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.
Thickness Readings
Alarms
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
Trend
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)