Applying Good To Great Principles To Bolting Accuracy and Conversion Applications

Conversion charts for bolting are essential to helping MRO professionals — like you perhaps, to make wise decisions when using industrial precision bolting tools.

And, when you are in the market for a calibrated torque wrench or bolt tensioner one of the main things you look for are the units output of ft. lbs., as well as, the PSI maximum limits of the hydraulic power pump pack that powers the tool.

You do this because you want to ensure that your fasteners are tighten with accuracy, and that the torque tool you are using is capable of helping you complete the job successfully the first time.

Torque Calibration - TORC Measurement Tools - Conversion Charts For Bolting
IMAGE SOURCE: AccuServe, Inc.

Why precise conversion of threaded fasteners is so important

Bolts and nuts also known as “threaded fasteners” are used around the world and within practically every of industry. Threaded fasteners are used to assemble and secure equipment, infrastructure, machinery, storage units and much more.

AMG Bolting Solutions most commonly fulfills the needs of production and maintenance personnel responsible for pipelines, heavy-duty earth movers, petro-chemical, wind engineering, cranes, commercial trucking, rail roads and bridges. Every application has its own unique set of required specifications.

For safety purposes, you look up conversion charts for bolting to ensure everything lines up and is fastened as recommended by the instruction manual, or given industry standard.

IMAGE SOURCE: 2010 1st Place GBRIA Safety Award presented to Global Contractors
IMAGE SOURCE: 2010 1st Place GBRIA Safety Award presented to Global Contractors

At AMG Bolting Solutions, we supply torque tools to an audience who places safety #1, yet is conscience of cost-effectiveness and efficiency.

Every visitor to our website, whether a customer or not has access to our downloadable conversion charts for bolting, because we believe safety matters.

But, we are not alone.

For example, the folks over at Global Contractors offer a flexible outsourced operations with the ability to meet and exceed the needs of industrial customers while touting a special safety distinction … 2.7 Million Man-hours OSHA Free.

Jim Collins Good to great

Separating the good from the great.

In the New York Times Bestseller “Good to Great“, author and leadership guru Jim Collins introduces the “Flywheel Effect“, which is a path to change for companies.

Eventually on this path to change, these organizations reach a breakthrough point called the Hedgehog Effect, where they are doing three (3) things intentionally, and very well.

Jim Collins - Hedgehog Concept

  • Pay attention to detail, because they are passionate about what they do.
  • Use the best tools for the job, because they believe they can be the best in the world.
  • Measure everything twice, mistakes do not drive your economic engine forward.

Now, let us look at these three things a little more closely from the view point of an engineer, maintenance, operational, or purchasing professional within the industrial services, infrastructure construction, or manufacturing industry as it relates to bolting and the use of conversion charts.

*HINT: This will be a deep, but insightful read. If you want your conversion guides quickly, simply click here or scroll to the bottom of the page. Otherwise, enjoy this read.

Hedgehog Circle #1: Passionately Pay Attention

The concept here is simple.

If you genuinely love what you do — it will be easy to spot opportunity, and to perform your best.

Most industrial jobs involving nuts and bolts are critical projects that if performed half-heartedly can potentially have a negative impact on the triple bottom-line; people, planet, and profit.

As a result, it is extremely important to always select the correct type of threaded fasteners and proper size fitting.

Here are two examples of companies who are passionate about fasteners – one with a love for safety, another with a love for chess.

  • Tight bolts are safe bolts

A company called Stress Indicators Incorporated has a product line called SmartBolt, which essentially are fasteners with a color-signal Visual Indication System™ that allows MRO and equipment operators to perform Total Performance Maintenance (TPM) activities more effectively and efficiently.

As a SmartBolt is tightened, tension forces it to stretch, and their patented Visual Indication System™ correlates fastener tension with a color as seen here:

SmartBolts-Tigthening Visual Indicators

This allows you, as the user, to know at a glance that your bolts are properly tightened, and most importantly doing their job.


  • Playing with fasteners?

On the ecommerce front, an online store called House of Staunton, offers for sale a unique chessboard featuring nuts and bolts as the games pieces selling for over $200.

While the creator of the pieces was probably inspired more by a passion for the game of chess, versus bolts and nuts — the fact remains, passion allows the idea of using fasteners for something beyond its intended use.

Bolt Chess Set

So, it is fair to say that passion for what you do helps you see things as they are, while helping you see what can potentially be.

Now getting back to the application of traditional fasteners, passion for the task helps you better understand the importance of calculating the optimal pressure and tightening conversions for the bolt(s) and nut(s) used to complete the job.

Attention to detail also means using the proper tools for the job.

A case for using calibrated torque tools for the tightening of large industrial nuts

There is a saying that goes something like this:

“Don’t bring a knife to a gunfight”.

There is also a vintage poster used in the Navy to remind machinist to “Use proper tools for the jobs“.

NAVAL - Use the right tools - wrenches and bolts

Along the same lines, I would argue don’t bring a manual or impact wrench to jobs requiring a high level of bolting accuracy and/or more foot pounds of torque than those tools can output.


Your goal when tightening a bolt is not solely to hold a object in place, instead it is to create a clamping force across the joint which is able to sustain the operating conditions without easily becoming loose.

No matter how strong you are “Samson”, you can only torque your manual wrench so much before you slip and end-up with busted knuckles.

And, as for your impact wrench — it shocks the nut with sharp blows similar to the way a hammer would strike and pounds on the stud, meaning fatigue can occur leading to breakage, or damage.

Think of it sort of like a piston in your engine that makes contact with the head of an engine valve, which leads to a valve fracture at stem to head radius.

Image Source: Advanced Engine
Image Source: Advanced Engine

Calibrated torque tools like pneumatic torcguns allow you to set and apply evenly distributed pre-load on the bolt.

In doing so, the torque tools delivers precision gearing which produces a consistent, calibrated turning of the fastener to assure you will achieve the optimal bolt load within your range of accuracy every time.

Again, passion for what you do means the pursuit of perfection and doing things right the first time.

With that in mind let us think for a moment.

  • You have the right tools for the job.
  • You have studies the proper usage of your fasteners.
  • You have researched the benefits and safety features of the torque tools.
  • You are ready to go ….

But wait,…

How can you be certain the specification of the tool you are looking to buy, or use can really perform as stated?

Who keeps the claims of torque tool manufacturer’s in check, and who holds them accountable?


Hedgehog Circle #2: Be The Best. Have A Higher Standard

The highest standards - hydraulic torque wrench

This is a often the toughest pill to swallow, yet, the concept is simple — if the core of your business can only be good, and not great at something — why are you doing it?


As done within other industries and verticals, the industrial bolting world relies heavily on accredited laboratories to ensure the torque and tension tools being manufactured are achieving the results they state they will help you attain.

Conversion charts and high quality standards of pneumatic torque torcgunFor example, Accuserve, Inc. is an ISO/IEC 17025: 2005 (General requirements for the competence of testing and calibration laboratories) accredited laboratory meeting numerous industry standards, including NIST Traceable, ANSI-Z540-1, ISO 9000, manufacturers and GIDEP procedures, AMS 2750D, TS 16949, FDA, and Mil-Spec, among others important requirements to ensure the safety and precision of torque tools.

At minimum, as an engineer or MRO you want to make certain the torque tools you are using to properly tighten fasteners are 3rd party tested, and have passed.

However, odds are you have not solely looking for torque tools that meet the basic standards, rather, we want to find the one the exceed the standards.

Of course, there are costs involved with exceeding the standards, such as:

  • Better materials
  • Fair wages for employees
  • Safety inspection costs
  • Quality certification costs

More than paper standards

Of course, you want to keep in mind that every torque tool has to meet minimum standard prior to hitting the market.

And, you need to know 3rd party testing cost money.

Manufacturers, at least those in the hydraulic torque wrench and pneumatic torcgun space typically pass these cost on to their customers.

To save money you should consider buying directly from a manufacturer’s representative.

Buy hydraulic and pneumatic torque tools manufacturer Direct

Benefits of buying torque tools directly from manufacturer

It is important to note that most manufacturers of any product will have you buy from a large distributor, dealer, or reseller depending on the estimated frequency and size of your orders.

There are a few who offer manufacturer direct sales via a manufacturer’s representative agreement.

