How to Avoid Excessive Galvanizing Buildup on Steel Structures

Posted by Brooke Barone on Nov 13, 2014 2:43:08 PM

Something that might be viewed as a small, insignificant venting hole on a 10,000 pound steel structure, if not well thought out, could really have an adverse effect on production.

When creating fabrication drawings for galvanized structures, it’s important, as well as valuable, to know proper draining and venting provisions. If adequate venting and draining holes are not provided, it can really have an intangible effect.

5 Problems to Watch Out For:

1. Air pockets can form, causing structures to rust out from the inside

2. Excess galvanizing buildup

3. Lead to longer fabrication times

4. Welded plate can blow out, causing safety concerns

5. Poor coating

It’s hard to put a dollar amount on what happens when a structure either doesn’t have proper venting, or one of the five stated above occurs. It’s usually not too hard to correct if it’s caught up front, but the further it gets in the process and closer to delivery dates, it can really put a stop to production, causing low production numbers and possibly delayed shipping. But working with a trusted steel fabricator, can help avoid these issues.

Some standard shape structures, such as square and rectangular tube columns and beams, are hollow, so provisions need to be made in order to allow galvanizing to easily flow and coat the inside portion of the structure. Tapered tubular structures are also hollow so the same principles can apply with provisions.

Other standard shape structures, like channels, wide flanges and angles are solid, so just the outside receives coating, but keep in mind that air pockets can form without proper drainage, causing excessive galvanizing buildup. For these shapes, you need to watch where stiffeners, connection plates and brackets are welded that could form large pockets of air as the section is dipped into the kettle.

For standard shape and tapered tubular structures, using removable cover plates on the ends of beams is a good option instead of welding solid plates or expanded metal to the ends. This allows for faster flow through the member and more adequate galvanizing, also helping to eliminate buildup.

galvanizing_build_up-1

But ensuring proper venting doesn’t mean place a bunch of holes all over the structure, but rather strategically supply the venting and drainage provisions. For example, if dealing with corners in a square and rectangular tube, slots or holes can be provided near these corners to prevent air pockets from forming, which can decrease the amount of galvanizing coating in the area.

It’s key that along the process, there are people in place who know what to look for or have an eye for knowing what will work when it goes to the galvanizer. If it passes through the line of engineering, detailing, quality control and then is delivered to the galvanizer, modifications can be more costly and difficult.

The more you understand how the member is lifted and dipped in and out of the galvanizing kettle, the better you can locate the venting and draining provisions. As a designer, you are always trying to find the balance of putting enough holes for galvanizing, while not putting too many to impact the structural integrity of the steel member.

Read More

DIS-TRAN Take2: How to Design Anchor Bolts

Posted by Brooke Barone on Nov 3, 2014 11:46:21 AM

In this edition of DIS-TRAN Take2, led by Senior Civil Engineer, Bill Elliott, PE, he will explain and demonstrate how to design anchor bolts after calculating the axial loads. To learn more about developing loads in anchor bolts, click here to watch his previous video. 

In this short, six minute video, Bill walks through four steps for designing anchor bolts:

1. Calculate the shear bolt load. 

2. Calculate the max shear stress per bolt. 

3. Calculate the max permitted tensile stress per bolt. 

4. Take max bolt load and calculate actual tensile stress. 

 (You can also click here to view the video on YouTube.) 

Design_Question_CTA

Read More

DIS-TRAN Take2: Calculating Anchor Bolt Loads

Posted by Brooke Barone on Oct 8, 2014 1:58:00 PM

Calculating anchor bolt loads can be tricky when you have more than your standard four anchor bolts in a square pattern. This video shows how to determine how much load is going into each anchor bolt so that you can calculate anchor bolt requirements and embedment depths. 

Bill Elliott, P.E., senior civil engineer at DIS-TRAN Steel, explains how to determine distance, calculate the moment of inertia and anchor bolt loads... Watch here! 

If you missed the previous DIS-TRAN Take2 Video: Manipulating Loads for Steel Transmission Pole Design, click here to view it. 

Subscribe_Pic

Read More

What is Chemthane 2260 and Why Is It Used on Steel Poles?

Posted by Brooke Barone on Sep 25, 2014 3:51:10 PM

After fabrication, every utility structure made from carbon steel undergoes some type of protective coating such as galvanizing and/or painting. Utility structures made with 588 weathering steel form a patina over time that protects the steel from rusting.

Galvanizing has been around for a century (if you’re not familiar, then read What Everyone in the Hot-Dip Galvanizing Industry Should Know.) These protective coatings improve the overall lifespan of the steel, but sometimes embedded steel poles or casings may need an additional protective coating to combat soil conditions. 

Chemline? Corrocote? What’s the difference?

While both Chemline and Corrocote offer below grade coatings that can be applied to direct embedded steel structures or casings to protect against soil conditions, the main difference is that Chemline is an American made product and Corrocote is formulated in Canada.  

Chemthane, which is the below grade coating produced by Chemline, can be applied to the embedded portion of a galvanized or weathering steel pole, and come in a variety of colors. Typically, the standard coating is Chemthane 2260, which is an equivalent to Madison Chemicals Corrocote 2 Classic.Chemthane 2260 forms a hard polymer film that acts as an adhesion and is abrasion and chemical resistant. This coating provides corrosion protection with cured films between 18 and 30 mils (0.5-0.75mm) in thickness. The more common application is sprayed with a spray gun,using plural component painting equipment. 

chemthane_picture

For galvanized structures it’s not mandatory to apply this coating, however, the Chemthane provides an extra barrier to help protect the embedded portion from soil conditions. With weathering steel embedded structures this coating is highly recommended since the self weathering properties can’t perform underground. In order for weathering to perform, it must be exposed to oxygen and go through wet/dry cycles that are needed to form an oxidized, or rust, protective coating. Also, if the weathering structure is not hermetically sealed and in an area with a lot of ground water, then in some cases, it’s recommended to coat the inside with Chemthane to protect the structure if water seeps in. 

The standard colors for Chemthane 2260 are black and brown, but depending on things like aesthetics or safety precautions, they can come in a variety of colors, as well as safety colors. 

CHEMLINE_COLORS

 

Chemthane 3300

Something to keep in mind is that these coatings are sensitive to direct sunlight and will chalk and become brittle if left above ground for longer than 30 days. So, for customers that store above ground for a longer period of time, we recommend an additional coat on top of the standard Chemthane 2260, which is the Chemthane 3300 UV protection coat. Sometimes, customers request to have the Chemthane 3300 applied over the 2260 even if poles or casings are installed right away to provide extra protection to the portion above, below or at ground line.

Chemthane 3300 is an acrylic polyurethane finish coating that’s formulated to provide an extreme durable high performance finish that is UV stabilized, chemical resistant with a high gloss finish and  color retention.

*Side note: If you need a specific color for the 2260 like the safety red but also decide to apply the 3300 UV protection, note that it will not affect the color because the 3300 is a clear coating that goes over the 2260.

Have more questions or comments about Chemthane? Feel free to comment below! 

 

 

Read More

4 Things to Keep in Mind When Testing Transmission Davit Arms

Posted by Brooke Barone on Sep 12, 2014 2:56:47 PM

We like to call our engineers at DIS-TRAN Steel “myth busters.” Their day is spent crunching numbers and designing steel structures based off of standards, customer specifications and experience. Although they rarely get the opportunity to see their designs performing in the field, they love seeing their “babies” put to the test.

In a continuous effort by our Research and Development team, we recently conducted a full scale testing for transmission davit arms. Not only did we gain insight to how our arms performed, but we were also able to boost our confidence (and some bragging rights).

arm_2_110 It’s always good to have empirical knowledge through testing and research to confirm assumptions and know where improvements can be made, eliminating surprises in the field.

When testing, you want to make sure that your samples are a good representation for what will be in the field. Below we’ve listed out four things to keep in mind when testing transmission arms:

1. Make sure you have a good overall sampling- especially if you’re testing for a particular project where there can be different types of arms. For example, you might want to test a conductor or static arm, or if there are several tangents and deadends, you could test one of each.

