Nate's FAQs


What is the difference between ASTM and SAE Fastener Standards?

When looking at a bolt specification you may notice that some are ASTM standards, such as ASTM F1554, and some are SAE standards, such as SAE Grade 5 (a common bolt found in the SAE J429 specification). Outside the technical differences (mechanical requirements, chemical requirements, and other requirements) that vary between any fastener standard, the... Read more

A194 Grade 4 vs. Grade 7 Nuts

What is the difference between A194 Grade 4 and A194 Grade 7 heavy hex nuts?

While A194 Grade 4 and A194 Grade 7 nuts are mechanically identical and have the same intended applications, the only difference is the chemical values (aka steel used to manufacture). Grade 4 was created to be a low-cost alternative to Grade 7 by using a lower cost raw material. Unfortunately, this did not work out.... Read more

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

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

3/8″ Diameter F1554 Grade 36

Are 3/8” diameter F1554 Grade 36 anchor bolts available?

No they are not, although this is a somewhat recent change. In the 2015 version of the ASTM F1554 specification, the smallest diameter allowed was changed from ¼” to ½”. This means that prior to 2015, 3/8” diameter F1554 anchor bolts were allowable, but since then it is no longer an option. The F16 committee of... Read more

Specification Diameter Limits

Are there diameter limitations for various fastener specifications?

Every bolt grade has specific requirements including chemical makeup and strength properties. Virtually every grade of fastener also has diametrical limitations on both the small end and large end of sizes. For many grades the smallest diameter is ¼”, but some start at ½” (like ASTM F3125 and F1554). On the large end most bolts grades end... Read more

A193 Grade B8 vs. A320 Grade B8

What is the difference between A193 Grade B8 and A320 Grade B8?

The simple answer is none. The two specifications were written in tandem to be identical. The only difference between the two bolts is intended application. A193 bolts are intended for high temperature and high pressure applications, while A320 bolts are for cold temperature applications. Both bolt grades are made from type 304 stainless steel, have the same mechanical... 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

Standard Flat Washer

F436 vs F844

Are you allowed to substitute F436 hard washers when F844 cut washers are called out?

In general substituting one grade of fastener for another is a bad idea, as that substitution can open you up to liability concerns, but does this apply to washers? ASTM F844 covers standard, unhardened steel washers for general use. ASTM F436 covers hardened steel washers used with most high strength bolts and F1554 anchor bolts. F844 is... Read more


My plans specify A36M55. Is that a bolt grade?

A36M55 is an outdated call out for anchor bolts primarily used by the light pole and traffic signal industries. It was used to specify ASTM A36 steel (36 ksi yield strength) that had been chemically modified to develop a minimum 55 ksi yield strength. In 1994 the F1554 specification was introduced, and F1554 Grade 55... Read more