Impact Testing for Low Temperature Material for Pressure Vessel 1

[SmallInfo]

Hello Experts,

I have to design a pressure vessel with following design parameters

Pressure 1.8 Mpa
Lowest operating temperature -65C
Size Dia 24"
Length 60"

In PVElite I opted material SA 516 Gr. 70 which goes lower upto -48C but my required MDMT is -65C, after checked to impact tested it lowered to -85C providing required thickness 8 mm.
Is there something I am missing or I can design pressure vessel with this material with impact testing?
Thanks

 

[JStephen]

You would need to confirm that the actual materials can pass the impact test at that temperature. I believe this would also affect weld qualification testing as well.

 

[Cobra17]

assuming it's VIII-1, don't forget to check UCS-66(b)(2)/(3).

 

[r6155]

Alternative is seamless pipe SA-333.

Regards

 

[SmallInfo]

JStephen, thanks for valuable answer, how can we pass weld qualification at this temperature - 65C?

 

[SmallInfo]

r6155, thanks for valuable suggestion. What material we use for dishes if we select a333 seamless pipe for dish?

 

[JStephen]

For large quantities of material, the material producers can oftentimes furnish information on expected values that material would meet.
For small quantities, you may be limited to testing available material.
If I remember right, the A333 material is tested to specific low temperatures, and if the available material meets your requirement, you're good. If not, further testing may be required there.
On the heads, check with your head supplier and see what they have available.
On the welding, the consumables-producers may have information on what the particular products can meet.

 

[SmallInfo]

JStephen,
Thanks for detailed answer, can we use simply 304/316 material without impact testing I think stainless steel is exempted from impact testing?

 

[SmallInfo]

Cobra17, temperature is too low to get excepted from impact testing.

 

[r6155]

@ SmallInfo
I suggest you contact a pressure vessel engineer.

Regards

 

[Geoff13]

Why is the MDMT so low? Is this a temp that will be experienced by the vessel?

I've designed many pressure vessels for northern Canada and I've never seen such a low MDMT. Just wondering where it gets this cold.

 

[Christine74]

Yes, assuming this is an ASME Section VIII Div. 1 vessel you take go as low as −320°F (−196 C) for 304/316 stainless steel without performing impact tests. See paragraph UHA-51.


-Christine

 

[SJones]

If you want something a little cheaper, how about A203 Grade D?

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[Cobra17]

I can't believe I'm saying this, but I agree with r6155. "I suggest you contact a pressure vessel engineer."

from 3 below: you are colder than -48°C, but warmer than -105°C, so, if the coincident ratio<=0.35, no impact test is required. How to increase your ratio? use a thicker shell.

(2) For minimum design metal temperatures colder
than −55°F (−48°C), impact testing is required for all materials,
except as allowed in (3) below and in UCS-68(c).
(3) When the minimum design metal temperature is
colder than −55°F (−48°C) and no colder than −155°F
(−105°C), and the coincident ratio defined in Figure
UCS-66.1 (Figure UCS-66.1M) is less than or equal to
0.35, impact testing is not required.

 

[Morcuse]

You can philosophize all you want on getting your SA-516 GR 70 material to pass the impact tests required / derrating it according to the membrane stress ratio. Then again, I wish you the best of luck in passing the production weld impact testing that is required for this vessel.

I concur with r6155: please hire a pressure vessel engineer to get you through these requirements.

 

[SnTMan]

Keep in mind: All components of the pressure boundary must meet the MDMT, not just shell and heads.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[Trestala]

Use stainless (304/316) or 3.5Ni (SA-203 D/E), but SS is more feasible.

 

[SmallInfo]

Geoff13
Its minimum operating temperature.
Christine74
Thanks for your valuable time and knowledge.
SJones
I will search on it, thanks for your valuable time and knowledge
Cobra17
Thank you so much for your valuable time and knowledge, it helped alot.
Morcuse
Thank you so much for your valuable time and knowledge, I will consider weld as well.
SnTMan
Thank you so much for your valuable time and knowledge
Trestala
Thank you so much for your valuable time and knowledge, I am considering these