Hi Jose,
Here are some brief responses to your queries on P-91/T-91 Steel:-
1. Weather Section II/ Part A/ SA 335/10.1.1 is meant for parent materials & B31.3 /Table 331.1.1 is for weld materials after heat treatment?
· Yes ,SA-335 applies to base materials in heat treated condition (265HV max), in N&T condition. While B-31.3 /Table 331.1.1 specified hardness of 253 HV is after welding and PWHT. If the as received hardness is 265HV then meeting 253 HV after welding and PWHT would be extremely difficult.
· SA-335 specified tempering temperature range for this material is 730-8000 C, while B-31.3 recommended PWHT temperature range for these welds is 704–760 0C. If hardness after PWHT is a requirement then it’s always advisable to get the material tempered at higher temperature and perform PWHT @ temperatures below or close to tempering temperature. Should one has to perform PWHT above the tempering temperature in order to meet hardness , then the microstructural balance of P-91 steel would get disturbed and may affect the long term service performance (creep rupture properties) of this steel.
2. Is anywhere other than here hardness values(Weld metal, HAZ & Parent metal) are mentioned?—What’re the design codes and specifications involved for your application ? For P/T-91 other than ASME codes you would finds hardness restriction clauses in the following documents:-
· NACE MR-103- Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining Environments-248 HBW Max
· API TECHNICAL REPORT ,938-B- Use of 9Cr-1Mo-V (Grade 91) Steel in the Oil Refining Industry-Recommended maximum allowable hardness is 248 HBW for process applications and 275 -300 HBW for electric utility services.
3. Can anyone tell me hardness values (at WM, HAZ & PM) of commonly used materials of parent material group numbers P1,P4,P5 etc.....—
· If your query is on hardness requirement as per B-31.3 code after welding and PWHT, then see table 311.1.1. For other applications you have see the individual codes. Usually hardness restriction is a service requirements, to avoid/ lessen environmental assisted cracking, predominantly various types of SCC. Since ASME is followed by all types of industries, hardness requirements or restrictions are not incorporated as a general rule.
Hope this would help to clarify your query. If you have any further queries on P/T-91, feel free to drop a line. Correct specification is very important for this steel, then fabrication and other issues are lot easily solved.
Thanks.
Pradip Goswami, P.Eng.
Welding & Metallurgical Engineer/Specialist
Ontario Power Generation Inc.
Email-pgoswami@sympatico.ca,
pgoswami@quickclic.net
-----Original Message-----
From: materials-welding@googlegroups.com
[mailto:materials-welding@googlegroups.com] On Behalf Of JOSE SEBASTIAN
Sent: Wednesday, July 21, 2010 5:56 AM
To: Materials & Welding
Subject: [MW:0] Hardness Values at Weld Metal, HAZ & Parent Metel
Dear Friends,
It is mentioned in ASME Section II Part A,SA 335 10.1.1 that the maximum hardness value of T91 materials should be 265 HV, Also in ASME B 31.3
process piping Table 331.1.1 Requirements for heat treatment it is mentioned that the maximum hardness value should be 253HV for P5 group(T91).
My questions are..
1.Weather Section II/ Part A/ SA 335/10.1.1 is meant for parent materials & B31.3 /Table 331.1.1 is for weld materials after heat treatment?
2.Is anywhere other than here hardness values(Weld metal, HAZ & Parent metal) are mentioned?
3.Can anyone tell me hardness values(at WM,HAZ & PM) of commonly used materials of parent material group numbers P1,P4,P5 etc.....
Regards
Jose Sebastian
+919687660525
--
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to
materials-welding-unsubscribe@googlegroups.com
For more options, visit this group's bolg at
http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and
meant for educational purposes only, Users must take their own decisions
w.r.t. applicable code/standard/contract documents.