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Pressure Drop on EXPANSION BELLOWS for Steam Line 6

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ROMEOMC

ROMEOMC

Mechanical
Oct 14, 2020
3
I am designing a Steam Transmission Pipeline having approximately, 1.5km length. The steam Pipeline is Medium Pressure, 12Bars, saturated, 10" Pipe size, ASTM A106GrB, STD, above ground Piperack.
In some pipe location, I need to change the pipe direction to suit pipe routing/land-space availability.

1. Can I [highlight #FCE94F][/highlight]apply an anchor point to the elbow(mitered or 90deg,[highlight #FCE94F][/highlight] to control the expansion direction, quantify expansion length and thereby position/locate my expansion bellow/pipe loop.

2. I am considering two(2) options to handle the pipeline thermal expansion:
2.a Install an Expansion Bellow
2.b Install an expansion loop​

To decide which of the two, I need to determine the pressure drop as comparison. Which of the two has less pressure drop?​

Appreciate your kind/prompt comment.
T/r, Romeo
 
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Your decision should not depend on minimizing pressure drop, as that is solely a flexibility and stress problem. You will minimize required space but, you will also maximize maintenance with the expansion bellows. Generally it is advisable to use a loop if at all possible.

Reality used to affect the way we thought. Now we somehow believe that what we think affects reality.
 
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Hmmmm. You would need to ask the bellows vendor as bellows are a strange thing to calcualte pressure drop. I assume you mean axial bellows?

The equivalent length of a loop can be calculated by adding four elbows plus the offset length of pipe x 2.

But bellows are not easy things to contain in an axial direction

I would let the bend move myself but only if you use an elbow. Mitred joints shouldn't be being used in such a service IMHO. the SCF is horrendous.

Needs a good stress analysis run on the whole thing.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
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6 elbows is the usual for a horizontal loop, unless it is a lone pipe, so as not to intersect adjacent pipes, or block future runs of parallel pipes, make the loop in a different horizontal plane. You also get a lot more flexibility. Vertical loops can avoid those 2 ells, but then support of a vert loop is far more complex.

Reality used to affect the way we thought. Now we somehow believe that what we think affects reality.
 
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Hi RomeoMC,

Yes, you have to ask expansion joint supplier. I think, it will be almost the same or close to 4 elbows expansion loops.
Usually, in a long run, you do not save anything by installing expansion joints. It is because no matter what you do, they all leak and need replacements. On a long pipe bridge like this (1.5 km = 5,000 ft long) there are other costs to consider like condensate return line. Are you planning a condensate return line too?

Thanks,
Curtis
 
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By the way, you don't mention the temperature. Kind of nice thing to know about steam lines.

Reality used to affect the way we thought. Now we somehow believe that what we think affects reality.
 
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Non of operators and engineers would usee expansion bellows inn succh a steam line.
The best to use the expansion loops in horizontal if possible. However you need to add condensation pots along the line at suitable locations not to cause ultimately failure in the line due to the condensate.

 
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Dear All,
Thank you for the comments and replies.

(1)
The reason for considering the use of both, Expansion Bellows and Pipe Loops, is that, at certain locations of the pipeline, the pipe shall pass through a limited space wherein pipe loop is not applicable. While for installing pipe loops, there is substantial space for that arrangement. So, both are considered.

(2)
The pressure drops are needed to be known, since, from the steam source to the delivery point(after 1.5kms) the receiving unit can only work satisfactorily, if the pressure shall be 10bars. So, a maximum of less than 2 bars pressure drop is acceptable.

At this point,I already sent inquiry to Expansion (metallic) Bellows suppliers to provide data.

Thank you once again & regards...Romeo Consolacion

 
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Looking up T in steam tables is not MY job!

If pressure drop becomes critical enough to prohibit loops, you should most probably use a larger diameter. Splinti is trying to give you many years of his experienced advice. "No operators and engineers would use expansion bellows in succh a steam line."

Reality used to affect the way we thought. Now we somehow believe that what we think affects reality.
 
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twentytwo said:
Looking up T in steam tables is not MY job!
Click to expand...

It takes less than 30 seconds to look it up online...is that really that onerous?
 
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In case the internal is left corrugate the following migh help;


However you may find the following information helpful:



Please note that type of expansion bellow is absolutely important. The espansion joints lined internally will give you the least pressure drop similar to pipe. However all of the expansion joints seem to collect condensate which will be big problem for operation. You can search the failure types with a search engine.

Hope it helps
 
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Tici4 Have at it. I'll give you the star.

Romeo, thats great that you didn't buy the bellows yet.


Reality used to affect the way we thought. Now we somehow believe that what we think affects reality.
 
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Dear All,
Thank you for the continued comments & helpful tips.

My apology if I missed to include data that can give immediate idea on the problem.

[highlight #FCE94F]Is it acceptable to apply anchor point on this steam line at the elbow of the pipeline[/highlight] [highlight #FCE94F]when it changes direction[/highlight]?
Best regards,

Romeo Consolacion[bigsmile]
 
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I would not. Elbows already have stress intensification factor and I would not go further than that. However you can use guides close to change of directions,This may provide you the stiffness you are after if i may understand correctly since you have not given us a kind of indication where and how the anchor will be, perhaps skeches would be more effficient.
Please note that every support may need to be looked after separately since you will not provide exact dimensioning and support arrangementt, I asume.

Some cases trunnion supports are used at elbows but this may/may not be suitable for your case I do not have any clue.
Your questions are not specific and focusion on an individual location unfortunately.

Hope it helps.
 
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Why put an anchor at a location/region that you just tried to make flexible by locating a loop or bend there.


Reality used to affect the way we thought. Now we somehow believe that what we think affects reality.
 
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If you can find a copy of "The Piper's Pocket Handbook" by Rip Weaver, it has a number of simple calculations (with examples) that you can use as a quick-check method for most piping flexibility problems. It also has a caveat that if the calculated value is greater than 0.03, you should perform a more detailed analysis.

I've used the information in this small, inexpensive soft covered book a number of times in past lives to determine things like how long I needed
to make the legs on an expansion loop, and it always worked for me.
 
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