Global Preferences

Multiple records with varying temperatures and stress values may exist for a given combination of Material Specification, Material Grade, and Design Code values. So, after a match is found on Material Specification, Material Grade, and Design Code, Thickness Monitoring (TM) evaluates Design Temperature.

If the Design Temperature in the TML is an exact match to a temperature value in a Piping Stress or PV Stress record, TM will simply use the corresponding Allowable Stress value. For example, consider a TML that contains the following values:

• Material Specification = SA-216
• Material Grade = B
• Design Code = ASME B31.3
• Design Temperature = 100

Now, consider a Piping Stress record that contains the following values:

• Material Specification = SA-216
• Material Grade = B
• Design Code = ASME B31.3
• Design Temperature = 100
• Allowable Stress = 20000

In this case, the values in the TML are an exact match to the values in the Piping Stress record. Therefore, TM will use the Allowable Stress value of 20000 to calculate Maximum Allowable Working Pressure and T-Min.

Thickness Monitoring uses reference tables to look up the Allowable Stress values for performing T-Min calculations and for calculating Maximum Allowable Working Pressure. You have two choices regarding how the stress reference tables will be used to determine Allowable Stress when an exact match cannot be found:

• You can specify that the lowest temperature in the established range should be used.
• You can specify that Thickness Monitoring should use linear interpolation to determine the Allowable Stress.

By default, interpolation is disabled.

Thickness Monitoring Tasks will be created automatically when you create Corrosion Analysis Settings for an asset or TML Group, or a record that stores equipment or component data for a Corrosion Analysis. GE Digital APM provides an option that allows Thickness Monitoring Tasks to be updated automatically when you make changes to a Thickness Measurement Location (TML) record.

The Auto Manage Tasks setting is disabled by default. If the Risk Based Inspection (RBI) license is active, you should not change the default setting because you will use the Task records generated from RBI, rather than TM, to determine your inspection intervals. If the Risk Based Inspection license is not active, you should enable the Auto Manage Tasks setting.

Thickness Monitoring includes several baseline TML-level corrosion rates that you can choose to calculate for TML Corrosion Analyses. In addition to using these baseline corrosion rates, you can define custom corrosion rate calculations to use within Thickness Monitoring. Using the options on the Global Preferences workspace, you can define up to two custom calculations.

Before you can enable the use of custom corrosion rates, you must first create rules that define those corrosion rates. This documentation assumes that the necessary rules have already been defined.

Nominal T-Min is a value that represents the minimum thickness of a pipe based upon accepted industry standards. The Nominal T-Min value takes into account various design specifications and determines the minimum thickness associated with that criteria. The Nominal T-Min value is retrieved using values from Thickness Measurement Location records and records in the Piping Nominal T-Min reference table. Using the Nominal T-Min Preferences section, you can configure which fields you want to use for retrieving the Nominal T-Min value for Thickness Measurement Location records that are linked to Equipment or TML Group records that represent pipes, or records that store equipment or component data for pipes.

In the Nominal T-Min Preferences section, under the Fields for Nominal T-Min Lookup heading is a list of all these fields that exist in the Piping Nominal T-Min family.

Each field in the Piping Nominal T-Min family corresponds to a field in the Thickness Measurement Location family. By selecting a field in the Fields for Nominal T-Min Lookup list, you are indicating that you want to use that field for looking up Nominal T-Min values. This means that values in the associated fields in Thickness Measurement Location records will be compared to values in the Piping Nominal T-Min reference table and that a Nominal T-Min value will be returned only if a match is found. Any field that is not selected in the Fields for Nominal T-Min Lookup list will not be used for looking up the Nominal T-Min value. In other words, values in those fields of Thickness Measurement Location records are not required to match values in corresponding field in the Piping Nominal T-Min reference table.

If you enable this option and create Measurement Not Taken records and then later disable this option, any Measurement Not Taken records that you created will be ignored in the Corrosion Analysis (i.e., all calculations will be performed as if the Measurement Not Taken records did not exist).

When you make changes to the Common Measurement Data Field Mappings section, the new fields you map will be made available on the Measurement Data Entry workspace, in the common measurement data section. By default, Measurement Comment and Measurement Status Indicator fields are available to map. Additionally, any custom fields you create for the Thickness Measurement family will appear in the list of available fields.

For example, if you select the Measurement Comment and Measurement Status Indicator fields to be mapped to the common measurement data section, the following screenshot illustrates how they will appear on the Measurement Data Entry workspace.

Thickness Monitoring Rules Lookup records create a reference table of values that are used by GE Digital APM Thickness Monitoring for performing certain calculations. Like all reference table records, Thickness Monitoring Rules Lookup records can be viewed most easily in the Bulk Data Form or through a query. For your convenience, the TM Administrative Tasks page contains a link that allows you to open Thickness Monitoring Rules Lookup records in the Bulk Data Form, where you can view and modify the reference table values as needed.