Y coefficient value

[irish]

According to ASME B31.3, for the value of Y coefficient in which category among ferrite, austenite and ductile materials Plain Carbon Steel grade pipes fall? For example grades of A106, A333, A334, A369 etc.

[Fizza]

All material mentioned by you fall under ferrite category.
The value of Y is a function of material and the design temperature. The use of Y is also contained in ASME Section I and B31.1.
ASME Section VIII-1 and ASME Section IV use the value of Y always 0.4 and is incorporated this value in UG-27 formula. To use the value of Y always 0.4 is a conservative approach.
The range of Y is 0.4 to 0.7.

[irish]

So at 950 deg F, the value of Y would be 0.5 for A106 grade B, API5L grade B, A333 grade 1 & 6?

[salzx64]

Yes ofcourse Irish as per B31.1 table 0.5 is required value at 950 C.

Regards,
Salz

[Fizza]

Correct, it is 0.5 as per B31.3.

[irish]

Thanks for the confirmation, friends.
Was just confused between ductile and ferrite materials. Do you know what common pipe materials fall under the category of other ductile materials?

[salzx64]

As per B31.3, search from materials mentioned in specification index of Appendix A and if desired material is not ferritic or austenitic or cast iron than it must be in 'other ductile metals' category. Ductile is just a property of mostly all metals/alloys e.g. like A-395 is "Ductile and ferritic" i.e. both (B31.3-Table A-1A)
This is my opinion of course. Lets see it holds true or not

B31.1 is very clear and in the notes of Table A-1, A-2, .... and so on it mentioned what category "ferretic/austenitic or nickel based" the material lies. This is of what i'm 100 percent sure.

Regards,
Salz

[arcpro]

I would agree with Nasir to take a rather safe value for Y where not sure about the material which is 0.4.

[irish]

This is the approach I think different softwares also use. Am I right?
However, I know about CAESAR not confirmed about others.

[salzx64]

Dear arcpro yes it seems 0.4 is the conservative value but remember for Cast Iron and Non-Ferrous materials B31.1 put y factor value as Zero (in the table notes). Similar is observed in B31.3. So range is from 0 to 0.7 though when you try to calculate the difference it becomes very less in terms of positive or negative thickness values but still it matters.

Dear Irish softwares like Caesar, Autopipe or any other popular stress tools just simply put a USER DEFINED value and they do not calculate automatically or based on your material and temperature selection. I think personally that they too are a bit unclear. Besides B31.1 also has some discrepancies assigning y factor values to different group of materials. For me most material commonly used e.g. Carbon steel like A106 Gr.B which I know is ferretic & A213, A312 stainless steels are mostly austenitic etc.

Regards,
Salz