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
• Inocoloy lock nut features and benefits
• Download the Incoloy 800 datasheet and 825 datasheet

Not to be confused with Inconel, Incoloy lock nuts 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 nuts 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, 800HT
• Incoloy 825
• Incoloy 925

Datasheets: Incoloy 800, 800H 800HT; Incoloy 825; and Incoloy 925

Resources: Incoloy Torque Specs, Flange Dimensions, Flange Bolting Chart

Incoloy Fastener Types: Bolts, Nuts, Screws, Threaded Rods, Washers

Flange Types Available: Blind Flanges, Lap Joint Flanges, Slip On Flanges, Socket Weld Flanges, Threaded Flanges, Weld Neck Flanges

Incoloy Lock Nut Features and Benefits

An Incoloy locknut resists loosening from vibrations and torque. One of the most common styles is a prevailing torque locknut. This kind of Incoloy locknut has a prevailing torque feature which deforms elastically, preventing it from freely spinning like a standard nut.

The two most common and reliable forms of prevailing torque locknuts are the flexloc style and the polymer insert lock nut. A Incoloy flexloc nut is all-metal in composition with a segmented collar that creates six “locking fingers,” that act as a spring. Incoloy polymer insert lock nuts are often referred to as nylon insert locknuts, although various high performance polymers can be used for the screw threads to “bite into.” Both flexlock and polymer insert locknuts are available in both hexagonal and 12 point configurations.

All Metal Flexloc Lock Nut	Polymer/Nylon Insert Lock Nut
Can be used at high temperatures Distributes load evenly due to the fact that it is manufactured as one solid piece. Is THE most reliable all-metal self-locking nut. As it is all metal, it is best for high temperature or corrosive applications One of the only all-metal lock nuts that is certified to 15 cycles of prevailing torque – which is military standard.	Overall the most reliable locknut, with the only limitation of application temperature Best for low temp applications, typically less than 350°F Various polymers inserts available (Nylon, Vespel, PVDF, etc.) for higher temp. or corrosive applications. Excellent reusability – can reliably be re-used 15 times Eliminates galling and cold-welding common with exotic alloys

Other all metal lock nuts available include the Incoloy stover and elliptical styles. Though these styles are often a cheaper initial cost, they are less reliable than the flexloc style. As these styles delivering less prevailing torque cycles and often result in more failures, the flexloc style is a better investment for both reliability and cost savings.

Common Incoloy Chemistry, Grades & Specifications

Incoloy 800, 800H, H00HT

Incoloy 800 nuts 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)

Incoloy 825

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

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 

Mechanical Properties of Incoloy