HFIC Cleaning FAQ's
Q. What is HF Cleaning?
A. Hydrogen Fluoride Ion Cleaning (HFIC, FIC or HF) is a high temperature, controlled atmosphere, Ion Cleaning Process.
Q. How do I know I need HFIC cleaning before weld or braze repair?
A. Any hot section part made primarily of Nickel, or trade name Inconel, requires an HFIC cleaning prior to repair. The oxides from the front of the engine of parts made from Aluminum and Titanium need to be removed. If not the welds will most likely crack and the braze could run.
Q. What are the indicators a part should have been HFIC cleaned prior to repair?
A. First, consider the material. If it is of high Nickel content, it probably will need HFIC cleaning. Second if a repair is accomplished by welding and the weld continues to crack or if repaired by brazing and the braze seems not to have penetrated below the surface, chances are good that the oxides formed during operation are still present and not allowing the repair to be complete.
Q. How do the oxides prevent a braze repair from being successful?
A. The oxides present rise to the surface as heat is applied and stop the braze material from penetrating the surface. Not allowing penetration keeps the braze material applied from doing its intended action.
Q. What do you clean?
A. The Gaseous HFIC process was developed by Ti-Coating, Inc. to remove metal oxides from high temperature alloys used in turbine engines.
Q. How does HF Cleaning work?
A. The Hydrogen Fluoride Ions react with the metal oxides on the part to form metal fluorides and water vapor. The HF ions clean not only the surface of the alloy component but inside the microscopic cracks.
Q. What are the by-products of HF Cleaning?
A. The by-products of HF cleaning are metal fluorides, water vapor and unused HF gas.
Q. Isn't HF gas Toxic?
A. Yes!! Hydrogen Fluoride is very Toxic by inhalation. HF gas forms Hydrofluoric Acid in the presence of water vapor and may cause severe chemical burns. All personnel should be familiar with the HF MSDS sheet.
Q. How is the HF disposed of?
A. The Ti-Coating, Inc. HFIC System incorporates an off gas scrubbing system utilizing Sodium Hydroxide or Potassium Hydroxide to convert the metal fluorides to metal salts and Sodium or Potassium Fluoride. The residual unused HF is also converted to Sodium or Potassium Fluoride.
Q. What is the size of the HF Equipment?
A. Ti-Coating, Inc. HFIC Systems are available with three standard furnace diameters accommodating multiple reactor chamber diameters and lengths.
- 16" & 20" diameter by 24" or 38" tall work zone
- 30" to 42" diameter by 24" to 50" tall work zone
- 50" diameter by 38" to 50" tall work zone
Q. What are the floor space requirements for a system?
A. Floor space requirements will vary with equipment size, and can be adjusted to adapt to existing plant conditions. However, they may typically be as follows:
- Smaller system; 15 feet wide by 25 feet long
- Medium system; 22 feet wide by 30 feet long
- Large system; 24 feet wide by 38 feet long
Q. What is the Equipment Loading Arrangement?
A. The loading arrangement can be either Top Load (the load is lowered into the reactor)
or Bell Style.
- Top Load: the reactor cover, support grid and parts are lowered into the reactor
- Bell Style: the parts are loaded on the base support and the reactor chamber and furnace are lowered over the load.
Q. Is a permit required to operate an HF system?
A. Most Countries and/or States require emissions permitting for HF System operation. Exhaust stack testing may be required also. Special considerations should be given to on site HF storage. Always check with local authorities for the requirements in your area.
Q. What is the power requirement for an HF system?
A. Ti-Coating, Inc. Standard HFIC Systems are designed to operate on 380 Volt, 50 Hz. 3 Phase Power or 480 Volt, 60 Hz. 3 Phase Power. Other voltage options may be available by contacting the factory.
Q. What process gasses are used with an HF system?
A. The process gasses used in HFIC systems are Argon, Hydrogen, Hydrogen Fluoride, Anhydrous Ammonia and on some systems Nitrogen.
- Argon - used to purge the reactor chamber before and after Hydrogen use - customer supplies, liquid source preferred.
- Hydrogen - the carrier gas for the process - customer supplies, liquid source preferred.
- Hydrogen Fluoride - reactant gas for the process - customer supplies, 2 bottles housed in special gas cabinet on HFIC system.
- Anhydrous Ammonia - neutralizing agent for HF gas - customer supplies, 2 bottles mounted on HFIC system.
- Nitrogen - sometimes used for cold reactor purging and scrubber system purging - customer supplies, liquid source or gas bottles.
Q. Does the HF system require a separate building?
A. Each end user of HFIC Equipment should access their usage patterns and determine their safe operating practices and emergency procedures. Ti-Coating, Inc. can provide engineering assistance in these concerns. While a separate building may not be necessary, an isolated enclosed process location might be considered.
Q. Do we need a dedicated Operator Control Room?
A. The Ti-Coating, Inc. HFIC System comes as a Modular Unit and is self-contained including process control and touch screen computer operator interface. Should your processing procedures require a separate control room for the operator during HF operation, an optional control console with duplicate operator machine interface is available.
Q. How do we handle process room ventilation?
A. The process room should have continuous ventilation during HFIC operations to provide fresh air in the room, a continuous flow of room atmosphere past gas leak detectors and a negative pressure in the process room with respect to the surrounding areas in the plant. In the event of a Hydrogen or HF leak in the process room all gas flow will be stopped on the system and a large exhaust fan should be turned on to provide additional purging of the process room.
Q. Can the HF process be used to Strip Coatings from parts?
A. The HFIC process was originally developed to remove the metal oxides from high temperature alloys after the coatings had been removed. Today, the HFIC process is also being utilized to strip coatings from turbine engine components. New uses for the HFIC process are being developed as our technology advances. Should you have a potential new use for the HFIC process, contact Ti-Coating, Inc. to investigate and test your process needs.
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