAINTENANCE RECORD

DATE: TANK ID OR SERIAL NO.:

ITEM CONDITION ACTION CHECKED BY

UE controller

Apollo actuator

3-way hot oil valve

Dial thermometer

Capillary bulb

Dry well oil (2)

Lubrication of valves

Pipe joints

Internal vent/overflow pipe

External overflow pipe

Skin and insulation

Ladders and handrails

Hinged manhole locking lever

Hinged manhole gasket

High level float switch and sleeve

Mixer box vent

Mixer box lube level

Mixer shaft and impellers

Gauge board cable and pulleys

Gauge board P-trap oil

Gauge board empty level switch

Gauge board full level switch

Radar antenna

Radar high-level control

Radar low-level control

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