A Ni-Cr alloy with very good high temperature stability
- Good high temperature strength
- Oxidization and carburization resistant at high temperatures
- Good corrosion resistance, which increases with the various grades
- Socket weld flange features and benefits
Not to be confused with Inconel, Incoloy socket weld flanges are made of a nickel alloy which contains iron and a lower content of nickel. Incoloy is essentially a more economical option to Inconel, yet with more restricted corrosion resistance and temperature limits. Typically, Incoloy is an ideal material for long-term exposure in high temperature environments due to its oxidation, carburization and creep resistance. Incoloy is widely used for its resistance to seawater, brine, sour gas and high chloride environments at elevated temperatures, which make it a popular choice in the oil and gas and power industries.
The most commonly used grades of Incoloy flanges are Incoloy 800, 800H, 800HT;Incoloy 825; and Incoloy 925. For more indepth information on these specific grades, visit our specific web pages or contact one of our engineering experts:
Incoloy 800, 800H, H00HT
Incoloy 800 series flanges are best utilized for applications that require stable structure and good strength during prolonged exposure to high temperatures.
Incoloy 800, 800H & 800HT Specifications: UNS N08800/ N08810 / N08811 (800, 800H, 800HT), ASTM B408, ASME SB408, ASTM B564/ASME SB564, EN 10204-3.1, Werkstoff 1.4876 (800), Werkstoff 1.4876 H and 1.4958 (800H), Werkstoff 1.4876 HT and 1.4959 (800HT)
Related to the Incoloy 800 series alloys, Incoloy 825 differentiates itself with the additional elements of molybdenum and copper, which provides it improved corrosion resistance.
Incoloy 825 Specifications: UNS N08825, , BS 3076NA16, ASTM B 425, ASTM B 564, ASME SB 425, ASME SB 564, ASME Code Case N-572, DIN 17752, DIN 17753, DIN 17754, VdTÜV 432, ISO 9723, ISO 9724, ISO 9725, Werkstoff Nr 2.4858
Incoloy 925 is a precipitation hardened alloy. It offers comparable corrosion resistance to it’s sister alloy Incoloy 825, but with the increased strength resulting from the age hardening process.
Incoloy 925 Specifications: UNS N09925, ASTM B637, NACE MR0175
Similar to a slip on flange, an Incoloy socket weld flange has an added shoulder inside the bore hole. The socket weld flange is designed so that a pipe can be inserted into the socket of the flange until it hits the shoulder of the socket. The pipe is then backed away from the shoulder approximately 1/16 inches before being welded to the flange hub. This internal weld provides this type of flange added strength. In addition, by grinding the internal weld smooth, turbulence and flow restriction are minimized. Incoloy socket weld flanges are most commonly used on small diameter applications (1/2" through 4") and high pressure piping systems.
Socket Weld Flange Benefits
- Best for small size, high pressure applications
- Static strength equal to a slip on flange yet boasts a fatigue strength 1.5 times that of the slip on design
- Employs both a backside hub weld and an internal shoulder weld for increased strength
- Socket weld flanges delivers a lower risk of leakage than threaded flanges
- Socket weld pipes do not have to be beveled for weld preparation
- Butt-welded joints are easily fitted and no special machining
Socket Weld Flange Disadvantages
- The expansion gap and internal crevices left in socket welded systems can promote crevice corrosion.
- Socket weld flanges have two welds which makes them stronger yet more labor intensive to install. Due to the increased welding, it has become the practice to weld only at the hub of the flange, which is not recommended.
The socket weld pipe fittings should allow for expansion gap of 1/16 inch (1.6 mm) between pipe and the shoulder of the socket.