Flushing And Pickling Process Of Engine Piping{1071} Caterpillar

Engine:

3606 (S/N: 8RB)

G3606 (S/N: 3XF)

3608 (S/N: 6MC; 8LL; 7WR)

G3608 (S/N: 4WF)

3612 (S/N: 9RC; 9FR; 2NZ)

G3612 (S/N: 1YG)

3616 (S/N: 1PD; 1FN)

G3616 (S/N: 4CG)

3618 (S/N: 2MW)

Introduction

The following procedure details the flushing and pickling process. This instruction will also show the requirements for cleanliness that are related to the engine piping that is external to the engine and the auxiliary equipment. This procedure should be used as a guideline.

This entire Special Instruction should be read and understood before beginning any work on the engine.

Flushing Information And Guidelines

General

The quality of the medium that is used for flushing is essential. The medium's quality ensures the performance and the long life of the Caterpillar Engine and the auxiliary equipment. The following items are needed in order to get proper performance from the equipment:

• a well designed system

• a flushing medium of good quality

These prerequisites are useless unless the engine piping is initially cleaned in order to prevent equipment damage during the initial start-up. The piping must also be cleaned in order to remove any debris that may have been dislodged in the piping.

Cleaning and flushing the new engine piping and the existing engine piping is accomplished by using essentially the same procedure. Contaminants that are introduced during the manufacturing, storage, and installation of the new engine piping must be removed. The flushing of the existing piping removes contaminants that are generated during normal operation, failures, and debris that is introduced during an overhaul. Do not flush the valves, the instrumentation, or the other critical components. If necessary, use temporary bypasses.

All of the cleaning and flushing procedures must be done with the agreement from the equipment manufacturer, the installer, the operator, and the flushing medium supplier. No portion of these procedures should be done without a thorough understanding of the possible effects of improper preparation of the system. The installation, cleaning and flushing of the engine piping must not be done by someone without experience.

Flushing Program For The Engine Piping

For a system that is assembled in the field, the ability to keep the piping sufficiently clean so that flushing is not necessary is not economical or practical. The flushing must take place after the installation of the system is complete. This must be done prior to the start-up of the system. The success of the flushing depends on the following items:

• the success of the initial efforts to keep the particles out

• the proper attention to flushing

• the design of the system

If the flushing is successful, a clean pipe and system components are obtained without damage to the equipment from debris.

Keeping the particles out of the engine piping from the beginning will make cleaning the piping easier. This is achieved through the work of many people. The following items are examples of these efforts:

• The design of the system should allow the system to be cleaned successfully.

• The piping and equipment should be properly cleaned and maintained prior to installation.

• Contaminants should be prevented from entering the piping during modifications.

This list is not nearly complete. This list shows that the manufacturer, the sender, the installer, and the operator help to ensure that no contaminants enter the piping or the equipment. The preventive efforts make the flushing procedure easier, safer, shorter, and less costly.

The success of flushing depends on the ability of the pump to provide a substantial flow rate. This creates a turbulent flow within the engine piping.

Note: The turbulent flow will be maintained when the Reynolds number exceeds 20,000.

If necessary, an outside pump is recommended in order to achieve this flow. The velocity of the medium moving through the engine piping is the most important part of successful flushing. The velocity should be two or three times the normal velocity in the system.

Solids may be loosened by vibrations at pertinent points in the engine piping. The following points should be considered:

• welded joints

• flanges

• bends

• low points beneath a weld

• locations of past work on the system

After the solids are broken loose, the solids will settle in the main tank or the foreign matter will be trapped by the temporary screens. The solids can be filtered out of the system by the user's bypass or by the full flow filtration system.

It is not normally necessary to flush through certain systems and devices that have been assembled, cleaned, and sealed before the shipment to the site. Such equipment must be carefully protected against contaminants. During flushing, this equipment should be bypassed.

For assemblies that can be flushed freely, this flushing procedure does not have the ability to flush out all possible contaminants. During the installation of the system, carefully prevent the contamination of unnecessary impurities that cannot be easily removed by flushing. These contaminants will cause problems in subsequent operations when the contaminants are dislodged by vibration or operation.

The system will be flushed prior to start-up, but harmful contamination may enter the system during assembly.

Preparation Of The Engine Piping For Flushing

Prior to flushing the engine piping, thoroughly inspect all accessible areas. If any evidence of contamination is found, the contamination should be removed manually.

The cleanliness of the engine piping is always questionable. All leads must be blanked as close as possible to the engine and auxiliary equipment. Bypasses may be installed on the engine and auxiliary equipment. The bypasses should only bypass small sections of the piping and the flow path. All other areas in the engine piping that should not be flushed must be blanked with numbered plates. At the end of the flushing, ensure that all of the plates that were installed are removed.

