material construciton hydrogenation autoclave

[dan1949]

Acting as a consultant, I have been asked to comment on design a hydrogenation autoclave operating at 120C and 1000 psig.

Is there any problem with using SA 516 GR 70 Normalized HIC as material of construction?

thanks

Dan

 

[XL83NL]

What size do you have? Commercial small scale autoclaves are often in stainless steel or nickel alloys, I believe.
Also review API RP-941 for Nelson curves.

 

[dan1949]

Thanks for your questions and observations. The proposed size is 1000 gallon.

Review of the Nelson curve indicate the proposed choice is acceptable. However, as you has noted, I find all references in literature for autoclaves are for more exotic materials of construction. 300 series stainless steel or higher. I wonder shat I am missing.

 

[EdStainless]

For a 1000psi autoclave you want the long term risk of embrittlement to be nil, not just low.
That is why these are usually made from Ni alloys such as 625.
They also are usually designed with higher safety factors, such as 5 to 1.
1000 gal is a large volume at that pressure, play it safe.
We used small ones, about 1gal. They were 316L and were designed at 6 to 1 SF.

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P.E. Metallurgy, Plymouth Tube

 

[metengr]

Yes, you are missing something, you need to supply more information on what process material is being subjected to hydrogenation before selection of suitable material. Second, you need a construction code to work with for design.

 

[moltenmetal]

What are you hydrogenating? Even if carbon steel were OK on the Nelson curve, the rest of the "soup" might not be. And even if it were OK, the product cleanliness requirement might STILL push you toward stainless steels or nickel alloys. At 120 C it's likely an austenitic stainless steel rather than a nickel alloy like 625.

 

[dan1949]

Is there a specific code that is applicable to hydrogenation or is the ASME code with a higher safety factor sufficient?

The raw material and products are compatible carbon steel. I do wonder about the effect of Fe ions on the catalyst.

I assume full x-ray and/or dye penetration of all welds would is recommended.

Dan

 

[DeleteriousPhases]

100% RT and LP would not be bad for that size and pressure. Also covering off by specifying a tighter tolerance on permissible indications on both test methods would yield better weldments, though it will increase production time and costs.

 

[metengr]

ASME Section VIII, Div 1 would suffice.