Support spacing Sch 10 pipe

[slayman]

I did a quick search for support spacing recommendations and find plenty for sch 40 and up but not Sch 10.
Does anyone know of a reference for this info?

Thanks

Scott Layman

 

[Montemayor]

slayman:

Schedule 10 pipe is not a common application in the carbon steel version. If you're talking 10s (stainless version), then you have many applications in the milk, beverage, and food processing industries. Any recommendations on the support spacings is probably going to be proprietary: either from a contractor or an operating company. If I had to guess on a reasonable spacing, I would say 8 ft assuming 2" pipe filled with water. I'm accustomed to not employing any size smaller than 2" on a pipe rack.

 

[slayman]

Thanks Montemayor, I should have mentioned stainless, 3" to be exact and we are using it for a compressed air system.
We will be sharing a pipe rack with other services (pneumatic conveying and cooling water) in an injection moulding facility. Considering the other service, we are not likely to require the amount of support that they will but.....I am not sure what size lines they are running.

slayman

 

[codeeng]

Generally pipe support spans are governed by deflection, usually 1" max. Deflection is calculated by this equation:

5 x W x L^3
-----------
384 x E x I

W = weight full of water or fluid whichever is heavier
L = span
E = Elastic modulus
I = Moment of inertia

 

[Frank1344]

hi,

for 3" sch.10S we used 21'-6" for straight span with 3/4" maximum deflection.
Faraz
WorleyParsons MEG
Calgary, Alberta

 

[CRG]

codeeng,
Why is there a factor of 5 in the numerator?
Is this for a single span or continuous straight run?

 

[codeeng]

CRG
Supported both ends, evenly distributed load.

 

[CRG]

slayman,

Pipe support spacing can be divided into two main categories. The following is the maximum deflection of these two main categories in inches (Ref, “Piping Handbook”, by Crocker & King):

y1. Single span, free ends. Note: Spans adjacent to changes in direction (lateral or vertical) or more than 30 deg should be considered as single spans with free ends.

y2. Continuous straight line.

y1 = 22.5*W*L^4/(E*I)

y2 = 4.5*W*L^4/(E*I)

E = modulus of elasticity at service temperature, psi
I = moment of inertia of pipe, in^4 (based on the nominal pipe wall thickness less the corrosion allowance and the mill tolerance)
L = length of pipe span in, ft
W = Wp + Ww + Wc, lbf/ft
Wp = weight of pipe, lbf/ft
Ww = weight of fluid in pipe, lbf/ft
Wc = weight of covering, lbf/ft

Note: codeng’s equation is the same as y1 when the above referenced equations are made dimensionally homogeneous. Also, the equation codeeng posted is for a single span with free ends. It is my understanding most pipe support spacing tables are based on continuous straight runs and not the single span, free ends.

Help clarify this if the “Piping Handbook” referenced above gives the incorrect formulas. I have used the referenced equations to validate the commercial pipe stress program that I use and it matches the output of the program.

Also note that if the pipe is connected with flexible couplings (such as Victaulic, push joints, etc.) that the above referenced formulas are not valid.

 

[TD2K]

Just curious, why are you using SS for instrument air lines, I've commonly seen galvanized carbon steel pipe used for this.

 

[jonesey]

TD2K,
I've seen both stainless steel and galvanised carbon steel pipe for instrument air lines. Depends on what you want. with a stainless steel system you can have a completely welded construction and minimise use of flanges. With a galvanised carbon steel system you typically weld CS components together and then hot dip galvanise them afterwards. The length of spools is therefore dependant on the size of the galvanising bath the contractor has. This typically gives spools in the 8-10m length. This type introduces more flange in your system with the possibility of leakages. When you consider the cost of stainless steel against carbon steel which is then galvanised tthe price difference is not as large as you think. We use glavanised carbon steel headers with instrument tubing from the headers in stainless steel.

Slayman,
you don't mention if your installation is new or existing. If you are installing a new instr. air header on existing pipe support spacing i would consider the use of an intermediate support using a piece of ss angle iron and a u-bolt clamped to an adjacent line to help support the new ss line. As regards a new installation remember that you could install temporary supports when testing the ss line if you find out the span does not match those of your CS lines. We never test instrument air lines with water as it is nearly impossible to get them dry afterwards. We only service test them for leaks.

 

[carthago]

My opinion only.


I believe there is a table in ANSI B31.1 ( Power Piping)
which gives with some conservatism the allowable piping span for cases such as :
-pipe filled with gas or steam
-pipe filled with water
---------------------
Several criteria could/shall be considered for pipe supports:
- Deflection to avoid ( condensation)
- Limiting the bending stress to allowable.
- Also: minimize effect of vibration
- l imit flange rotation (and hence: leakage)
- limit loads on equipment ( pumps)
- Minimize structural loads at some locations...
----------------

The factor ( 5/384) is for a beam simply supported with ä uniform load Q.
This a bit conservative.

I have read somewhere that formula used for pipe support is AVERAGE of beam with uniform load simply supported AND fully clamped.
The load is:
Q= pipe + liquid + insulation weights [N/mm ]or[lb/in]

 

[slayman]

Thanks for all of the responses.
We are using the stainless steel because of the customers preference. Mostly aesthetics I think. At their European facility they used "plastic" pipe for the CA system and had problems with it.
As it turns out the other services in the rack require more support than we do so we will be fine.
On this project we will be using grooved joint connections with rigid couplings for the loop and a crimp type connection for the 1 1/2" drops.