stainless steel pipe spans

[FG3]

Hi all,
I'm looking for pipe span information. I need to know the maximum unsupported spans of 12", 14" and 16" stainless steel pipe, and at what wall thickness. The pipe will carry air at 214 F. Does anyone know of a good resource for this information?

 

[MikeHalloran]

Pipe is quite heavy in those diameters, and not necessarily needed if the air is at low pressure. But you didn't tell us the pressure. Depending on that, tube or duct might be appropriate.

If the pipe is mobile, e.g. in a ship, additional considerations having to do with the dynamics, and class rules, would apply. If it's stationary, the unsupported span is usually not entirely arbitrary, e.g. it may be hung from structural members in a building, and those may need modification to support the extra weight.

Is there a chance of human contact with the heated pipe? Or is the heat not free? ... in either case you would probably want to insulate the pipe, to avoid liability or to save money respectively.

The request for info about several sizes suggests that you are designing a system, and really should engage the services of a local engineer.



Mike Halloran
Pembroke Pines, FL, USA

 

[BigInch]

One question for us and 10 for you.

What is your design code? What type of stainless? What's the internal pressure? Do you have wind, snow and or ice? Do you have seismic loads? What are the minimum and maximum ambient and operating temperatures, (max alone won't do by itself for calculating thermal stresses)? Is there thermal insulation weight? Will there be temporary loads during maintenance or inspection? Any valves in the span? Will the pipe ever be hydrotested, or retested at sometime in the future or have any possibility of containing anything else but air?

http://virtualpipeline.spaces.msn.com

 

[FG3]

Mike,
There is no chance of human interaction at the point in question. The piping will be spanning across two tanks and will be open to the air above. The system I am designing is for a diffuser grid in a tank. The 12", 14", and 16" piping are branches off of a main 32" stainless steel header which is insulated. The pressure at the blower outlet is 9.0 psig. I estimate that the minimum pressure at the points in question will be ~ 7.7 psig. It has to be 316L stainless steel pipe because it is a municipal specification. Some of the piping will be submerged. I have similar span information for carbon steel piping, however, I know that stainless is lighter and I need to know what wall thickness the pipe will need to be to span 35' unsupported. Does that narrow it down any?

 

[BigInch]

If its submerged, add buoyant loads. Most steel pipe above 8" diam with air inside floats.

http://virtualpipeline.spaces.msn.com

 

[FG3]

Big Inch,
I'm not concerned about the submerged portion because that part will be supported. What I'm saying is that between the two tanks I have open space where the pipe will be unsupported. I'm simply wondering how far I can span the pipe between supports.

Thanks,

 

[pipingdesigner]

FG3,

I can't link you to span charts at the moment, but briefly:

Size 12"
Sch 5S
Span (M)
Pipe/Flg Pipe/flg/water Pipe/flg/lg Pipe/flg/lg/water
15.6 9.0 13.4 8.5

Size 12"
Sch 10S
Span (M)
Pipe/Flg Pipe/flg/water Pipe/flg/lg Pipe/flg/lg/water
14.9 9.1 13.1 8.6

Size 12"
Sch 40S
Span (M)
Pipe/Flg Pipe/flg/water Pipe/flg/lg Pipe/flg/lg/water
15.6 11.4 14.4 10.9

Size 14"
Sch 5S
Span (M)
Pipe/Flg Pipe/flg/water Pipe/flg/lg Pipe/flg/lg/water
15.0 8.7 13.1 8.3

Size 14"
Sch 10S
Span (M)
Pipe/Flg Pipe/flg/water Pipe/flg/lg Pipe/flg/lg/water
15.3 9.3 13.6 8.9

Size 16"
Sch 5S
Span (M)
Pipe/Flg Pipe/flg/water Pipe/flg/lg Pipe/flg/lg/water
16.2 9.1 14.3 8.7

Size 16"
Sch 10
Span (M)
Pipe/Flg Pipe/flg/water Pipe/flg/lg Pipe/flg/lg/water
16.5 9.5 14.6 9.1

I hope this is what you require ... the all easily span 35 feet (~10.5M).

pipingdesigner

http://www.pipingdesigners.com

 

[NozzleTwister]

There is a lot more to this than just "will it span?"

My biggest concern about letting the pipe span the distance is high moments causing possible overstresses at the branch connections to the larger header and local stresses in the pipe wall at the support points if there are any. Supports locations should be evaluated for the need of shoes or a wear-pad.

When evaluating your system, don't forget wind loading, seismic, tank settlement and hydrotest if any of these are applicable.

I recommend you have an experienced Piping Engineer evaluate this system for you.

Good luck,


NozzleTwister
Houston, Texas