ISO 898

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 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.

Where:

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

m is the height of the nut, in millimetres

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 Class Style 0 Style 1 Style 2
04 M5≤D≤M39, M8x1≤D≤M39x3
05 M5≤D≤M39, M8x1≤D≤M39x3
5 M5≤D≤M39, M8x1≤D≤M39x3
6 M5≤D≤M39, M8x1≤D≤M39x3
8 M5≤D≤M39, M8x1≤D≤M39x3 M5≤D≤M39, M8x1≤D≤M39x3
9 M5≤D≤M39
10 M5≤D≤M39, M8x1≤D≤M16x1.5 M5≤D≤M39, M8x1≤D≤M39x3
12 M5≤D≤M16 M5≤D≤M39, M8x1≤D≤M16x1.5

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.

STANDARD DESCRIPTION PITCH RANGE 04 05 4 5 6 8 9 10 12
BS 4929-1:1973 Nylon Insert Nuts C M3-M36 M3-M36 M3-M36
BS EN 1666:1998 Flanged Nylon Insert Nuts F M8-M20 M8-M20 M8-M20 M8-M20
DIN 439-2:1987 Lock Nuts C, F M1.6-M52 M1.6-M39 M1.6-M39
DIN 557:1994 Square Grade C Nuts C M5-M16 M5-M16
DIN 562:2013 Square Thin Nuts C M2-M10 M2-M10
DIN 798:2009 Square Foundation Nuts C M24-M100 M24-M100
DIN 917:2015 Hex Cap Nuts - Low C M4-M72 M4-M20
DIN 917:2015 Hex Cap Nuts - Low F M4-M72 M8-M20
DIN 935-1:2000 Hex Castle Nuts C, F M12-M100 M12-M39 M12-M39 M12-M39
DIN 935-1:2000 Hex Slotted Nuts C M4-M100 M4-M39 M4-M39 M4-M39
DIN 935-1:2000 Hex Slotted Nuts F M8-M100 M8-M39 M8-M39 M8-M39
DIN 935-3:1987 Hex Slotted Nuts C M12-M33 M20-M33 M12-M16
DIN 936:1985 Hex Lock Nuts - Thin C M8-M52 M8-M18 M8-M18
DIN 936:1985 Hex Lock Nuts - Thin F M10-M52 M10-M18 M10-M18
DIN 979:1987 Thin Slotted Nuts C M6-M52 M6-M39 M6-M39
DIN 979:1987 Thin Slotted Nuts F M8-M52 M8-M39 M8-M39
DIN 979:1987 Thin Castle Nuts C, F M12-M52 M12-M39 M12-M39
DIN 980:1987 All Metal Prevailing Torque Nuts (Type V) C M3-M39 M3-M39 M3-M39 M3-M39 M3-M16
DIN 980:1987 All Metal Prevailing Torque Nuts (Type V) F M8-M39 M8-M39 M8-M39 M8-M39 M8-M16
DIN 982:1987 Nylon Insert Nuts C M5-M24 M5-M24 M5-M24 M5-M24 M5-M16
DIN 982:1987 Nylon Insert Nuts F M8-M24 M5-M24 M5-M24 M5-M24 M5-M24 M5-M16
DIN 986:1987 Nylon Insert Cap Nuts C M4-M20 M4-M20 M4-M20 M4-M20
DIN 986:1987 Nylon Insert Cap Nuts F M8-M20 M8-M20 M8-M20 M8-M20 M8-M20
DIN 1587:2000 Hex Dome Cap Nuts C M4-M24 M4-M24
DIN 1587:2000 Hex Dome Cap Nuts F M8-M24 M8-M24
DIN 6330 Hex Nuts 1.5d C M6-M48 M6-M48 M6-M48
DIN 6331:2003 Hex Collar Nuts C M6-M48 M6-M36 M6-M36
DIN 6334 Coupling Nuts C M5-M36 M6-M20 M6-M20 M6-M20
DIN 6915:1999 Large Hex Nuts C M12-M36 M12-M36
DIN 6923:1983 Flange Nuts C M5-M20 M5-M20 M5-M20 M5-M20
DIN 6923:1983 Flange Nuts F M8-M20 M8-M20 M8-M20 M8-M20
