Cryogenic Vessel Design Specification

[Sruthish]

I have seen one of the datasheet for cryogenic vessel which specifying the vessel shall be designed for Allowable temperatures of -196 Deg C as the minimum and -20 deg C as the maximum.
I beleive that this implies the vessel can withstand with a lowest temperatue of -196 deg.C and maximum temperature of -20 deg.C.. please suggest me whether my understanding is correct or not If my understanding is correct , then it means that the vessel can not withstand a temperature which is higher than -20 Deg.C.. then how we can do the fabrication and keeping of the vessel before commissioning at ambient temperatures which is for sure higher than this -29 Deg C.
once we are filling the vessel with cryogen the vessel temp will reduces to very low values say -196 Deg C.. but still doest it make sense to consider the maximum allowable temperature as -20 deg c for the design ??.. please clarify my doubt ..

 

[EdStainless]

It is only rated for use in service up to -20. In fabrication and storage it can be just about any temp, but the design loads and conditions only apply for the temp range given.
How would you ever get it above -20 filled with liquid gas?

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P.E. Metallurgy, Plymouth Tube

 

[pradipgoswami]

Cryogenic vessels usually are fabricated either from Austenitic stainless steels(304L, 316L) or aluminum alloys. For design temperature of -196 Deg C, austentic stainless steels would be default choices. These steels are pretty stable with respect to mechanical properties(especially charpy impact), from +400 Deg C to -(-) 196 deg C.Hence no concern.


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

 

[keyen]

pradipgoswami, why did you specifically mention 304L and 316L and not for example 304, 316, 304H, or 316H?

 

[victorpbr]

Sruthish

What is the fluid it is containing? I`ve seen a similar specification before, the justificative was that the vessel was designed for LOX/LIN/LAR, but also refrigerated CO2. So when using LOX/LIN/LAR, the maximum temperature would be -196C and when using refrigerated CO2 maximum temperature would be -20C, they do that to make sure the pressure inside does not exceed the designed value. When temeperature increases, so does the pressure because the liquid starts to boil, so they used it as reference for when using CO2.

 

[metengr]

Cryogenic vessel materials can be either 304 or 304L or 316 or 316L. Typically, the H grades would be for elevated temperature service because of demand for elevated temperature creep strength.

I beleive that this implies the vessel can withstand with a lowest temperatue of -196 deg.C and maximum temperature of -20 deg.C.

Correct

If my understanding is correct , then it means that the vessel can not withstand a temperature which is higher than -20 Deg.C.

Only applies to in-service conditions where the vessel is under pressure.

but still doest it make sense to consider the maximum allowable temperature as -20 deg c for the design

Yes, it does because the vessel can be pressurized internally up to -20 deg C in service and this must be taken into account for design purposes.

 

[Sruthish]

EdStainless
I totally agree with you. Its just a rating temperature. But the same thing you mentioned in your reply makes my question more specific. The design loads and conditions apply only for the temperature range given. so if the calculations done taking higher temperature as -20 Deg.C, then it cleary means that this vessel when subject to the loads or conditions of ambient temperature may have some problems. Eventhough in actual condition it wont have any probelm because the vessel is fabricated of SS 304. Surely it will withstand higher temepratures. My concern is that, whether the specification considered is right or wrong ? what will be the problem if we design the vessel considering atleast ambient temperature as maximum allowable temperature ?

 

[LittleInch]

The datasheet should include an empty, zero pressure, ambient temperature condition case so revert to whoever supplied the data sheet or just add into the design cases being studied that particular case. Perhaps the data sheet provided thought that this was bleeding obvious so omitted it from his cases??

Commissioning cyro vessels is an interesting procedure usually involving cold gases to allow the metal to come down to its operating range in a gradual manner before introducing cold liquid.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Sruthish]

Hi Pradip Goswami

I understand your point. The vessel I was talking about is made of SS 304. Obviously for the continuous operation it can withstand upto 950-1000 Degree C. so Im also not concerned about the vessels actual operation .. it will withstand . my concen is if this material could withstand this much higher temperatures why the design engineer who made the calculations or datasheet considered only -20 Degree. C.. ? Does it make any sense .. or is there any specific point Im missing regarding the cryogenic point of view.?

