Pressure ratings 2

[Spyral]

Anyone have a formula or know of another way to get the pressure rating of std steel pipe? I have to find out the rating on a piece of 3/4" XXH blk pipe.

Thanks!

 

[lookintomyeyes]

Pipe Pressure ratings appear to be based off of ANSI/ASME B31.1.
For example,

http://www.sorinc.com/usefulInfo_pipeSize.stm#A106 Grade B Carbon Steel

gives info similar to that which you are looking for.

However, if you are designing a system, you would usually know the pressure and temperature of the system and consult with a reference book to select the most appropriate type of pipe for the job.

 

[BigInch]

Pipe pressure allowables depend on the code you intend to use for the design of the piping system. All codes DO NOT allow the same pressures. Pipeline codes do not even allow the same pressure for the same pipe used in different area classes. Determine which code you will use, then find the appropriate formula for the allowable pressure for your material and temperature.

Going the Big Inch!

http://virtualpipeline.spaces.msn.com

 

[pipexp]

Pressure rating is generally based on pressure rarting of flange connected to the pipe. In ASME B 16.5 pressure-temperature rating with respect to material of the flange is available. Considering maximum pressure and temperature applicable for the piping system you can find out suitable pressure rating for the flange if you know the material. There after considering maximum pressure of that particular pressure class you can find out thickness for the pipe.

 

[BigInch]

pipexp,

Only the flange pressure ratings are based on flange pressure ratings. The pipe could be designed for any other pressure rating one choses. There are many systems that have no need to be designed to a specific flange rating pressure. There are many pipelines designed for maximum allowed operating pressures of 500 psig, 800 psig, 1000 psig, 1200 psig etc.

Going the Big Inch!

http://virtualpipeline.spaces.msn.com

 

[Ashereng]

pipexp and BigInch are both correct.

Flange pressure ratings are based on flange pressure ratings.

Yes, it is also common to have a pipe rated to the same pressure as the flange.

This is one of those intra-discipline arguements where both sides understand what the others is saying, and for the most part are in agreement, just not the exact wording.





"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[BigInch]

Right, no argument intended. Its just a case of one man's rule is another man's exception, in which case, I don't see the point in stating it as a meaningful value in any sense other than being just another of many possible limitations. And ... it does leave one wondering what to do in the case of completely welded systems or in cases where B31.5 does not apply.

My maximum allowed operating pressure limits are decided by economics rather than B31.5 values.

Going the Big Inch!

http://virtualpipeline.spaces.msn.com

 

[Cockroach]

But why would anyone want to design a system where the pipe performance is different from the flange ratings?

And why would any designer unnecessarily let economics drive the cost of the end product?

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

 

[BigInch]

If you want to pay for 1467 miles of pipeline designed for 1460 psig (ANSI#600), when you really only can ever need 800 psig to transport the maximum flow you're ever going to get our of your oil patch and can justify doint that to your stockholders, by all means try it. You'll have a very short life either as a CEO or as an engineer working for one.

Going the Big Inch!

http://virtualpipeline.spaces.msn.com

 

[Zapster]

What does Spyral's question about 3/4" XXH pipe have to do with 1467 miles of pipe line? BigInch, your comments are correct for a pipeline; however, they have less to do with a 3/4" XXH pipe. Most pipelines use a pipe specification specifically detailed for the given line’s requirement. In contrast, most 3/4 inch pipe design materials are selected per company’s standard pipe specifications that are based on the flange rating and service.

 

[BigInch]

Zapster,
I was answering the question immediately above my answer.

But why would anyone want to design a system where the pipe performance is different from the flange ratings?

And why would any designer unnecessarily let economics drive the cost of the end product?

Going the Big Inch!

http://virtualpipeline.spaces.msn.com

 

[JLSeagull]

Different piping standards would apply to transportation; ASME B31.8 gas and B31.4 liquid. Money and safety considerations apply to most projects.

Within the B31.3 work, process engineers may assign the piping specification from the available contractor or client selection list. The basis is the fluid composition, pressure, temperature, etc. The selected piping specification identifies the pipe schedule for each size line as well as some valve specification code, etc. This normally works well with little real engineering; - a sort of 80:20 thing.

Eveything looks the same on a P&ID. Some of the senseless details are only noticed in the field with the "full-scale" model. When the piping size was reduced from 16 NPS to 12 NPS near a block valve it is noticed if the valve is 16 NPS instead of 12. The CEO rarely hears about such details. However, we should pay attention to all of these details during design.

Oh, yes the piping wall thickness may be tapered on cross country pipelines.

 

[BigInch]

JLSeagull, Thank you. And right.. you are. Sometimes the MAOP on a mountain top is 20 Barg psig and in the valley, 100 Barg. The BTC Pipeline goes from 0 to 2800 meters in elevation, (we call it) "telescoped" and (I believe) is using at least 9 different wall thicknesses.

Going the Big Inch!

http://virtualpipeline.spaces.msn.com

 

[Cockroach]

Wow BigInch, 1467 miles of 3/4 inch XXH pipe. I missed the "1467 miles" part in SpyRal's original post and subsequent responses. Sounds like a real moneymaker project!

I would of expected something like 48 inch or 60 inch pipeline for such a distance, you know, the Alyaska big bore stuff. But your response certainly explains why the XXH wall is needed on the 3/4 inch pipeline, 1467 miles long. What kind of compressor would you specify to get a viscous working medium, like crude oil, over the peaks of the Rocky Mountains? What kind of cost to build such a pipeline and where what kind of financial returns could be expected in the present market place? Must have just a huge end user, aye?

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

 

[BigInch]

BTC is 42.

Look, what's the problem? This thread went off topic a long time ago. If you don't like off-topics, you can ignore them.

Did you not ask?

But why would anyone want to design a system where the pipe performance is different from the flange ratings?

And why would any designer unnecessarily let economics drive the cost of the end product?

I think those questions were answered, and without mentioning any specific wall thickness or diameter for that matter.

Do you have another question?

Going the Big Inch!

http://virtualpipeline.spaces.msn.com