Pipe Wall Thickness for external Pressure 1

[pdp123]

Hi
However Pipe Thickness is very common but Please let me know the following..
-Simple rule to obtain ratio L/Do where L is Distance between stiffeners and D is external Diameter of Pipe.
-Procedure for thickness calculation for the case when Do/t < 10.
-Why we are using the demarcation of number 10 according to UG-28.

Thanks Experts....

 

[racookpe1978]

Are you mixing up "external pressure" forces and stresses on a pipe caused by a pipe carrying fluids and gasses less than atmospheric of ground loading, with "excessive pipe stresses caused by improper support design"?

 

[pdp123]

No

 

[XL83NL]

simple rule for L/D ration.

your question is too vague, but ill give it a shot. determine L, and divide it by your diameter.
to find out what L is (i.e the definition), go from B31.3 para 304.1.3 (your topic says 'pipe, so Im assuming B31.3 applies) to VIII-1 UG-28, and look up to definition of L;

L = total length, in. (mm), of a tube between tubesheets,
or design length of a vessel section between lines of
support (see Figure UG-28.1). A line of support is:

(a) a circumferential line on a head (excluding
conical heads) at one‐third the depth of the head
from the head tangent line as shown on
Figure UG-28;
(b) a stiffening ring that meets the requirements
of UG-29;
(c) a jacket closure of a jacketed vessel that
meets the requirements of 9-5;
(d) a cone‐to‐cylinder junction or a knuckle‐to-cylinder
junction of a toriconical head or section
that satisfies the moment of inertia requirement of
1-8.​

Procedure for thickness calculation for the case when Do/t < 10.

refer to VIII-1 UG-28 (c)(2)

Why we are using the demarcation of number 10 according to UG-28.

Dont know. Ask the code committee. Read books on pressure vessel design, maybe they will tell you.