Fabricated Orifice & Transition Rings for Steam Boiler Applications

Orificed Backing Rings

Orifice rings are commonly used in forced circulation boilers to maintain proportional flow or produce a throttled/choked flow at the ring's location within the line. By controlling flow rate, orifice rings help to prevent steam blanketing and tube overheating, which can cause damage to boiler systems. Imperial's orifice rings can also serve as diameter transition rings, commonly referred to as "step rings" or "step-down rings," for welding pipe or tubes with different inside diameters. The step-down ring has a tapered transition at its center, which serves as the weld root opening. This not only simplifies fit-up, but also eliminates an abrupt shoulder at the joint.

At Imperial Weld Ring, we are regularly asked by our utility, power generation, energy, and steam turbine customers to fabricate orificed backing rings for steam boiler applications. We manufactured these orifice rings for joints with similar and dissimilar walls, and often supplied them for use with flat or taper-bored ID prep. After we developed custom work holding fixtures, we employed CNC turning and milling to precision machine the rings, and then polished all surfaces to 63Ra max finish, followed by a coating of weldable primer. We also conducted go / no-go gauging inspections, fully maintained material heat/lot traceability, and confirmed precision machined tolerances of ±0.002" with custom gages and calibrated measuring equipment.

We were comfortable producing anywhere between 1 and 20,000 of the parts. We also prototype the rings and provided maintenance contracts and rush or emergency services for our customers. These rings are fabricated to ASME Boiler & Pressure Vessel Code, Section III, Division I, Subsection NCA-3800 standards, as well as customer engineered specifications. We made 20,000 of the rings in only one to two weeks and delivered them to customers worldwide.

At Imperial Weld Ring, we used this project to demonstrate ourselves as an industry leader in the fabrication of boiler components and pressure parts. To discover more about our skills, contact us directly.

Orifice & Transition Rings Project Highlights