Monel Thermal Spray Oilfield Submersible Pumps
Blasting Pressure Pot System
Compressed air pressure blasting can be used to manually blast. Pressure blasting cabinets have abrasive recovery systems to remove spent abrasive and dust from the usable abrasive. Pressure pot blasters are more effective than the suction blast styles.
Thermal Spray Monel coatings protect the submersible pump housing from corrosive down hole conditions. The submersible pump housing is coated with Monel and a chemical sealant. The Monel thermal spray coating mechanically protects the sealer which has soaked into and cured inside the Monel coating. Thermal Spray monel coatings range from 200 micron to 300 microns. Surface preparation is essential for good adherence of the metallic coating to the pump housing.
Step # 1 - Remove all oil, old paint and coatings, De-grease, mask and Plug Holes ffrom the pump housing surface. Tape exposed machined threads and areas that may trap abrasive which can be released later when assembled to the down hole equipment.
Step # 2 - Blast Clean - to remove surface contaminants, previous coatings, and to provide an "Anchor Pattern". Steel abrasive is the most typically used because of its long life. Aluminum oxide can also be used but has a short life and can't be used in high production blast wheels. G-25 to G-14 steel grit is used to remove previous coatings quicker and provide a deeper anchor pattern. Steel grit come is at least 3 hardness ranges with the 50-58 Rc range being most typical.
Step # 3 - Thermal Arc Spray Coating - Monel Spray Coating
Two Wire Spray Coating, The thermal arc spray melts wire, with two wires shorted against each other and a jet of compressed air to blow the molten metal against the work. .
The metal spray gun travel must be mechanized for consistent coating thickness. The fumes from the process must be contained in the cabinet and removed by the dust collector which is vented outside.
The dust collector ventilating the coating process is also important. The coating dust consists of a very light powder, smoke, plus heavy particulate. The cabinet has access areas for the spray guns and open area for the work to pass through. Smoke must not escape into the operator's area.
Step # 4 - Apply Sealer -
Sealers are applied to the exterior of the submersible pumps over the thermal arc spray coating to provide a chemical barrier to down hole corrosive fluids. The sealer has to also withstand elevated temperatures. It also has to be fluid enough to soak into the spray coating and still dry quickly as to not delay shipping.
Two part epoxy is typical. Paint application follows state and federal rules, but generally paint spraying necessitates a proper booth while brushing or rolling may only require extra ventilation.
Bexxon Global Pte Ltd designs, builds, and supplies thermal spray equipment and and turnkey systems for monel coatings on electric submersible pumps ESP. These monel coatings are specifically designed to comply to the rigid standards of the drilling industry.
A typical thermal spray for monel coating on submersible pumps system includes: