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 indicate an SAE grade 8 fastener. These are the most common grades, but there are others. Our Fastener Identification Markings Chart has a complete list of bolt grades with accompanying head markings.
I have a bolt taken from my triumph bonnivale it has nf stamped on it. I need a replacement but slightly longer. I have tried all suppliers christchurch Dorset area. Nobody can help me with this
@Phil- Apologies, but we do not handle any automotive fasteners. Perhaps a local machine shop can help with this special.
Check out the Brittish Standard specifications for National Fine threads. They are often close to metric so don’t get them mixed up.
I the I beam with the b and s I believe would be for Bethlehem steel.
I have a large eye bolt with a 1-1/2 NC thread pitch, no shoulder. There is a “B” in a diamond shape on the top and on the bottom of the eye it says “H3175”. Can you supply me with the manufacturer?
@Teri- We are familiar with a eye bolt manufacturer that uses a diamond and a ‘D’-that is Edward W Daniel, but we do not know who uses the same design with a ‘B’.
I was wandering if anyone knows why /or has also found a bolt with a swastika on it ….I found a couple at work and thought it a little more than odd???
Hello I have. Hex bolt with MNP marked on the head do you no what brand this is
@Joe- Apologies, but we are unable to find that head marking in our literature.
Male national pipe = MNP