ASME FFS-1/API-579-1-----Hardness and Tensile

[Fizza453]

Good evening.
I have question on Table 2E.1 (by using this table tensile strength can be estimated by using hardness value).
If hardness value is 90 BHN. Lowest value as per Table 2E.1 is 114 HBN. How to estimate tensile strength for 90 BHN? table does not enlist lower than 114 BHN. Any idea?



Javed Nasir
Inspection Engineer
Technip-France Abu Dhabi

 

[metengr]

If you are bound to use FFS-1 you must use the table values or try to approximate the lower tensile value using other references.

 

[TGS4]

What sort of damage did you experience that results in that low of hardness?

 

[Fizza453]

TSG4
Plant got fire due to leakage of propane. Hardness survey was performed on affected piping, material of construction is A671 CC65. Minimum hardness value we did measure 90 and max 129. Average is 114. Almost 500 readings were taken on 12meter pipe.

Javed Nasir
Inspection Engineer
Technip-France Abu Dhabi

 

[TGS4]

Other than enlisting the expertise of a fire damage specialist, I can opine that your material has been damaged beyond hope, unless you can take full-thickness samples to directly measure the strength (hardness being an indirect measure of strength).

 

[metengr]

I would agree with TGS4. But as a metallurgist, I would caution that field hardness test results alone can be subject to discretion. I would perform field metallographic examination (replication) in addition to hardness testing to ensure material is compromised.