2H vs DH Heavy Structural Nuts
2H vs DH heavy hex nuts.
Are these two hex nut grades interchangeable?
This is a question we get asked all the time. The short answer to the question is “sometimes” and that is what makes it confusing.
Generally, 2H is the safer nut to use if available. This is because it does not matter if your job requirements specify DH or 2H nuts, the 2H nuts will always fully meet the strength needed.
We have also found that 2H nuts have better availability, and they usually cost less.
The larger problem comes when you are trying to use DH nuts instead of 2H nuts. DH nuts have a proof load of 150,000 ksi vs 175,000 for the 2H nuts. This means that you need to check your bolt strength and providing it is under 150,000 ksi the DH nuts will likely work just fine.
As always it is wise to confirm with the customer before moving ahead with any alternate products. Sometimes, job engineers will not allow these substitutions even though they are perfectly safe. This is especially true on DOT and other government projects.