Newest FAQs

Heat-treatment After Forging

Do headed bolds receive heat treatment before or after the heads are forged?

Not all grades of bolts require heat-treating, but those specifications that do are heat-treated after the heads are forged. Heat-treating is performed in a controlled environment using specific quenching and tempering temperatures and durations. The bolts are then tested to ensure the strength of the heat-treated bolts meet the requirements of the given specification. Since... Read more

Shipping Quantities of +/- 10%

Why do some manufacturers have a policy of shipping quantities of +/- 10%?

Portland Bolt does not abide by the practice of shipping quantities of +/- 10%. We feel this policy is ludicrous. We ship exact quantities and the reason is explained below. Shipping +/- 10% is done as a cost-cutting measure by many manufacturers. Since several parts are lost during the manufacturing process (some are used for... 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

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

Can A490 bolts be galvanized?

Can A490 bolts be galvanized?

The ASTM F3125 Grade A490 specification does not allow either hot-dip galvanizing (per ASTM F2329) or mechanical galvanizing (per ASTM B695) due to the risk of hydrogen embrittlement. The only coating currently allowed on A490 bolts is a zinc aluminum coating meeting any of the following specifications: ASTM F1136, F2833, or F3019. ASTM Committee F16... 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

Galvanizing A320 Grade L7M Bolts

Can A320 Grade L7M bolts be hot-dip galvanized?

The A320 Grade L7M is a variation of the A320 Grade L7 specification used in low-temperature, low-pressure applications. Nowhere in the A230 specification does it discuss whether or not A320L7M fasteners can be galvanized. In theory, there is nothing preventing someone from galvanizing the material, however, the L7M designation comes from heat treating being the... Read more

Rust on Stainless Steel Nuts

Why are my stainless steel nuts rusting?

Stainless steel fasteners are often used in highly corrosive environments. When stainless nuts begin to rust, this can occur when hot forged nuts that are manufactured only to a material grade such as 18-8, SS304, and SS316 or to the ASTM A194 Grade 8 or 8M specifications. None of these steel grades or nut specifications... Read more