Charpy testing required ? 1

UCS 66 is all about avoiding brittle fracture. If the material requires impact tests

You may be able to escape impacts or reduce the impact test temperature depending on the ratio of stresses in the vessel. This can be expressed as a thickness or a stress.

If you don't know the stress in the vessel then I suggest you have the welding procedures impact tested at the MDMT.

I developed a little calculator for impacts to UCS 66, which guides you through the stress reduction bit.

Regards

John

1.Data known

(1) Material ; SA516-70
(2) Normalized or Not ; expected of normalized condition
(3) PWHT or Not ; unknown
(4) Temperature on Nameplate: -75F (top)/ -55F (mid.) ; expected of design condition
(5) Wall thickness (tn) : 0.5 “ for SA516-70/ 0.05: Monel clad
(6) Calculated Minimum Thickness (tr): Unknown
(7) Joint Efficiency (E) : Unknown
(8) Maximum Design Temperature: Unknown
(9) Impact test done or Not : Unknown ; expected of exempted from the test for mid. section/ questionable whether impact tested or not for top section ( ; to be confirmed by the exemption condition)
(10) Built date ; Unknown

2.Use of the Fig. UCS-66 Curve B (non-normalized) & D (normalized), ASME Sec.VIII Div.1, 2001 Edition – Basic Consideration Guide

(1) According to Fig. UCS-66 Curve D, the minimum exemption temperatue is –55F.
; exempted from the impact test for mid. section/ required the impact test for top section (To be checked from para.3)
(2) The impact test requirements for the WPS/PQR depend on the requirements of the base metal unless otherwise required in user’s specifications. Based on the expected condition, the impact test for the top section is required according to Fig. UCS-66 Curve B because the impact test is essential variable in Sec. IX.

3.Use of the Fig. UCS-66.1, ASME Sec.VIII Div.1, 2001 Edition ; Alternative Ratio (AR)

(1) AR = trE/tn = Unknown = cannot be calculated
(2) Reduction temperature without impact testing = cannot be calculated

4.Use of UCS-68(c), ASME Sec.VIII Div.1, 2001 Edition ; PWHT effect

If it was done the PWHT that is not required this code, the minimum exemption temperatue of the top section can be –85F because the reduction temperature without impact testing is permissible to 30F. Therefore, in thic case, the impact test of the top section is not required. But it will be repair welded, it should be PWHT after welding.

5.Use of Table UG-84.4, ASME Sec.VIII Div.1, 2001 Edition ; Effect of minimum specifiec yield strength

When the minimum specifiec yield strength (MSYS) <=40 ksi, the impact test temperature may be warmer the the minimum design temperatue (-75F) by 10F.
MSYS of A516-70 = 38ksi

If it was not done the PWHT, the impact test may be tested at -65F. But, in this case, the top section cannot be exempt from the impact test.

6.Conclusion

Based on the expected condition in para.1, Para. 3 & 4 should be confirmed for the exemption of impact test.

Hope it helps.

Thomas Eun
NATCO CANADA
thomase@natco.ab.ca
thomaseun@hanmail.net