What Is A 2H Hex Nut?

Hex nuts come in wide variety of styles, finishes, and designs. The 2H hex nut is a specially designed medium carbon steel fastener falling under the ASTM A194 standards, and should only be used in applications where the advantages are fully realized.
The 2H hex nut bears a clear mark on the fastener face, indicating the grade (2H). The grade 2H designation signifies nut formation, including the method of heat treatment, quenching, and temperature range required for tempering. Other markings are also found the same face, designating any plating or coatings applied to the fastener.
A 2H heavy hex nut is used in high temperatures and greater levels of pressure, with adequate strength and engineering to withstand extreme conditions. All of the standard heavy hex nut shape and dimensions are similar to other grades, including the double chamfered, six-sided design.

2H Hex Nut Applications

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High temperature applications and high-pressure conditions require the use of a 2H hex nut. Typical 2H hex nut applications include:
•    Pressure valves and vessels
•    Pipelines
•    Pressure controls
•    Chemical, gasoline, and oil storage systems
•    Natural gas and steam storage
•    Transmission of chemicals, gasoline, oil, steam, and natural gas

Appropriate 2H Hex Nut Substitutions

In certain applications, a 2H hex nut can be used as an appropriate substitute, providing the required strength. Grade 2HM hex nuts are manufactured in a similar way, yet deliver lower levels of proof load stress and hardness. Often 2H nuts can be substituted for 2HM, although the reverse may not be true.
Grade DH hex nuts are formed from medium carbon steel materials and need to be heat treated and quenched. Because a 2H hex nut is tempered at a higher heat than other grades, namely C, DH and DH3, it could be considered stronger and used as a substitute. Galvanized 2H hex nuts can be used in place of Grade DH nuts in structural applications, but these fasteners are marked with an asterisk to indicate galvanization – a galvanized 2H hex nut should not be used in extreme temperatures or high-pressure applications.