Nuts FAQs

Nuts Dimensions by Grade

Do different grades of nuts have different dimensions?

The grade of the nut does not have any implicit bearing on the physical dimensions. For example, an ASTM A563 Grade DH heavy hex nut will be the exact same dimensions as an ASTM A194 Grade 2H heavy hex nut and an A563 Grade A finished hex nut will have the same dimensions as an... Read more

High Strength Square Nuts

Are high strength square nuts readily available?

Most square nuts in the marketplace are made from low or medium carbon steel and are typically used with square head bolts. Their strength is not compatible with high strength bolts.  These nuts are readily available in plain finish and hot-dip galvanized and are typically mass produced overseas. If you are looking for high strength... Read more

A193 Grade B8 Class 2 Nut Requirement

Do A193 Grade B8 Class 2 bolts require a class 2 nut?

ASTM A193 Grades B8 and B8M Class 2 are grades of stainless steel bolts that are strain hardened and therefore have higher yield and tensile strengths than A193 Grades B8 and B8M Class 1 bolts. However, the ASTM A193 specification does not indicate a nut requirement used with Class 2 bolts, other than simply A194... Read more

Hex vs. Heavy Hex Jam Nuts

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... Read more

Large Diameter A563-A Hex Nuts

Are A563 Grade A standard hex nuts available larger than 1½” diameter?

No. According to the specification, A563 Grade A hex nuts, sometimes referred to as finished hex nuts, stop at 1-1/2” diameter. A563 Grade A nuts are only available larger than 1-1/2” diameter in a heavy hex pattern. Portland Bolt stocks both import and domestic A563 Grade A standard hex and heavy hex nuts.

Coupling Nut Tapping

Are Portland Bolt’s stock coupling nuts tapped from one end or from each end?

Portland Bolt’s stock ungraded coupling nuts are tapped all the way through from one end, while our high strength and custom manufactured coupling nuts are tapped from both ends. What does this mean for your project? Coupling nuts are typically intended to connect two separate threaded fasteners together, although some applications require the coupling nut... Read more

ASTM A194 Grade 2H vs. 2HM

What is the Difference between ASTM A194 Grades 2H and 2HM Nuts?

A194 2H nuts are a common high strength nut used with many different bolt grades, including A193 Grade B7, A325, A490, F1554 Grade 105 and others. Occasionally Portland Bolt will be asked to provide A194 Grade 2HM nuts, most often with A193 Grade B7M. In many grades an ‘M’ refers to metric, which is not... Read more

Hex Nut

Hex vs. Heavy Hex Nuts

What is the difference between a standard hex nut and a heavy hex nut?

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... Read more

Custom Coupling Nuts

Can coupling nuts be made in custom lengths?

Hex and heavy hex coupling nuts can be made in custom lengths. Depending on the size and grade, however, there may be an extended lead time associated with doing that. Off-the-shelf coupling nut lengths have fairly few options for a given diameter. As long as the coupling nut is long enough to achieve the desired thread... Read more

Waxed Nuts

Why are some hex nuts blue in color?

It is often asked why some high strength hex nuts that are supplied with high strength bolts appear to be blue or some other color. This is normally the case with galvanized, high strength, heavy hex nuts and the reason for this is because of the wax lubricant applied to the nuts. According to the... Read more