DIS-TRAN Steel Blog

9 Must Haves for a Steel Structure Specification

Posted by Wendy Gintz on Apr 22, 2015 3:30:00 PM

Specification are to Steel Structures like...Cherries are to a Banana Split.BananaSplit

Specifications come in all shapes and sizes.

From the very informal 3 page document to the all-encompassing formidable documents.  The specification is a tool for the Owner (End User) to convey their minimum project requirements to the supplier.  Defined by Wikipedia, it is a set of documented requirements to be satisfied by a material, design, product or service and also a type of technical standard.

In the utility industry we see specifications presented in many different formats.  As a result, it is very important that a specification be clear and easy to follow.  Be careful about providing multiple specifications and documents that start contradicting one another. In these wordle_2situations the Owner’s requirements and overall message can get lost in a sea of documents resulting in different interpretations by the suppliers.  This can ultimately lead to proposals that can’t be compared properly, Owners not getting what they want, or additional unforeseen costs. When it comes to fabricating substation and transmission steel structures there are many variables that need to be relayed during the design, detail, and fabrication phases.  These specifications provide that direction.  Whether you are using an already created specification, updating a previous version or crafting a brand new one, there are certain sections you want to include.  Below are 9 sections that are not to be missed when deciding the content for your specifications. 

  1. Purpose/Scope – This is the heart of the document.  This is the owner’s chance to define the purpose of the document and clearly layout their expectations for the scope of work.  Example: Intended to serve as a system wide guide for structural design of steel structures.
  2. References – This section typically lists out the required design standards and any other applicable documents.   (e.g. ASTM Standards, ASCE Design Stanards, etc.) 
  3. Submittals – This section typically covers the owner’s expectations of any document to be submitted by the supplier.  This includes things like bid proposal requirements listing out the needed forms and design summaries.  It also covers formal design and drawing submittal requirements.
  4. Loading and Geometry – If the scope of work includes design, this section typically covers the minimum information needed by the Structure Designer to design the structures.  This would include things like loading criteria, unique weather conditions and terrain for the service area, and any other usual loading conditions the designer should consider.    This section also covers the different structure types, general layout of the structures, and the types of connections permitted.  (e.g. slip-fit vs. flange, embedded vs. base plated)
  5. Design – This section typically includes any restrictions to the design, material, field erection, fabrication, etc.  Examples of this include anchor bolt circle limits, minimum material thicknesses allowed, deflection limits, aesthetic preferences, weight limitations, etc.
  6. Fabrication – This covers owner’s expectations of workmanship and quality. 
  7. Finishing/Coating – What type of coating is supposed to be used such has galvanizing, painting, sandblasted, etc.
  8. Inspection – This section typically covers the type of inspections and testing required for the project. 

Of course these are just a few of the main sections.  There may be other sections that pertain to your specific product need, corporate formalities and/or industry.  No matter what your final Specification Document instills, it is important that you and those that use them agree on what is expected from a product and/or service.  This form of communication between the two parties can be a key component to a successful project.

How do you communicate your expectations to your vendors?  We would love to hear from you so please leave a comment below and let us know if this information has been useful.

Pole Design References

Tags: substation design, specific standards for structures, Engineering, design of steel transmission pole structures

Two ASCE Must-Have References for Transmission & Substation Design

Posted by Brooke Barone on May 29, 2013 4:28:00 PM

Whether you’re a seasoned Engineer or still working on your P.E., there are a few ASCE must-haves when it comes to designing substations and transmission structures.

The first reference, Substation Structure Design Guide, also referred to as ASCE Manual 113, was first published in 2008 and is the first of its kind for substation design. The second must-have is the Design of Steel Transmission Pole Structures, also known as ASCE Standard 48-11.

Now let’s see how good you are…

Do you know the main difference in the two? (Besides the obvious that one is intended for substation design and the other for transmission pole.)

Well, if you said one is a guide and the other is a standard then you are correct! It should be addressed that while guides, standards and codes are all used, there is a difference between them.

ASCE

There is a level of importance that falls with these, meaning that if a guide contradicts a standard, the standard typically wins, and if a standard contradicts a code, the code typically wins.

The substation design guide is currently being updated along with a handful of other design guides, standards and codes.  Jennifer Gemar, Vice President of the Engineering Department at DIS-TRAN Steel, is on the ASCE 113 Design Committee which is responsible for revising the guide, and has a few updates from the latest meeting that was held in the Houston area last month. 

The plan is to have the revision ready for submittal to ASCE by late 2015.  Since this is the guide’s first time going through a revision, it will remain a design guide with the thoughts that it will eventually become a design standard through enough revisions and time.  Overall, it seems the guide has been well received throughout the industry, especially being the first time published.  It has quickly become a “go-to” book, and a great reference and training tool for newer engineers.  It’s pretty much straight forward, and has general definitions of equipment and types of structures found inside a substation.  The fundamentals are basic, and while it points in the right direction when designing, it doesn’t actually give the formulas to design the steel structures.

 The second book, ASCE Standard 48-11, was published in 2012 as a revision to the ASCE Standard 48-05, that was first published in 2005.  This standard replaced the ASCE Manual 72, which at the time, was the main design reference for transmission pole structures.  The standard outlines the minimum criteria that must be considered in the structural design, fabrication, testing, assembly and erection of these type structures.  Unlike the substation guide, ASCE 48-11 explains how to design steel poles and their corresponding connections.  There is a committee currently updating this standard as well.

It’s important that these references stay updated as knowledge and experience permits.  It’s also beneficial to be active on one of the committees responsible for these updates.  Though it can be hard work, it can also be a very educational with opportunities to contribute and shed light on problems or issues that need addressing.

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Tags: steel structures, DIS-TRAN Steel, transmission, asce manual, asce 113, pole structures, substation design, asce standards, asce, high voltage substation structure design

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