Ask the Expert

Question: What is the difference between a bolt with rolled threads and one with cut threads and does a fastener with a reduced body and rolled threads meet ASTM specifications?

Answer: Threads of a mechanical fastener, regardless of whether it is a headed bolt,rod, or bent bolt, can be produced by either cutting or rolling.  Read More...

Question: Are SAE Grade 2, 5, and 8 bolts available in diameters over 1½”?

Answer: No, SAE only covers bolts up to and including 1½” diameter. SAE J429 (1999), the specification that covers Grade 2, 5, and 8 fasteners, states, “This SAE standard covers the mechanical and material requirements for inch-series steel bolts, screws, studs, SEMS, and U-bolts used for automotive and related industries in sizes to 1½ in. inclusive.” Read More...

Question: How do I determine the strength of a specific diameter of bolt?

Answer: In most cases, the strength of a given material used to make a fastener has strength requirements or parameters described as pounds per square inch (psi) or thousands of pounds per square inch (ksi). This is helpful when analyzing what grade of material should be used for a given application, but this doesn’t tell us the actual strength of that diameter of material. In order to calculate the actual strength values of a given diameter, you would use the following formulas:

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Question: What are my thread pitch options when ordering bolts?

Answer:There are several different thread series available for construction fasteners. Below are the three of the most common thread series utilized in the fastener industry.

Coarse Thread Series Unified National Coarse (UNC) – Coarse threads have fewer threads per axial distance than fine threads and a larger thread form relative to the diameter. Read More...

Question: What is the difference between Grade 5 and A325 bolts?

Answer: While these two bolts are virtually identical in terms of chemical and physical strengths and properties, there are several differences between the two. The Grade 5 specification falls under the Society of Automotive Engineers (SAE) classification system, while A325 is an ASTM specification. ASTM A325 bolts are more commonly specified by engineers for use in structural steel connections on heavy construction projects, while SAE Grade 5 bolts are more common in OEM-type applications.

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Question: What are the differences between 18-8, type 304, and type 316 stainless steels?

Answer: To answer this question, you first need to know some basic information about stainless steel. “Stainless Steel” is the general name for a large family of alloy steels that contain at least 10.5% chromium as part of their composition.

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Question: Can a bolt be reused? If so, what grades and in what scenarios?

Answer: A bolt that has already been used in a given application may or may not be reused, depending on the grade, application, and recommendation of the “Engineer of Record”. There is a tremendous amount of conflicting opinions on this subject, but the only definitive published information we can find on this issue from a reputable source is in regards to ASTM A325 and A490 structural bolts.

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Question: What are the differences between hex bolts ordered as type 304 stainless steel, A193 Grade B8, and F593 Group 1 (type 304 stainless)?

Answer: Hex bolts are often ordered as a type 304 stainless and not to a specific ASTM specification. When bolts are ordered under the raw material grade (type 304) and not to an ASTM fastener specification, there are no specific requirements other than that they meet the chemical and physical requirements of 304 stainless steel and ASME B18.2.1 dimensional requirements for hex bolts.

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A common question that we get here at Portland Bolt is in regards to the shear strength of bolts. The shear strength is the value at which the lateral stress on a bolt or screw causes it to fail. It is an important factor to take into consideration when designing structural steel or timber connections. [...] Read More...

Question: 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? Answer: Most grade 8 bolts require a permanent marking symbol that is designated by 6 radial lines. However, the [...] Read More...