thickess measurement location tml

IDMS integrity database management system best practice – Thickness measurement location TML

Recording Thickness Measurement Location – TML

we will continue the previous article about IDMS integrity database management system. Previously we talk about design code and inspection method involved. now will focus on trending of inspection result represented by a term called Thickness measurement location or TML. Thickness Measurement Location records contain various fields that store information to identify a TML. When we create a new Thickness Measurement Location record, we will need to supply information in some of fields. The following information provides various fields that are defined for the Thickness Measurement Location such as

  • TML ID
  • design pressure
  • design temperature
  • corrosion allowance
  • Allowable Stress
  • Design Code
  • Code Year (Allowable Stress Lookup)
  • Material Specification
  • T-min formula
  • Critical thickness
  • structural thickness
  • number of reading
  • nominal thickness
  • inspection date
  • previuos inspection date
  • inspection interval
  • expire date
  • corrosion rate

IDMS integrity database management system – understanding Thickness measurement Location – TML trending

In practice, the fixed interval of pressure vessel inspection is 5 years. UT inspector takes the measurement shell & head thickness at some locations. we call it as TML, thickness measurement location. an IDMS data entry populates TML readings into IDMS software. IDMS software calculates short corrosion rate, long corrosion rate, remaining life, next inspection date based on half-remaining life method.


required thickness0.35in
inspection date1-Jan-00
TML reading0.525in
required thickness0.35in
inspection date1-Jan-05
TML reading0.510in
required thickness0.35in
inspection date1-Jan-10
TML reading0.505in
short corrosion rate0.001in/year
long corrosion rate0.002in/year
available thickness0.155in
remaining life from Short CR155.084932year
remaining life from Long CR77.5636986year
half remaining life38.7818493year
next inspection schedule3-Oct-48


result of Integrity database management system – trending:

dateTML reading
6-Jul-87 ( projection )0.350 ( required thickness)
thickness measurement location TML trending
integrity database management system – thickness measurement location  ( TML trending )


  • 1 = last inspection date
  • 2 = next inspection date based on half-remaining life method
  • 3 = expired date


Leave a Reply