Wall Thickness Calculation of Straight Pipes on Offshore Liquid Pipeline Systems
 
  Calculation as per Chapter IX by ASME B31.4 for D/t ≥ 30
                   
  (Enter values in yellow cells for calculations and in blue cells as information)
  DATA INPUT
Material =
Design Temperature = ᵒC
Design temp. between −29°C and 120°C 
 External Diameter,  D =  mm Internal design pressure (gauge), Pi =   barg
  Hoop stress design factor, F1  =    Water Depth, H =   m
  See table A402.3.5-1     Water Density, ɣ =   Kg/m³
External pressure (gauge), Pe =   barg
  Allow. for corrosion, A =   mm Spec. min. yield strength, Sy =  MPa
optional
Select T ≥ tn =    mm After Nominal thickness calculation, tn, as per chapter IX, it's
must be selected T ≥ tn from ASME B36.10M or ASME B36.19M
        or ASTM A377 or ASTM A692.
           
  CALCULATIONS
                   
Applicable allowable stress value, S =   MPa
D/t =
 D/t ≥ 30
  Nominal thickness as per chapter IX, t =     mm t = (Pi-Pe)D        
  Minimum thickness required     20S        
  Nominal thickness + Corr. Allow., tn =    mm  tn = t + A      
                   
  Nom. pipe wall thickness, T =    mm            
  from ASME B36.10M or ASME B36.19M                
  or ASTM A377 or ASTM A692                
  - Additional information for pressure design can be found in API RP 1111, paras. 4.3.1 and 4.3.2.
                 
  Wall Thickness Calculation of Straight Pipes on Offshore Liquid Pipeline Systems
 
  Calculation as per Chapter IX by ASME B31.4 for D/t ≥ 30
                   
  (Enter values in yellow cells for calculations and in blue cells as information)
  DATA INPUT
Material =
Design Temperature = ᵒF
Design temp. between −20°F and 250°F 
 External Diameter,  D =   in. Internal design pressure (gauge), Pi =   psig
  Hoop stress design factor, F1  =    Water Depth, H =   ft
See table A402.3.5-1
Water Density, ɣ =   lb/ft³
External pressure (gauge), Pe =   psig
  Allow. for corrosion, A =   in. Spec. min. yield strength, Sy =  psi
optional
Select T ≥ tn =    in. After Nominal thickness calculation, tn, as per chapter IX, it's
must be selected T ≥ tn from ASME B36.10M or ASME B36.19M
        or ASTM A377 or ASTM A692.
           
  CALCULATIONS
Applicable allowable stress value, S =   psi
D/t =
 D/t ≥ 30
  Nominal thickness as per chapter IX, t =     in. t = (Pi-Pe)D        
  Minimum thickness required     2S        
  Nominal thickness + Corr. Allow., tn =    in.  tn = t + A      
                   
  Nom. pipe wall thickness, T =    in.            
  from ASME B36.10M or ASME B36.19M                
  or ASTM A377 or ASTM A692                
  - Additional information for pressure design can be found in API RP 1111, paras. 4.3.1 and 4.3.2.
                 
    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 A402.3.5-1 Design Factors for Offshore Pipeline Systems
-  ASME B36.10M-Welded and Seamless Wrought Steel Pipe
-  ASME B36.19M-Stainless Steel Pipe
-  ASTM A377 Ductile Iron Pressure Pipe 
  -  ASTM A691 Electric-Fusion-Welded Steel Pipe for High-Pressure Service at High Temperatures 
Equations for Wall thickness calculation of straight pipes on Offshore Liquid Pipeline (chapter IX):
For D/t ≥ 30, the wall thickness should be calculated by the equations:
    t = (Pi-Pe)D     (U.S. Customary Units)    
    2S        
    t = (Pi-Pe)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 A402.3.5-1.
    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.