SS to LTCS flanged connexion
SS to LTCS flanged connexion
(OP)
I have an equipment made of SS304L with nozzle flanges I need to connect to LTCS piping, according to project piping class.
I'm guessing some precautions are required to prevent corrosion contamination on my equipment... or maybe not... any advice?
Processed fluid is waste water / sludge.
Thanks for your help.
I'm guessing some precautions are required to prevent corrosion contamination on my equipment... or maybe not... any advice?
Processed fluid is waste water / sludge.
Thanks for your help.





RE: SS to LTCS flanged connexion
http://www.apsonline.com/gasket.html
RE: SS to LTCS flanged connexion
Sometimes people might internally coat for a distance of 10x diameter as this will greatly reduce the current flow through the fluid and reduce the potential for galvanic corrosion - this would be an alternative to the insulating gasket.
The extent of the problem would be dependent on the relative mass of carbon steel vs stainless steel. If there is a large amount of carbon steel piping then the galvanic corrosion may not be significant enough to cause a problem but it is better to err on the side of caution.
RE: SS to LTCS flanged connexion
Carbon steel and stainless steel do not have a significant galvanic couple between them and are not far enough apartin the galvanic series
An insulating flange kit/design is not required when there is a a bolted connection between carbon steel and stainless steel. This is additional cost that is not necessary.
As a reference, I cite the book "Defects and Failures in Pressure Vessels and Piping" by Helut Thielsh.
http:/
-MJC
What are your references,
RE: SS to LTCS flanged connexion
1) the difference in galvanic potential between the materials
2) the specific properties of the process fluid (the electrolyte)
3) the difference in relative masses of the metals in contact
i'll leave it to the OP to evaluate these factors and the responses received to decide if they feel action is necessary or not.
RE: SS to LTCS flanged connexion
If you want references, try:
http
BS PD 6484
For this statement, you may be looking at stainless steel in its ACTIVE state, i.e. it is corroding in the electrolyte anyway. In its passive state, the stainless steel will have a significantly different electrode potential which can drive bimetallic corrosion in carbon steel.
As rneill points out, the proposed arrangement presents a risk of bimetallic corrosion and it is up to the responsible party to assess that risk and remove or mitigate it if it is deemed necessary to do so. Mitigation could simply be an 'inspect and replace' policy for the carbon steel piping, for example.
Steve Jones
Materials & Corrosion Engineer
http://www.oilandgaspeople.com/cv/11499664
http://www.linkedin.com/pub/8/83b/b04
RE: SS to LTCS flanged connexion
I also wanted to double check ISO 21457, the NORSOK Materials Specifications and a couple of my reference texts, but alas I don't think I'm going to have the time in the next while to dig through this.