Technical FAQs
SAE Grade 8 markings
What visual markings does a grade 8 piece of all thread rod have that would identify it as being so? Meaning, how can you tell just by looking at a stick that it's grade 8?Most grade 8 bolts require a permanent marking symbol that is designated by 6 radial lines. However, the SAE J429 specification that covers grade 8 fasteners does not require grade markings for studs (fully threaded rods) or slotted and cross recess head products. Therefore, you will not be able to visually identify a threaded stud... Read more
Bolt Thread Length
Is there a standard thread length for bolts?Depending on the type of bolt you are using the thread length can vary greatly. There is not an inclusive thread length standard that covers all fasteners. Depending on the applications, manufacturer, and a number of other factors the amount thread may change. It is important to clearly communicate at time of purchase your desired... Read more
Tie Rod Assembly Configurations
How are tie rods, turnbuckles, and clevises configured?Tie rods, clevises, and turnbuckles are an important part of many architectural designs. Canopy supports, structural steel bracing, and walkway hangers are a few of the applications that use these assemblies. The unique configuration allows for field adjustments in both length and tension. Adjustment Adjustments are possible by threading opposing ends of the rod right hand... Read more
Concerns Calculating Torque
How do I calculate torque for construction fasteners?Torque is a difficult value to calculate accurately, especially for construction fasteners and should be used cautiously. The primary challenge is accounting for environmental factors, coatings, and a number of other variables including surface texture, material hardness, and thread series. In most situations, it is challenging to give reliable allowable torque values for bolted assemblies.... Read more
Lag Screw Shear Strength
How do I determine the shear capacity and strength of lag screws?Unfortunately, we have no specific data to answer this question. First, “standard” lag bolts that are readily available in the marketplace are ungraded, meaning they are not manufactured to any ASTM specification and have no verifiable mechanical requirements. Therefore, it is impossible to determine the strength characteristics of a lag screw unless they are custom... Read more
Rotational Capacity Testing
What is rotational capacity (ROCAP) testing?Per ASTM F3125 Annex section 2.1.1, the rotational capacity test is defined as a test, “intended to evaluate the presence of a lubricant, the efficiency of lubricant and the compatibility of assemblies.” In a 1970 study referenced by the Research Council on Structural Connections (RCSC), it was shown that galvanizing increases the friction between the... Read more
Clevis Pin Question
When using a clevis pin and using a cotter pin, or a spring pin, or a spring clip, or a retaining ring to capture the outer end, my practice has always been to place a washer under the retaining device to discourage deformation and/or loss of the retaining device due to rotation of the clevis pin. Who agrees out there?It seems like this question is directed toward clevis pins that are used to connect control assemblies, linkages and perhaps hinges. In these applications where rotation of the clevis pin is anticipated, I agree that a washer would protect the retaining device from possible ‘side effects’ of the rotation. In the case of pins that... Read more
Grade 8 vs ASTM A325
Is a Grade 8 bolt the same as an ASTM A325?ASTM A325 and SAE J429 grade 8 are not the same fastener. As a matter of fact, they couldn’t be more different. SAE (Society of Automotive Engineers) establishes specifications covering fasteners intended for use in automotive, OEM, and equipment applications, while ASTM (American Society for Testing and Materials) provides specifications for construction fasteners. There are... Read more
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