Q1: What material does ASME SB 407 UNS N08811 refer to, and what is its main application?
A1: ASME SB 407 UNS N08811 is the specification for Incoloy 800HT (a high-temperature nickel‑iron‑chromium alloy) seamless boiler and heat exchanger tubes. It is mainly used in high-temperature sections of boilers, superheaters, reheaters, and petrochemical cracking tubes.
Q2: What are the key high-temperature properties of this boiler tube?
A2: It has excellent creep‑rupture strength, outstanding oxidation resistance, good carburization resistance, and stable microstructure under long‑term high‑temperature service. It also maintains good mechanical strength at temperatures up to around 1100°C.
Q3: What is the difference between UNS N08811 and ordinary Incoloy 800/800H tubes?
A3: UNS N08811 (800HT) has stricter control over carbon, aluminum, and titanium content and a coarser grain size, giving it higher creep strength and better high‑temperature durability than Incoloy 800 and 800H.
Q4: What production and testing standards must this boiler tube meet?
A4: It must comply with ASME SB 407 for chemical composition, mechanical properties, and dimensions. Common tests include hydrostatic testing, eddy current or ultrasonic testing, tensile test, hardness test, and intergranular corrosion test.
Q5: In what types of boilers and industrial equipment is this tube commonly used?
A5: It is widely used in power station boilers, industrial boilers, superheater tubes, reformer tubes, ethylene cracking furnaces, waste incineration boilers, and high-temperature process piping in petroleum and chemical plants.