DIN 6924:1987 Nylon Insert Nuts C M3-M48 M3-M39 M3-M39 M3-M39 M3-M16
DIN 6924:1987 Nylon Insert Nuts F M8-M48 M8-M39 M8-M39 M8-M39 M8-M16
DIN 6925:1987 All Metal Prevailing Torque Nuts C M3-M36 M3-M36 M3-M36 M3-M36 M3-M16
DIN 6925:1987 All Metal Prevailing Torque Nuts F M8-M36 M8-M36 M8-M36 M8-M36 M8-M36 M6-M16
DIN 6926:1987 Nylon Insert Flange Nuts C M5-M20 M5-M20 M5-M20 M5-M16
DIN 6926:1987 Nylon Insert Flange Nuts F M8-M20 M8-M20 M8-M20 M8-M16
DIN 6927:1983 All Metal Prevailing Torque Nuts C M5-M20 M5-M20 M5-M20 M5-M16
DIN 6927:1983 All Metal Prevailing Torque Nuts F M8-M20 M8-M20 M8-M20 M8-M16
ISO 4032:2001 Hex Nuts - Style 1 C M1.6-M64 M3-M39 M3-M39 M3-M39
ISO 4033:1999 Hex Nuts - Style 2 C M5-M36 M5-M36 M5-M36
ISO 4034:1999 Hex Nuts - Grade C C M5-M64 M16-M39 M5-M16
ISO 4035:1999 Hex Lock Nuts (thin) C M1.6-M64 M3-M39 M3-M39
ISO 4161:1999 Flange Nuts C M5-M20 M5-M20 M5-M20 M5-M20 M5-M20
ISO 7040:2012 Nylon Insert Nuts C M3-M36 M3-M36 M3-M36 M3-M36
ISO 7041:2012 Nylon Insert Nuts C M5-M36 M5-M36 M5-M36
ISO 7042:2012 Nylon Insert Nuts C M5-M36 M5-M36 M5-M36 M5-M36 M5-M36
ISO 7043:2012 Nylon Insert Flange Nuts C M5-M20 M5-M20 M5-M20 M5-M20
ISO 7044:2012 All Metal Prevailing Torque Flange Nuts C M5-M20 M5-M20 M5-M20 M5-M20 M5-M20
ISO 7413:1984 Structural Nuts C M10-M36 M10-M36 M10-M36 M10-M36
ISO 7719:2012 All Metal Prevailing Torque Nuts C M5-M36 M5-M36 M5-M36 M5-M36
ISO 7720:2012 All Metal Prevailing Torque Nuts C M5-M36 M5-M36
ISO 8673:2012 Hex Nuts - Style 1 F M8-M64 M8-M39 M8-M39 M8-M16
ISO 8674:1999 Hex High Nuts - Style 2 C, F M8-M36 M8-M36 M8-M16 M8-M16
ISO 10511: 2012 Nylon Insert Nuts - Thin C M3-M36 M3-M36 M3-M36
ISO 10512: 2012 Nylon Insert Nuts F M8-M36 M8-M36 M8-M36 M8-M16
ISO 10513: 2012 All Metal Prevailing Torque Nuts F M8-M36 M8-M36 M8-M36 M8-M16
ISO 12125: 2012 Nylon Insert Flange Nuts F M8-M20 M8-M20 M8-M20 M8-M20
ISO 12126: 2012 All Metal Prevailing Torque Nuts F M8-M20 M8-M20 M8-M20 M8-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.

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

CLASS 04 05 5 6 8 9 10 12
Thread min max min max min max min max min max min max min max min max
  Brinell Hardness - HB
<M16 179 287 259 336 124 287 143 287 190 287 179 287 259 336 280 336
<M39 179 287 259 336 139 287 162 287 221 336 179 287 259 336 259 336
M8x1<M16x1.5 179 287 259 336 166 287 179 287 238 336 - - 280 336 280 336
M16x1.5<M39x3.0 179 287 259 336 181 287 221 287 280 336 - - 247 336 - -