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Up Topic Welding Industry / Inspection & Qualification / HARDNESS TEST FOR BLANK EXISTING VESSEL
- - By maxilimiano (**) Date 03-10-2007 07:55
Can I use only Hardness Test to determine stress used for vessel calculation.?? Because in API 510 doesn't explain for using hardness method.
Vessel is for Pig Launcher, and using spiral plate.

THX ...:)
Parent - - By G.S.Crisi (****) Date 03-12-2007 14:28
It's a mistake to believe that there's a precise relationship between hardness and tensile strength in metals, i.e., that to a given hardness number it corrisponds an exact tensile strength.
Hardness numbers give only a rough idea on what the tensile strength is.
There are several "conversion tables" around showing the relationship between hardness numbers and tensile strength, but the serious ones, like SAE's and ASTM's in the USA and ABNT's here in Brazil (our local ASTM), warn the reader that the conversion is only approximate and MUST NOT be used for calculation purposes. Their intention is to give the reader just an idea.
So, the answer to your question is no, you can not.
Giovanni S. Crisi
Sao Paulo - Brazil
 
 
Parent - - By js55 (*****) Date 03-12-2007 15:17
Giovanni is, as usual, exactly correct. Brilliant minds for decades have tried, for obvious NDE reasons, to directly link hardness with tensiles and failed. And I believe for good reason. The deformations are different, and demonstrate differing properties. Though they are very close, as Giovanni again explained with the available conversions.
Parent - - By G.S.Crisi (****) Date 03-12-2007 22:43
js55,
thankyou for your kind (and somewhat exaggerated) words. As everybody, sometimes I'm right and sometimes I'm wrong.
Giovanni S. Crisi
Parent - By js55 (*****) Date 03-13-2007 13:36
Giovanni,
I'm willing to pretend thats not true on your behalf,  if you're willing to do so for me.  Hah!!  Now if we can just bring everyone in on this we'll all be brilliant.
Parent - - By new tito (***) Date 03-13-2007 13:09
I may be a little out of my league here, but couldn't you use a PMI (possitive material identification) to find out what the material actually is, and then find the stress value in the referencing section of you code book?  I'm not familiar with API 510, and not too familiar with PMI and the process used in determining identification.
Parent - - By js55 (*****) Date 03-13-2007 13:44
A suggestion such as that doesn't indicate your out of your league. Although, if the PMI is a XRF type you still need to get carbon (most critical to any strength evaluation). There are some fellas in here that know a heck of alot more about current materials testing methods than I and might chime in.
However, I do not know if creative methods such as that can be utilized under that code. That to me would be the question.
Parent - By maxilimiano (**) Date 03-25-2007 08:00
Thanx a lots Gentlemen..After I open metalurgy Handbook..I remember definition about what is Hardness , Toughness, Modulus Resilience, Tensile & Yield Stress,etc..used for.
I agree with you all.

Good Luck :))
Up Topic Welding Industry / Inspection & Qualification / HARDNESS TEST FOR BLANK EXISTING VESSEL

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