×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Exterior Steam Piping

Exterior Steam Piping

Exterior Steam Piping

(OP)
What is typically done to prevent freezing on exterior steam lines? I may need to run about 800' of 4" steam and 2" condensate across a flat roof.  What do I need to do to prevent freezing, especially in the event of a power failure?  Job is in Chicago.

RE: Exterior Steam Piping

A good insulation system and adequate trapping should get you there.  The insulation thickness will depend on the operating and ambient temperatures as well as the type of insulation.  Calcium silicate is fairly common.  Metal jacketing should be applied, with sealant, to prevent water from getting into the insulation.  Also along those lines, I'd suggest a 2 layer epoxy phenolic paint system be appiled to the piping if it's carbon steel and operates at or below 300F.  That's probably not the case unless you've got very low pressure steam.

Make sure the lines have no (un-trapped) pockets and are sloped towards traps.  The traps should be located at the bottom of "boots" where condensate can collect from the main flow of steam.  

RE: Exterior Steam Piping

dtn6770 has provided very good info.
I am not familiar with commercial projects, but if your project is heavy industry than you must select appropriate jacketing.  If the environment is corrosive than a stainless stl jacket is warranted.  If not corrosive than an aluminum jacket is suffice.

RE: Exterior Steam Piping

As mentioned good insulation, well maintained, is essential. I would use SS covering with SS tie wire for the insulation clamshells.
Based on my limited experience the biggest problem is keeping the steam traps from freezing. Hopefully someone from the cold country will jump in and offer a solution.

Here in NW Florida freezing traps bit us twice.  Both incidents caused plant wide shutdowns that were quite expensive.  

RE: Exterior Steam Piping

Proper trapping is essential, of course nothing will freeze unless there is a steam shut-down or no flow in the condensate line.
In this case the traps on the steam line must be piped correctly AND have gravity drainage (no vertical lift after trap)
For the condensate line, there is a 'freeze protection' valve that basically opens when the temperature reaches a lower limit.  This must also be piped to a gravity drain.
Sarco makes this as well as Ogontz, for the latter look at: http://www.ogontz.com/products/freezeprotection.htm

RE: Exterior Steam Piping

Try adding electrical heat tracing under the insulation.

RE: Exterior Steam Piping

We operate in Canadian winters with steam lines, some 600# and some 100#.

Slope steam mains to drain boots which are trapped to the condensate line.  We use mineral wool on low pressure, cal sil on high pressure.

The condensate lines should be insulated and steam traced with stainless tubing.  The steam tracing itself is trapped back into the condensate line.

The traps are capable of operating with some lift, dependent of course on the steam pressure.  Our condensate main is 20' higher than the condensate trapping manifold.

We have removable insulation blankets on the thermodynamic traps.  The Spirax TD42 trap has been a particularly good performer for me.  We have hundreds of them, and it is a rarity to freeze one up, even at -30C.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources