Bolting for Duplex Stainless Steel Flange
Bolting for Duplex Stainless Steel Flange
(OP)
Hi,
Generally, I applied B8 (SS304) bolting for duplex stainless steel flange bolting. I think that this has no problem.
However,
I think that B8 bolting is not suitable if the bolting is in the environment that Chloride Stress Corrosion Cracking could occur.
Someone recommended to use B7 (1.0Cr-0.5Mo) bolting.
However,
In my opinion,
Application for B7 bolting could cause galvanic corrosion between low alloy steel and duplex stainless steel.
Is it right?
what is the solution for this problem if it was right?
At this point of time, it is difficult to apply the isolated kit for bolting.
Generally, I applied B8 (SS304) bolting for duplex stainless steel flange bolting. I think that this has no problem.
However,
I think that B8 bolting is not suitable if the bolting is in the environment that Chloride Stress Corrosion Cracking could occur.
Someone recommended to use B7 (1.0Cr-0.5Mo) bolting.
However,
In my opinion,
Application for B7 bolting could cause galvanic corrosion between low alloy steel and duplex stainless steel.
Is it right?
what is the solution for this problem if it was right?
At this point of time, it is difficult to apply the isolated kit for bolting.





RE: Bolting for Duplex Stainless Steel Flange
The suggestion of Cr-Mo bolts is correct provided they are hot dip galvanized.
If if you look in Norsok specification for piping, L 001, they specify STUD BOLT C/W NUTS A193 B7/A194 2H
with Surface protection, "All low alloyed steel bolts, nuts and washers shall be hot dipped galvanized according to ASTM A 153."
http://www.standard.no/imaker.exe?id=1355
hope this help
S.
http://www.corrosionist.com
RE: Bolting for Duplex Stainless Steel Flange
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Plymouth Tube
RE: Bolting for Duplex Stainless Steel Flange
I don't understand how hot-dipped galvanized low alloy steel bolts are expected to provide long service life when in contact with high chromium content steels in a marine environment. Are they supposed to be replaced at regular intervals?
Regards,
Cory
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RE: Bolting for Duplex Stainless Steel Flange
http://
http://www.bufab-stainless.se/eng/teknisk_1.htm
RE: Bolting for Duplex Stainless Steel Flange
Z100 super duplex would work also and is commonly used for bolting.
Riadsala
Metallurgist in the Offshore O&G industry