In the engine piping, install temporary strainers of 80 to 100 mesh on the suction side of the flushing pump. Install fine mesh strainers on the discharge side of the pressure source upstream of the flushing tank. The mesh should be no finer than 100 mesh. Use the auxiliary filters that are not reactive in order to increase the rate of the filtration. The filters also decrease the maximum particle size of the contaminants in the flushing medium.

When a heater for the flushing medium has not been installed or when the heater is inadequate, supply heat to the flushing medium with the aid of the electrical heaters that are in the tanks. Sending hot water through the coolers is recommended. When steam at low pressure is used, check the use of the steam with the manufacturer's recommendation.

Heat the flushing medium to 60 to 82 °C (140 to 180 °F). Use steam at a maximum pressure of 34.5 kPa (5 psi). Apply the heat to the water side of the flushing medium's cooler. The flushing medium may also be heated with the electrical heaters in the main tank. Ensure that the fluid is circulated during this period.

The flushing medium that is selected for the flushing of the engine piping can be the system's operating fluid or a flushing oil. If a flushing oil is used, special attention must be given in order to ensure that the flushing oil is compatible with the entire system. After a thorough inspection of the engine piping, an experienced serviceman should select the proper type of flushing medium.

When the system's operating fluid is used, the fluid should not be used for operation. It is necessary to fill the system with new fluid because contaminants that are picked up during the flushing may cause foaming, reduced oxidation resistance, and premature component failure.

Prior to filling the system with the flushing medium, establish the proper configuration in order to bypass the Caterpillar Engine and the auxiliary equipment. Fill the reservoir with the flushing medium to the minimum operating level so the pump inlets are always submerged below the level of the reservoir. Start the pumps and circulate the flushing medium. Because the system's pump cannot generally give an adequate amount of velocity for effective flushing, use external pumps at three times the system flow rate. Do not exceed the system's rated pressures. Heat the flushing medium gradually to 60 to 82 °C (140 to 180 °F) by using the cooler. Continue the circulation as long as necessary in order to flush the engine piping.

It is necessary to flush the system for at least 24 hours. This will ensure the cleanliness of the engine piping. The size of the system will dictate the extent of the flushing time. Throughout the flushing period, maintain the flushing medium in the system at 60 to 82 °C (140 to 180 °F). This temperature is necessary in order to maintain the low viscosity of the flushing medium in the system. The temperature dissolves the flushing medium, which helps to loosen the adhesive particles.

The discharge pressure of the pump may need to be reduced for flushing by lowering the relief valve setting or by lowering the compensator's setting in order to prevent possible damage.

Most of the foreign matter is collected in the temporary strainers during the first hours of flushing. During this time, whenever a noticeable increase in the pressure drop occurs across the strainers, the strainers should be cleaned. The frequency of this occurring may be in intervals of 15 minutes. The flushing medium's filters and strainers must be inspected and cleaned frequently. Auxiliary filters must be operated within the limits of the pressure drop. Refer to the manufacturer's guidelines.

Flushing The System

During the early phases of the flushing period, vibrate and hammer the piping in order to dislodge any scale and weld deposits that have adhered to the surface. When the inspection of the strainers and the accessible parts of the system shows that there is no evidence of contaminants, the system is considered clean. Contaminants could be lint, welding beads, and other foreign matter.

After the inspection of the strainers and the temporary filters shows that there is no evidence of contaminants, flush the other parts of the system by removing the bypasses. Continue flushing the system until the entire system is considered to be entirely cleaned. Take a sample in order to verify the cleanliness.

Replace all of the inspection plates on the openings except for the plates that are being used. When no evidence of contaminants appear in the strainer and filters, stop the circulation of the flushing medium. Inspect the components for cleanliness. The condition of these components is used to determine whether further flushing is needed.

When the flushing is completed, remove the flushing medium from the system. Open the fluid lines at the lowest points in the system and allow the fluid to drain. After the system is completely drained and the surfaces are cleaned, the engine piping should be thoroughly inspected for evidence of contamination. After the cleanliness is verified, the system is rechecked in order to determine that the system is ready for operation.

If the system is going to be idle for a long period of time, it is very important to prevent corrosion. In these cases, the use of oil can protect the system from corrosion by condensation. During this period of time, the system should be inspected frequently for signs of corrosion.

Pickling Information And Guidelines

General

Pickling is the process of removing mill scale by chemically reacting, or by electrolysis, or through both processes. When the pickling is completed, the surfaces should be free of all visible mill scale and rust when the surfaces are viewed without magnification. Pickling is not used for cleaning.

