Mike and Chris both have part of the HIC picture (although this is a
subject very difficult to "prove" a mechanism in). Essentially what
happens is that the hydrogen atom, being very small and mobil, works
into the crystal structure, and either 1) stresses a previously strong,
stable, crystal, leading to failure at the smallest level of crystal or
2) forces a change in the crystal structure (i.e., from a BCC to a FCC
or other combinations), resulting in a material change (austenitic to
ferritic?), in that particular crystal or region of crytals, and often
releasing energy that induces changes adjacent to it.
I did a fair amount of study on hydrogen formation back in my nuke days. Some level of hydrocarbon cracking or even water hydrolysis happens all the time. Conditions aggravate it. Some materials are apparently catalysts to inducing it.
The mechanisms of SIC are quite different. A good reference on it is "Corrosion handbook" by HH Uhlig.
... Bruce D. Bullough ...
Sebesta Blomberg & Associates, Inc.
2381 Rosegate
Roseville, MN 55113 USA
+ 651-459-6659
www.sebesta.com
-----Original Message-----
From: Michael Waugh [mailto:mike@waudesign.com]
Sent: Thursday, May 13, 2004 8:31 PM
To: <a href="/group/PipingDesign/post?postID=vgSj79xszgfwbcig2SSlMlujW3HHFSRYzFzOOTwJ-w5FDVxkuP3P7KW5efwFhOpaEIP0RBSMZlbjLGDS-74NCo8C">PipingDesign@yahoogroups.com</a>
Subject: RE: [PipingDesign] Cracking [text][bcc][faked-from][bayes]
Rakeesh:
It has been some time since I visited this subject, but I'll stick my
neck out anyhow. Hydrogen Induced Cracking (HIC) and Sulphur Induced
Cracking are a result the formation of hydrogen ions formed through
various means in the material. Hydrogen ions will react with the
material, I believe causing the formation of various acids, metal oxides
and sulphates etc. The chemistry here is quite vast but are largely
dependent on the many conditions, heat, water, steam, pH etc that you
encounter in processes.
Relatively speaking, you cannot prevent it from occurring, it will
occur.
You can only go to higher cost materials, lined piping, anticorrosion
devices to reduce the likelyhood of it causing failures in your
processes.
Mike
-----Original Message-----
From: Rakesh Patil [mailto:rpa@lntenc.com]
Sent: Thursday, May 13, 2004 10:59 PM
To: <a href="/group/PipingDesign/post?postID=vgSj79xszgfwbcig2SSlMlujW3HHFSRYzFzOOTwJ-w5FDVxkuP3P7KW5efwFhOpaEIP0RBSMZlbjLGDS-74NCo8C">PipingDesign@yahoogroups.com</a>
Subject: RE: [PipingDesign] Cracking [text][bcc][faked-from][bayes]
Dear Bruce,
Thanks for your resonse. I have a background of material science. But
when I checked HIC from my superiors, I found some controversy. One told
me that it happens when hydrocarbon flows in CS pipes due to formation
of
CH4 which generally occurs at welded joints and results in a crack.
whereas another told, it happens when a fluid (hydrocarbon) passing
through pipe enters inside the gaps between bonds (metal composition)
which forms a crack after certain period.
so can you please suggest me which one is correct? I have not searched for it on net but will do it simultaneously. About Sulphur Cracking, I am not getting anything. can you please suggest me any paper or literature available on the same.
cheers,
rakesh
Rakesh:
This is rather complex and not conducive to an e-mail, unless you want to limit the discussion to "it's bad" and "use the right material for the service to avoid it". I have corrosion and materials texts and took courses on solid-phase chemistry and materials science of corrosion to get a basic understanding. Have you done thorough on-line searches (like Google) to get some basic information? Do you have a background in solid-phase chemistry and material science?
... Bruce D. Bullough ...
Sebesta Blomberg & Associates, Inc.
2381 Rosegate
Roseville, MN 55113 USA
+ 651-459-6659
www.sebesta.com
-----Original Message-----
From: Rakesh Patil [mailto:rpa@lntenc.com]
Sent: Wednesday, May 12, 2004 8:44 PM
To: <a href="/group/PipingDesign/post?postID=vgSj79xszgfwbcig2SSlMlujW3HHFSRYzFzOOTwJ-w5FDVxkuP3P7KW5efwFhOpaEIP0RBSMZlbjLGDS-74NCo8C">PipingDesign@yahoogroups.com</a>
Cc: <a href="/group/PipingDesign/post?postID=vgSj79xszgfwbcig2SSlMlujW3HHFSRYzFzOOTwJ-w5FDVxkuP3P7KW5efwFhOpaEIP0RBSMZlbjLGDS-74NCo8C">PipingDesign@yahoogroups.com</a>
Subject: [PipingDesign] Cracking [text][bcc][faked-from][bayes]
Hi All,
Can anybody guide me about Hydrogen Induced Cracking (HIC) and Sulphur Induced Cracking. What is the basic concept of it and How it can be tested and rectified.
regards,
rakesh
[Non-text portions of this message have been removed]
<a href="http://www.pipingoffice.us/">http://www.pipingoffice.us/</a> =========================================Main site: <a href="http://www.pipingdesign.com">http://www.pipingdesign.com</a>
Yahoo! Groups Links
<a href="http://www.pipingoffice.us/">http://www.pipingoffice.us/</a> =========================================Main site: <a href="http://www.pipingdesign.com">http://www.pipingdesign.com</a>
Yahoo! Groups Links
[Non-text portions of this message have been removed]
<a href="http://www.pipingoffice.us/">http://www.pipingoffice.us/</a> =========================================Main site: <a href="http://www.pipingdesign.com">http://www.pipingdesign.com</a>
Yahoo! Groups Links
<a href="http://www.pipingoffice.us/">http://www.pipingoffice.us/</a> =========================================Main site: <a href="http://www.pipingdesign.com">http://www.pipingdesign.com</a>
Yahoo! Groups Links Received on Fri May 14 09:11:00 2004
This archive was generated by hypermail 2.1.8 : Tue Mar 04 2008 - 11:40:34 EST