2. As a fabricator, you don’t want to notify the shop that these particular arms are being tested. You want to be able to just pull an arm off of the shop floor that properly represents a typical arm that would be supplied on a project. Don’t do anything special to it that wouldn’t be done on a typical job.

 3. Make sure a representative from the fabricator is there to ensure that the arm is bolted to the testing apparatus properly and that’s its being installed similar to how it would be in the field. You want to make sure that everything from fabrication to how it’s loaded and installed is as close as possible to how it is in the field so that you get true test results.

 4. Make sure the loads that are applied correctly represent design conditions of the field. You want to get it as close as possible to what is really going to be in the field.

After everything is loaded and taken down, it’s very important that there is a thorough inspection to look for any damages, like cracks or permanent deformation. 

While the purpose is to test the whole unit together, you can also break it down even further to see how other components, like hardware or connections, behaved under loadings. This provides proof and validity to your design standards.

Key things to remember: gain as much knowledge from the tests; have a true representation of what will be in the field in order to get true, honest results and make sure the arms can take the ultimate loads they were designed for.

The main goal with all the four steps listed above is to truly represent what is going to be in the field. You don’t want to assume anything, nor do you want to cheat. If you specially prepare the arm for testing, ultimately you’re cheating yourself and the end user. You want to know what to truly expect so that if anything pops up, you can make corrections for future designs.

 

Read More

Topics: Engineering, transmission davit arms

ALS Real Life Stories That Will Change You Forever

Posted by Brooke Barone on Aug 29, 2014 10:35:55 AM

Rick Herring, shipping manager at DIS-TRAN Steel, took on the ALS Ice Bucket Challenge like a champ, but had a trick up his sleeve...

Being an "avid Alabama fab," Rick challenged all the "avid LSU fans."

And this was their response.

 

They say laughter is the best medicine.

This brilliant marketing campaign to not only raise funds for medical research but also raise awareness, has generated over $94.3 million so far as compared to $2.7 million that was raised this time last year. At the moment, there is no cure for ALS, nor are there many treatment options that are effective, but with this social media phenomenon, it will help make the impossible possible.

Here are a few ALS real life stories that will change you forever from the ALS Association website.

Rebecca M. Franklin, Indiana, "My Sweetheart, Jason M., was diagnosed 18 days after we found out we were expecting our daughter. He was told he had six months to two years life expectancy. Rather then to dwell on the negative, my husband wanted to live life to the fullest, to make each moment count, to make memories with our children and his Sweetheart. He didn't want ALS to define him or the time we had together. I am so grateful we lived in the moment and made each moment count. I would recommend everyone struggling with this disease to live the same way. The laundry, the dishes, the bills will still be there tomorrow, but your loved one isn't guaranteed another day, so enjoy that day with them and live in the moment. Take a ton of photos and videos. They will bring you comfort in the days ahead. Cherish these moments now."

"Two weeks before my Sweetheart died, we went on our last date. I was carrying his oxygen tank, giving him morphine by the hour, but to see the smile on his face, I will cherish it forever. My Sweetheart and I had a lifetime of dreams before this disease. After his diagnosis, he dreamed he would see our son off to his first day of kindergarten. He didn't get to see that dream and so many others, and so now my dream is to help fight for a cure, so others will be able to fulfill their dreams with their loved ones. "'Life is not measured by the number of breaths we take, but by the moments that take our breath away.'"

 

liz_jason-1054 Katherine W. Orange, California, "My father, Tom Wilkes, was a world-renowned graphic artist and photographer who made his living designing, photographing and illustrating famous rock and roll album covers and art. He was diagnosed in the spring of 1998 with a preliminary form of ALS, known as PLS. It robbed him of his vitality, his inspiration, and to a great extent, his ability to create art."

