DIS-TRAN Steel Blog

The 8th Deadly Sin of Shipping Steel Structures

Posted by Brooke Barone on Jul 17, 2013 2:45:00 PM

Last week we provided a blog of what we felt were the 7 Deadly Sins of Shipping Steel Structures and captured the most critical in the world we live in with Utility customers. 

However, it was quickly pointed out by some of our friends that not all structures are meant for that industry.  Some of you ship steel structures into the commercial and industrial market and many of those structures require painting prior to delivery.  That painting may only be a primer coat or may be some exotic finished coats of paint to give your products that long life needed to survive those environments.  Where is this going?  As noted, there might be an 8th “Deadly Sin” which could fit in that case. 

galvanized steel structure

 8. Never ship a painted steel structure that is not completely cured or dry.

Occasionally, structures are loaded onto flatbed trucks or rail cars and the painted coatings have not been allowed to adequately dry in accordance with the manufacturer’s specifications.  This can cause real issues with that coating or with the finished coat, which will be applied later.  More often it is a cause of much grief between the trucking company, contractor and the owner.  In this situation, the fault is with who or what caused the painter to rush the steps required and not those downstream who handled the product. 

So why does the painter ship steel that is not completely dry? 

You might find that the painter was not provided adequate time to perform the work or that there is such pressure from the manufacturer to deliver the product they hope to “air dry” the product in route to the job site.  We all need to recognize that this attempt to rush this process only adds much effort and the resulting cost to the job and should be avoided at all costs.  Let’s all remind ourselves and our contractors to READ THE LABEL and allow for the adequate curing time for any coating so that this potential Deadly Sin can be avoided.

To our Friend on LINKEDIN, Thank you for bringing this potential 8th Deadly Sin to our attention and to your friends in the biz.

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Tags: steel structures, steel supplier, bolts, painted steel structure, painted coatings

The Beginner’s Guide to Bolts of Assembly Hardware

Posted by Brooke Barone on Jun 13, 2013 4:55:00 PM

Who knew steel assembly hardware could be so complex? There’s shop bolts verses field bolts, galvanized verses weathered bolts, different step bolts, tower bolts and the list continues.

So what are the different types of assembly hardware?

Well, for starters, assembly bolts may be designated as shop bolts or field bolts. Shop bolts are used to sub-assemble steel structures at the shop, whereas field bolts are shipped out to the field in containers (or whatever packaging) and are used to assemble steel structures at the job site by construction crews.

There’s also three factors to consider when determining what type of assemble hardware to use:

Length- based on the thickness of the joining parts, as well as considerations for your nut, washer and locking mechanism.

Diameter- needs to be able to withstand the load and strength requirements of the connection, and is also generally based on ASCE and AISC requirements.  

Chemistry- a commonly used bolt is ASTM A325, but it’s important to keep in mind that there are two types of A325 bolts.

A325 bolts are available in both weathering and galvanized.  Weathering bolts are designated as A325 – Type 3 while galvanized is A325 – Type 1.  Some vendors typically assume galvanized hardware if not shown the Type 1 at the end.

a325 bolt

Other common specifications for bolts include A394 and A193-B7.

ASTM A394, also known as tower bolts, are lower in strength than A325, which is high strength bolts, and are commonly used in lattice towers. ASTM A325 has a longer shank and only about 2 inches of threading, compared to A394, which is threaded the length of the bolt. You can reference Part 7 of the AISC Steel Construction Manual for additional details.  

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ASTM A193-B7 is being more commonly used in high strength connections, since they are extra high strength bolts. These bolts mainly come galvanized, and are commonly used in substation and transmission dead-end applications.  

The industry standard for bolts is hex head, but they can also be round button head bolts and square headed bolts. Hex head bolts are six sided and are commonly used in assembly, button head bolts are often used for climbing bolts and square head bolts can be used for both assembly and climbing.

Step Bolts are generally designed by A394 Type 0 (galvanized - low carbon steel) or A394 Type 1 (galvanized - medium carbon steel) or Type 3 (weathering – medium grade steel).  These are supplied as button head and here is an example of how they can be found on the shelf:

Step bolts

There are two strength requirements that go into bolted connection design:

Tensile Strength- resistance to forces applied through the longitudinal axis of the bolt.              

Shear Strength- resistance to forces passing through the cross sectional area of the bolts   

Yield Strength- when the bolt starts to deform

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Tags: bolts, assembly hardware, a325 galvanized bolts, hex head bolts, button head bolt, square head bolts, astm 325, a193-b7, weathering steel

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