Wall Thickness Calculation of Straight Pipes Under Internal Pressure
 
  Calculation as per par. 841.1 Steel Piping Systems Design Requirements by ASME B31.8
                     
  (Enter values in yellow cells for calculations and in blue cells as information)
  DATA INPUT
                     
  Diameter Nominal,  DN =
 mm Longitudinal Weld Joints  =
 
                     
   External Diameter,  D =  mm Material =
 
               
  Internal Design Pressure (gauge), Pi =  barg Design Temperature =  ᵒC  
     KPag Design temp. between −29°C* and 232°C     
        * For temp. below of -29ᵒC see parag. 812    
  Location Class  =
 Long. joint factor, E =    
  Table 841.1.6-1     See table 841.1.7-1      
  Design factor, F  =     Spec. min. yield strength, S =  MPa  
  See table 841.1.6-1 o 841.1.6-2                  
  Temperature derating factor, T =    It's optional for the designer to include it in the calculation.
  See table 841.1.8-1                  
  Allow. for corrosion, CA =   mm After Nominal thickness calculation, t as per 841.1.1,
         it's must be selected T̅ ≥ tn from ASME B36.10M. 
                     
  CALCULATIONS
                     
  Nominal thickness as per 841.1.1, t =  mm t = PD          
  Minimum thickness required     2000SFET          
                     
  Nominal thickness + Corr. Allow., tn =  mm  tn = t + CA        
                     
   Nom. pipe wall thickness T̅ ≥ tn =  mm              
  From ASME B36.10M (Thickness most commonly used)                
  SCH =  (Minimum acceptable when applicable)    
                     
                     
  Wall Thickness Calculation of Straight Pipes Under Internal Pressure  
   
  Calculation as per par. 841.1 Steel Piping Systems Design Requirements by ASME B31.8  
 
  (Enter values in yellow cells for calculations and in blue cells as information)  
  DATA INPUT  
                       
  Nominal Pipe Size,  NPS =
 in. Longitudinal Weld Joints  =
   
                       
   External Diameter,  D =  in. Material =
   
                 
  Internal Design Pressure (gauge), Pi =  psig Design Temperature =  ᵒF    
        Design temp. between −20°F* and 450°F       
        * For temp. below of -20ᵒF see parag. 812      
  Location Class  =
 Long. joint factor, E =      
  Table 841.1.6-1     See table 841.1.7-1        
  Design factor, F  =     Spec. min. yield strength, S =  psi    
  See table 841.1.6-1 o 841.1.6-2                    
  Temperature derating factor, T =    It's optional for the designer to include it in the calculation.  
  See table 841.1.8-1                    
  Allow. for corrosion, CA =   in. After Nominal thickness calculation, t as per 841.1.1,  
         it's must be selected T̅ ≥ tn from ASME B36.10M.   
                       
  CALCULATIONS  
                       
  Nominal thickness as per 841.1.1, t =  in. t = PD            
  Minimum thickness required     2SFET            
                       
  Nominal thickness + Corr. Allow., tn =  in.  tn = t + CA          
                       
   Nom. pipe wall thickness T̅ ≥ tn =  in.                
  From ASME B36.10M (Thickness most commonly used)                  
  SCH =  (Minimum acceptable when applicable)      
                       
 
                 
    Discussion and References
      Information about Wall thickness calculation of straight pipes under internal pressure:
      ASME B31.8 Gas Transmission and Distribution Piping Systems, para. 841.1.1
    Tables and Standards
  -  Table D-1 Specified Minimum Yield Strength for Steel Pipe Commonly Used in Piping Systems
  -  Table 841.1.6-1 Basic Design Factors
-  Table 841.1.6-2 Design Factors for Steel Pipe Construction
  -  Table 841.1.7-1 Longitudinal Joint Factor, E 
  -  Table 841.1.8-1 Temperature Derating Factor, T, for Steel Pipe
  -  ASME B36.10M-Welded and Seamless Wrought Steel Pipe
-  ASME B36.19M-Stainless Steel Pipe
Equations for Wall thickness calculation of straight pipes under internal pressure (841.1.1):
    t = PD     (U.S. Customary Units)    
    2SFET        
                 
    t = PD     (SI Units)    
    2000SFET        
     tn = t + CA   Corrosion allowance is not included in the parra. 841.1.1
            It is optional to the designer its inclusion in the calculation.
             
                 
    The parameters in the wall thickness calculation of straight pipes under internal pressure
    equations above are:        
    D = nominal outside diameter of pipe, in. (mm)
    E = longitudinal joint factor obtained from Table 841.1.7-1 [see also para. 817.1.3(d)]
    F = design factor obtained from Table 841.1.6-1.
    P = design pressure, psig (kPag) (see also para. 841.1.3)
    S = specified minimum yield strength, psi (MPa), from appendix D
    T = temperature derating factor obtained from Table 841.1.8-1
    CA = Sum. of Allow. for Corrosion, in. (mm)
t = nominal wall thickness, in. (mm)