air receiver corrosion allowance ASME VIII Div 1 1

[deckie1026]

Is there a minimum corrosion allownce for air receivers in ASME Section VIII Div 1 ? I can not locate this requirement.

 

[gr2vessels]

There is no specific corrosion allowance for air receivers. However, the plant air is normally "wet", hence corrosion allowance is required, unless you paint it inside.
The instrument air is normally dry, the corrosion allowance is not required.
It depends much on the vessel specification, if you asked or not for internal surface treatment, blast cleaning or left it with mill scales, painting, etc..
gr2vessels

 

[jte]

gr2vessels-

I admire your optimism!

Yes, instrument air *should* be dry. But that's not always the case... Coatings *should* prevent corrosion, but small coating failures can cause major headaches if the vessel has no corrosion allowance to work with. I'd go with 1/16" min CA and consider using 1/8" CA on the bottom head.

Section VIII provides no guidance for setting CA's so the designer is stuck with using industry experience combined with good engineering judgement by your friendly local metallurgist.

jt

 

[gr2vessels]

Perhaps practical;- most of the workshops buy "standard" air receivers, say 4' dia x 12' tan-tan vertical receivers for "general" service, barely making it for the pre-approved design. My specification for the refinery instrument air receiver requires corrosion allowance, blast cleaning inside -out, full painting inside / outside and guarantees for design to 20 years (the most I've got was 2 year warranty). I don't believe that any car repair workshop can afford your and mine specification. I doubt it they can spell metallurgist also.
cheers,
gr2vessels

 

[jte]

gr2vessels -

I agree with your perspective, but wonder how much adding a 1/16" CA adds to the delivered price of the 4' x 12' receivers?

Just don't get me started about mounting the recip compressor directly to the knuckle of the top head with intermittent fillet welds!

jt

 

[athomas236]

Back in my days as a preesure vessel designer, we used a minimum corrosion allowance of 1/16" for air receivers.

Regards,

athomas236

 

[rhg]

See UG-16, minimum thickness for shell and heads is 1,5mm, .....minimum thickness for compressed air service (UCS-23) is 2,5mm. Conclusion: 1mm is the minimum corrosion allowance in ASME VIII Div.1

regards
rhg

 

[MJCronin]

dickie..

It is a little off topic, but both ASME and Occupational Safety and Health Administration (OSHA) requires a bottom drain at the lowest point of every air receiver to mitigate corrosion.

Federal Law 29 CFR 1910.169(b)(2) describes this.

In ASME review Section VIII, Div. 1, paragraph UG-25(f) requires a suitable drain opening in such vessels.

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=DIRECTIVES&p_id=1712

Also see:

http://www.nationalboard.org/Nation...nspectorGuides/CInsp_Guide_Air_Receivers.aspx

Some people offer galvanized recievers to extend the usefull life:

http://www.kaeser.com/Images/P-775-ED-tcm8-7411.pdf

My opinion only

-MJC

 

[JStephen]

I would not take a difference in minimum thickness to imply a minimum corrosion allowance. IE, if a minimum corrosion allowance were intended, it would be stated as such.