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Fabricated Custom Weld Spools for the Power Generation Industry

Custom Weld Spools
Custom Weld Spools

We were confronted with a tricky project. Imperial Weld Ring was asked by a power generation customer to fabricate custom dissimilar metal weld spools-low alloy ferritic steel (T22) to austentic stainless steel (304H). These transition spool sections were designed to be used as superheater boiler tube replacements and upgrades. We were also required to engineer the inner diameters of the spools to project specifications, which enabled them to achieve desired steam flow. First, we used our CNC horizontal turning centers and performed external turning, boring, and profiling of the ASME SA-213 TP347H austentic stainless steel. We then drilled, swaged, and beveled the steel before it was deburred and polished to 63Ra max, confirmed by our custom gages and surface finish comparators. We then heat and lot marked the tubing, which was done with a combination of dot peen computerized marking heads, low stress dies, and an electrochemical etcher. Our staff end prep beveled the weld spools, which were 3" to 36" long, 0.740" thick, and 2.110" in diameter, to 37-1/2°. At Imperial Weld Ring, we fabricated the weld spools to precise tolerances of ±0.002" and followed with in-process dimensional inspections as well as go/no-go gauging. We completed 800 spools in only two weeks, all to customer specifications and ASME Section IX standards, and we then delivered them to domestic and international locations.

With this project, we clearly demonstrated our ability to produce long-length, non-standard parts with tight internal tolerances, and we did it in a timely manner. To learn more about the project, or the processes used to complete it, see the table below or contact us directly.

Custom Weld Spools Project Highlights

Project Name
Weld Spools
Project Description
Superheater / Reheat Pendent Welding Tubes
Capabilities Applied/Processes
Turning: External, Boring, Profiling
Tubular Swaging
Pipe Beveling

Heat / Lot Marking
Measuring and Inspecting
Equipment Used to Manufacture Part
CNC Horizontal Turning Centers
Band Saws
Custom Gages
Surface Finish Comparators
  • Dot Peen Computerized Marking Head
  • Low Stress Dies
  • Electrochemical Etcher
Overall Part Dimensions
Product Length: 3-36"
Product Thickness: 0.740"
Diameter:  2.110"
End Prep Beveling: 37-1/2 deg.
Tightest Tolerances
± 0.002"
Material Used
ASME SA-213 TP347H Austentic Stainless Steel
Material Finish
63Ra max
Additional Facts
Used at dissimilar metal weld (DMW) joint:
Low Alloy Ferritic Steel (T22) to Austentic Stainless Steel (304H)
In Process Testing/Inspection Performed
Go / No-Go Gauging
Industry for use
Power Generation
800 Spools
Delivery/Turnaround Time
2 - 3 Weeks or as Required
Delivery Location
Domestic and International
Standards Met
Customer Specifications
ASME Section IX