Vitreous coating application by induction heating and integration with induction kinetic weld joining
Induction heating facilitated coating systems and processes for pipes overcome corrosion and erosion of the pipes at extreme temperatures and pressures in applications including oil and gas downhole tubulars and pipelines as well as processing facilities. Being based on vitreous fused inorganic compounds, the present invention achieves very high corrosion resistance at remarkably modest cost. Attractive economics and immunity to chlorides and moisture permeation at extreme concentrations and temperatures also make it well suited to desalination plants and potable water piping applications. Due to its extreme temperature resistance, it also is very well suited for geothermal wells. Additionally, due to its characteristic smooth durable surface, the present invention is ideally suited for applications involving the opposite of corrosion, namely scaling problems, such as fouling in sewage systems and scale buildup in heavy oil wells.
1. A method of applying a vitreous coating to a steel pipe by a dry process using a fluidized bed and induction heating, the method comprising:
holding a steel pipe in a substantially vertical orientation;
advancing an induction heating apparatus along an interior surface of the pipe, wherein the induction heating apparatus comprises:
at least one ring-shaped induction coil horizontally oriented in the pipe,
a top baffle and bottom baffle horizontally oriented and vertically spaced apart in the pipe, wherein the top baffle and bottom baffle at least partially and circumferentially seal off a portion of the interior surface of the pipe in proximity to the at least one ring-shaped induction coil,
wherein the top baffle and bottom baffle enclose a processing area in the pipe;
energizing the at least one ring-shaped induction coil to controllably heat the interior surface of the pipe in proximity to the enclosed processing area;
flowing a dry frit into the enclosed processing area;
fluidizing the dry frit in the enclosed processing area, wherein the dry frit is fluidized with at least one of air and a gas; and
forming a vitreous coating on the interior surface of the pipe from the dry frit by fusing the dry frit onto the interior surface of the pipe as the induction heating apparatus advances along the interior surface of the pipe.
2. The method of claim 1 , wherein the at least one ring-shaped induction coil of the induction heating apparatus comprises at least two ring-shaped induction coils, wherein the at least two ring-shaped induction coils are horizontally oriented and vertically spaced apart.
3. The method of claim 1 , wherein the induction heating apparatus further comprises a plurality of U-shaped flux concentrators, wherein the U-shaped flux concentrators prevent stray heating effects and concentrate the heating to a narrow ring shaped zone on the interior surface of the pipe.
4. The method of claim 1 , wherein the induction heating apparatus further comprises at least one water cooled busbar connected to the at least one ring-shaped induction coil, wherein the at least one ring-shaped induction coil is water cooled.
5. The method of claim 1 , further comprising, controlling an induction frequency and a power level of the at least one ring-shaped induction coil to enable the dry frit which has fused onto the interior surface of the pipe in the enclosed processing area to be below the tack fusing temperature of the dry frit, wherein the vitreous coating will not stick to the baffles as the induction heating apparatus advances along the interior of the pipe.
6. The method of claim 1 , further comprising, controlling the interior temperature of the pipe by means of external fluid quenching to enable the dry frit which has fused onto the interior surface of the pipe in the enclosed processing area to be below the tack fusing temperature of the dry frit, wherein the vitreous coating will not stick to the baffles as the induction heating apparatus advances along the interior of the pipe.
7. The method of claim 1 , wherein the dry frit is fluidized with at least one of air, argon, nitrogen and carbon dioxide.
8. The method of claim 1 , wherein the induction heating apparatus further comprises an impeller, the method further comprising:
rotating the impeller to circulate the fluidized dry frit.
9. The method of claim 1 , further comprising:
quenching the pipe with a ring-shaped quench head, wherein the quench head cooperatively advances along the exterior of the pipe as the induction heating apparatus advances along the interior surface of the pipe.
10. A method of applying a vitreous coating to a steel pipe by a dry process using induction heating and electrostatic sprayers, the method comprising:
advancing an induction heating apparatus along an interior surface of a metal pipe, wherein the induction heating apparatus comprises:
at least one ring-shaped induction coil horizontally oriented relative to the pipe in a vertical orientation,
a first baffle and second baffle horizontally oriented and vertically spaced apart in the pipe, relative to the pipe in the vertical orientation, wherein the first baffle and second baffle at least partially and circumferentially seal off a portion of the interior surface of the pipe in proximity to the at least one ring-shaped induction coil,
wherein an enclosed processing area is proximate to the at least one ring-shaped induction coil, wherein the enclosed processing area includes at least one electrostatic sprayer;
energizing the at least one ring-shaped induction coil to controllably heat the interior surface of the pipe in proximity to the enclosed processing area;
energizing the least one electrostatic sprayer and electrostatically spraying a dry frit onto the interior surface of the pipe; and
forming a vitreous coating on the interior surface of the pipe from the dry frit by fusing the dry frit onto the interior surface of the pipe as the induction heating apparatus advances along the interior surface of the pipe.
11. The method of claim 10 , wherein at least one of the first baffle and the second baffle are porous to gases.
12. The method of claim 10 , wherein at least one of the first baffle and the second baffle is associated with a fabric seal circumferentially contacting the interior surface of the pipe.
13. The method of claim 10 , further comprising:
quenching the pipe with a ring-shaped quench head, wherein the quench head cooperatively advances along the exterior of the pipe as the induction heating apparatus advances along the interior surface of the pipe.