System and method for additively manufacturing boiler tubes

1. A method of manufacturing a tube comprising:

selecting a core pipe having a thickness that is initially less than a desired thickness of the tube;

building-up an outer layer over an exterior surface of the core pipe via additive manufacturing so as to increase the thickness of the core pipe, wherein the core pipe becomes the tube when the thickness of the core pipe is equal to the desired thickness; and

building a fitting into the outer layer via additive manufacturing such that the fitting is integral with and incorporated into the outer layer, wherein the fitting includes at least one of a nipple, a nozzle, a weld-o-let, an elbow, and a reducer;

wherein the step of building-up the outer layer includes rotating the core pipe a plurality of full revolutions so as to deposit multiple layers on a same axial location of the core pipe in a progressive manner, such that a thickness of the outer layer increases with every successive rotation of the core pipe.

2. The method of claim 1 , wherein building-up an outer layer over an exterior surface of the core pipe via additive manufacturing comprises:

weld strip cladding the outer layer onto the exterior surface of the core pipe.

3. The method of claim 1 , wherein the core pipe comprises a first material and the outer layer comprises a second material different from the first material.

4. The method of claim 1 wherein the fitting defines a flow path and the method further comprises:

boring through the outer layer and the core pipe such that the flow path is fluidly connected to an interior cavity of the core pipe.

5. The method of claim 4 , wherein:

the steps of building-up the outer layer and building a fitting into the outer layer are carried out using a torch;

wherein the step of boring through the outer layer are carried out using a boring device;

wherein the torch and the boring device are mountable to a common mobile arm.

6. The method of claim 1 further comprising:

cutting the core pipe such that a length of the core pipe is equal to a desired length of the tube.

7. The method of claim 1 further comprising:

extending a length of the core pipe via connecting the core pipe to another core pipe such that a combined length of the connected core pipes is equal to a desired length of the tube.

8. The method of claim 1 further comprising:

storing a plurality of core pipes at a manufacturing site; and

wherein the core pipe is selected from the plurality of stored core pipes, and building-up an outer layer over an exterior surface of the core pipe via additive manufacturing is performed at the manufacturing site.

9. A method of manufacturing a tube, comprising the steps of:

selecting a core pipe having a thickness that is initially less than a desired thickness of the tube;

building-up an outer layer over an exterior surface of the core pipe via additive manufacturing so as to increase the thickness of the core pipe, wherein the core pipe becomes the tube when the thickness of the core pipe is equal to the desired thickness;

building a fitting into the outer layer via additive manufacturing such that the fitting is integral with and incorporated into the outer layer, wherein the fitting includes at least one of a nipple, a nozzle, a weld-o-let, an elbow, and a reducer; and

heat treating the fitting by receiving only the fitting within a heating coil so that only the fitting is heat-treated.

10. The method of claim 9 , further comprising the step of:

heat treating the tube, including at least the outer layer, prior to building the fitting into the outer layer, such that the step of heat treating the tube and the step of heat treating the fitting occur at different times.

11. A method of manufacturing a tube, comprising the steps of:

selecting a core pipe having a thickness that is initially less than a desired thickness of the tube;

building-up an outer layer over an exterior surface of the core pipe via additive manufacturing so as to increase the thickness of the core pipe, wherein the core pipe becomes the tube when the thickness of the core pipe is equal to the desired thickness; and

building a fitting into the outer layer via additive manufacturing such that the fitting is integral with and incorporated into the outer layer, wherein the fitting includes at least one of a nipple, a nozzle, a weld-o-let, an elbow, and a reducer;

wherein the fitting defines a flow path;

wherein the method further includes boring through the outer layer and the core pipe such that the flow path is fluidly connected to an interior cavity of the core pipe;

wherein the steps of building-up the outer layer and building a fitting into the outer layer are carried out using a torch;

wherein the step of boring through the outer layer are carried out using a boring device;

wherein the torch and the boring device are mountable to a common mobile arm; and

wherein the method further includes cutting the core pipe to length utilizing a saw connected to the common mobile arm.

12. The method of claim 11 , wherein:

the fitting includes at least one bend.