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
                     
  Diameter Nominal,  DN =
 mm Material  = 
 
                     
   External Diameter,  D =  mm Design Temperature =   ᵒC  
        Design temp. between −29°C and 120°C       
  Location  =
Internal design pressure (gauge), Pi =   barg  
  See table A402.3.5-1                  
  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
  optional     Spec. min. yield strength, Sy =  MPa  
                     
                     
                     
  CALCULATIONS
               Check for Applicability    
  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 ≥ tn =   mm              
  From ASME B36.10M (Thickness most commonly used)                
  SCH =   (Minimum acceptable when applicable)      
                     
  - 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
                     
  Nominal Pipe Size,  NPS =
 in. Material  = 
 
                     
   External Diameter,  D =  in. Design Temperature =   ᵒF  
        Design temp. between −20°F and 250°F       
  Location  =
Internal design pressure (gauge), Pi =   psig  
  See table A402.3.5-1                  
  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.              
  optional     Spec. min. yield strength, Sy =  psi  
                     
         
                     
  CALCULATIONS
               Check for Applicability    
  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 ≥ tn =   in.              
  From ASME B36.10M (Thickness most commonly used)                
  SCH =   (Minimum acceptable when applicable)      
                     
  - 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.