"I found out in 2006 that my younger brother and only sibling, David Harrison, was also afflicted with ALS. He is my half-brother, not related to my father, and he continues his brave battle with the disease to this day. David is the longest living patient of the Oregon Chapter of the ALS Association, and he endures his illness with grace and humor, far more than I believe I could muster under similar circumstances. Until you experience this disease up-close, you don't really have any concept of the devastation it wreaks on those who have it, those who love them, and those that are the caregivers. David has taken part in clinical trials that he knew were too late to benefit him but that we all hope will further the necessary research to end suffering for those diagnosed in the future.  I pray daily that a cure will be found to help those still suffering and for those who may be afflicted in the future."

yolanda-rodriguez-fernandez-2 Cecilia R. Orlando, Florida, "My mother's name was Yolanda Rodriguez. She was born March 15, 1946. She was 66 years old and lived in Kissimmee, Florida. Mom first started complaining of right arm atrophy and loss of right hand strength, inability to grasp objects, open car door or turn car on, unable to button blouse or wash her hair, which started gradually in the beginning of January 2012. Neck pain followed by arm and hand pain. Mom complains of her head dropping when walking and is unable to raise her head due to muscle pain. She is unable to speak clearly, slurring of speech. She is unable to swallow her food properly, which can take up to three hours. She gags and is unable to breathe easily. There was unexplained weight loss of four pounds per week for a period of six months."

"She now has lost 82 pounds and was desperate for answers and made an appointment with the neurologist for January 7, 2013, one year later after her very first condition began in her mouth. She was diagnosed with ALS on January 7, 2013 and passed on Febuary 20, 2013."

"This disease has devastated my family in more ways than one! I lost my best friend!! I miss my mother every single day. There was no warning of this devastating disease, and we knew nothing of this disease. I am a medical student and will become an integrative physician and will specialize in palliative care for ALS patients. I want and wish for a cure. I don't want another family to endure the pain this disease causes. Watching the one you love die before your eyes is the most helpless feeling a human being can face. Help us find a cure!"

If interested in learning how you can help make a difference, click here. 

For those who would like to donate to the local ALS chapter in Louisiana, here is the information:

The ALS Association Louisiana-Mississippi Chapter
P.O. Box 66825 - Baton Rouge, LA 70896-6825 
(225) 343-9880 or (800) 891-3746

 Keep the ice bucket challenge going for all those battling ALS. 

history-lou-gehrig

Read More

7 Obvious Reasons to Use Wood Distribution and Transmission Structures

Posted by Brooke Barone on Aug 27, 2014 11:17:47 AM

While many say “Out with the old and in with the new,” this might be true for hairstyles, tube socks or shag carpet, but with over 130 million wood utility structures across America that are still in service today, this is simply not the case.

Wood utility structures have an undeniable reputation for being reliable, versatile and cost-effective.Wood distribution and transmission structures remain highly preferred in the utility industry due to their ease of construction, climbability and design flexibility.

Wood Transmission Structures

Reliability Wood transmission structures have higher Basic Insulating Levels (BIL), which can help reduce lightning flashovers, cutting down on power outages.

Cost-effective With economical initial costs and low overall life cycle costs, wood can directly reduce the impact of operating expenses.

Safety Since wood transmission structures have been around for decades, utilities and lineman are very familiar with proper use and handling of the products.

Why use wood transmission structures?

  1. Lower cost
  2. Long and proven service life
  3. Adaptable to many different applications
  4. Easy to handle and store the structures
  5. Natural flexibility providing  high performance under load
  6. Can be easily modified in the field
  7. Can be supplied quickly in times of crisis

trans pic green

The general standards that wood transmission structures must meet include ANSI, RUS, NESC, WCLIB and AWPA. And just like steel, concrete and other materials, there are countless configurations for wood transmission structures. 

Just to name a few, there are:

  • Single Pole with Traditional Crossarms
  • Wishbone Structures
  • Two Pole H-Frame Structures
  • Multi-Pole H-Frame Structures

trans 2 green

When considering which manufacturer to choose, you might want to consider their history in the supply of products in the utility market, the location and number of facilities, in-house design capacity, access to raw materials and available inventory for standard items, especially when time is critical. All of these factors could make or break your recovery response when natural disasters strike.

