Inconel 926 Alloy 926 Hex nut Hex Heavy Nut Nickel Alloy Fasteners
1.ISO 4033 - 1999 Hexagon nuts
2.ANSI/ASME B 18.2.2 - 1987 (R1999) Heavy Hex Nuts
3.What is the difference between hex and heavy hex jam nuts?
A jam nut is a thin nut primarily used as a locking device, run up
against a full-height nut that has been tightened into place to
prevent that primary nut from loosening. Jam nuts are not used as
structural parts and are commonly not manufactured to meet any
specific nut specification since their primary function is to
prevent the larger nut from backing off the threads. They are also
occasionally used for leveling purposes.
Hex vs. Heavy Hex
The two styles available for a jam nut are hex and heavy hex
patterns. The biggest difference between these two is sizing. The
heavy hex pattern has a larger width across the flats and corners
and is slightly thicker in comparison to the smaller hex pattern.
Due to its larger pattern, the heavy hex jam nut is likely to have
a higher proof load in comparison to its standard hex pattern
counterpart. However, because these nuts are typically non-graded,
there are not any strength comparisons available between the two.
Imported hex and heavy hex jam nuts are readily available in plain
finish and hot-dip galvanized conditions. Imported stainless steel
hex jam nuts are also available. These nuts are not graded in any
way as mentioned above and do not come with any form of
certification documents. For graded and/or domestic jam nut
requirements they can be custom manufactured.
4.What is the difference between a standard hex nut and a heavy hex
A standard hex nut, also referred to as a finished hex nut, has a
smaller width across the flats and corners compared to a heavy hex
nut, and a heavy hex nut is slightly thicker than a standard hex
nut of the same nominal size.
In fact, heavy hex nuts are exactly a 1/8” larger across the flats
than a standard hex nut in all sizes, requiring a 1/8” larger
socket or wrench to install. Also, heavy hex nuts have a higher
proof load strength compared to a hex nut according to ASTM A563.
A563 Mechanical Properties
|Grade||Style||Size, in.||Proof Load, ksi||Hardness, HBN|
|A||Hex||1/4 - 1-1/2||90||68||116 - 302|
|Heavy Hex||1/4 - 4||100||75||116 - 302|
|B||Heavy Hex||1/4 - 1||133||100||121 - 302|
|Heavy Hex||1-1/8 - 1-1/2||116||87||121 - 302|
|C / C3||Heavy Hex||1/4 - 4||144||144||143 - 352|
|D||Heavy Hex||1/4 - 4||150||150||248 - 352|
|DH / DH3||Heavy Hex||1/4 - 4||175||150||248 - 352|
|For UNC, 8UN, 6UN, and Coarse Pitch Threads|