 

[Sruthish]

Hi Keyen

its possible to manufacture the Cryogenics vessels with 304 and 316 grades. when using 304 its good to check the strength at lower temperatures with an impact test. But if we are using 316 grade without the impact test its safe to use. Anyway in my opinion no need to go for 304L and 316 L etc.

 

[Sruthish]

Hi Victorpbr

The vessel is designed for LNG and commissioned with LIN. There are no consideration for refrgerated or Liquid CO2 .

 

[Sruthish]

Metengr

Thank you for quoting and answering my question one by one . The points you mentioned is make sense for me . But i would say the the vessel design doesnt address for the condition of keeping the vessel with ambient temperature. one they started the operation with cryogen with in the vessel the temp can not be more than -20 deg in any case. But if the client who uses this vessel stopped the operation for temperory and taken out all the cryogen inside the vessel amd allowed imthe vessel to come into normal ambient temperature for some spcefic purpose . so at this situation the vessel design loses its validity .. correct or not ? please correct me if im wrong ??

 

[Sruthish]

Hi LittleInch

I think you said the right thing. The datasheet may be missed the point of ambient temperature. It should have considered somewhere the condition of ambient temperature In the calcs or docs the design person should have considered this one. Eventhough it is safe to use at normal temperature it shalle be shown in the proper documents also.

 

[Sruthish]

I would like to provide more details regarding the design conditions that i was talking about.
please see the attached image herewith.

 

[Caloooomi]

It would be the allowable temperature during normal operation, i.e. when filled and used for storage. Unless it is being installed in the arctic, it is going to sitting above that when not filled due to ambient conditions...

You have a jacketed vessel, the inner vessel contains the cryogen while gap between the vessel and jacket is insulated and a vacuum is pulled to minimise heat ingress.

Additionally, part of EN 13458 is to calculate the maximum allowable working pressure when the inner vessel is filled with warm gas (20 degC). You can always ask for that value from the supplier, but I suspect they have just put the larger of the 2 (comparing with cooled down and storing cryogenic liquid).

 

[Sruthish]

Hi Caloooomi
Thank you so much for reminding me the point that i missed .As per EN 13458-2 the inner vessel must be designed considering various loads,in which MAP with vessel contains gaseous products at 20 Deg C is also required . And more over I find out the client specification for the design. Client datasheet specified -196 to +50 deg C as the min and max allowable temperatures.
please see the attached images for EN code mentioning and Client Spec Respectively.
I hope that the design missed this points somehow.

 

[metengr]

But if the client who uses this vessel stopped the operation for temperory and taken out all the cryogen inside the vessel amd allowed imthe vessel to come into normal ambient temperature for some spcefic purpose . so at this situation the vessel design loses its validity

No, that is not correct

 

[pradipgoswami]

Sruthish,
There are not many options with respect to materials for cryogenic applications. Sec-VIII, DIV-1, chapter ULT, lists all approved materials.
304 or 304L is a designers call, subject to the fact that consistency of charpy impact values are most important @-196 Deg C, assuming that's the lowest design temperature as per the exhibited data sheet.
Selection of welding consumables with [highlight #8AE234]Zero or maximum 2FN[/highlight] is desirable for consistent & good impact values at -196 Deg C. Read UHA-51 to that effect.
A choice between 304 OR 304L, would call for higher design wall thickness,if 304L is used for construction due to lower allowable stress applicable. However should 304 is used as material of construction , use of 308L welding material with ferrite no as stated above should be mandatory.
For cryogenic services(@-196 Deg C) correct material and welding conditions are of paramount importance.
Thanks.

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

 

Back when I was constructing gas separation equipment, economics drove the choice between aluminum (5083) or 304SS.
Some filler metal suppliers offer SS consumables with low ferrite designed specifically for cryogenic applications. Look up Metrode, their online technical literature is very good. Don't be afraid of low or even zero ferrite austenitic fillers, they can produce sound welds.
SMAW process is the trickiest, and for that you require a basic flux system; the welders complained of poor operability. Conventional types (-15, -16) will not consistently pass Charpy requirements @ -196°C.

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

 

[pradipgoswami]

To All,
This paper shows some useful insights on welding of austenitic stainless steels for cryogenic applications.
Minimizing ferrite to Nil or 2FN max is one of the keys to achieve highest integrity of the weldments.
Thanks.

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