 

Read More

Topics: utility industry, wood distribution crossarms, wood crossarms, utilities, transmission, wood crossarm, wood transmission structures, wishbone structures, H-Frame structures, wood structures

VIDEO: Manipulating Loads for Steel Transmission Pole Design

Posted by Brooke Barone on Aug 18, 2014 1:50:00 PM

Check out our first DIS-TRAN Take2 where Bill Elliott, senior civil engineer at DIS-TRAN Steel, demonstrates in under four minutes how to transpose loads from the wire coordinate system into the structure coordinate system, while also pointing out one common mistake to avoid.

Terms you'll hear:

  • Longitudinal component
  • Transverse component
  • Longitudinal axis
  • Transverse axis
  • Vectors
  • Wire coordinate system
  • Structure coordinate system 

 

 

Subscribe_Pic

 

Read More

Proper Draining and Venting Provisions for Steel Structures

Posted by Brooke Barone on Aug 7, 2014 1:33:00 PM

Something that might be viewed as a small, insignificant venting hole on a 10,000 pound steel structure, if not well thought out, could really have an adverse effect on production.

These mistakes, big or small, can delay or even put a halt to jobs. It’s key that all along the process, from engineering to detailing and quality control, there are people in place who know what to look for. Once the structure gets delivered to the galvanizer it can become difficult and more costly to make modifications because plates might already be cut, or everything might be welded up.

When creating fabrication drawings for galvanized structures, it’s important, as well as valuable, to know proper draining and venting provisions for these steel structures. If adequate venting and draining holes are not provided, the structures can run into many problems.

5 Negative Effects:

1. Air pockets can form, causing structures to rust out from the inside

2. Excess galvanizing buildup

3. Lead to longer fabrication times

4. Welded plate can blow out, causing safety concerns

5. Poor coating

Not having adequate venting and draining holes can really have an intangible effect: it’s hard to put a dollar amount on what happens when a structure either doesn’t have proper venting, or one of the five stated above occurs. It’s usually not too hard to correct if it’s caught up front, but the further it gets in the process, and closer to the delivery date, is when the scrambling might start. All the man hours it takes to call the engineer on record to approve revisions, or contact customers, plant personnel, the galvanizer, etc. can really put a stop to production, causing low production numbers and possibly delayed shipping. (But working with a trusted steel fabricator, can help to avoid these issues.)

excess galvanizing buildup

Some standard shape structures, such as square and rectangular tube columns and beams, are hollow, so provisions need to be made in order to allow galvanizing to easily flow and coat the inside portion of the structure. Sometimes fabricators will provide a small bar with a removable cover plate, attached with two (2) small stainless steel self-drilling screws. However, if the customer doesn’t feel this is sufficient enough, then the next suggestion could be to use a thicker bar with drill and tap holes, and two (2) A307-TAP bolts.  Some might suggest the use of expanded metal, but excessive build up can take place, which is unsightly and also impairs vision into the tube, hindering the Quality Control Department from being able to adequately determine if interior galvanizing coating is sufficient.

Other standard shape structures like channels, wide flanges and angles, are solid, with just the outside receiving coating. Some issues that can arise with this are air pockets and excessive galvanizing buildup. For these shapes, you need to watch where stiffeners, connection plates and brackets are welded that could form large pockets of air as the section is dipped into the kettle. Tapered tubular structures are also hollow like square and rectangle tubes.

As a designer, you are always trying to find the balance of putting enough holes for galvanizing while not putting too many to affect the structural integrity of the steel member. For example, if dealing with corners in a square and rectangular tube, slots or holes can be provided near these corners to prevent air pockets from forming, which can decrease the amount of galvanizing coating in the area.

The more you understand how the member is lifted and dipped in and out of the galvanizing kettle, the better you can locate the venting and draining provisions.

For more information about galvanizing and how it works, click here to read past articles.

