Minimum Wall thickness for open drain lines 2

[EdPerth]

Hi Guys,

I'm supposed to do wall thickness calculation for open drain lines while design pressures are "0". I couldn't find any criteria in ASME B31.3. Do you know how can I get it done?

 

[BigInch]

With zero internal design pressures, you're probably looking at the external pressure from soil and taffic loads, etc. from collapsing the pipe, and/or the minimum wall thickness you should be using for installation and handling loads and the maximum bending loads from any spanning or other environmental loads you might get after the pipe has been installed.

Look to see that the pipe's diameter to wall thickness (D/wt) ratios in your code are satisfied. The maximums are often near a value of 100 or so.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[racookpe1978]

The other side of the coin: Often I see the drain lines of the pipes are specified to be the exactly same as the high pressure side so there is no possibility of the field/the fab shop/later maintenance putting the wrong spec pipe (form the drain side of the fitting) into any part of the high pressure (fluid side) of the fitting. After all, even a small length cut off piece, a stub, or a small section left over from one part of a pipe assembly from "before lunch" can very, very easily be attached into a different part "after lunch" or the "next shift"

Yes, a 12 foot drain line could be purchased separately, stocked separately, stored separately, and installed separately and NDE'd separately from the rest of the 1200 foot pipes needed for a project .... but at what extra real-world cost?

 

[EdPerth]

guys thanks for your answers,
racookpe1978
I think I had to explain it more. this is a maintenance job so I hd to calculate the minimum require thickness with the available corroded thickness. reverse!

BigInch
Thnks for your very practical guideline