Steam Distribution Piping

[simplemath2]

I would like your support for the following problem:

My two questions are regarding aboveground outdoor steam distribution piping approximately 2km in length. Pressure is 17.5bar.

1. Between B31.3 and B31.1, which one will be the best design code?
2. In pressure loss calculation, crane fluid book are employed. In this process, I did not find any procedure to consider the condensation of steam and its resulting positive pressure driven force. Could you advise me related method we can employ regarding this to make the piping sizing a little less conservative?

I searched this wonderful forum and could not find specific answers.

Any comments are appreciated. Thanks.

 

[ColonelSanders83]

ASME B31.1 is applicable to steam piping as follows:

B31.1 Power Piping: piping typically found in electric power generating stations, in industrial and
institutional plants, geothermal heating systems, and district heating and cooling systems. B31.1 has
requirements for
• Piping for steam, water, oil, gas, air and other fluids
• Metallic and nonmetallic piping
• All pressures
• Temperatures greater than -29ºC (-20ºF)

There may be local juristictional legal requirements you need to look into, they more will than likely invoke B31.1 for steam at the pressure you listed.

As to you second question we use the crane values.


Always remember, free advice is worth exactly what you pay for it!

 

[katmar]

Regarding the condensate - the usual practice is to use sufficient steam traps so that the line can be regarded as vapor only.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[DSB123]

I have worked on several petrochemical plants where the distribution steam system has been designed etc to ASME B31.3. If the Client does not specify or there are no "local" rules then it's up to you as to whether you use B31.1 or B31.3. Personally for distribution systems away from the boiler extents and what is categorised as boiler external pipework I would go for ASME B31.3

 

[ione]

I will go for ASME B 31.1

http://www.engineeringtoolbox.com/asme-b31pressure-piping-d_39.html

Further to condensate, Katmar got the point: be sure your line is fitted with enough steam traps and adequate drainage.

 

[DSB123]

ione,
Have a look at the link you posted and what the Codes cover. B31.1 "Boiler external pipework" and B31.3 steam is listed in the piping systems covered. Steam distribution systems are not "Boiler External piping" hence B31.3 is the more logical choice.

 

[BigInch]

Good intro to steam piping peculiarities,

http://www.kirsner.org/pages/training.html

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[ione]

DSB123,

Well, it was obviously just my opinion, but since ASME B 31.1 does not apply to:
• economizers, heaters, pressure vessels, and components covered by Sections of the ASME Boiler and Pressure Vessel Code;
• building heating and distribution steam and condensate piping designed for 15 psig [100 kPa(gage)] or less, or hot water heating systems designed for 30 psig [200 kPa (gage)] or less;
• piping for hydraulic or pneumatic tools and their components downstream of the first block or stop valve off the system distribution header;
• piping for marine or other installations under Federal control;
• towers, building frames, tanks, mechanical equipment, instruments, and foundations.
And we are talking about a pipeline with steam at 17.5 barg (approx 254 psig), I do not seen any violation of the code.

Moreover

B31.1 Power Piping: piping typically found in electric power generating stations, in industrial and institutional plants, geothermal heating systems, and district heating and cooling systems. B31.1 has
requirements for
• Piping for steam, water, oil, gas, air and other fluids
• Metallic and nonmetallic piping
• All pressures
• Temperatures greater than -29ºC (-20ºF)

B31.3 Process Piping: piping typically found in petroleum refineries, chemical, pharmaceutical, textile, paper, semiconductor, and cryogenic plants, and related processing plants and terminals. B31.3 has requirements for
• Piping for all fluid services
• Metallic and nonmetallic piping
• All pressures
• All temperatures

I have never stated “You must use B 31.1”. Both B 31.1 and B31.3 should be suitable. You probably prefer B 31.3 as by your own admission have dealt with petrochemical plants, where B 31.3 finds a wide application.

 

[BigInch]

Those systems in the B31.1 list do have piping directly associated with boilers.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[DSB123]

ione,
Appologies as I obviously hit a raw nerve.

 

[ione]

I apologize if my reply seemed somewhat stern, I didn’t mean to offend anybody. I have just expressed an opinion and tried to support it. As already said in the past, I have always more to learn than to teach., and I am always ready to change my mind if I am wrong.

 

[stanier]

Two texts I recommend to you are:-

Efficient Use of Steam Oliver Lyle

Steam Trapping and Venting Northcott & Barber

These were the bibles 35 years ago. Steam has not changed much in that time.

I find it strange that you have used an SI unit for pressure yet refer to ASME B31.1. Are you in the USA? Is there perhaps a local standard you should be using? Just curious.

 

[Gator]

BigInch, Kirsner's stuff is excellent. Tech people are not supposed to get emotionally involved but "What Killed Jack Smith" brought a tear to my eye.

 

[BigInch]

Yes it is really good. Perhaps what tech people need most IS some emotional involvement in their work.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[Gator]

Now you're making me cry Dennis...

Software that you have no control over tends to lead to a state of apathy, n'est ce pas?

 

[racookpe1978]

If he's going over several kilometers, how do you treat the steam traps (condensate drains from them actually) when going up and down hills? Drain, collect and pump? Seems the condensate would be subject to freezing, need cleanout sumps and tanks at every low spot.....

(Hasn't affected me in previous work, since all of my traps and drains, condensate, cooling etc have inside a single plant. Just being curious about traps in the great outdoors where I would be unable to control "floor level" of the drain system.)

 

[nhliew]

I have worked on a plant where steam is produced from a biomass (processed oil palm kernel)-fired boiler and piped about 1.7km to the process area. We had one trap set at 150ft intervals. Drained condensate from the traps was not recovered. But that's in Southeast Asia where it is warm all the time and the boiler fuel costs next to nothing.

 

[MJCronin]

racookpe.....

Condensate collected from steam distribution systems is frequently not recovered due to the expense of the return piping system.

Condensate collection from steam piping systems going uphill and downhill is not a problem if steam is collected in short drip/drainlegs as has been done for eons...

http://www.velansteamtraps.com/challenge/dripleg.aspx

It is also a good idea to generate steam with a little bit of superheat in long distribution systems to decrease the production of condensate.

My opinion only...

-MJC

 

[eadwine]

As for the Code requirements, there are boundary limits as to where they apply. In the Codes and Owners std./spec's.

Now for condensate removal from steam headers, they're called drip legs which hookup to continous drainers, condensate pumps, flash tanks, steam traps, etc. All depending on condensate load and what one is trying to do with the condensate. As for the installation and location of drip legs, that is dependent on cond.load and Header layouts.

For a full blown analysis of the problems and solutions of condensate removal, see the Armstrong Machine Works site and above all contact a rep..