ISO 898-2:2012

Mechanical properties of fasteners made of carbon steel and alloy steel —
Part 2: Nuts with specified property classes — Coarse thread and fine pitch thread

ISO-898ISO 898 consists of the following parts, under the general title Mechanical properties of fasteners made of carbon steel and alloy steel:

  • Part 1: Bolts, screws and studs with specified property classes — Coarse thread and fine pitch thread
  • Part 2: Nuts with specified property classes — Coarse thread and fine pitch thread
  • Part 5: Set screws and similar threaded fasteners with specified hardness classes — Coarse thread and fine pitch thread
  • Part 7: Torsional test and minimum torques for bolts and screws with nominal diameters 1 mm to 10 mm)

This part of ISO 898 specifies mechanical and physical properties of nuts with coarse thread and fine pitch thread made of carbon steel and alloy steel when tested at an ambient temperature range of 10 °C to 35 °C.

Nuts conforming to the requirements of this part of ISO 898 are evaluated at that ambient temperature range. It is possible that they do not retain the specified mechanical and physical properties at elevated and/or lower temperatures.

Nuts conforming to the requirements of this part of ISO 898 have been used in applications ranging from –50 °C to +150 °C. It is the responsibility of users to consult an experienced fastener materials expert for temperatures outside the range of –50 °C to +150 °C and up to a maximum temperature of +300°C to determine appropriate choices for a given application.

This part of ISO 898 is applicable to nuts:

  1. made of carbon steel or alloy steel;
  2. with coarse thread M5 ≤ D ≤ M39, and fine pitch thread M8×1 ≤ D ≤ M39×3;
  3. with triangular ISO metric thread according to ISO 68-1;
  4. with diameter/pitch combinations according to ISO 261 and ISO 262;
  5. with specified property classes, including proof load;
  6. with different nut styles: thin nuts, regular nuts and high nuts;
  7. with minimum height m ≥ 0,45D;
  8. with a minimum outside diameter or width across flats s ≥ 1,45D;
  9. able to mate with bolts, screws and studs with property classes according to ISO 898-1.

Designation of Nut Styles

  • style 2: high nut with minimum height mmin ≈ 0.9D or mmin > 0.9D;
  • style 1: regular nut with minimum height mmin ≥ 0.8D;
  • style 0: thin nut with minimum height 0.45D ≤ mmin < 0.8D.


D is the nominal thread diameter of the nut, in millimeters

m is the height of the nut, in millimeters

Ranges of nominal diameters in relation to nut style and property class

The ranges of nominal diameters in relation to nut style and property class are as given in Table 1.

Property ClassStyle 0Style 1Style 2
04M5/?id=DM39, M8x1/?id=DM39x3
05M5/?id=DM39, M8x1/?id=DM39x3
5M5/?id=DM39, M8x1/?id=DM39x3
6M5/?id=DM39, M8x1/?id=DM39x3
8M5/?id=DM39, M8x1/?id=DM39x3M5/?id=DM39, M8x1/?id=DM39x3
10M5/?id=DM39, M8x1/?id=DM16x1.5M5/?id=DM39, M8x1/?id=DM39x3
12M5/?id=DM16M5/?id=DM39, M8x1/?id=DM16x1.5

Which nuts can come in higher tensile grades?

Fastener grade ranges are always given within the specification standard for particular nuts. We must ensure that a non-specified fastener is not quoted as a higher tensile one.

For example, it is common practice for customers to ask for Whitworth Grade 8 nuts. However, BSW/Whitworth nuts come in letter grades only. Or for customers to ask for lock nuts (thin) to be made in grade 8 – whereas these fasteners can not be torqued to grade 8 figures because there is not enough thread engagement.

See the following table for those standards covered under ISO 898-2 standard.

This specification only covers metric fasteners.

Specifications and Allowed Sizes as Specified to ISO 898-2:2012

C= Coarse Pitch
F= Fine Pitch

Fastener Ranges are given for each grade of fastener as specified within ISO 898-2 specification.

