Alloy Steel Lap Joint Flanges by MTS Forge

A lap joint flange is a two-piece assembly consisting of a stub end and a loose backing flange that slides freely over the pipe. Unlike weld neck or slip-on flanges, the lap joint design allows the bolt holes to be aligned without rotating the pipe, making it ideal for systems that require frequent disassembly, use of costly alloy materials, or alignment flexibility in tight spaces.

MTS Forge works with a broad range of alloy steel grades to manufacture lap joint flanges, including standard carbon and low-alloy steels as well as high-performance materials such as stainless steels and specialty alloys. Our metallurgical team can advise on the best material for your operating conditions, pressure class, and compliance requirements. Contact us with your specifications for material availability confirmation.

MTS Forge manufactures flanges up to 14 inches in size. Our in-house forging capabilities — including closed die and upset forging on presses with adjustable tonnage — allow us to produce lap joint flanges across a wide dimensional range while maintaining tight tolerances and consistent mechanical properties throughout the run.

Yes. Every flange produced at MTS Forge is accompanied by complete material and process traceability documentation under our comprehensive Quality Assurance Program. This includes certified material test reports (CMTRs), heat numbers, and process records. This level of documentation is a standard requirement for our nuclear, defense, and aerospace customers and is available for all orders.

MTS Forge operates under a Quality Assurance Program that encompasses Mil I 45208, NCA 3800, and Mil Q9858 certifications. These cover inspection, quality management, and nuclear-grade requirements respectively. The majority of our flanges are currently produced for the commercial nuclear sector, which demands the highest levels of quality control and process documentation in the industry.

Yes. MTS Forge performs in-house normalizing heat treatment at our Coatesville, PA facility. Normalizing heats forged flanges above their upper critical temperature then allows controlled air cooling, which eliminates irregular grain growth from the forging process and produces a refined, uniform microstructure. The result is improved tensile strength, toughness, ductility, and machinability — essential for demanding service conditions.

Absolutely. Custom flange configurations are a core part of our offering. Our team reviews your engineering drawings and specifications, selects appropriate alloy steel materials, and designs or selects tooling from our large in-house inventory to produce flanges to your exact dimensions and tolerances. Custom forgings are available for both small-quantity prototype needs and larger production runs.

MTS Forge supplies alloy steel lap joint flanges to a broad range of industries including commercial nuclear, aerospace, defense, power generation, chemical processing, gas and petroleum, construction, and machine manufacturing. Our primary customer base includes manufacturers and procurement teams located in Pennsylvania, Iowa, Kentucky, and Texas, though we serve customers throughout the United States.