Forging pressurized parts

[komposites]

I want to fabricate a metallic polar boss, which I would classify as a nozzle (large diameter) for a Section 8, Division 3, high pressure, FRP tank. I want to make sure that I have the proper material cert for my inspector. I want to make the part out of 316 stainless round bar (probably SA-479 annealed, while applying CODE CASE 2156 for hollow parts with large diameter), which appear to be approved materials per Section 2 and 8.
My questions:
1. Am I permitted to FORGE the SA-479 annealed stainless to near-net shape, then post-machine?
2. Or should I have it certified to SA-965 (316 Stainless forgings) as a near-net shape part, then post-machine??
3. Does that mean I have to extract coupons from the near-net shape parts for tensile testing/ultrasound NDE testing? I believe SA-965 is the only way to buy the material, correct? This path would require that I find a forging shop that can supply to SA-965, and also provide the extra testing.

Thanks.

 

[komposites]

Forum,
I believe the correct path is to buy the rough shaped part to SA-965 as a forged part based on my interactions with a forging shop. It looks like they can outsource testing that is required.
Does it appear like I'm on the right track? I'm a bit new to ASME code requirements.
Thanks.

 

[XL83NL]

Wait, a Div 3 FRP tank? You're in excess of 700 bar?

 

[MJCronin]

XL8NL......

Sure.... FRP and 700 bar....that is what he said....!

and Im willing to bet that this is the first FRP vessel that he has designed....

I don't see a problem here.....Uuuummm .....do you ?

 

[XL83NL]

FRP; Fiber Reinforced Plastic. Right?

 

[doct9960]

Right. ASME Section X, Class III FRP vessels can be designed up to 1030 bar (15,000 psi)

 

[XL83NL]

Sure, but he's talking bout an Sec VIII-3 FRP tank, not an Sec X tank.
Not familiar with Sec X, so if you say 15ksi can be done .... but that didnt answer my question.

 

[doct9960]

He probably did not pose the question properly. ASME Section X is the only Code that applies to FRP vessels.

The OP was about a metallic polar boss. According to ASME Section X, for a Class III FRP vessel, metallic pressure parts must comply with the applicable requirements of ASME Section VIII, Division 3.

Not familiar with Sec X, so if you say 15ksi can be done .... but that didnt answer my question.

Didn't you ask if you are right in saying that FRP = Fiber Reinforced Plastic? And my answer was "Right."

 

[XL83NL]

My initial answer still wasn't answered in it's full context, not even by MJCronin.

 

[komposites]

Thanks for the responses so far. Let me clarify my post. doct9960 is on the right track. I am following Section X (FRP tanks), which requires design and fabrication of any metallic parts per Section VIII-division 3. I kept the question simple in hopes of more responses, which is why I only referenced Section VIII-3.

To answer my original question about forgings... I am almost certain that if I buy a forging to SA-965 (forgings) for a metallic part and have it certified by the forge shop, then I post machine, then I will have all the necessary paperwork for the AI. I also discovered that my part does NOT exceed the NPS 4 size, which means CODE CASE 2156 (for parts made of bar) is irrelevant. In fact, the CODE CASE might be irrelevant from the fact that I am using a forging, not bar stock (even though the forging is originally pressed from bar). (Feel free to concur or clarify).

The Division 3 tanks can be designed to any pressure, and from my understanding it will yield optimal usage of material. In other words, it won't be as beefy or over-designed, which should save on material costs.

Followup question:
Section VIII-Division 3 requires materials be in accordance with Section II. The strange thing is that Section II-Part D does not have strength allowables for VIII-div 3 except for TABLE U-2, which is only for wire material. Where are all the strength allowables for other materials like SA-965 (forgings)? Does Section II-Part D omit most allowables to VIII-div 3 because the design is validated from qualification testing to Section X or Section VIII-div 3??

At this point, all I have to rely on is Section II-part D-Table 1A's strength allowables (and unfortunately the the allowables seem extra conservative). Since Table 1A doesn't reference division 3, I suspect that shouldn't be using it. Any clarification is based on specific references to the ASME code would be greatly appreciated.

Thanks.

 

[doct9960]

komposites,

Material and NDE requirements in ASME Section VIII, Div. 3 are more restrictive than ASME Section VIII, Div. 2. It also requires more complex analyses than ASME Section VIII, Div. 2. Your followup question suggests that you are not capable of performing the analyses required in ASME Section VIII, Division 3. I strongly recommend that you leave this type of work to a Professional Engineer that meets the requirements of KG-324.1.

 

[Karloss12]

If you have even a basic understanding of Part 5 of Section VIII div 2 than you would be able to understand how the Div 3 material requirements work within a couple of minutes.

Part 5 of ASME VIII Div 2 and Div 3 require a mentor that is close by all the time.

 

[racookpe1978]

The original poster needs to "talk" to gstrcomp - who also asking how to mount this metal boss into the high pressure FRP tank in a different thread, so I'm not sure the problem is as straightforward as combining the two codes appears.

 

[komposites]

Thank you all for your guidance and suggestions. I am learning the ASME Code, which is clearly not a trivial task. It has a learning curve which I will overcome, just as many of you all have. Your comments help me target the information I am looking for, and give me a perspective of what has been successful in the past. I am very grateful for the information that I can gather from this forum.

I will take a closer look at the specific material requirements for the division 1 and 3 to do a thorough comparison. I hope it will help me understand why there aren't strength allowables in division 3, except for wire materials. I suspect that it is encompassed in the more stringent requirements of div 3. I will also try to get a hold of gstrcomp.

Thanks!