[MW:15028] RE: 15027] Sulfidation and High Temp H2/H2S Corrosion

Hi Gopala Krishna,

The correct document is API-RP-571 not NACE 571.For sulfidation the good
references would be API -RP-939C or NACE International Publication 34103,
Overview of Sulfidic Corrosion in petroleum refining. Sulfidic corrosion
(sulfidation i.e. formation of iron sulfide) is well recognized in refining
industry. Steel alloys containing 5% chromium (Cr) or greater (i.e., 7% Cr,
9% Cr, and 12% Cr, in this order), were found to have increasing resistance
to sulfidic corrosion and are better suited alloys to prevent such attack.

High temperature hydrogen attack is a different phenomenon. API RP-571
Clause 5.1.1.5(as stated before) describes the problem, root causes,
mitigation and inspection/damage assessment techniques.

HTHA attack, can happen in two forms:-

a) surface decarburization, and
b) internal decarburization and fissuring.

You get better and extensively detailed description of this problem in API
RP-941, including the design parameters, material restrictions etc.

Hope this would help.

Thanks

P.Goswami, P.Eng, IWE
Welding & Metallurgical Specialist
Ontario, Canada,
pgoswami@quickclic.net
pgoswami@sympatico.ca




-----Original Message-----
From: materials-welding@googlegroups.com
[mailto:materials-welding@googlegroups.com] On Behalf Of Krishnnaa26
Sent: Sunday, August 05, 2012 9:46 PM
To: Materials & Welding
Subject: [MW:15027] Sulfidation and High Temp H2/H2S Corrosion

What are minor / microlevel diffrences between Sulfidation and High Temp
H2/H2S Corrosion wrt NACE 571 4.4.2 and 5.1.1.5 except the role of H2? Can
anybody post web resources on this topic?

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