Steam - Tracing or double-pipe 1

[ruikp]

For heating a pipeline with steam, is there a simple definition/procedure to decide the use of a double-pipe or tracing?

Is there a site where I could read more of these (already tried a few, but didn't found what I'm looking)?

Thanks in advance

 

[DSB123]

ruikp,
When you say double pipe do you mean a jacketted pipe system (i.e. inner product pipe with an outer heating medium pipe)? Also you mention a "pipeline" which to me signifies a long line. If it is a "pipeline" then perhaps steam may not be the most economic method of heating.

 

[ruikp]

DSB123,
Yes, I meant jacketted pipe. And its not really a pipe-line, but it's a line with about 100 meters. The problem is that we have cut the pipes to put another entry in the line. In means the outside was cut off and we became without jacket in a small part of the line. So, I'm wondering if its enough to put some tracing in that part (about 1 m) or we have to make a jacket again. And the problem is that the substance becames solid at around 90ºC.

 

[unclesyd]

Do you require heating on the branch connection?

How was the existing jacket terminated when you cut it for the branch connection?

Is the branch connection configured, welded or flanged?

Here is the Controls Southeast site, a very good site for information concerning heating pipe by different means. Look at CSI University Tab for comparison of the different heating technologies.

http://www.csiheat.com/home.aspx

 

[ruikp]

Qo you require heating on the branch connection?
A:Yes. But it was decided to let it traced.

Q:How was the existing jacket terminated when you cut it for the branch connection?
A:According to the site you mentioned, it was swaged jacketed piping.

Q;Is the branch connection configured, welded or flanged?
A:Welded.

Thanks for the info so far!

 

[BigInch]

Unless its a new project, the method usually depends on what's most readily available. You wouldn't normally want to install a boiler to get steam for a 100 m pipe, so electric is typically the easiest.

"I am sure it can be done. I've seen it on the internet."

"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.live.com

 

[ruikp]

Big,
My question is more about - would tracing be enough? So, I'm looking for something like: If process fluid solidifies at 90ºC, for a 3" pipe one tracing line/two tracing line/jacketed line/etc is enough. We have steam available and we also have some electric tracing available, but this last is very energy costly, when compared to vapor.

 

[BigInch]

Like I say, it's an availability question. A lot of people don't like the cost of installing and operating a boiler just to make some pipe heat, so electric is often easiest, but if you're making steam close by, then steam is typically cheaper.

For a 3" pipe maybe the difference in payback time of either option isn't worth the calculation to figure it.

"I am sure it can be done. I've seen it on the internet."

"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.live.com

 

[Duwe6]

Another possibility is Hot Oil Trace. You can get up to 250-deg C without any pressure other than what it takes to circulate the oil. Using a small C-shaped fluid conduit, you can get a lot of wetted surface area for direct, contact transfer.

Problem with jacketed pipe is that the carrier and jacket must have very similar coefficients of expansion, or else put in expansion joints on each pipe spool.

 

[ash9144]

Since you removed jacketed pipe you need to put jacketing back on the pipe. The tracing won't provide enough heat. Especially if the line is down for awhile and solidifies your tracing won't melt that section.

I saw this issue on a sulfur pipeline where someone replaced a small section of pipe and just traced instead of rejacketing. Caused huge headaches for about 8 months until we finally just tore out the tracing and rejacketed.

 

[ruikp]

Duwe and ash, thank's for your input. About the expansion coefficients, we already took those in mind. Tha ash experience, might be very usefull for a decision.

 

[StressGuy]

I agree with Ash. You are really going to want a full jacket to provide the carrier pipe with a sufficient uniform temperature to keep the product from solidifying, especially with a 90°C freezing point.

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.