This calculator is available in a number of modules, where potentially useful. It allows computation of:

       MAWP for ASME Section VIII, Div. 1 components

       MAWP for ASME B31.3 Piping 

       MFH for API 650 Atmospheric Storage Tanks

In the General Thinning Modules, this calculator can also be used to calculate minimum required thickness for components built to ASME Section VIII, Div. 1, ASME B31.3 or API 650 Construction Codes. Care should be taken in using these calculators so that the thickness requirements arising from shell reinforcements due to nozzles, and non-pressure loads are accounted for.

Construction Code

Select the construction code to be used to calculate the component's Maximum Allowable Working Pressure (MAWP) or Maximum Fill Height (MFH). This calculator only includes:

       ASME Section VIII, Div. 1 components

       ASME B31.3 Process Piping

       API 650 Atmospheric Storage Tank (in this case MFH is computed)

Basis for Dimensions

Select whether to use nominal or corroded dimensions as the basis for data entry. Nominal dimensions are the original design dimensions; this option should be selected if input is based on original design documentation. Corroded dimensions are the dimensions in the current, corroded state; this option should be selected if input is based on recent measurements.

Component Shape

Select geometry based on the type and shape of the component.

Location of Metal Loss

Select whether corrosion is located on the inside or outside. The assessment is not valid when corrosion is present on both the inside and outside diameter.

Nominal Inside Diameter

Enter the original inside diameter of the component in requested units. This input will appear only if Nominal Dimensions are selected as the Basis for Dimensions.

Nominal Thickness

Enter value in requested units. This input appears if Nominal Dimensions are selected.

For piping components, it should be noted that the nominal thickness is not adjusted for the lower bound mill tolerance value.

Prior Uniform Metal Loss Remote From Damaged Region, LOSS

Enter the amount of uniform metal loss away from the local metal loss location at the time of the assessment.

Corroded Inside Diameter

Enter current inside diameter including corrosion in requested units. This input appears if Corroded Dimensions are selected.

Uniform Corroded Thickness Away from Pits, trd

Enter current thickness including corrosion in requested units. This input appears if Corroded Dimensions basis is selected.

Future Corrosion Allowance Remote from Damage, FCA

Enter value in requested units. 

Design Temperature

Enter the design temperate value. This value is not used in calculations, but is for reference only.

Allowable Stress at Design Temperature

Enter the allowable stress of the material at the design temperature per the material specification.

Specific Gravity

Enter value of specific gravity in requested units. 

Internal Design Pressure

Enter the internal design pressure for the component. This input will appear only for pressurized components assessed to the API-579 code.

Longitudinal Weld Joint Efficiency

Enter the weld joint efficiency for the longitudinal welds of the component. Enter 1 for components with no longitudinal welds (e.g. seamless pipe). This input will appear only for assessments to the API-579 code on cylindrical components

Circumferential Weld Joint Efficiency

Enter the weld joint efficiency for the circumferential welds of the component. This input will appear only for assessments to the API-579 code

Damaged region is in the center section of the head

Check this box if the local metal loss is located within the center portion of the head. For elliptical heads this is a section within 0.8D centered on the head centerline. For torispherical heads this is the section in the spherical portion of the head, beyond the knuckle radius. This input will appear only for elliptical and torispherical head geometries.

Elliptical Head Ratio, Rell

Enter the elliptical head ratio, i.e. the ratio of the major to minor axis of an elliptical head. This input will appear only for elliptical heads.

Crown Radius, Cr

Enter the inside radius of the spherical portion of the torispherical head. This input will appear only for torispherical heads.

Inside Knuckle Radius, rk

Enter the inside knuckle radius of the torispherical head. This input will appear only for torispherical heads.

Cone Half Apex Angle, á

Enter the angle between the shell of the cone and the centerline of the cone. This input will appear only for cones.

Mechanical Allowances (Thread or Groove Depth)

Enter Values in requested units. Displays for ASME B31.3 Construction Code

B31 Piping Code Coefficient

Enter value which can be found in [4] Table 304.1.1 for the case where t < D/6. Displays for ASME B31.3 Construction Code.

Supplemental thickness for non-pressure mechanical longitudinal loads

Enter value supplemental thickness for mechanical loads other than pressure that result in longitudinal stress in requested units. This thickness is usually obtained from the results of a weight case in a stress analysis of the piping system (see [1] paragraph A.2.6).

Calculate

Click this button to compute the MAWP or MFH result.