NEWSLETTER

Here’s a recent field test showing the installing of a 2”x 4.5 nut that highlights the issue. Left: Nuts were initially tightened with an impact wrench set to 4500 ft lbs to achieve the required clamp load of 138,000 lbs. Right: Next,

Surprise results testing bolt tension with different lubricants. Test Setup Bolt and Nut Used for the Tests Components used: bolt and nut 7/8"-9 thread, grade 5 Torque used for all tests: 400 ft-lbs SAE J429Material Strength (psi)Force (lbs) Note Proof Strength85,00039,000Max safe load without inducing

Castellated nuts, often called a castle nuts, employ cotter pins as a locking mechanism. We will walk through two key points that render many castle nut bolted joints ineffective and unreliable. 1. The castle nut must be in a certain

Let's compare a typical assembly using one nut and a bolt against the use of double nuts. Single Nut Figure 1 When the nut is rotated in the counterclockwise direction, it moves toward the bolt head. Each full rotation (360°) moves the

Security Locknut Last time, we discussed why you may not need a locknut if the joint is properly designed and assembled. But, in the real world, on critical applications, this is often difficult to consistently achieve. In these common situations, a

You shouldn’t need a locknut if the bolted joint is properly designed and assembled. This means it’s designed to hold the working load, is tightened to the specified value, and the preload force is maintained. This seems simple enough. If

The relationship between input torque and tension is the governing principle behind a well-designed bolted joint. Often, calculated values are not reciprocated in field applications. To determine the tension (also known as preload, clamp force, or clamp load), a Skidmore-Wilhelm

It is well understood that a fastener will fail if it is loaded above its capacity, as shown in example #1 below. What is less obvious is a fastener will also fail if it is loaded below its capacity but

Hint: not as much as you think. To answer this question, let’s start with an example of a fastener assembly with a 3/4" x 10 Grade 5 bolt and nut and a 2” clamp distance, as shown in figure 1. Figure 1 For

Answer: a very small but important amount. In previous posts we discussed how a bolted joint works, how clamp force is calculated, and how to determine torque required to achieve the clamp force. This month we’ll present more details about the