Condensate Line Erosion
Condensate Line Erosion
(OP)
I'm trying to prevent erosion in an elbow in our condensate line. I read an article of the National Board of Boiler and Pressure Vessel Inspectors about increasing plain carbon steel to a low chromium alloy.
Has anyone had any experience with erosion in the elbows of condensate lines and did they ever change to a different material other than carbon steel.
Has anyone had any experience with erosion in the elbows of condensate lines and did they ever change to a different material other than carbon steel.





RE: Condensate Line Erosion
Sizes included 6" and up to 18" I believe. This was in 1988.
RE: Condensate Line Erosion
First I'd remove a sliver of the elbow and find out how much Cr it has. There is a big diff. between erosion-corrosion (now simply called wear) rates for a Cr level of .02 and .10%.
Once you know what level of Cr you have, together with your wear rates, you can attempt to determine how much Cr you'll need.
You might get by with 1 1/4Cr (P11), or even a selected carbon steel that contains close to the max. allowable Cr.
RE: Condensate Line Erosion
Regards,
RE: Condensate Line Erosion
FYI my plan goes something like this:
I examined all the variables including Dissolved Oxygen,pH, temperature, pressure and flow and have conclude that I can't really change any of them so I'm looking into the velocity, geometry and materials.
The velocity could be changed by increasing the pipe size or the pipe geometry (elbow close to control valves) could be changed but for the space available it looks like a material change is probably my best bet.
Thanks.
RE: Condensate Line Erosion
Condensate (LPG ?)
thanx
RE: Condensate Line Erosion
I have piping replacement experience at a nuclear power plant with "flashing heater drains".The situation is similar to your elbow problem
This plant had problems over a number of years (17 total)with the feedwater heater drain piping going to the plant's main condenser. The 3 and 4" NPS piping was eroding away at the extrados of the downstream elbows.
After evaluating several possible soultions that involved material substitution, piping reconfiguration etc. The piping consultant recommended replacement of the Schedule 40 carbon steel system (ASTM A106 GradeB) with one of 2-1/4 Chrome- 1 Moly (ASTM A335-P22). This material substitution was recommended by several other power plants. For good measure, schedule 80 material was used.....
The consultant also evaluated and recommended 304L/316L piping as it also offered erosion resistance. In what are called "boiler blowdown" tanks at fossil fired plants, a 304SS insert is used to protect the tank interior from flashing flow.
The SS material was not selected for the piping system based on the additional cost over the P22...........
I recommend that you evaluate using threaded P22 or SS elbows.....in sched 80 if you can afford them. Periodically replace the elbows as they wear..
My opinions only
MJC