The following are some frequently asked questions (FAQ) that we often get about High Velocity Oil Flushing.

  • Is there a minimum size (total volume) of a system to justify the cost of this HVOF service?

    No, the size of the system is not as relevant as the amount of contamination or criticality of the system.

  • Based on oil analysis, what are some indications that flushing is required?

    High particle count as well as type and size of debris (i.e. wear particles including but not limited to cutting, severe sliding, fatigue, ferrous, rust, black iron.) Also a membrane patch test can show your oils varnish saturation level, this could be a good indication of when to conduct a varnish removal flush or add Chevron Vartech.

  • When is the best time to consider using this method? Particle count, Time Based PM, etc.?

    A lot of our customers will make this a time based PM scheduled for the machines outage. Also can be based on the machines needs, this could be high particle count, plugging multiple onboard filters, excessive vibration or noise, plugged suction strainers, visible debris in sight glasses.

  • What advice do you have for developing a cost-benefit analysis for HVOF?

    Your plant would have to weigh the cost of the HVOF vs. unplanned downtime and repair cost of equipment failure.

  • How effective is a flush in removing varnish from a turbine control oil system that contains Fyrquel EHC Plus?

    You would have to add a varnish removal chemical and ensure special precautions and tactics are taken with this procedure.

    • Must be capable of manually cycling all valves to ensure all components are flushed with the varnish removal chemical.
    • Must ensure that all of the varnish removal and oil is removed from the system.
    • Must conduct a sacrificial flush and fully drain.
  • Will these flushing process work for Rotary Screw air compressors?

    Rotary screw compressors are in a category all by themselves.

    • We can conduct an HVOF on a rotary screw compressor by adding our own manifold for the drain line and using an external oil reservoir.
    • If you are experiencing varnish problems in the compressor, we can also add Chevron Vartech to the oil system while the compressor is running at normal operating conditions then we add our high pressure filtration units to remove all of the freed varnish.
  • How do different flush types affect sealing?

    Flushing pressure are normally lower than normal operating pressures due to restrictions being removed (such as filters, flow orifices).

  • How long should a system be flushed?

    The length on the flush is always determined by the final qualification standards. These standards are supplied to us either from the OEM, customer, or end users IAW API614. The flushing time can vary based on many different things.

    • Amount of contamination in the piping.
    • Configuration of piping
      • Carbon or Stainless steel
      • Types of welds
      • Piping size
      • Max pressure that the flushing company can supply
    • Flushing crews tactics used
      • Pipe vibrators
      • Pump size
      • Sparging
      • Piping isolation
  • How can you be sure the flushing is completed successfully, and not just breaking loose deposits to recirculate?

    Flushing qualifications are always agreed upon before we start the flush. Industry standard normally dictates back to back one hour verification screens along with a particle count that meets the systems needs. Best practice is to clean the reservoir after the flush to ensure all debris has been removed.

  • Do I use the same turbine oil to flush, or do am I supposed to add in a cleaning agent?

    HVOF is a mechanical means of cleaning, cleaning agents are a chemical way of cleaning.

  • Is the velocity of the flushing oil monitored? Are flow meters installed to verify?

    We start by calculating a Reynolds number to anticipate the velocity. If we believe there is an issue with reaching the anticipated velocity, we do have ultrasonic flow meters that can be affixed to the piping system.

  • Are there any risks of using solvents to remove oil sludge from the equipment?

    Standard solvents will destroy the oil. Also any kind of chemicals that are used need to be compatible with the metal type as well as all seals in the system.

  • How does one typically verify the velocity is high enough to remove varnish and sludge adequately? Calcs, testing, etc?

    We start by calculating a Reynolds number to anticipate the velocity. If we believe there is an issue with reaching the anticipated velocity, we do have ultrasonic flow meters that can be affixed to the piping system.

  • Is there oil sampling / filtration involved before and after?

    We always verify particle count prior to removing our equipment. We also recommend installing screens on start up to avoid any “reinstatement debris” being pushed to critical components.

  • Is there a standard procedure or method such as ASTM, ISO etc for this flushing?

    Most manufacturers will supply a flushing procedure, if they do not we will create our own process and procedure following API614 for the final qualification of the flush.

  • How do you evaluate the pressure you choose to flush the systems?

    We follow the piping manufactures specifications. Most large equipment uses 150 or 300 pound flanges. In the event that we are flushing a hydraulic or high pressure system we will bring in a high pressure flushing skid.

  • Are HVOF machines available for purchase and would it be cost effective?

    These machines are available for purchase on the market, however we have seen that it is not cost effective in the long run. The flushing skid is a piece of equipment that “hopefully” your plant will not have to use very often and the flushing process is very labor intensive and can pose high environment and safety risks if not conducted by an experienced crew.

  • Are there chemicals in the flushing oil that could contaminate the system? How can cleaning chemicals be drained completely?

    When we use a flushing oil we use a very base oil with a low viscosity to increase the turbulence. This oil does not have any additives or chemicals that can damage the system. In the even that chemicals are used to remove varnish or other contaminates we have a few tactics that we use including:

    • Low point draining including
      • Reservoir
      • Oil coolers
      • Filter pots
      • Accumulators
      • Rundown tank
      • Supply and return piping
    • Blowing system down with either nitrogen or clean dry compressed air
    • Sacrificial flush
    • We would also follow up with a spectro chemical analysis that would indicate if anything was left in the system.
  • Will this work with sludge or other contaminants that may settle in stagnant areas in the pipe?

    Yes, the heat and the velocity of the flushing oil normally has the ability to move the sludge or contamination through the pipe into the oil reservoir or our filters. In the even that sludge does not break up with the hot oil we can add chemicals to the oil flush that will assist with breaking down the sludge.

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