










Discussion
and References



Information about Wall
thickness calculation of straight pipes on Offshore Liquid Pipeline Systems:



ASME B31.4
Transportation Systems for Liquids and Slurries, chapter IX.












Tables and Standards




ASME B31.4 Specified Minimum Strength  US
Units




ASME B31.4 Specified Minimum Strength 
Metric




Table A402.3.51 Design Factors for Offshore
Pipeline Systems




ASME B36.10MWelded and Seamless Wrought
Steel Pipe




ASME B36.19MStainless Steel Pipe




ASTM A377 Ductile Iron Pressure Pipe




ASTM A691 ElectricFusionWelded Steel Pipe
for HighPressure Service at High Temperatures












Equations
for Wall thickness calculation of straight pipes on Offshore Liquid Pipeline
(chapter IX):






For D/t ≥ 20, the wall thickness should be
calculated by the equations:












t =

(PiPe)D



(U.S. Customary Units)





2S
















t =

(PiPe)D



(SI Units)





20S














tn = t + A


Corrosion
allowance is not included in the chapter IX







It
is optional to the designer its inclusion in the calculation.












The
parameters in the wall thickness calculation of straight pipes on Offshore
Liquid Pipeline



equations above are:







Pe = external
pressure, psig (barg).



Pi = internal
design pressure, psig (barg).



D = external diameter, in. (mm).



A = sum of
corrosion allowance, slots, threads and safety in special areas, in. (mm).



t = nominal
thickness, in. (mm) as per chapter IX.



S = Applicable allowable stress
value, psi (MPa), as determined by the following equation:












S = Fi(Sy)
















Where:



F1 = hoop stress design factor from Table A402.3.51.



Sy =
specified minimum yield
strength, psi (MPa)












* Additional information for pressure design can be found in API
RP 1111, paras. 4.3.1 and 4.3.2.