  

Read More

Topics: standard shape steel structures, galvanized steel, steel fabricator, galvanized structural steel, rectangular steel tube, steel square tube

Increased Thickness Doesn't Always Give Enough Deflection in Steel Pole

Posted by Brooke Barone on Jul 31, 2014 1:27:30 PM

 

In marketing, catchy titles and inspiring phrases are my forte. However, when it comes to numbers, let’s just say I rely heavily on my calculator app. But with civil engineers, numbers are their friends. There’s this “numbers game”, if you will, that they play daily. When designing steel structures, engineers first develop the loads and then apply the loads in their design. Once loads are applied, they are tasked with finding the best possible combination of steel members and connection types while paying special attention to section properties, weights, aesthetics, constructability, etc. 

Pretty straight forward, right? Well not exactly. There are two major things that the engineer must consider: first, make sure the structure doesn’t over deflect, and second, make sure it doesn’t over stress. If the steel structure experiences over deflection, especially in a substation, this could potentially damage the equipment that are mounted on the structure. If the structure over stresses, it could cause things like yielding, cracking or even falling down.

It’s important to take all possible loading scenarios into account, such as combined ice and wind loads, extreme wind loads, earthquake loads or wind-induced oscillations, and apply them to ensure the structures stay within their set limits required by code, contract documents, customer specifications, etc. These structures can consist of an assortment of pipe, channels, wide flanges, square tubes, or even custom shapes like tapered tubular poly members. 

While it’s important to find the best possible combination of section properties, an engineer should also always be looking at the most economical choice when designing the structure for the customer. Steel fabricators can design structures from standard shape steel, all the way to tapered tubular steel, so it’s important that the engineer takes a good look at the entire picture, because remember, at times there is a direct correlation between heavier steel and higher costs. This is where the numbers game comes into play.

So, let’s say an engineer is designing a basic shape like a square tube, also known as hollow structural sections, they might start out with HSS 6x6x3/16 and keep increasing the thickness, which immediately helps with the stress but doesn’t help as much with deflection. At this point they need to start paying attention to the section properties by finding the best possible combination between things like the I Value (moment of inertia) and the S Value (section modules) while watching for overall member weight. So while the tube itself is smaller, the walls are getting thicker, making the structure weigh more.

The example below shows that moving up to the larger size, HSS 8x8x3/16, gives a significant increase in the I Value, which helps deflection, while also giving a slight increase in the S Value, which helps the overall stress, as compared to the HSS 6x6x3/8. In doing this, there is a 38 percent increase in the section modules, while at the same time a 28 percent decrease in weight. So going with a smaller member doesn’t always give you more bang for your buck.

HSS 6x6x3/8

                wt = 27.41 lb/ft

                I = 39.5 in4 (deflection)

                S = 13.2 in4 (stress)

 

HSS 8x8x3/16

                wt = 19.61 lb/ft

                I = 54.4 in4 (deflection)

                S = 13.6 in3 (stress)

 

Structure Classifications & Deflection Limitations, Design Guide per ASCE 113

In substation design, there are three different structure classifications: Class A Structures, Class B Structures and Class C Structures.  This is slightly different the old NEMA SG 6 that just had the substation structures broken out into only two classes: Class A and Class B. With ASCE 113, for determining the maximum deflections, they are broken down by horizontal members and vertical members. Horizontal Members are where the span of a horizontal member is the clear distance between connections to vertical supporting members, or for the cantilever members, the distance from the point of investigation to the vertical supporting member. To determine the maximum deflections, the span of a Vertical Member is the vertical distance from the foundation support to the point of investigation on the structure. The deflection to be limited is the gross horizontal displacement of the member relative to the foundation support.

Deflection_Limitations_Chart

As an experienced engineer, they understand that all structures should be designed to withstand applicable loads from things like wind, ice, line tensions, electrical equipment or other unusual service conditions when providing reliable structures for substation and transmission projects. Make sure to subscribe to the DIS-TRAN Blog today in order to receive next week’s article on loading criteria for substation structures.

 

 

Read More

Topics: Deflection

Subscribe

  

Posts by category

see all

Follow Me