ASME Weld Procedure using non-asme material

[timsch]

I have an application where I need to weld 310SS to a 35/45 Cr Ni+Nb microalloy, the latter of which is not an ASME material. I'm working to create a WPS, and every WPS I've worked on before was for ASME base materials.

In this case, the 35/45 Cr Ni+Nb microalloy is not expected to bend when subjected to the bend test. How should this situation be dealt with? A WPS is required by our customer, but I don't know how to evaluate the test coupons.

 

[metengr]

In this situation you can do a destructive examination versus tensile and bend tests using a cross section of a weld coupon to evaluate weld quality. No different than an ASME Section IX hardfacing weld overlay procedure qualification.

 

[timsch]

So following the instructions in QW-453 for procedure qualification would be the plan going forward. Is there a way to write up the procedure to explain this deviation that would still be ASME code acceptable? This is a groove weld.

 

[metengr]

ASME Code acceptable? ASME Section IX is a service code book that provides a guide for qualification of a WPS and Welder. The engineer responsible for design or the construction code determines what is applicable regarding type of tests and acceptance criteria. Read the Introduction of Section IX.

For your application, since you are not using a construction code, you as the designer can elect to qualify a WPS using Section IX with the proviso that in lieu of bend testing because of anticapted low ductility, you are using a cross section to evaluate weld quality. You can still run tensile testing to determine the strength of the groove weld.

 

[timsch]

Thank you for this information and guidance. It is much appreciated.

 

[timsch]

I obviously have some shortcomings in my knowledge about creating weld procedures for materials that fall outside the bounds of ASME SECTION II.

What books or other resources would best get me more competent in this regard? I've had no welding education or training.

 

[metengr]

I would advise purchasing a used copy of the CASTI series book;

https://www.amazon.com/CASTI-Guidebook-ASME-Section-Qualifications/dp/1894038800

Also, the American Welding Society provides various reference books on the topic of welding procedures.

 

[fleischfresser]

I am not familiar with the property of 35/45 Cr Ni+Nb microalloy.
But please note with Addenda 2008 a footnote (e) was added to table of QW-466.1. Actual this footnote is now general note (d):
"For materials with less than 3% elongation, a macro‐etch specimen shall be used in lieu of bend test at each bend test location. Acceptance criteria shall be in accordance with QW-183(a)"
So if 35/45 Cr Ni+Nb microalloy has a elongation less than 3% you may perform 2 tensile test specimen and 4 macro-etch specimen.
But the use of specimen as required for hard facing weld overlay for test of a butt weld as recommended by metengr is a code violation.


Regards - Juergen

 

[timsch]

Juergen,

Thanks for pointing this section out to me.

 

[metengr]

fleischfresser
You misread what I stated above.
In this situation you can do a destructive examination versus tensile and bend tests using a cross section of a weld coupon to evaluate weld quality. No different than an ASME Section IX hardfacing weld overlay procedure qualification.

Perhaps I could have stated it differently, but a cross section of a weld and evaluating weld quality is a macroetch. This is similar to evaluating hardfacing as well, that was the concept.

 

[pradipgoswami]

Timsh,

This alloy is relatively a new alloy for ethylene environment. European practice is to go for welding products of matching chemistry. Around 4% elongation is usually achievable for welding of similar alloys of 35/45 Nb chemistry.

You may get slightly more elongation due to dilution effects while welding 310SS to 35/45 Nb.

The following data sheet may provide you some guidelines.

https://www.rapidwelding.com/files/T3545NB-X.pdf.

Thanks.




Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
ca.linkedin.com/pub/pradip-goswami/5/985/299

 

[DekDee]

So if you have 4% elongation or above you must bend test as per QW 466.1 ?

 

[metengr]

You can use a different sized bend mandrel to lower the outer fiber elongation for bend testing at values above 3% elongation to 22% elongation (standard). My point is that in Section I for just this type of situation you can use a cross section and macroetch of the weld, in lieu of bend testing.

 

[weldstan]

ASME IX has modified its bend testing requirements to include for low ductility materials. 35-45 Nb typically has ductility of about 5% but sometimes under 3% elongation. With proper selection of filler metal and noting the high ductility of the 310 SS, you should have no problem in qualifying a WPS with bends providing a 5% elongation in the outer fibers. I have written and directed qualification of at least a dozen procedures involving this alloy, the first time was almost 20 years ago.

 

[jrtei]

If you want a formula to determine the actual die post diameter you need for materials with 3% to less than 20% elongation, use the following. It's just the formula from note 1 of QW-466.1 reworked to solve for die post diameter.
DP = 100x(t/e)-t.
DP = die post diameter
t = bend thickness
e = % elongation
So if you were processing 3/8" thick side bends (or face and root) for a 4% elongation material you would use a 9" diameter die post.
A 9" die post is obviously not very practical. I would suggest treating it like a 6061 aluminum and machining bends to 1/8" thick (if accepted by engineering). In that case you would use a 3" diameter die post.

 

[weldstan]

You should also review API 560 for fired furnace applications.