Additive Manufacturing of Pressure Vessels 2

[IdanPV]

Hello all,

Few weeks ago, Shell obtains CE Certification for a 3D Printed Pressure Vessel.
Link
I wanted to know if a additive manufacturing of pressure vessels and/or pressure parts for a U-stamped vessel (ASME Section VII Division 1) is allowed.

I guess this subject has been discussed here before, if someone can share a link, information or articles regarding this issue it will be great.

Thanks,

 

It's been done for ages. Welders have been doing additive manufacturing since long before it became trendy.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[EdStainless]

As long as you can verify that your method generates acceptable properties (in all directions) then why not.
The catch is that most additive methods generate highly non-homogenous properties, both through the build as well as in in different orientations. To overcome this requires extensive post-fab heat treatment.

Most of the aerospace work either involves parts with no structural load (fuel nozzles) or taking a part that was forged and machined with a 50:1 SF and redesigning it with a 25:1 SF in additive. You cut the weight in half even if it is still super over built.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[XL83NL]

Section VIII has task groups or subcommittees on AM iirc.
There might be a code case already. This thread at least covered one CC, though for sec I:

https://www.eng-tips.com/viewthread.cfm?qid=391985

Huub
- You never get what you expect, you only get what you inspect.

 

I know a fabricator now making small nozzles on heavy PVs by filling a mold (a short length of 3" or 4" pipe) with weld metal, followed by machining.
This avoids the always fraught nozzle penetration weld in the through-thickness direction, as well as fairly simple volumetric NDE, before machining to make the nozzle.
Wish I'd thought of it!


"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[IdanPV]

Thank you all for your valuable comments. I appreciate it.

My intent is to "print" small locking mechanism parts which now made of casting (SA351-CF8) or bars (SA479-304).
Does a "printed" stainless-steel can be used instead of traditional bar material or casting material?
Is there any special requirement in the Code or any Code Case which is relevant for Section VIII-1?

Thanks,

 

[XL83NL]

ASME PTB-13 wasn’t mentioned yet:

https://www.asme.org/codes-standard...g-additive-manufacturing/2021/drm-enabled-pdf

Huub
- You never get what you expect, you only get what you inspect.

 

[XL83NL]

And another one: code case 3020, applicable for section IX. Can be found in supplement 1 if the 2021 code case book for BPVC.

Huub
- You never get what you expect, you only get what you inspect.

 

[EdStainless]

This is going to be long, but here it is.
When you make the part additive are you planning on following with HIP and anneal and quench?
If so then you can likely match the properties of a casting, and your test bars will show this.
If you are not going through those steps, then woe to you.
Your properties will depend on part orientation, direction within the part (wrt build), powder (composition, particle size and distribution, age, re-use), atmosphere, build rate, model of machine, and a few others.
How you would go about showing that the properties in all directions meet the requirements is an interesting question.
I saw a test build of simple bars in 10 different orientations. The range in properties as built was about 60%.
After annealing them it came down to about 30%.
Some bars in skew orientation were just awful.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[IdanPV]

Thank you all.

Few more questions:
1. Assuming the material properties (mechnical, chimical, etc.) are the same. Can I stated the the "3D printed" part is actually SA479-304/SA35-CF8?
I guess not, so, in this case what is the the exact specification of a "3D printed" Austenitic part?

2. I have the Code Case book, arrived few months ago, but I cant find Code Case 3020, is it published already?

 

[XL83NL]

I think CC3020 is in either supplement 1 or 2.

Huub
- You never get what you expect, you only get what you inspect.

 

For question 1 - no.
ASTM material standards and the ASME standards that mirror them always have the manufacturing method as an integral and primary distinguishing element. So there are separate standards for stainless steel as forgings, as plate/strip, as castings, as pipe, etc. Even though the corresponding grades (e.g., 304) have nominally the same composition. That is where UNS numbers come in - they can encompass different product forms.
I don't follow developments in this sphere but it seems to me some new standards (or even new approaches to standards) will be necessary to address products that are essentially all weld deposit. As EdS alluded to, addressing the anisotropy inherent in materials will be one of the challenges.


"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[IdanPV]

XL83NL and ironic metallurgist,
Thanks for you answers.

As for my first question (and the answer), that's what I thought, the next question regarding that issue is: Is there new specification for 3D printed austenitic materials, like SAXXX-304 or something? Shall we expect to see new specification for this kind of materials?

As for the Code Case 3020, I will try to find it, I guess contact with ASME will be the best way to order it.

Thanks again,

 

[XL83NL]

Some leads.

https://www.twi-global.com/technical-knowledge/faqs/faq-standards-used-for-additive-manufacture

https://sn.astm.org/?q=features/5-most-important-standards-additive-manufacturing-.html

As IM and EdS have mentioned, there are some hurdles to overcome. It might years, but my gut feeling is that this is one of the next major steps in PV MFG.

Huub
- You never get what you expect, you only get what you inspect.

 

[EdStainless]

My personal hunch is that formal specs will be a while yet.
And they will likely involve special sub-grades (304P?) just like castings have a slightly different chemistry and properties from wrought products.
Until the AM people can tell me beforehand what the properties will be they don't have a controlled process.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

Thinking a bit more about anisotropy: we have learned how to handle the different types of those according the the product form. Steel plate is a good example - we are careful about loading in the through-thickness direction, and if we want to do it heavily we must manufacture it differently and use special validation tests.

AM will introduce a variety of new anisotropies that we will need to somehow address.
I will speculate that the validation by testing will need to be more flexible, being unique to each product's manufacturing method and more complex geometry, encompassing both with a kind of fitness-for-purpose assessment philosophy.
I suspect that new classifications of welding materials will be developed.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[IdanPV]

The supplement 1 of the 2021 code case book for BPVC arrived today, I will deep dive into it to see what the exact requirements are.

I hope that the subcommittees on AM will publish some information regarding the use of AM for pressure parts\vessel under VIII-1.

Thanks all,