Pipe thickness

[faisal99]

Code ASME B31.3 only gives formula for thickness calculation under internal pressure ...... what if external pressure is exerting on piping(e.g under sea piping where external pressure of water is applicable .....furthermore which code will be applicable...)...?

[gunnarhole]

Faisal,
while ASME B31.4 and 31.8 can be used I recommend that you review DNV OS-F101 Subsea Pipeline Systems. In some cases it is the installation of the system which is the controlling case (i.e. buckling). You can download it at

[link Point to another website Only the registered members can access] Regards

[maskedsperm]

faisal99

Find attached the ASME B31.3 (Process Piping) approach regarding pipe wall thickness calculation under external pressure:

304.1.3 Straight Pipe Under External Pressure. To
determine wall thickness and stiffening requirements
for straight pipe under external pressure, the procedure
outlined in the BPV Code, Section VIII, Division 1, UG-28
through UG-30 shall be followed, using as the design
length, L, the running centerline length between any
two sections stiffened in accordance with UG-29. As an
exception, for pipe with Do/t < 10, the value of S to be
used in determining Pa2 shall be the lesser of the following
values for pipe material at design temperature:
(a) 1.5 times the stress value from Table A-1 of this
Code, or
(b) 0.9 times the yield strength tabulated in Section
II, Part D, Table Y-1 for materials listed therein
(The symbol Do in Section VIII is equivalent to D in this
Code.)

I hope this helps... at least a little (as guidence)