ASTM FAQs

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

What is the meaning of U.N.O?

What is the meaning of UNO?

What is the meaning of UNO? UNO is an acronym that stands for, “Unless Noted Otherwise”. UNO is a blanket statement that covers all specified items related to the callout but leaves exceptions in specific situations. For instance, A325 bolts may be specified in the general notes, but a different fastener specification/grade may be specified... Read more

Measuring Round bend U-bolts

How does Portland Bolt measure round bend U-bolts?

Portland Bolt measures round bend U-bolts based on the dimensions outlined in the Industrial Fastener Institute Standard IFI-136. The length (L) is measured from end of bolt to inside of the bend, while the width (C) is measured between the legs. Some companies will show the length to the bottom or centerline of the bend... Read more

Fine Thread Structural Bolts

Can A325 and A490 structural bolts be supplied with fine thread?

No. The specification calls out that those bolts must be Unified National Coarse thread and have class 2A tolerances. The F3125/F3125M specification reads: 4.2 Threads: 4.2.1 Uncoated bolt threads shall be as specified in Table 1. 4.2.2 Coated bolts shall have threads meeting Table 1 requirements before coating. TABLE 1 Thread Fit, ASME 120 ksi... Read more

Plain Finish Bolts

What is a "Black" Bolt?

The vast majority of bolts that Portland Bolt provides are either hot-dip galvanized or plain steel with no coating. In the construction fasteners industry, we typically refer to the plain steel as “black.” On our quotes and orders at Portland Bolt, we abbreviate that to “blk”. Other companies may refer to bolts with no coating... Read more

Fully Threaded Headed Bolts

Can Portland Bolt make fully threaded headed bolts?

It depends. To answer this question, we have to go into the details about the different ways to we can thread a bolt. As well as different head styles.  Roll Thread  We can thread to within 2” of the head. We can thread up to 1” diameter bolts that are mild steel, stainless steel, or... Read more

A320 Grade L7 vs. A320 Grade L7M

What is the difference between ASTM A320 Grade L7 and A320 Grade L7M?

ASTM A320 possesses several fastener grades manufactured from either alloy or stainless steel and are intended for cold temperature applications. Both Grade L7 and L7M are manufactured from a quenched and tempered alloy steel. While the chemical requirements for both Grades L7 and L7M are identical, there are several differences that separate the two grades.... Read more

ASTM A193 vs ASTM F593

What are the differences between F593 and A193 stainless steel headed bolts?

There are many differences between these two specifications.  In order to understand these dissimilarities there are overviews of each specification below followed by a short summary of these variances.  For the purposes of this FAQ we will be focusing on A193 Grades B8 (Type 304) and B8M (Type 316) versus  F593 Alloy Group 1 (Type... Read more

Large Diameter ASTM F1554

Can F1554 Grade 105 Anchor Bolts Be Made Above 3” Diameter?

ASTM specifies the diameter range for F1554 grade 105 anchor bolts as ½” through 3”. What are the options for anchor bolts larger than 3” diameter of similar strength? Because the diameter range is clearly defined as ½” through 3” in the F1554 specification, an anchor bolt larger than 3” diameter can’t be certified to... Read more

ASTM A47 vs. A48 vs. A536

What is the difference between ASTM A47, A48, and A536?

ASTM A47, A48, and A536 are all casting specifications. Each grade has its own strength requirements and base material used. Each grade is also commonly associated with a particular finished part that Portland Bolt stocks. ASTM A47 ASTM A47 covers ferritic malleable castings intended for general use at temperatures from normal ambient to approximately 750°... Read more