Steaming Piping for Removal
Steaming Piping for Removal
(OP)
We are looking at steaming a line that is used for normal pentane service. The line will be fully evacuated (drained) but we want to steam it to removor flammable vapours and liquid residue. Questions I have are:
-any method to calculate amount of time we need to steam the line? What info do I need (steam tables?)
-how would someone vent the line so it doesn't collapse under full vacuum (piping might be able to handle full vacuum)?
-hooking up to steam the line, need a valve to block off the steam connection?
Thanks
-any method to calculate amount of time we need to steam the line? What info do I need (steam tables?)
-how would someone vent the line so it doesn't collapse under full vacuum (piping might be able to handle full vacuum)?
-hooking up to steam the line, need a valve to block off the steam connection?
Thanks





RE: Steaming Piping for Removal
RE: Steaming Piping for Removal
Any worries about draining the condensate that accumilates in the line? Or do you think the steam pressure (80 psig) will be able to push the condensate through the pipe line.
Problem with nitrogen is that it would not vaporize the pentane left in the line.
Why would the steam velocity need to be 3 ft/sec?
Thanks.
RE: Steaming Piping for Removal
We use warm nitrogen from a pumper truck eqipped with a heater (if we want to work on the line and then put it straight back into service).
RE: Steaming Piping for Removal
The condensate created during initial warm up can be fairly significant in some cases, but your steam will keep it hot push it out of the way to the extent needed to get through. If you N2 dry then you can get the rest during dry out. Pressure and depressure at low points is the best way to dry, but operators rarely have the time for this so they usually leave it as a continuous blow which can take longer.
The two hazards with condensate are: 1) hot condensate can burn, so be sure to direct the discharge drain safely away rather than blowing wildly; 2) introducing large volume of uncontrolled steam into a cold line can create a long slug of fast moving condensate which can hammer and even rupture a pipe. The latter hazard is why you want to use a 1" steam hose, and warm the pipe up in a controlled manner. If you are steaming from a steam hose station which has a valve to control the steam flow, then you don't really need one at the pipe you are steaming.
These are just my opinions from general experience with preparing equipment, others may have different experience. best wishes as always, sshep
RE: Steaming Piping for Removal
"Geordie87" offers good advice on vacuum limitations, however, he was not specific enough in his limitations on piping.....
You do not have to worry about vacuum collapse of carbon steel or SS piping of at least 12"NPS and smaller when it is Schedule 40 or greater.
Schedule 10S and 5S piping systems are another matter, however
_MJC