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Up Topic Welding Industry / Inspection & Qualification / UT in Lieu of RT on Cryogenic Tanks
- - By NDTIII (***) Date 03-26-2007 12:39
This tank has a 57.5cm concrete casing with a Carbon Steel Liner. Inside that is a 9% nickel steel butt welded liner(Shell). In accordance with API-650, can RT be substituted with AUT?

Any restrictions on it?
Parent - By dbigkahunna (****) Date 03-26-2007 20:35
Is this 650 or 620?
Parent - - By G.S.Crisi (****) Date 03-26-2007 21:23
Cryogenic tanks are designed and built to API 620 Appendix R, not API 650.
Sorry, I don't have the standard on hand to see if what you propose is allowed.
Giovanni S. Crisi
Sao Paulo - Brazil
 
Parent - By CWI555 (*****) Date 03-27-2007 03:57
Appendix R is for refrigerated tanks within the temperature of +40F to -60F per appendix R.1.3
Parent - - By CWI555 (*****) Date 03-27-2007 03:53
API 620 appendix U ut in liu of radiography. Yes there are many restrictions. the Key one being the minimum Charpy V notch values. I am on one of these projects now.

APPENDIX Q--LOW-PRESSURE STORAGE TANKS FOR
LIQUEFIED HYDROCARBON GASES

APPENDIX U--ULTRASONIC EXAMINATION IN LIEU OF RADIOGRAPHY

You will have to pay particular attention to those two appendixes of 620.

Welding material will likely be SFA 5.11 and 5.14 ECRNIMO 3 through 6 depending on your project spec. The plate will be ASTM A553M
There is also some restrictions on use of TOFD. The filler will end up around 60 to 65 percent NI. This gives you effectively a dissimilar weld that is prone to center line hot cracking when it goes south. Combined with the large grain structure of the weld vs the fine grain structure of the base metal, the primary constituents of the AUT exam will likely be (all refracted longitudinal) round trip tandem, creep wave, and direct wave. The Aut primarily consisting of composites of those methods with limited use of the TOFD function.

Shoot me an email if you need any further info.
Parent - - By NDTIII (***) Date 03-27-2007 05:02 Edited 03-27-2007 05:34
Thanks everyone for that information. Yes API-620 is the code for this. I found App. U. It sounds like the only real limitation for ToFD is the lack of near surface resolution. It can be supplemented with pulse echo techniques as agreed by the owner and contractor.Thanks again
Parent - - By CWI555 (*****) Date 03-27-2007 16:24
Thats true, but bear in mind the nature of the weld material. This particular weld does not lend itself well to TOFD.
Parent - By NDTIII (***) Date 03-28-2007 11:34
Yes I know. Thanks
Up Topic Welding Industry / Inspection & Qualification / UT in Lieu of RT on Cryogenic Tanks

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