BS 4929-1:1973Nylon Insert NutsCM3-M36M3-M36M3-M36
BS EN 1666:1998Flanged Nylon Insert NutsFM8-M20M8-M20M8-M20M8-M20
DIN 439-2:1987Lock NutsC, FM1.6-M52M1.6-M39M1.6-M39
DIN 557:1994Square Grade C NutsCM5-M16M5-M16
DIN 562:2013Square Thin NutsCM2-M10M2-M10
DIN 798:2009Square Foundation NutsCM24-M100M24-M100
DIN 917:2015Hex Cap Nuts – LowCM4-M72M4-M20
DIN 917:2015Hex Cap Nuts – LowFM4-M72M8-M20
DIN 935-1:2000Hex Castle NutsC, FM12-M100M12-M39M12-M39M12-M39
DIN 935-1:2000Hex Slotted NutsCM4-M100M4-M39M4-M39M4-M39
DIN 935-1:2000Hex Slotted NutsFM8-M100M8-M39M8-M39M8-M39
DIN 935-3:1987Hex Slotted NutsCM12-M33M20-M33M12-M16
DIN 936:1985Hex Lock Nuts – ThinCM8-M52M8-M18M8-M18
DIN 936:1985Hex Lock Nuts – ThinFM10-M52M10-M18M10-M18
DIN 979:1987Thin Slotted NutsCM6-M52M6-M39M6-M39
DIN 979:1987Thin Slotted NutsFM8-M52M8-M39M8-M39
DIN 979:1987Thin Castle NutsC, FM12-M52M12-M39M12-M39
DIN 980:1987All Metal Prevailing Torque Nuts (Type V)CM3-M39M3-M39M3-M39M3-M39M3-M16
DIN 980:1987All Metal Prevailing Torque Nuts (Type V)FM8-M39M8-M39M8-M39M8-M39M8-M16
DIN 982:1987Nylon Insert NutsCM5-M24M5-M24M5-M24M5-M24M5-M16
DIN 982:1987Nylon Insert NutsFM8-M24M5-M24M5-M24M5-M24M5-M24M5-M16
DIN 986:1987Nylon Insert Cap NutsCM4-M20M4-M20M4-M20M4-M20
DIN 986:1987Nylon Insert Cap NutsFM8-M20M8-M20M8-M20M8-M20M8-M20
DIN 1587:2000Hex Dome Cap NutsCM4-M24M4-M24
DIN 1587:2000Hex Dome Cap NutsFM8-M24M8-M24
DIN 6330Hex Nuts 1.5dCM6-M48M6-M48M6-M48
DIN 6331:2003Hex Collar NutsCM6-M48M6-M36M6-M36
DIN 6334Coupling NutsCM5-M36M6-M20M6-M20M6-M20
DIN 6915:1999Large Hex NutsCM12-M36M12-M36
DIN 6923:1983Flange NutsCM5-M20M5-M20M5-M20M5-M20
DIN 6923:1983Flange NutsFM8-M20M8-M20M8-M20M8-M20
DIN 6924:1987Nylon Insert NutsCM3-M48M3-M39M3-M39M3-M39M3-M16
DIN 6924:1987Nylon Insert NutsFM8-M48M8-M39M8-M39M8-M39M8-M16
DIN 6925:1987All Metal Prevailing Torque NutsCM3-M36M3-M36M3-M36M3-M36M3-M16
DIN 6925:1987All Metal Prevailing Torque NutsFM8-M36M8-M36M8-M36M8-M36M8-M36M6-M16
DIN 6926:1987Nylon Insert Flange NutsCM5-M20M5-M20M5-M20M5-M16
DIN 6926:1987Nylon Insert Flange NutsFM8-M20M8-M20M8-M20M8-M16
DIN 6927:1983All Metal Prevailing Torque NutsCM5-M20M5-M20M5-M20M5-M16
DIN 6927:1983All Metal Prevailing Torque NutsFM8-M20M8-M20M8-M20M8-M16
ISO 4032:2001Hex Nuts – Style 1CM1.6-M64M3-M39M3-M39M3-M39
ISO 4033:1999Hex Nuts – Style 2CM5-M36M5-M36M5-M36
ISO 4034:1999Hex Nuts – Grade CCM5-M64M16-M39M5-M16
ISO 4035:1999Hex Lock Nuts (thin)CM1.6-M64M3-M39M3-M39
ISO 4161:1999Flange NutsCM5-M20M5-M20M5-M20M5-M20M5-M20
ISO 7040:2012Nylon Insert NutsCM3-M36M3-M36M3-M36M3-M36
ISO 7041:2012Nylon Insert NutsCM5-M36M5-M36M5-M36
ISO 7042:2012All Metal Prevailing Torque NutsCM5-M36M5-M36M5-M36M5-M36M5-M36
ISO 7043:2012Nylon Insert Flange NutsCM5-M20M5-M20M5-M20M5-M20
ISO 7044:2012All Metal Prevailing Torque Flange NutsCM5-M20M5-M20M5-M20M5-M20M5-M20
ISO 7413:1984Structural NutsCM10-M36M10-M36M10-M36M10-M36
ISO 7719:2012All Metal Prevailing Torque NutsCM5-M36M5-M36M5-M36M5-M36
ISO 7720:2012All Metal Prevailing Torque NutsCM5-M36M5-M36
ISO 8673:2012Hex Nuts – Style 1FM8-M64M8-M39M8-M39M8-M16
ISO 8674:1999Hex High Nuts – Style 2C, FM8-M36M8-M36M8-M16M8-M16
ISO 10511: 2012Nylon Insert Nuts – ThinCM3-M36M3-M36M3-M36
ISO 10512: 2012Nylon Insert NutsFM8-M36M8-M36M8-M36M8-M16
ISO 10513: 2012All Metal Prevailing Torque NutsFM8-M36M8-M36M8-M36M8-M16
ISO 12125: 2012Nylon Insert Flange NutsFM8-M20M8-M20M8-M20M8-M20
ISO 12126: 2012All Metal Prevailing Torque NutsFM8-M20M8-M20M8-M20M8-M20

ISO 898-2:2012

If a customer requests a fastener to a grade that is not specified within it’s dimensional specification, it will be made to within the hardness limits below.

Brinell Hardness limits of nuts according to ISO 898-2:2012 Property class 04 to 12.