Greg's FAQs

SAE 4340 and ASTM F1554

Do bolts made from SAE 4340 material meet the requirements of ASTM F1554?

I have a client out of Israel and they manufacture equipment for use in power plants. They have a question about anchor bolts in seismic zones. They want to use anchor bolts made from SAE 4340 material and they would like to know if that is equivalent to ASTM F1554 material. Will this material be... Read more

Tap Bolt vs Cap Screw

What is the difference between a tap bolt and a cap screw?

A tap bolt is (typically) a fully threaded hex bolt, while a cap screw is (typically) a hex head bolt that will be installed by turning the head of the bolt (screw) instead of tightening it with a nut. Usually cap screws are being threaded into something (a piece of machinery for example), rather than... Read more

A320 Head Requirements

Does A320 require bolts or cap screws to have heavy hex heads?

Your page says A320 requires bolts or cap screws to have heavy hex heads. I have the 2003 edition of A320 and can’t find that requirement. Where is that requirement stated? The ASTM A320 specification does not specifically address the physical dimensions of headed bolts. However, it does refer you to ASTM A962 for some... Read more

High Strength Headed Bolts

Can I get Grade 8 heavy hex anchor bolts?

It not uncommon for us to get requests or for bolt configurations that don’t match the specifications. Anchor bolts called out as headed Grade 8 bolts are only available with a hex head. From your description ASTM A354 BD would be the correct fastener. This specification has mechanical properties that are very similar to SAE... Read more

Rod with Nut vs Headed Bolt

Can I substitute a rod with a nut for a headed bolt?

We do not recommend allowing this type of substitution without approval from the Engineer of Record. Based on performing mechanical tests to the ASTM specification F606 which covers the testing of construction fasteners, a rod with a nut would typically not produce the same strength characteristics as a bolt with a forged head. Under F606,... Read more

Headed or Bent Anchor Bolts

Is it better to use a headed anchor bolt or a L-bolt?

Engineers often design anchor bolts in one of four common configurations. We see anchor bolts with forged heads, 90 degree bends, straight rods often with anchor plates on the bottom, and swedged rods. Engineers will design a structure using different grades and configurations based on the size, weight and design of a structure, wind forces,... Read more

External Thread Image

External Thread Summary

What is the meaning of thread pitch, major diameter, minor diameter, crest, root, flanks, angle, and run-out in the context of external thread?

Portland Bolt forms threads using two methods: cut threading and roll threading. Cut threading is a process that removes steel to form the threads. The roll threading method we utilize starts with reduced body pitch diameter steel. To make a one inch bolt we would use .912 inch round bar. This steel is forced between... Read more

Large Diameter Bolt Increments

Is 2-3/8" diameter rod stocked, or should we stick to 1/4" increments at those sizes?

Generally speaking, bolts over 1-1/2″ in diameter should be designed in 1/4″ increments, regardless of grade. While it is possible to manufacture bolts in 1/8″ increments (i.e. 2-3/8″), there are several reasons why you would want to avoid it. Steel Availability Steel round bar used to manufacture bolts is not readily available in 1/8″ increments over... Read more

A325X vs. A325 Bolt Head Markings

Do A325X bolts have a special marking on the head that would differentiate them from a standard A325?

The “X” designates the connection type (bearing-type connection with threads excluded from the shear plane) and has nothing to do with the bolt itself. Therefore, an A325 structural bolt used in this type of connection will have no different markings than an A325 bolt used in a different type of connection (N or SC). All A325... Read more

“High Strength” Bolts

Are there any other "high strength" bolts other an A325, A449 or A490? Would SAE Grade 5 and 8 qualify?

The term “high strength” is a somewhat ambiguous fastener term. Most people in the industry would interpret the phrase “high strength” to refer to any bolt that has been quenched and tempered (heat treated) to develop its strength. Additionally, the ASTM specification F1554 Grade 55 is commonly referred to as being manufactured from a “high... Read more