None and nobody.

So what are the factors that go into determining the nut and bolt compatibility? And why is this important to the strength of the fastener?

Factors for Nuts and Bolts to Get Along

Similar to finding the right fastener material for your application, finding the nut material that will work well with your bolt is vital. The IFI standards claim it is “relatively straightforward,” although from personal experience (being married to an engineer for 13 years) I’ve found that nothing in engineering is anywhere near straightforward.

That being said (sorry, hun), the IFI guidelines are summed up fairly easily.

For average needs when using carbon steel fasteners you should take a look at the strength of both mating parts: bolt / screw and nut. Make sure that the nut has the same level of strength or higher than the bolt or screw. Nut proof stress (aka strength) is also measured in pounds per square inch (or psi) – so if you have a fastener made of medium carbon that has been heat treated (usually somewhere around 120,000 psi), you need to look for a nut with at least 120,000 psi strength as well.

Easy, right?

If you are concerned about safety and want to provide a high level of assurance, IFI recommends that you choose a nut with a proof stress that is 20 percent higher than the strength of the fastener.

Stainless steel and non-ferrous fasteners require a nut with equal strength – so match the psi of your bolt with the proof stress of the nut (also in psi). Full thickness nuts generally don’t fall any lower than 90,000 psi, which is good for most fasteners unless you move into the stronger stainless steel or Nickel-based alloy products.

Matching Alloys

It’s also recommended that, if at all possible in your application, the same alloy is used for both the fastener and the nut. You could be introducing a whole other set of issues by mixing and matching alloys.

Overtapped Means Less Strength

You may hear of a nut being overtapped, which occurs when plating and coatings are applied. This process actually lowers the proof stress of the nut (although it improves resistance to corrosion) and can reduce the lowest grade of full thickness nuts to as low as 60,000 psi.

When hardware is hot dipped galvanized the plating process may clog up the threads, making it even more important that the mating parts both be hot dipped galvanized.  Coordination is about more than matching your shoes and socks.

Balance is Vital

Another element to remember is that you need balance between the nuts and bolts. Don’t choose a nut that is near the minimum accepted proof stress level and mate it with a fastener that sits at the maximum end of the range of accepted strength. In stress situations your bolt will hold up nicely, but the tension will be too much for the weaker nut and you’ll end up stripping the nut thread entirely.

To be sure this doesn’t happen (in case your application demands complete assurance), choose a nut that meets or exceeds the maximum strength of the bolt.

Also, opting for a larger diameter nut (with a thicker wall) is a cheaper option than going with a heat treated nut – which will save on the cost. In certain situations space may be tight and the heat treatment may be your only option.

There are a lot of factors that go into matching the right bolt with the proper nut. Count on the strength and durability of a well paired combo. That’s the kind of thing those engineers are looking for.

Get ‘Er Done – Basic Productivity Apps

CalenGoo

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• CalenGoo – Perfect for syncing your Google calendar on your iPhone, iPad or iPod Touch on the fly. Book appointments, check your schedule and merge with other Google users to amalgamate schedules. This app will let you know where you should be and when. – $6.99 on iTunes for newest version 1.5.3

Bento

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• Bento – Want to have everything you need to organize life in one app? This does is it. For less than the price of lunch, you can use one of the 25 preloaded templates or sort through the app and create your own customized tools to get the ultimate in organization. – $4.99 on iTunes for the newest version 1.0.5

Dropbox

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• Dropbox – This app is an excellent way to share files across multiple computers and mobiles. Hooked up to your Dropbox account, you can access, view and share files of all sorts from anywhere. OK, not just an excellent way, Dropbox should be the only way. Did I mention that it’s completely free? – Free on iTunes for newest version

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Business Card Reader

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• Business Card Reader – Think of all that time you’ve spent inputting contact info into your iPhone. No more. With this handy app you can take a photo of someone’s card and have all of the info right at your fingertips, no fiddling with data processing in any way. – $5.99 on iTunes for newest version 1.3

OnTask

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•    OnTask – This one will keep you productive in every sense of the word.  Hooked up to your OnTask account (which is a subscribed service), you can easily keep track of schedules and present that information to your team and client easily.  $4.99 on iTunes for newest version 2.0 that comes with 6 month subscription
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Geek Squad – Techy Tools for Your Job

Bump

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• Bump – It’s marketed as a social networking tool, but this app can do wonders for inter-company communications. Just “bump” your iPhone (literally) with other users of the app and you can share photos, calendar info and even chat/text phone to phone for free. Great for streamlining and keeping in touch. – Free on iTunes for newest version 2.0.1

Quad Level

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• Quad Level – You might never need that bulky level again with this handy app. Displaying horizontal, vertical, 2D and diagonal readings, this baby also reads in metric and imperial for those necessary times of conversion. – $0.99 on iTunes for newest version 1.1

HVAC Duct Sizer

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• HVAC Duct Sizer – If you’re working in the HVAC field, get this app. Pronto. You’ll be surprised at how many times you use it for quick calculations or to double check your figures. Perfect for employees in training, too. – $6.99 on iTunes for newest version 1.6

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Carpenter's Helper Pro

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• Carpenter’s Helper Pro – The big daddy of this article, the Pro version gives contractors almost everything they need to make calculations, create accurate estimates and plan out your projects. The Quick Job feature has a selection of the usual contractor suspects including drywall, fencing and roofing. There’s a Lite version at no cost, but for the serious contractor the Pro level is a must. – $9.99 on iTunes for newest version 2.0

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Piggy Bank – To Help the Cash Flow

Expensify

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• Expensify – Organize your receipts the easy way and create expense reports that “don’t suck,” as the app review so clearly states. Make your bookkeeper happy for a change with this one. The price is another kicker that’s good for the cash flow. – Free on iTunes for newest version 2.4

Co-Pilot Live

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• Co-Pilot Live – So it’s not strictly a financial tool for your company, but this app is bound to save you money. Skip the GPS with its subscriptions and huge sticker price. Opt instead for this app that will get you where you need to go, fast. – $19.99 on iTunes for newest version 8.0.0.815

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Whether you’re looking to network, schedule, keep the books or do an accurate estimate, don’t worry – there’s an app for that.  Get moving and do business better with these must have titles for your iPhone.  Look for the list of top Blackberry and Droid apps coming soon, a range of mobile tools to keep your business at the top of its game.