Category Archives: ARTICLES

Hydrogen Embrittlement Susceptibility of Case Hardened Steel Fasteners

Hydrogen embrittlement is a potentially catastrophic failure mode of high strength steel fasteners. One of the leading indicators of susceptibility to this phenomenon is hardness. While the susceptibility of case hardened fasteners is undisputed, minimal data exist to explain how the variables of case hardness, case depth, and core hardness work together to influence overall… Read More »

Peak Princ. Eng. John Medcalf featured in Assembly Mag

Peak’s Principal Engineer, John Medcalf, was featured in a recent article posted to the April 6, 2018 issue of Assembly Magazine, specifically discussing “Why Threaded Fasteners Fail.” John contributed expert testimony on the subject as quoted: “The geometry, material, heat treatment, finish and other factors all play into how well a fastener performs from assembly… Read More »

It’s 10 PM, Do You Know Where Your Fasteners Are?

While some fastener manufacturers and distributors get involved with customer product design, more often than not, they are simply asked to quote and provide a fastener to a print or industry standard.  A reputable supplier can ensure the specification requirements are met, but where it goes from there is all up to the customer or… Read More »

Bolted Joints from End to End

Like most subjects, bolted joint development contains a number of important considerations, some of which are often overlooked. While estimating the bolt tension achieved for a given tightening strategy is certainly a common focus, the effect that load has on the joint components is less fully discussed and understood. One of the reasons threaded fasteners… Read More »

In Response to the 2015 Bolt Failure on the Lemnhult Wind Farm

On Christmas Eve 2015 a 390 ft. tall wind turbine located in the Lemnhult wind farm near Vetlanda Sweden collapsed when the bolts in the tower’s lowermost flange joint, containing one hundred M64 bolts, failed. The incident came into the news recently with the release of the Swedish Accident Investigation Authority’s final report. Based on… Read More »

Part 2: The Three Least Understood Truths in Bolted Joint Design

By: David Archer In Part 1 of this article, we discussed the tension of structural joints and external tensile loads applied to joints and the effect on bolt tension. The third least understood truth, sizing fasteners, will be revealed in this final installment. What follows is more of what you always wanted to know about… Read More »

Part 1: The Three Least Understood Truths in Bolted Joint Design

In fastening, as in most endeavors, the most common misconceptions relate to the most fundamental principles. These errors are commonly made simply because their universal nature provides the greatest opportunity for making them. For example, the reason that most auto accidents occur within a small radius of the driver’s home isn’t because those streets are… Read More »

ASTM F16.96 Subcommittee on Bolting Technology

Special Meeting at IFI Headquarters In 1986, 17 engineers met at the United Engineering Center in New York for the purpose of establishing an expert group.  John Bickford, who organized the meeting, was concerned about the lack of real knowledge about how we use threaded fasteners in our designs.  The meeting resulted in the formation… Read More »

Threaded Fastener Loosening

A common frustration of threaded fastener suppliers is their customers pointing to their fastener as the cause of their joint loosening problems. Even when the problem is failure from fastener fracture, in the vast majority of instances the fastener meets all specifications and the root cause of their problems is the joint design or assembly… Read More »

Thinking About the Unthinkable

Recently, I was asked to serve as an expert witness in a case where a catastrophic bolted joint failure led to severe, debilitating injury. The discovery phase, where information is requested and where people are deposed under oath, is a sobering, expensive and time-consuming process for all on its receiving end. I came to realize… Read More »