Len-IDEA
Posted on behalf of Bob Smith, RMF Engineering, bob....@rmf.com; 800-938-5760:
A district energy provider has experienced an unusual pattern of degradation in its direct buried condensate system. The pipe was installed with a nonmetallic outer jacket with insulation adjacent to a companion steam pipe. The steam system operates at 100 psi. The outer jacket of the steam and condensate pipe has been damaged and both pipes have subsequently been exposed to groundwater.
While this is not uncommon, the condensate pipe has completely rusted through on the top half of the pipe from the outside in. The bottom half is still in good condition and the inner surface of the pipe is still in good condition. See attached pictures. The pipes were installed in the mid 90’s. Has anyone else seen this type of failure and determined a cause?
Rundle, Gordon
Where was the condensate pipe in relation to the steam pipe? (i.e. 12 , 3 or , 6 o’clock?)
Gordon Rundle
Engineering Project Manager
366 Kentucky Ave, Indianapolis IN 46225
Office / Fax 317.693.8854
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Ontiveros, Juan M
Bob
I suggest sending this to a metallurgist for analysis. If the corrosion is from the outside then the insulation barrier probably failed and allowed whatever soil condition along with the ground water to corrode the exterior of the pipe.
There are many variables:
How good is the deaerator. Is it allowing oxygen to ride on top of the pipe which caused a pin hole on top which then destroyed the insulation which then let the ground water in?
Was the pipe installed correctly with backfill that did not destroy the insulation?
If the pipes are not installed properly the pipe movement could have damaged the insulation.
I have now exceeded what I know about this.
Juan
From: distribut...@googlegroups.com [mailto:distribut...@googlegroups.com]
On Behalf Of Len-IDEA
Sent: Wednesday, May 11, 2016 5:01 PM
To: Distribution Forum <distribut...@googlegroups.com>
Subject: {Distribution Forum} Unusual pattern of condensate pipe corrosion
Posted on behalf of Bob Smith, RMF Engineering, bob....@rmf.com; 800-938-5760:
A district energy provider has experienced an unusual pattern of degradation in its direct buried condensate system. The pipe was installed with a nonmetallic outer jacket with insulation adjacent to a companion steam pipe. The steam system operates at 100 psi. The outer jacket of the steam and condensate pipe has been damaged and both pipes have subsequently been exposed to groundwater.
While this is not uncommon, the condensate pipe has completely rusted through on the top half of the pipe from the outside in. The bottom half is still in good condition and the inner surface of the pipe is still in good condition. See attached pictures. The pipes were installed in the mid 90’s. Has anyone else seen this type of failure and determined a cause?
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Hugh Bahar
Never seen that before.
Hypothesis:
Check this out RE vapor phase corrosion-scroll down to the second page: http://www.woodgroup.com/SiteCollectionDocuments/news-tech-articles/2011-06_Cond-Corrosion-Modeling-ISOPE_WGIM.pdf
If the above happened and provided the mechanism for perforation, the hole would tend to be in the top half of the condensate return pipe. Saturated vapor would emit from the perforation and subsequently condense inside the non-metallic jacket. The leaking vapor would tend to collect in the top half of the jacket and condense, accelerating top-of-pipe corrosion as condensate pH is about 5.5 if not treated with an amine. Once the jacket was degraded from increasing vapor loss as corrosion progressed, ground water was introduced, accelerating corrosion.
Once the vapor began finding its way out of the jacket, it degraded the adjacent steam line jacket until it perforated as well, subsequently exposing the steam line to steam, condensate and ground water.
Just a hypothesis…until a more informed answer is provided.
Hugh
From: distribut...@googlegroups.com [mailto:distribut...@googlegroups.com]
On Behalf Of Len-IDEA
Sent: Wednesday, May 11, 2016 6:01 PM
To: Distribution Forum
Subject: {Distribution Forum} Unusual pattern of condensate pipe corrosion
Posted on behalf of Bob Smith, RMF Engineering, bob....@rmf.com; 800-938-5760:
A district energy provider has experienced an unusual pattern of degradation in its direct buried condensate system. The pipe was installed with a nonmetallic outer jacket with insulation adjacent to a companion steam pipe. The steam system operates at 100 psi. The outer jacket of the steam and condensate pipe has been damaged and both pipes have subsequently been exposed to groundwater.
While this is not uncommon, the condensate pipe has completely rusted through on the top half of the pipe from the outside in. The bottom half is still in good condition and the inner surface of the pipe is still in good condition. See attached pictures. The pipes were installed in the mid 90’s. Has anyone else seen this type of failure and determined a cause?
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