Fasteners: SAE, Metric, Titanium, Stainless. Yes, We Can Accommodate.

In a previous life I worked in the metal cutting industry on machines that were all imported to the USA. Every machine we brought in had to have the air inlets changed out to match the NPT ports that most of our domestic customers had within their facilities. This simply made sense, why force someone to change an air fitting or something as simple as that to match the rest of their facility. The option we did not offer was to change all the hardware on the machine to match the rest of the SAE sized hardware and limit the number of tools their staff needed. That didn’t make sense. Well, here at EXAIR we like to do things differently.

There are several companies that I deal with here who always prefer their air inlets be different, whether it be a metric BSP thread or a larger NPT thread, maybe a global thread, or even a special fitting like a taper lock fitting. No matter the needs, as long as it will physically fit on the product, chances are we can offer the fitting that will simplify installation. Even past the installation we like to look forward to the complete ownership of our products. Once a machine is located in a facility, what other types of fasteners are used, what is the rest of the machine tooled with. When working on a machine as a maintenance person or adjusting the operation, not having to struggle with determining which Allen wrench or hex size a bolt is and risk damaging the bolt can be extremely helpful.

Most EXAIR products come from stock with standard fractional hardware. We do offer a number of products with a BSPT air inlet and they are often available with the same expediency as our other stock products, same day on orders received by 2 PM ET that are shipping within the U.S. As mentioned above, we can customize a product with the fasteners of your choice, as long as they pass our design criteria. Some of the most common fastener changes I have seen are converting a Super Air Knife to an M6-1.0 threaded bolt rather than the stock 1/4-20 fastener. There are a multitude of other requests that I recall throughout the years. Some of the most intricate are listed and explained below.


Specialty Hardware

From left to right: M6-1.0 stainless steel bolt, a titanium hex-head bolt, a Hastelloy hex-head bolt, brass hex-head bolt, Kolsterized hex-head bolt, special acorn head fastener, Allen key flat-head bolt. Each of these fasteners has been used within a custom configuration to meet a specific need, whether it be simply to match the metric or SAE hardware in the rest of the machine or to meet the demands of the environment they are going into. The bottom row are, integral star washer nut, serrated safety washer, and spring washer. Each of these has, again, been requested by a customer to meet the design and safety standards they have a requirement for. These are just a sampling of the custom hardware we have used over the years to support our customer base and fill their need with product that meets their standards.

If you would like to discuss custom hardware in a stock product or even a full on custom point of use compressed air product, the Application Engineer team here is ready to help. Contact us and we will do our best to understand what your need requires and offer a solution to fit.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

Torque Values and Tapered Threads – Do They Go Together?

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Over the past few weeks, I have been working on various cars in the garage with some good friends. We generally get together and help each other out to make the jobs go easier as well as help each other learn more about keeping our family’s vehicles safe and even helping out some others that don’t have the means to work on their own vehicles. Throughout these repairs, we always end up in some type of discussion over something fairly technical. Sometimes it is the proper installation of a part such as take the bolts to snug, back them out, then torque to half the total torque value, back off again, then finally tighten to the complete torque.

We also share different ways of doing the jobs, such as how to lessen the amount of hot oil you are about to pour all over your hand, or how to get that rusted bolt out without a torch and without breaking it. One discussion that comes up quite frequently is torque specs and then the torque spec for a tapered thread.

In case you were not aware, the NPT or BSPT (male) inlets on EXAIR products are both a tapered thread. Tapered threads are generally used on pipe fittings under pressure to seal better and provide a secure engagement. When comparing this to a standard bolt, or straight thread, one is generally accustomed to receiving a torque spec on just how tight to get the fitting or threaded product. For example, the 1/4-20 bolts used in our Super Air Knives are torqued to 7.5 ft-lbs. in order to properly seal the cap, shim, and body together. These are straight threads and thus a torque spec is often driven by the material, size, and thread of the bolt. Torque on tapered threads such as NPT or BSPT fittings is not as easy to find, and not really reliable.

For tapered threads, the engagement of the thread is not always at the same point due to differing tolerances on thread dimensions. These differences create different points of thread engagement with the corresponding thread it is tightening into. For these scenarios, the torque specification is not always best suited as a numeric value. If you search hard enough you can find a table like the one shown below, but again, not the best value to use when installing a tapered thread.

Size in-lbs N-m
1/16″ 5 0.57
1/8″ 7 0.79
1/4″ 16 1.81
3/8″ 23 2.6
1/2″ 30 3.39
3/4″ 54 6.1
1″ 78 8.81

I personally would not use a straight numeric torque when tightening something with stainless steel thread into a brass fitting, or other dissimilar materials together. For this scenario, I would recommend using something like the table below. The TPFT value is, turns past finger tight. This means you would snug the super air nozzle, vortex tube, or other fittings by hand to finger tight. Then using a wrench or two if needed, turn the fitting to the correct number of revolutions for the given thread size. By utilizing this method and the correct amount of thread sealant, see John Ball’s video blog below, you can ensure there will not be a concern on whether or not the joint will leak and also if the fitting is tight enough.

NPT Size TPFT
1/8″ 2-3
1/4″ 2-3
3/8″ 2-3
1/2″ 2-3
3/4″ 2-3
1″ 1.5-2.5

If you would like to discuss torque settings, installation of your engineered compressed air solution, or even what might be wrong with your minivan, contact us.

Brian Farno
Application Engineer/Garage Mechanic Extraordinaire
BrianFarno@EXAIR.com
@EXAIR_BF