Brinell Hardness
Brinell Hardness
(OP)
Hi All
How is acceptable hardness values determined for material/HAZ/weld metal on API 650 tanks? The material is ASTM A 516 Gr 70 and PWHT to API 650 is done due to wall thickness.
Should this have been determined during weld procedure qualification or does published acceptance ranges exist? Some petrochem companies limit the hardness to 200 Brinell, but API 650 specify Rockwell C 22 (~237 Briness) max for HIC conditions.
Any tips?
How is acceptable hardness values determined for material/HAZ/weld metal on API 650 tanks? The material is ASTM A 516 Gr 70 and PWHT to API 650 is done due to wall thickness.
Should this have been determined during weld procedure qualification or does published acceptance ranges exist? Some petrochem companies limit the hardness to 200 Brinell, but API 650 specify Rockwell C 22 (~237 Briness) max for HIC conditions.
Any tips?





RE: Brinell Hardness
if the tank is in HIC service, you could look at NACE MR 0175 or 0103 for guidance, though these are mainly for pressure retaining equipment (eg. vessels).I'm not a metallurgist, but hardness can be directly related to tensile strength, the higher the hardness, the higher the tensile strength.In HIC equipment, the hydrogen attack can occur in areas of high hardness (eg. weld HAZ).If the weld hardness is a lot greater than the parent metal, it would make sense that the hardness would mean preferential attack in the HAZ.I would say tht the ideal situation would be to get the parent material/HAZ/weld hardnesses as cloe to each other as possible.API also referneces the material specs in ASTM, review these, hardness values may be listed.The 22C hardness value listed in API 650 for HIC tanks can be found in the NACE documents.
John
RE: Brinell Hardness
http://www.gordonengland.co.uk/hardness/
as a full listing of approximate equivalencies for HV10 Rockwell C, Brinell etc
RE: Brinell Hardness
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/
RE: Brinell Hardness
The best idea is to start with the API 650 manual and follow the path through the different codes.
RE: Brinell Hardness
I'm a bit confused, API-650 does not require tanks to be PWHT. Why is your tank being subjected to PWHT?
Steve Braune
Tank Industry Consultants
www.tankindustry.com
RE: Brinell Hardness
Thanks for the replies. The tanks is stress relieved according to the requirements of API 650 par 3.7.4. The tanks are quite big - 25m high x 34m ID and 21mm bottom strake thickness.
Regards
RE: Brinell Hardness
Steve Braune
Tank Industry Consultants
www.tankindustry.com