Best price torque wrench toolsWhen you are able to buying your torque tools, or other equipment in this manner you are typically able to eliminate extra cost like:

  • Dropship handling fees
  • 3rd party testing fees
  • Distributor AND Retail mark-up

But, even more importantly then eliminating cost is the ADDED VALUE such as:

  • Direct manufacturer customer service
  • Highest level of tool knowledge
  • Over-night tool replacement

Being the best manufacturer’s representative

AMG Bolting Solutions primarily offers hydraulic torque wrenches and pneumatic torcguns manufactured by Torc, LLC.

This New Jersey based manufacturer is headquartered near by Hytorc, and is a quiet giant.

Certainly we could sell inexpensive torque wrenches from China or India that are replicas of USA models, but we don’t.

Likewise, if a customer insists on an Enerpac, RAD, or HydraTight product we will source it, however — remember the Hedgehog Concept here is to be the best, not just exceptional.

Hence, we provide tools that are cost-effective AND have set the highest standards, not either/or.

Torc hydraulic power pack on eBay

Enerpac for example makes and offers high quality tools, but for the price of a used Enerpac hydraulic power pump on eBay you can buy a new one of ours.

Not because of poor quality, but, because of the distribution model.

Enerpac requires us to resells via a large distribution warehouse. Torc, LLc does not.

In addition, our torque tools are manufactured by the same company that for over 30 years has made hydraulic torque tools for companies like Rapidtorc, Snap-On and Torcup.

However, by selling as a Manufacturer’s Representative, AMG Bolting Solutions is able to save customers 30% to 50% when compared to these other brands.

So we,

  • Eliminate Middle Man Costs
  • Provide Superior Customer Service & Support
  • Make Buying Easy
  • Create and Distribute Resources To Improve Your Relationship With Your Torque Tools

The latter two bullet-points are the difference makers for us.

TTP Pneumatic Torque Wrench - Accessories for Torcgun

While Torc, LLc makes great tools they are horrible at providing content relevant to your tool usage.

By creating posts like this one, and making bolting conversion charts easily accessible online we are positioning ourselves to be the best.

Even our pricing is right upfront, so you never have the guess or wait for a reply to an RFQ.

In other words, the best hydraulic torque wrench, at the best price for an American made hydraulic torque wrench, coupled with the best torque tool service, ultimately equals the highest standard for the customer.

This includes making it easy to use your tools efficiently, effectively, and safely.

So, now

  • You have identified the tools, accessories, and fasteners you need to get the job done right.
  • You have verified the calibration of your torque and tension equipment.
  • If looking to buy — you have sourced your tools at the best possible value [price + quality + service]

Now, you need to figure out how to convert various metrics into a torque compatible language.

Before, you go scouring the internet for torque conversion charts keep reading, we have already done the homework for you.

Hedgehog Circle #3: Actively Make Decisions That Make Money.

The idea here is to change thinking from how much profit are we making on this job to what is the potential life time value of this customer.

According to Bolting Science, “a survey was completed in the United States of automobile service managers which indicated that 23% of all service problems were traced to loose fasteners, with even 12% of new cars and industrial freight-liners being found to have fasteners loose.


In Download Conversion ChartsApril of 2014, the Federal Railroad Administration sponsored a two-part research project  to study the structural integrity of joint bars. And, while railway train system were found to be safer than ever, 31% of all accidents are a result of faulty tracks, mainly loose bolts.

These findings are the primary reason why AMG Bolting Solutions has created three (3) conversation charts to help professionals like you properly tighten your threaded fasteners.

Presented below are information and techniques intended to assist an Engineer and/or MRO professional in ensuring that threaded fasteners are tightened so that the desired pre-load is achieved.

The Conversation Charts For Bolting provides helpful information for simplifying the translation measurement unit into equivalent unit systems. You can also use the conversion charts for selecting the proper tools and equipment when shopping our online precision bolting tool store.

NOTE: All capacities and measurements on the AMG website and catalog are expressed in uniform value.

Download Conversion Charts

Now that you have the conversion charts, you might be wondering, what keeps the bolt and nut together.

How Bolts and Nuts Work Best

Correctly tightening bolts make use of the intended elastic properties of the threaded fasteners.

