Caution : Repeated PWHT may be harmful due as P22 material is prone to reheat cracking...
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-- On 26 February 2013 09:12, Dhinesh <dhinesh.theking@gmail.com> wrote:
According to me ASME B-31.1 does not have any limitations on HBN for P-22 metals. ASME B-31.3 has specified the limiting value of 241 HBN for P-22 weld metals (Table 331.1.1 Requirements for Heat Treatment).
The hardness of the weldment could be changed if we use any wrong electrodes. Local hardness could be affected by surface preparation also.
Repeating the stress relieving procedure can be think off to bring the hardness as per the standard.
While surfing in internet, I found this also. This may help.
"Since the material (A335 P22) is highly hardanable after welding, you can try with the following precautions/ restrictions to reduce the hardness level.
• Use increased preheat i.e. 250ºC
• Follow temper bead technique as suggested in QW-290 of ASME Sec. IX.
• Post heat immediately after welding – 250 to 300º C for 1 hour and cover the weld area with thermocool in order to reduce the cooling rate.
• Qualify welding procedure with E8018-B3L / ER80S-B3L (low carbon grade) instead of E9018-B3/ ER90S-B3 to reduce chromium/molybdenum carbides, which will increase the hardness of the weld.
Note: Though B31.3 & Sec. VIII Div. 1 allows upto 13mm or 16mm without PWHT, most of the client specification calls for PWHT for all thicknesses for this material due to more prone to hydrogen induced cracking and highly hardanable (air hardening) after welding. Check once again for the requirement of PWHT.
Hope some other experts can detail it more.
On Saturday, February 23, 2013 10:13:48 AM UTC+4, mohamed jubair wrote:--Dear all
After PWHT I want to check the hardness of the weldment,heat affected zone,parent metal of the welded joints. What is the brinell hardness value for the below two materials.
Material
SA 335 P22+SA 335 P22
Size
960 X 50 mm
Material
SA 106 Gr A+SA 106 Gr A
Size
540 X 62 mmAwaiting for reply
Thanks & Regards
Jubair
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C. K. Purohit
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