One of the key features of Credo is the recording of Thickness Readings. This data is typically stored against Points, which are Thickness Measurement Locations. Providing the correct information is supplied, Credo will use the Thickness Readings to calculate the corrosion rate and remaining life for your equipment.

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Alarms are stored against each Point. Credo can store data for 5 Alarm Levels.

Typically, the following data is used for each:

• Alarm 1 - Nominal thickness minus Manufacturers Tolerance
• Alarm 2 - Nominal thickness minus (Manufacturers Tolerance + Corrosion Allowance)
• Alarm 3 - Minimum pressure retention thickness based on Maximum Design pressure (DesMax)
• Alarm 4 - Minimum pressure retention thickness based on Maximum Operating pressure)(OperMax)
• Alarm 5 - Tmin. This is a manually chosen thickness reading which is the lowest allowed. If an item reaches this it should be replaced ASAP

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In Credo5, users have the ability to customise the calculator formulas and packages. Below lists some of the common wall thickness formulas which may be used by the Credo5 calculator by default.

• CODAP 2000 - French code for the construction of unfired pressure vessels
• ASME VIII - American society of mechanical engineers. Used for pressure vessel design
• BS5500 - 1997 Specification for unfired fusion pressure vessels
• ANSI B31.3 - Chemical Plant and Petroleum refinery code
• ANSI B31.8 - Chemical Plant and Petroleum refinery code

Some common data used when performing calculations on wall thickness are:

• Maximum design pressure allowed on the equipment
• Coefficient offset
• Corrosion Allowance
• Outside diameter of the pipe
• Joint quality factor (how good the seal on the pipe is)
• Manufacturers Tolerance (pipe can differ slightly in size, so there is generally a % tolerance which is allowed. Usually it is 12.5%)
• Nominal wall thickness of the pipe
• Allowable stress (the force/strain the pipe can withstand safely)