One of the properties of elasticity states that it takes about twice as much force to stretch a spring twice as far.

This linear dependence of displacement upon stretching force is called Hooke’s Law of Physics.

This video does a great job explaining Hooke’s Law of Physics.

It is essential to understand that the stress-strain of a bolt has an elastic range and a plastic range.

Within this elastic range Hooke’s Law always holds true.

Bolts and nuts are impacted by pressure, volume, force, load, weight, size, and several other units of measurement, as well as, external factors such as weather, environment, and temperature.

When a threaded fastener is at optimal tightness the bolt and nut will behave like springs. When load is applied, the bolt stretches and tries to return to its original length.

Typically this creates something called “compressive force” throughout all the joint members.

That said, according to a study published by the Fastening and Joining Research Institute, Department of Mechanical Engineering, and Oakland University : Clamp Load Loss due to Fastener Elongation Beyond its Elastic Limit

“The amount of clamp load due to an externally applied separating force is determined for a boiled assembly in which the fastener is elongated past its proportional limit, while the clamped joint remained within its elastic range.

After the initial tightening of the fastener, the joint is subsequently subjected to a tensile separating force, which further increases the fastener tensile stress into the nonlinear range. Such separating force will simultaneously reduce the clamping force in the bolted joint.

Upon the removal of the separating service load, the bolted joint system reaches a new equilibrium point between the fastener tension and the joint clamping force. At the new equilibrium point, the fastener tension is reduced from its value at initial assembly, due to the plastic elongation of the fastener.”

Note: The term strength in this context differs from stress by being defined for a specific bolt’sstress area and presented in units of force. Worth mentioning is that “strength” is also commonly used interchangeably with stress and presented in units of pounds per square inch (psi) for USCS or Megapascals (MPa) for SI. In this case, the value represents a more general property that can be applied to a variety of stress areas to derive the limits of applied forces. In other words, the ultimate tensile strength of the fastener material (MPa) can be presented as the ultimate tensile strength (kN) of a specific size fastener.

IMAGE SOURCE: Fastenal. (2009). [Illustration of Tensile: Stress-Strain Relationship] Bolted Joint Design: Mechanical Properties of Steel Fasteners in Service

As supported by the study, since a “separating force” is also present improper tightening of a fastener — be too loose or too tight can lead to compromising the joint integrity.

The study adds;
The reduction in fastener tension translates into a partial—yet permanent—loss of the clamping load that may lead to joint leakage, loosening, or fatigue failure.
Proper torque and tension, sometimes added by a specialized washer helps establish an elastic range that creates a nonlinear model  to interrupt the fastener behavior past the proportional limit of its material, and allows for the separating force to be removed.
To prove this point a test was conducted using the following methodology.
According a research paper published on the American Society of Mechanical Engineers website by Sayed A. Nassar and Payam H. Matin, Cumulative Clamp Load Loss Due to a Fully Reversed Cyclic Service Load Acting on an Initially Yielded Bolted Joint System – DOI,: 10.1115/1.2217971
Two fastener materials with significantly different rates of strain hardening are used for modeling the behavior of the bolted joint system.
The goal is to observe the effect of three nondimensional variables on the amount of clamp load loss. Each of these three nondimensional variables are identified as follows:
  • The first variable represents the stiffness ratio of the joint and the fastener.
  • The second variable represents the ratio of initial fastener tension to the fastener elastic limit.
  • The third variable represents the ratio of the separating force to the force that causes joint separation to start.
Analytical results are presented for a range of stiffness ratios that simulates both soft and hard joint applications. Experimental verification of the analytical results is presented.
Whether you are an MRO simply looking for the right calibrated tightening tool to complete an upcoming bolting project, or an engineer looking to prevent or solve a bolt failure, it is critical to know the precision torque ranges and limitations of your fasteners and industrial bolting equipment.

Therefore, if you have not yet done so already, …

download these FREE Conversion Charts For Bolting

Download Conversion Charts

Finally, I’d like to hear from you. If you’ve used any of these conversion charts or methods successfully, I’d love it if you shared your experience in a comment below. Also, if you have any questions, feel free to leave them below too.

As always you are welcoming to share this with a colleague or friend.

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