A Fe-Ni-Cr alloy with excellent high temperature oxidation resistance
- Good material for high temperature oxidation resistance
- Maintains high strength at elevated temperatures
- A286 Chemistry, specs and heat treatments
- Lap joint flange features and benefits
A-286 lap joint flanges are known for their high strength, creep resistance and oxidation resistance at elevated temperatures. This iron-nickel-chromium alloy (once age-hardened) provides A-286 lap joint flanges with high levels of strength from room temperature up to about 1300°F (700°C).
A-286 lap joint flanges are mildly corrosion resistant. While they should not be used for strong acid environments, they provide excellent oxidation resistance up to 1300°F (700°C) in conditions that would typically be found in high temperature exhaust streams.
Because of these properties, A-286 lap joint flanges are often found in high temperature engine, manifold, exhaust and turbine applications as well as off-shore oil & gas applications.
A-286 Heat Treatments: There are several heat treatment combinations for A-286 all with slight variations in performance. They can be specified via an AMS number or a 660 Class: A, B, C or D, with most common specified as class A or D. The A-286 grades A, B and C all have the same min tensile strength and min yield strength of 130ksi and 85ksi respectively. However grade D is significantly better yield with a min tensile of 130ksi and a min yield of 105ksi.
By AMS numbers, the most common for A-286 is AMS 5737 (same as Grade A) and then AMS 5732 (same as Grade B).
A-286 Specifications: AMS 5525, AMS 5732, AMS 5737, AMS 5804, EN 1.4980, GE B50T1181, GE B50T12, GE B50T81, UNS S66286, Werkstoff 1.4980
Lap joint flanges are unique in that they are made of two pieces, the flange itself and the stub end.
- The backside, has a slight shoulder that is square cut at the center or pipe hole
- The front side has a flat face with a filleted (rounded) center hole to match the filleted back face of the stub end. Here the stub end will wrap tightly around the center hole of the flange.
- Shaped like a short piece of pipe with a weld bevel on one. This portion of the stub end is also called the sleeve.
- Narrow shoulder on the flange facing end called is the hub. The back face of the hub has a rounded transition (or inside fillet) that joins the hub to the sleeve
Because a lap joint flange has a two piece configuration, it offers a way to cut cost when piping systems requires
- For high cost alloys the only "wetted" part is the stub end. In this situation, it is only required for the stub-end to be made of the higher cost corrosion-resistant material, where the flange itself can be the produced from lower cost steel.
- Ease of Work
By using lap joint flanges, work can be simplified in situations that require frequent and rapid disassemble and assembly during the operation of a plant. The ability to spin that backing flange compensates for misalignment of the bolt holes during assembly.