Good day everyone,
I am a Welder Engineer in French Oil and Gas Company and there is a Question that everybody in Europe would like to have the answer.
I make you an actual Example:
An UNS 32750 Super Duplex Steel is to be qualified Ø168.3 x 18.26mm.
The COMPANY specification request to perform a charpy test @-20°C in WM/FL/FL2/FL5. Minimimum Design Temperature is -20°C.
Case A - Pressure Vessel ASME IX (No Piping)
Accoding to ASME IX the Semi Essential Variable are activated and then the thickness range is 15.875 to 36.52mm. I speak about 15.875mm and not 16mm because 5/8Inch is a actual Value = 15.875mm.
Do you confirm that Semi Essental Applies for ASME IX as mentioned above as the "COMPANY requests charpy".
Semi Essential is based on COMPANY requirement only for CHARPY?
The Semi-Essential are activated from ASME VIII or from COMPANY spec?
Case B - Pressure Piping ASME B31.3 (my case)
This case interest particually me as I work always wiith B31.3. and oil and Gas COMPANIES make to much confusion with ASME IX and B31.3 (always mixing)
The UNS S32750 is referenced as -51°C Impact Test exemption as per ASME B31.3 therfore
The Table 323.3.1 says that as the -29°C is not reached WM/HAZ is not requested. Therfore Impact Test is not requested.
However as my COMPAPNY requests to perform the charpy @-20°C whatever the table Table 323.2.2. WHat is the range that the PQR covers?
Answer:
1 - As COMPANY spec prevalence and ASME B31.3 is the Code
Therfore T/2 to T+6.35, here 9.13 to 24.61mm is to be used even the design température is >-29°C (here-20°C)
2 - Impact Test is performed @-20°C as per COMPANY spec but have no consequence of the Range of thickness Qualified but only on Temperature qualified for COMPANY spec. ASME IX semi essential Variable is not activated as ASME B31.3 does not request Impact Test normally.
Therfore the range covered is 5 to 2T, here 5 to 36.52
3 - Impact Test is performed @-20°C as per COMPANY spec but as ASME B31.3 does not request impact Test therefore ASME IX takes prevalence for Impact Test as "COMPANAY request impact Test"
ASME IX semi essential Variable is activated
Therfore the range covered is T (or 16) to 2T, here 15.875 to 36.52mm.
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Now Same Question be with Impact Testing @-46°C of UNS 32750 requested by COMPANY
1 - As COMPANY spec prevalence and ASME B31.3 is the Code
Therfore T/2 to T+6.35, here 9.13 to 24.61mm because <-29°C and therfore the range of ASME B31.3 must be respected
2 - ASME IX is to be used therfore 15.875 to 36.52mm.
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One of the thing is that for <-29°C (-46°C) there is no problem that the ASME B31.3 is to be respected (T/2 T+6.35) but when >-29°C (= - 20°C) the case is wird as the Code will considere the Pipe as "Pressure Vessel" if ASME IX takes place.
Therefore two range would applied:
9.13 to 24.31 mm for -20°C
15.875 to 36.52mm for -46°C
As you see the ASME B31.3 limites the Maximum thickness to avoid over-heat and here @-46°C the range is more open to the high thickness that is non-sense for ASME B31.3 philosophy. (less stringeant than @-20°C)
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This Question is a very blocking point for most of the Europeen Welding Engineer that work with very stringent COMPANY specification and ASME B31.3 code. At the end the quesiton is Does the costomer spec take prevalence to the CODE?
Therefore please can you answer without using only Yes or NO and explain where you answer come from? Code Cases...?
Thank you a lot for your answers