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RE: Seismic Piping Question

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I agree with your assessment of the current state of the design (or lack of) when it comes to piping components and bracing. In the nuclear industry, engineers design it all. In the hospitals of California, there are engineers that design piping. In the world of "normal" industrial and commercial buildings, there is often a void that is often left unfilled.

I would also suggest that the ISAT be considered as a good tool. ISAT has done what NUSIG attempted to do a while back.

Harold Sprague

From: "Haan, Scott M." <HaanSM(--nospam--at)>
Reply-To: <seaint(--nospam--at)>
To: <seaint(--nospam--at)>
Subject: RE: Seismic Piping Question
Date: Thu, 3 Jun 2004 18:20:18 -0800

I do not think many people understand the impact of the question that is raised in this thread. Knowing when piping is exempt from IBC component bracing design requirements is important. I believe most building departments are not well versed in IBC 1621 architectural, mechanical and electrical component bracing requirements. When they get savvy, watch out if you do not have component bracing design exempted from your scope of work. The most important sections to know are the ones that tell you when seismic restraint is not required. Deformability of the pipe determines some exemptions to component seismic bracing.

The SMACNA Seismic Restraint Manual outlines the mechanical and structural engineer's responsibilities. I would not rack your brains over when the piping has high deformability, it is the mechanical engineers responsibility to give you this information if you ask. Ask the mechanical engineer.

I have heard some mechanical engineers argue that they include general notes and indicate in their specifications that the mechanical and plumbing stuff needs to be braced per the SMACNA Seismic so why have any detail on the plans. I am sorry but relying on a note to brace stuff per the SMACNA Seismic Manual ensures that the component bracing requirements will not be met on smaller projects most of the time, even if you have a IBC 1705 quality assurance plan [which gets overlooked on smaller projects by building departments most of the time too].

The SMACNA manual is relatively easy to use and straightforward. It has standard details where the bracing member sizes and connections are picked out of schedules based on the a "seismic hazard level" which is determined from the IBC seismic coefficient. If you have to design bracing for duct work or pipes - buy the SMACNA Seismic Restraint Manual, put some sheets together with standard SMACNA details / notes and then put the schedules relevant to the details on the sheets - easy cheesy. Throw this on your plans and there is not much thought involved. I also recommend having a generic IBC 1705 quality assurance plan that can have the stuff that is not needed cut out of.


Scott M. Haan P.E.
Deputy Building Official

Municipality of Anchorage
Development Services  Department
Mission Statement: Guide safe construction and responsible development for the community.

-----Original Message-----
From: Christopher Wright [mailto:chrisw(--nospam--at)]
Sent: Monday, May 17, 2004 9:10 AM
To: ?
Subject: RE: Seismic Piping Question

>Basically, how do I determine the deformabilty of a piping system to
>know whether or not it's a high deformability, limited deformability,
>or low deformability piping system?
You may be in over your head here. Piping is considered under ASME/ANSI
B31.n, the n depending on the kind of system, refrigeration, refinery
what-have-you. It's nothing like the approach used for buildings. You
should look at the piping codes for guidance and rules covering external
loads; the combination requirements and thermal expansion are especially

Christopher Wright P.E.    |"They couldn't hit an elephant at
chrisw(--nospam--at)        | this distance"   (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)

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