×
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

What makes a Carbon Steel HIC Resistant?
4

What makes a Carbon Steel HIC Resistant?

What makes a Carbon Steel HIC Resistant?

(OP)
Could anyone explain what makes a Carbon Steel HIC Resistant?

I am involved in a relatively small fabrication in the UK, where the materials of construction are specified as ASTM A333, A350 LF2, P355, A420 WPL6 but the materials are also specified to be "HIC resistant Carbon Steel".

What steps do we need to take to ensure this requirement is met?

Thanks in advance

RE: What makes a Carbon Steel HIC Resistant?

The HIC resistant steel plates are a special product order that involves melting practices resulting in low sulfur contents (usually less than 0.002 w%).

Without getting into too much detail, the following publication by Bethlehem Lukens describes their HIC-Tested pressure vessel plate steels.

www.bethsteel.com/customers/pdfs/pressure.pdf

RE: What makes a Carbon Steel HIC Resistant?

In addition to low sulfur, keeping strength/hardness down (below ~ 23 HRC) is considered an important feature for steel that is used in hydrogen-containing environments.

Regards,

Cory

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

RE: What makes a Carbon Steel HIC Resistant?

CoryPad has the right criterion. Hardness is the single key factor that must be controlled. I would be more conservative than CoryPad. I would say HRC 22 max.

RE: What makes a Carbon Steel HIC Resistant?

NACE International has recommended practices for testing HIC resistance (NACE TM0284-2003). A corresponding DIN standard is DIN EN 10229. In the oil&gas industry it is not uncommon to specify that materials meet a certain performance level in those tests (or variations of those tests). see http://www.techstreet.com/cgi-bin/detail?product_id=1086107 for a brief descirption and orering info for the NACE doc.

RE: What makes a Carbon Steel HIC Resistant?

mcguire,

Thanks for your concurrence.  Just to clarify, if we maintain two significant digits, then < 23 HRC IS 22 HRC max.  This number is a guideline, but low sulfur, low segregation, and low grain size all allow higher hardness material to be used.

Regards,

Cory

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

RE: What makes a Carbon Steel HIC Resistant?

Adding to CoryPad's insights, I add that HRC 22 max ( i.e less than 23) is a maximum number. Failure is possible at lower hardness levels if microstructure causes lower toughness. Also this threshold decreases to lower hardness as temperature decreases.

RE: What makes a Carbon Steel HIC Resistant?

The maximum hardness cited above is pertinent to sulfide stress cracking typical of excessively hard heat affected zones of welds in sour oil&gas production and processing. Similar problems occur in refining environments, although the refining guys often (or at least used to ) use a different hardness criteria.  However, the hardness limit will not prevent hydrogen induced cracking (HIC) manifested as blistering or step-wise cracking that has an appearance similar to lamaellar tearing.  HIC can occur remote from welds and is typically associated with the presence of pancake shaped sulfide stringers.  Low sulfur and inclusion shape control are the most common method of preventing HIC.

RE: What makes a Carbon Steel HIC Resistant?

I should have added that even though sulfide stress cracking and the related hardness limit is ofetn a welding issue addressed through carbon equivalent limits and appropriate welding procedures, the cracking problem can certainly occur remote from welds if the hardness is too high and adequate stresses are present.

RE: What makes a Carbon Steel HIC Resistant?

For severe sour service, I would highlight more on the top of what has been correctly mentioned in this thread the calcium treatment (CAB, CaSi wire) to control the inclusion shape during steelmaking process as it improves a lot the HIC resistance. As a matter of fact, through this method the typically MnS sulfide stringers are then tranformed into globular shape, and this morphology is really advantageous for HIC resistance. In order to have a correct and balanced heat analysis for this purpose, one should require the ratio of Wght.%Ca/Wght.%S to be in the range of 2 to 3.

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