TMIN is the Minimum Wall Thickness required for a component (e.g., Pipe, Nozzle, Shell, or Pressure Vessel) to safely withstand the design pressure and mechanical loads over its intended service life, excluding corrosion allowance.
Several standards in the market indicate the minimum thickness at which you need to replace your Equipment. IMS TMIN calculators are based on ASME VIII (Vessels, Heat Exchangers) and ASME B31.3 (Process Piping) standards.
IMS enables you to utilize the IMS TMIN Calculators to determine the Minimum Required Thickness (TMIN) for Pressure Equipment Components. These calculations are performed at the CML level, where IMS recommends the appropriate calculator based on the Equipment group and CML Type.
All the TIMIN calculators available in IMS are located under Settings \ Maintenance \ Configuration \ Corrosion Data \ TMIN Calculators.
TMIN Calculators are located under Settings\Maintenance\Corrosion Data\TMIN Calculators.
The Calculators are organized into two equipment groups: Vessel and Heat Exchanger, and Piping. A total of 10 TMIN calculators are provided, which include options for:
Cylindrical Shell
Cylindrical Tube
Nozzle Neck
Spheric Shell
Head Ellipsoidal
Head Torispherical
Head Hemispherical
Bend or Elbow Piping (Intados)
Bend or Elbow Piping (Extrados)
Straight Piping
The first three calculators in the Vessel and Heat Exchanger group, namely Cylindrical Shell, Cylindrical Tube, and Nozzle Neck, each perform two separate calculations. They calculate TMIN for both Circumferential (Hoop) Stress and Longitudinal Stress. Both intermediate results are presented. The final minimum required thickness (TMIN) is the greater of the two values obtained.
The remaining 7 calculators perform one calculation and directly display the Minimum Required Thickness (TMIN).
Calculator with two outputs vs. calculator with one output.
The Info button next to the Calculator’s name displays the applicable ASME standard section and division reference, along with the relevant design formulas used by the calculator.
Click on the Info button to see the standard and the relevant formulas on which the calculator is based.
Calculating Minimal Wall Thickness from Settings
For instructions on using the TMIN Calculators in Settings, see Using TMIN Calculators.
Calculating Minimal Wall Thickness from CMLs Details Page
The Minimal Wall Thickness for a selected CML can be calculated directly on the CML Details page. For guidance, refer to Calculating Renewal Thickness using TMIN Calculators. This requires that the Calculator is configured for the Equipment group’s CML Type that the CML belongs to, under Settings \ Maintenance \ Configuration \ Configuration per Hierarchy Type. For setup instructions, see Adding TMIN Calculators to CML Types.