Pipe Span and Required Deflection

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16 years 1 month ago - 16 years 1 month ago #4553 by 2ndMoment
Replied by 2ndMoment on topic Jop, Too true! It is maximum pipe
Jop,

Too true!

It is maximum pipe span or conversely minimum number of supports per length of pipe.

Thanks

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15 years 10 months ago - 15 years 10 months ago #4640 by banerj1s
Replied by banerj1s on topic Thanks for the post 2nd
Thanks for the post 2nd moment. B31.1 is more stringent than B31.3. Most of the span charts that flood the web is for Oil and Gas Industry. For Power the allowable sagging is more stringent and the allowable sustained deflection is less. The factor that governs is the sustained stress. More the span more is the sustained stress that in turn increase the pipe stress under operating condition. So if the thermal stress is not too much ie the pipe operates under less temperture and pressure there is a room to increase the pipe span.
I dont know how the vibration frequency affects the sustained stress. I would appreciate if you throw more light on this part of the subject.

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14 years 5 months ago - 14 years 5 months ago #5389 by shrivallabha
Replied by shrivallabha on topic Re: Pipe Span and Required Deflection
Perhaps more stringent deflection in 31.1 than 31.3 also has to do with the life expectancy of the power plants which is significantly higher than process / chemical plants.

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14 years 4 months ago - 14 years 4 months ago #5443 by Mike Vezina
Replied by Mike Vezina on topic Re: Pipe Span and Required Deflection
On the subject of piping spans.
The petroleum industry has a standard of 1/2" to 3/4" maximum deflection, depending on the owner.

mnv

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13 years 3 months ago - 13 years 3 months ago #5836 by AbhijitN
Replied by AbhijitN on topic Re: Pipe Span and Required Deflection
All efforts to route a line considering Safety/Operation/Maintenance/Cost etc is a waste if you don not take care of supporting that line effectively.
Such an huge importance for pipe supports but I feel very bad when I see pipers not considering pipe supporting seriously.

Pipe supporting is called more oftnly as an art & I feel that, it is very very true when you are actually dealing with it...!

Let us talk about only dead load & let us not consider pressure / temp conditions etc initially to understand it.
- Make use of the pipe support span charts available on your project. (Engineering from macro level is no more done now a days. The well accepted things have been documented already to make use of them in similar cases & normally called as company standards.) You will definately have these support span charts in the company.
- Pls take care of the dead loads of the line considering the fluid (liquid/gas) flowing inside the pipes for all the lines. Higher is the dead load lower will be the span between the two supports. (Support standard must have been already developed by considering this logic)
- For stress critical lines you will get advised from stress engineer for supporting location changes needed to the line submitted line.

Simple logics to keep in mind while you are dealing with pipe supporting-
- Route a line in such a way that you will make use of the main steel (building steel, rack steel) etc. for pipe supporting. by just taking care of this simple rule you will save lots of money by avoiding new steel in the plant for pipe supports.
- Supports from equipment are also possible but we need to think of it very early so that we can take care of the pipe loads at the equipment design stage itself. Communication to the equipment vendor is also very crucial till the end of the project.
- Ideally, every point load acting in the pipeline need to be supported for ex- Valves/control valves etc.

Pipe supporting is very difficult to explain & one will learn it through his experience..& there is lot to learn in Piping.
Thnx

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