Difference Between Type I and Type II Hex Nuts

Hex nuts are divided into Type I, Type II, and thin types according to the nominal thickness. However, only nuts above level 8 are divided into two types: Type I and Type II. The main difference is the height of the Type I and Type II hex nuts, with Type II nuts being thicker than Type I nuts.

Type I Hex Nuts Are the Most Widely Used

Grade C nuts are used on machines, equipment, or structures that have rough surfaces and low accuracy requirements; Grade A (for nominal thread diameter D ≤ 16mm) and Grade B (for nominal thread diameter D > 16mm) nuts are used on machines, equipment, or structures that have smooth surfaces and higher accuracy requirements.

The thread specifications of Type I nuts range from M1.6 to M64, with performance levels of 6, 8, 10, A2-50, A2-70, A4-50, A4-70, CU2, CU3, and AL4. The product grades are A and B, with A-grade used for specifications under or equal to M16 and B-grade used for specifications larger than M16. (Here, A and B refer to accuracy levels)

The Application Range of Type II Hex Nuts

Thick Type II hex nuts are mostly used in occasions where frequent assembly and disassembly are required.

Thin Type II hex nuts are mostly used in occasions where the surface space of the connected parts is limited and as locking nuts to prevent the main nuts from loosening.

The thread specifications of Type II nuts range from M5 to M36, with performance levels of 9 and 12. The product grades are A and B, with A-grade used for specifications under or equal to M16 and B-grade used for specifications larger than M16. (Here, A and B refer to accuracy levels)

Type I hex nuts represent product GB6170; Type II hex nuts represent product GB6175.

The height of Type I hex nuts is 0.8d, and the height of Type II hex nuts is 1.0d.

The Application Range of Type I Hex Nuts

• Nominal pressure level is less than or equal to PN40.

• Non-toxic, non-combustible media, and non-severe cycling occasions.

In addition to this, special full-threaded bolts and Type II hex bolts should be chosen.

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