Dane's FAQs

RA% = “Reduction of Area”

What is "Reduction of Area (RA%)"?

RA% is a term that stands for “reduction of area percentage.” It is an important requirement of the ASTM F1554 specification, in addition to other specifications. This value is reported as a percentage of the original test piece. When fasteners undergo mechanical testing, they are pulled to failure and the diameter of the point at which... Read more

Fastener Head Markings Decoded

Sometimes there are lines on the bolt head. What do they mean?

The lines on the head of a bolt indicate its grade. SAE J429 (Society of Automotive Engineers) bolts have radial lines, whereas ASTM (American Society for Testing and Materials) uses a combination of letters and numbers to indicate the grade. Three radial lines will indicate an SAE grade 5 fastener, while six radial lines will... Read more

Large Diameter ASTM A325 Bolts

Does Portland Bolt manufacture 1-3/4” diameter A325 heavy hex bolts?

No. As a matter of fact, nobody does. The ASTM F3125 grade A325 specification clearly denotes the diameter range of this grade of fastener to be ½” through 1-1/2” inclusive. Therefore, an A325 bolt larger than 1-1/2” diameter simply does not exist. It cannot be manufactured because there are no dimensional or strength requirements for... Read more

Tension vs. Torque

Can someone explain how tension and torque relates to bolted connections?

We’ll try our best. The relationship between tension and torque should be looked at cautiously, since it is very difficult to indicate the range of conditions expected to be experienced by a fastener. Torque is simply a measure of the twisting force required to spin the nut up along the threads of a bolt, whereas... Read more

Galvanized Nuts Tapped Oversize

Can I use black (plain finish) or zinc plated nuts on galvanized bolts?

No. Hot-dip galvanized nuts need to be used with hot-dip galvanized bolts since galvanized nuts are tapped oversize to accommodate for the extra 2 – 6 mils (.002 – .006) of zinc that is added to the threads of the bolt during the galvanizing process. A common misconception is that bolts that are going to... Read more