Instructions Prior To Pickling

Prior to pickling, remove the heavy deposits of oil, grease, soil, compounds, and other foreign matter. Small quantities of the foreign matter may be removed in the pickling tanks provided that no detrimental residue remains on the surface.

Instructions For Pickling

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Add acid to the water at normal room temperature. Do not add water to the acid. Add neutralizing agents to the water. Do not add water to the neutralizing agents. There are many safety precautions when handling acid. Therefore, this should only be done by qualified personnel.

The pickling should take place in a solution. This solution contains 5% to 10% hydrochloric acid (HCl) at 40 to 50 °C (104 to 122 °F). The solution also contains 0.03% hydroxyl amine hydrochloride (NH₄ClO). The hydroxyl amine hydrochloride is a corrosion inhibitor that is used in order to minimize the corrosion of the base metal. Circulate the pickling solution until all of the mill scale is removed. The following table contains the formula for a proper solution:

Pickling is followed by a rinse with a neutralizing solution. This solution consists of 10% sodium hydroxide (NaOH) and 50 grams per liter of trisodiumphosphate (Na₃PO₄). The following table contains the formula for a proper solution:

Add the neutralizing solution in order to maintain a pH ≥ 6.5. If checking the pH is not possible, fill the tank. Circulate the solution through the engine piping, and drain the engine piping three times. Pass the total volume of the system through the engine piping five times or pass this volume for 30 minutes. Do this operation for the greater amount of time, before you change the solution.

Do not exceed a dissolved iron content of 10% in the hydrochloric acid pickling solution or 6% in the sulfuric acid pickling solution. Only clean water or condensate should be used for solutions and for rinsing. The tanks that are used for rinsing should be continuously supplied with new water.

Instructions For The Flushing And Pickling Process Of The Engine Piping

General

Note: Pressure test the engine piping prior to flushing and pickling.

1. All of the pipes that contain mill scale require pickling.

2. Isolate the Engine and auxiliary equipment from the system. Install bypasses around the isolated equipment.

3. Install a flushing pump and a flushing tank. The tank capacity should be 1.5 times the system capacity. The flow capacity of the pump must be approximately 2 times the maximum system capacity. The pump capacity should never be less than the maximum system flow rate. Do not exceed the rated pressure of the system. The heater must be able to heat the flushing medium to a temperature of 60 to 82 °C (140 to 180 °F). An 80 to 100 mesh strainer must be installed prior to the flushing pump in order to protect the pump from foreign matter. Install a 100 mesh strainer after the pump. The strainer should be installed upstream of the flushing tank.

The Initial Water Flush

Initially flushing the system removes the large debris from the piping that has been fabricated in the field before the piping is pickled.

1. Fill the system with clean water. If there is an excessive amount of grease in the pipes, an alkaline solution should be added to the water.

2. Flush the system. Stop in order to clean the strainer before the pump and after the pump. During the flushing process, the piping should be vibrated and the piping should be hammered in order to free any loose material.

3. Monitor the strainers and clean these strainers. Keep the differential pressure across the strainers within the manufacturer's recommendations.

4. The flushing is complete when the 100 mesh strainer is clean after 30 minutes of flushing.

5. Stop the pump and isolate the flushing tank.

6. Drain the flushing tank.

7. Clean the flushing tank.

8. Open the vents and the drains in the piping.

9. Drain the piping.

10. Blow out the piping with compressed air.

11. Close the vents and drains. Begin at the pressure air source.

12. Disconnect the compressed air.

Pickling

Note: The piping must be flushed with water before pickling. The Engine and the auxiliary equipment MUST be isolated from the pickling process. Only the piping that was fabricated in the field should be pickled.

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Add acid to the water at normal room temperature. Do not add water to the acid. Add neutralizing agents to the water. Do not add water to the neutralizing agents. There are many safety precautions when handling acid. Therefore, this should only be done by qualified personnel.

1. Fill the tank with the hydrochloric acid pickling solution. See the ""Instructions For Pickling" " section of this Special Instruction.

2. Open the isolation valves.

3. Start the pump and begin heating the pickling medium. After the pickling solution reaches a temperature of 40 to 50 °C (104 to 122 °F), begin timing the pickling process.

4. Monitor the dissolved iron content. The level of the dissolved iron content should not exceed 10% in the hydrochloric acid pickling solution or 6% in the sulfuric acid pickling solution.

5. The piping should be pickled for 5 hours. Check the piping after every hour. Ensure that iron is not excessively removed from the piping.

6. Stop the pump. Isolate the flushing tank.

7. Drain the flushing tank.

8. Clean the flushing tank.

9. Open the vents and the drains in the piping.

10. Drain the piping.

    Note: The pickling solution must be disposed of in accordance with the local laws and regulations.

