Criterion for Considering Vacuum Requirement for Piping Wall Thickness calculation

I/V*√*∞x + 3.14159.

This will get you close.

Then, there's this:

Railroad tank car vacuum implosion - YouTube

Why is the infinity sign in the formula, and what are you taking the square root of? Your formula sort of lost me. What is I, what is V, and what is x? definitions would be helpful. I am interested in learning from you on this one.

Don't wait too long. LynDoor™ product manuals are particularly difficult to understand...

It's gibberish.

Sorry, if you thought it made sense, but I was on a roll from the "JimmyJames" chronicles and was just being foolish.

There are far better people here to learn from than I.

Cheers.

Cheers Lyn. I have seen several noteworthy items from you sir. I am somewhat relieved by your present response, as I was concerned that due to my ancient education, mathematical nomenclature and symbology has passed me by (which I still suspect it has).

Thanks for the compliment.

nickname, tcmtech, Tornado, redfred and others, whose names escape me at the moment, would be far more knowledgeable than I, since I am long in the tooth and haven't seen the inside of a college in 40 years.

Cheers.

See also "external pressure"; if the pipe wall is thin compared to the pipe diameter, buckling is possible.

See also; Hoop strength.

Not Whoop...................hoop.

Do we need to consider the Vacuum requirments for all piping per ASME B 31.3?

Why would you?

Could you please specify for which all lines we should consider the requirement ?

Thanks inadvance...

How about yes for pipes that might be subjected to vacuum conditions? Versus no for pipes that will not be exposed to vacuum?

If this is considered necessary under the standard then yes, otherwise ask the piping engineer!

Well, what are the process conditions, like maximum and minimum temperatures and pressures? That would help!

The same as for any other piece of process plant: what are the materials of construction, the fluids, their max and min temperatures, and their max and min pressures.

Thank you very much for all your feedbacks

May Iconclude as below

if the following condition exists then the piping shall be done for full vacuum design.

1. To prevent any toxic substance into atmosphere.

2. Process requirement (eg. To decrease the process Temp)

3. Steam out process is required for a line.

How current thinking arrived at those conclusions is abstruse.

Here is an alternative conclusion set:

1. The purpose of piping is to contain without loss the process fluid while it is conveyed from one place to another.
2. The piping material must be selected so as to be compatible with the process fluids at the ends of their expected ranges of temperatures and pressures.
3. The piping thickness must be sufficient to withstand the difference in pressure between the inside and the outside of the pipe without failure of the pipe and loss of any contents.
4. The size of the piping must be economically compatible with the maximum expected flowrate of the process fluids. For gases, a velocity limit of 10ms^-1 and for liquids a maximum of 3ms^-1 will be found a good rule-of-thumb.
5. There is a relationship between the pipe material, its thickness, the diameter of the pipe and the pressure range of the fluids inside, which needs to be considered at design. For most applications, pipe manufacturers publish tables from which the safe operating window of pipes may be determined. Therefore, in most cases, there is no need to carry out additional calculations.
6. If in doubt, consult a qualified Piping Designer locally.

1. What level of vacuum (or external pressure)

2. Material modulus of elasticity, at the design temperature and Poisson's ratio

3. Pipe diameter and length of section between restraints (eg flanges)

Then with the right formula you can calculate thickness

I would make the pipe just a tad thicker than calculated unless calculated with the appropriate safety factor.

The formula I'm thinking of is from Roark and gives buckling vacuum. I would use a safety factor about 3 (ie calculate thickness for 3 x the external pressure) for real world. Similar to SF for buckling of columns.