Pipeline external pressure

[samadqureshi]

Hi everyone,
I m a new pipeline engineer, I have to design a offshore gas pipeline. I have read most of the codes and standards but all I want to know is that how to calculate the external pressure when the pipe is at the sea bottom?
is it the simple formula as P = density.gravity.depth
or its more than that?

 

[desertfox]

Doesn't the codes tell you how to do that?

desertfox

 

[BigInch]

Got a long way to go huh.

Yes, density x depth.

Don't be afraid to open a text book and read the first page or two sometimes.

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

 

[samadqureshi]

thanks guys.
I have read and it talks about wave height and tide height so I was confused that it have an effect on pressure on not.

 

[BigInch]

If it changes the water depth, of course it will have an effect.

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

 

[samadqureshi]

thanks.

 

[archeratslt]

For external pressure design we need to know maximum difference between external and internal pressure. So, the phenomena such as Tide, Wave, and storme surge should be considered for calculating the external pressure. For internal pressure the minimum pressure the the condition of interest should be used.

 

[EricFrance]

Hi,
The formula is the following :
P=(Roxgxh)+Pa
with :
Ro=density of sea water
g=gravity
H=depth
Pa=Athmospheric pressure.
Exemple : At 300m of depth, the water density is about 1026kg/m3, also the external pressure is :
P=((1026*9.81*300)/100000)+1
P=31.195 bar, with P=relative pressure applied onto the pipe on the bottom of the sea.
Eric