11. Close the vents and drains.

Neutralizing

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Add acid to the water at normal room temperature. Do not add water to the acid. Add neutralizing agents to the water. Do not add water to the neutralizing agents. There are many safety precautions when handling acid. Therefore, this should only be done by qualified personnel.

1. Fill the flushing tank with the neutralizing solution. See the ""Instructions For Pickling" " section of this Special Instruction.

2. Open the isolation valves on the flushing tank.

3. Start the pump. Monitor the neutralizing solution. Keep the pH ≥ 6.5 by adding the neutralizing solution. If checking the pH is not possible, fill the tank, and circulate the solution through the piping. Drain the piping three times. Pass the total volume of the system through the piping five times or pass the volume for 30 minutes. Perform this operation for the greater amount of time, before you change the solution.

4. Circulate the neutralizing solution until the pH ≥ 6.5 for a 30 minute period without adding more solution.

5. Stop the pump. Isolate the flushing tank.

6. Drain the flushing tank.

7. Clean the flushing tank.

8. Open the vents and drains in the piping.

9. Drain the piping.

10. Blow out the piping with compressed air.

11. Close the vents and drains. Begin at the pressure air source.

12. Disconnect the compressed air.

13. Visually inspect the pipe at several different locations in order to ensure that the mill scale has been removed. If the mill scale has not been removed, the pickling procedure must be repeated.

Final Flushing

Note: All of the piping with the mill scale must be pickled before flushing.

1. Bypass the Engine and the auxiliary equipment. All of the piping that was fabricated in the field must be flushed.

2. Flushing can be performed with water or flushing oil.

3. Fill the system with clean water or flushing oil.

4. Flush the system. Stop in order to clean the strainer that is located prior to the pump. Also clean the strainer that is located after the pump. During the flushing process, the piping should be vibrated and the piping should be hammered in order to loosen particles.

5. Monitor the strainers and clean the strainers. Keep the differential pressure across the strainers with the manufacturer's recommendations.

6. The flushing is complete when the 100 mesh strainer is clean after 60 minutes of flushing.

7. Stop the pump. Isolate the flushing tank.

8. Drain the flushing tank.

9. Clean the flushing tank.

10. Open the vents and drains in the piping.

11. Drain the piping.

12. Blow out the piping with compressed air in order to clean the low points. This allows you to change the system's fluid.

13. Close the vents and drains.

14. Disconnect the air supply. Begin at the pressure air source.

15. Fill the flushing tank with the following items:

    1. For the Lube Oil System, fill with lube oil.

    2. For the Heavy Fuel System, fill with distillate oil.

    3. For the Distillate Fuel System, fill with distillate oil.

    4. For the Cooling Water System, fill with cooling water.

    5. For the Compressed Air System, fill with water.

    6. For the Steam System, fill with water.

16. Install the following filters just prior to the flushing tank on the return line:

    1. For the Lube Oil System, install a 20 micron filter after flushing the pump.

    2. There is a segment of the Heavy Fuel System that is located between the day tank and the engine fuel supply and the fuel return. For this segment of the system, install a 10 micron filter after flushing the pump.

    3. Install a 100 mesh screen in the segment of the Heavy Fuel System that is not discussed in Step 16.b. Install this mesh screen after you flush the pump.

    4. There is a segment of the Distillate Fuel System that is located between the day tank and the engine fuel supply and the fuel return. In this segment of the system, install a 10 micron filter after flushing the pump.

    5. There is another segment of the Distillate Fuel System that is not discussed in Step 16.d. For this portion of the system, install a 100 mesh screen after flushing the pump.

    6. For the Cooling Water System, install a 100 mesh screen after flushing the pump.

    7. For the Compressed Air System, install a 100 mesh screen after flushing the pump.

    8. For the Steam System, install a 100 mesh screen after flushing the pump.

17. Open the isolation valves on the flushing tank.

18. Start the flushing pump.

19. Flush the system for a minimum of 24 hours after the flushing medium has been heated to a temperature of 60 to 82 °C (140 to 180 °F).

20. Flush the system until no debris is found in the screen for a one hour time period.

21. Stop the pump. Isolate the flushing tank.

22. Drain the flushing tank.

23. Open the vents and drains in the piping.

24. Drain the piping.

25. Blow out the engine piping with steam in the steam system. Use air for all of the other systems.

26. Close the vents and drains. Restore the system completely.

27. Dispose of the flushing medium in accordance with local laws and regulations. Do not use the flushing medium in the engine under any circumstances.

Note: If the engine piping is not going to be placed into service within one week, store the system with inert gas. Ensure that the system is airtight.