×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Bolting for Duplex Stainless Steel Flange
2

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.

RE: Bolting for Duplex Stainless Steel Flange

SS 304 can crack (CSCC) in an atmosphere with high chloride (eg marine atmosphere)
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

If you are really concerned you should use duplex or Ni alloy bolts.  Yes they are expensive and a pain, but they will do the job right.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

RE: Bolting for Duplex Stainless Steel Flange

strider6,

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

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.

RE: Bolting for Duplex Stainless Steel Flange

Careful if considering nickel 718 to ensure it is in accordance with API 6A718 and that they are not over-torqued, and that the hardness is 100% checked to be below 35 HRc, otherwise they could crack if there is any CP near...

Z100 super duplex would work also and is commonly used for bolting.

Riadsala
Metallurgist in the Offshore O&G industry

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources