If you are a regular purchaser of fasteners, you probably have noticed that the heads of many bolts have markings engraved. These markings indicate the type of bolt, its material and dimension. The purpose of these marks is to make it easier for customers to identify and use the correct bolt for a job. The markings are etched into the head of the bolt, and they can be found on both standard US Bolts and metric fasteners.

Stainless Steel Bolts

There are many different types of stainless steel alloys used in the manufacture of bolts. These alloys can have varying resistance to corrosion. They also have varying levels of strength, so it is important to know the grade of the bolt you are purchasing before making your purchase. The most common grades are 304 and 316. The difference between these two is that 304 has lower carbon content than 316, so it is stronger and more resistant to corrosion.

The next thing you need to consider is the thread pitch. This is the axial distance between two adjacent crests of the bolt’s thread. This is usually measured in terms of threads per inch (TPI).

Another factor to consider when selecting a bolt is its length. The nominal length of a bolt is the sum of the grip and thread lengths, and it is measured from the end of the shank to the first complete thread. This is an important measurement to take when ordering a bolt because it will determine the maximum torque that can be applied to the bolt.

A bolt’s length is also important because it will affect its ability to grip an object or hold a load. Typically, bolts are measured in inches, although some manufacturers also produce them in metric measurements. If you are using a metric bolt, it will have a millimeter size that is indicated by a number with a dot (the ISO system) on its head.

Once you have the bolt size, it is important to understand the bolt’s strength. In the US, the strength of a bolt is indicated by its grade. A higher number indicates a stronger bolt. Bolt grades are determined by the American Society of Automotive Engineers and are expressed as a combination of letters and numbers.

Another method to test a bolt’s strength is to examine its color. Most fasteners oxidize over time, and this is what makes them appear rusted or discolored. However, some metals oxidize faster than others. Bolts that are coated with Zinc will have a higher level of corrosion resistance than uncoated ones. This is especially true for hot-dipped galvanized bolts. These are generally used in outdoor applications because they have an added layer of protection from the elements. Bolts that are plated with Chrome or Nickel will have an even higher degree of corrosion resistance. They are often used in municipal infrastructure, including manhole covers, waterworks, ground vaults and electrical junction boxes.