DIS-TRAN Steel Blog

The Insider's Guide to Steel Hardware Assembly

Posted by Brooke Barone on Sep 27, 2013 9:43:00 AM

I heard this quote once about “the perfect couple,” and I think it could relate to different circumstances: “Perfect is not when two people are together. It’s when you’re both different but in a way, you complete each other.”

You’re probably scratching your head wondering how in the world assembly hardware relates to “the perfect couple.” Well, don’t worry, this isn’t a blog about 5 Ways to Save Your Relationship, but it is important to know that when it comes to assembly hardware, while they have their different roles, the right hardware needs to be paired with the right bolt.

Just like knowing if you’re compatible or not with someone, you should know which pairings are suitable when either ordering or supplying assembly hardware for steel structures. If the bolt and nut don’t match up in accordance with ASTM standards, you could run into strength problems, requirements issues or over match hardware when it is unnecessary. A low strength nut shouldn’t be paired with a high strength bolt because it would take away the strength of the bolt. In other words, the connection is only as strong as its weakest part. For example, if an A325 high strength bolt is specified for a connection, then you want to make sure the recommended nut and flat washer is supplied to match the A325 bolt’s loading capacity. The same applies if you pair a high strength nut with a low strength bolt, you’ll run into overkill.

In this situation, you end up paying for a more expensive nut when there may have been a more economical option without compromising the loading capacity of the bolt. In the ASTM A563 standard specification for carbon and alloy steel nuts, there is a good nut compatibility chart that shows which nuts are recommended for most bolts. This is also provided in our offer at the bottom of the page, which also includes locking devices and other pertinent information, like available bolt diameters and lengths. This can be helpful when sizing the bolts and selecting the proper locking device because some locking devices aren’t available in larger diameters.

**Just because the bolt you are ordering comes in that size, it doesn’t guarantee that the locking device you selected also comes in that size.

Common terms defined:

Bolt- headed and externally threaded fastener designed to be assembled with a nut.

Nut- An internally threaded product intended for use on external or male screw threads such as a headed bolt or a stud for the purpose of tightening or assembling two or more components.

Locking Device- a device used in conjunction with a fastener in order to positively lock the fastener, so that the fastener cannot work loose from vibrations. 

bolt assembly

One of the more common bolts used is the ASTM A325 Type 1 bolt (galvanized). The ASTM A325 specification covers two types of heat treated heavy hex bolts with starting tensile strength of 120 ksi for sizes 1.0 in. and less, and 105 ksi for sizes over 1.0 to 1.5 in. These bolts are used in steel connections, and the bolts are then classified by “type” based on their chemistry.

For the A325 bolt, Type 1 is described as a medium carbon, carbon buron or medium carbon alloy steel. If your project consists of galvanized steel, then you’ll need to order an A325 Type 1 bolt that is zinc coated…and of course it doesn’t stop there. When ordering these bolts, the supplier also needs to know size (including diameter), threaded pitch, bolt length, length of threads, etc. From there, if the bolt and corresponding hardware is ordered as an assembly, the ASTM A325 specification requires a ROCAP test (Rotational Capacity Test). A ROCAP test essentially tests the capaability between the bolt and nut of certain heat lots.

And just to add, for the A325 bolts, the nuts need to be A563-DH because this nut automatically comes lubricated, which is required in the ROCAP test. (Note: You may be able to get an A194-2H nut lubricated; check with your bolt supplier.) In the instance that you need custom thread lengths, A449 bolts are suitable to use in the place of A325.

Some other commonly used bolts in the utility industry include A307, A394 and A36. These bolts are low to mid strength and are galvanized. They are suitable with A563-A hex or square nut (same grades), or a USS washer (F884). To supply a heavy hex nut or hardened flat washer with these type bolts would be over matching. You can supply higher strength nuts and washers with these bolts; however it’s not as economical and doesn’t provide any extra benefits.

For connections that require a bolt with a higher tensile strength than an A325 bolt, an A193-B7 is a suitable option.  These come as fully threaded studs, and require an A194-2H nut.

So, just as important as it is to choose the right match, it’s critical to know what hardware is suitable, as well as their pairings. That’s also where your bolt supplier or fabricator can come in and service you better.


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Tags: bolt assembly, astm a325 bolts, heavy hex bolt, square nuts and bolts, steel hardware assembly, flange connections, lightning mast, tensile strength bolts

7 Deadly Sins of Shipping Steel Structures

Posted by Brooke Barone on Jul 10, 2013 11:14:00 AM

Just like fuel is needed for an engine or a bowl is needed for soup, communication between the steel supplier and receiver throughout all processes is essential.

Getting from point A to point B seems like an easy task, but when it is assumed rather than confirmed, you could run in to some problems. Shipping steel structures is an important piece of the puzzle.

The first, and what some would argue the most critical part when shipping, is to contact the customer to first let them know that their order is ready, as well as confirm the location that it will be shipped to. Next, the Bill of Lading should be checked to ensure that there are the correct number of pieces, pieces marked and weight.

Following that, it should be determined, or estimated, how many truckloads it will take to load and deliver all the material. The next step is to contact a carrier who either offers the best rate and service. The supplier should make sure that whichever carrier they choose, they should be experienced and know route planning, permitting and the delivery process. 

truckload carrier

Ok, I know that sounds simple, but there are several deadly sins to stay away from when shipping steel structures.

  1. Never ship assembly bolts on any other truckload than the first one. Why? Well, without the bolts, the customer cannot begin to assemble any of the structures.
  2. Don’t ship anything out that has missing pieces on the Bill of Lading, because this could hold up the project.
  3. Don’t ship without checking the structures’ cosmetic outer coat for obvious blemishes or defects, as this could hold up the project even longer if the customer doesn’t approve or if it needs repairing.
  4. Loads should not be cubed out. In other words, the structures must all be within the 8 x 8 “cube,” and if any poles or structures are over length, then the carrier needs to obtain an oversize load permit.
  5. Truckdrivers should never deliver to the jobsite before they pre-call the customer contact to confirm delivery time. (The customer contact and phone number is always typed on the Bill Of Lading.)
  6. Never ship anything overweight. Maximum weight is 40,000 to 45,000 LBS per truckload.
  7. Above all, the load must be loaded safely. It is up to the driver to determine whether or not the load is loaded correctly and can be hauled safely.

If the receiver requests for the structures to be delivered in a specific order, it is important to communicate this between the project coordinators, shop and shipping department to ensure this happens.  If not, it could end up costing the receiver lost hours as well as delays in the project. For example, they shouldn’t receive insulators and switches before columns and switch rack mounts. 

Safety is another concern when loading a truck. It’s critical to make sure the straps are secure, and that all material is locked in place. Also keep in mind that when dealing with tubular steel structures they can sometimes shift during delivery, which could create the danger of rolling.

All of the steps listed above can help a delivery run smooth and efficient so that the supplier, as well as the receiver, both experience a stress-free operation. Also, remember it is important when choosing a carrier, because once that truckload has left the premise, it is their responsibility to get the materials to the receiver in a timely and safe manner.  

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Tags: steel structures, galvanizer, truckload carriers, tubular steel structure, steel supplier, bolt assembly, switch rack mounts, oversize load permit, bills of lading, route planning

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