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IS 12474:1994 is the Indian Standard (BIS) for hexagon prevailing torque type all-metal nuts. This standard specifies the dimensions, material properties, and performance requirements for hexagon prevailing torque type all-metal nuts. It covers property classes 5, 8, 10, and 12, detailing mechanical characteristics like proof load, hardness, and the essential prevailing torque values that provide resistance to loosening under vibration.
Specifies characteristics of hexagon prevailing torque type all-metal nuts with threads from M5 up to M39.
! The 'all-metal' designation means the locking feature is created by deforming the nut's threads, not by using a non-metallic insert like nylon. This makes them suitable for higher temperature applications.
! These nuts are generally intended for single-use, as their prevailing torque performance may degrade upon removal and re-tightening.
! Ensure the property class of the nut (e.g., Class 10) is compatible with the property class of the mating bolt (e.g., Class 10.9) to prevent thread stripping.
ISO 7042:2012International Organization for Standardization (ISO), Global
HighCurrent
Prevailing torque type all-metal hexagon high nuts — Property classes 5, 8, 10 and 12
Defines the characteristics of all-metal, prevailing torque hexagon high nuts, which is the direct ISO equivalent.
DIN 980:1997-03Deutsches Institut für Normung (DIN), Germany
HighWithdrawn
Hexagon nuts with prevailing torque; all-metal construction
The former German national standard for this nut type, now harmonized with the ISO standard.
ASME B18.16.6-2017American Society of Mechanical Engineers (ASME), USA
MediumCurrent
Prevailing-Torque Type Steel Metric Hex Nuts and Hex Flange Nuts
Covers several styles of metric prevailing torque nuts, including an all-metal hex nut style similar to IS 12474.
BS EN ISO 7042:2012British Standards Institution (BSI), United Kingdom
HighCurrent
Prevailing torque type all-metal hexagon high nuts. Property classes 5, 8, 10 and 12
The British national adoption of the ISO 7042 standard, making it technically identical to the ISO version.
Key Differences
≠IS 12474 specifies only property classes 8 and 10, whereas the primary international equivalent, ISO 7042, covers a wider range including classes 5, 8, 10, and 12.
≠The size range covered by IS 12474 is M5 to M20. ISO 7042 covers a broader range from M5 up to M36.
≠While torque testing principles are similar, specific values for prevailing torque and the reusability requirements can differ. For example, ISO 7042 specifies minimum removal torque after the 5th removal, emphasizing reusability more explicitly than the IS code.
≠Marking requirements differ. IS 12474 requires the manufacturer's identification and the '8' or '10' for property class, while ISO 7042 has slightly different marking conventions, especially for higher property classes and left-hand threads.
Key Similarities
≈All standards specify a hexagon nut with an integrated, all-metal locking feature (typically a deformed collar or threads) that creates frictional interference for a prevailing torque effect.
≈The fundamental dimensions such as width across flats, nut height style ('high nut' profile), and metric thread profiles (based on ISO 68-1) are harmonized for any given nominal size (e.g., an M10 nut).
≈The materials specified are carbon or alloy steel, which is then heat-treated to achieve the mechanical properties defined by the respective property classes (e.g., Class 8, Class 10).
≈The intended application is identical: to provide a secure fastening that resists self-loosening caused by vibration and thermal expansion/contraction, without the need for secondary locking devices.
Parameter Comparison
Parameter
IS Value
International
Source
Property Classes Specified
8 and 10
5, 8, 10, and 12
ISO 7042:2012
Covered Size Range
M5 to M20
M5 to M36
ISO 7042:2012
Proof Load (M10, Class 10)
47.3 kN (based on 830 MPa stress on 57 mm² area)
47.8 kN
ISO 898-2:2012 (referenced by ISO 7042)
Prevailing Torque (M10, 1st Removal)
Min 3.5 Nm (for Class 10)
No value specified for 1st removal; focus is on 5th removal.
ISO 7042:2012
Prevailing Torque (M10, 5th Removal)
No value specified in the standard.
Min 3.5 Nm (for Class 10)
ISO 7042:2012
Thread Tolerance Class
6H before forming locking feature; performance tested after.
6H; a 6H GO gauge must pass, but a 6g thread may not run freely.
ISO 7042:2012
⚠ Verify details from original standards before use
Key Values6
Quick Reference Values
Proof Load Stress (Property Class 8)800 MPa
Proof Load Stress (Property Class 10)1000 MPa
Thread Tolerance Class6H
Maximum Test Temperature for Torque250 °C
Vickers Hardness (Property Class 8)180 to 302 HV
Vickers Hardness (Property Class 10)272 to 353 HV
Tables & Referenced Sections
Key Tables
Table 1 - Dimensions for Hexagon All-Metal Prevailing Torque Type Nuts