Location for Analysis Matrix (LAM)

The format and approach to the "Locations for Analysis Matrix" is described here as an orderly way to examine systematically the behavior of materials in subcomponents. However, the overall framework for analysis is the "System," such as a fossil power plant a building, an aircraft, an automobile or a petroleum refinery; but from a corrosion point of view analysis is not possible at this level. The next level in the hierarchy is a "subsystem." In petroleum refinery, this may be a depropanizing system. The third level is a "component." A component might be a condenser; this is still too general for detailed analysis. The detailed analysis must start with the subcomponents. For the condenser the subcomponents are the shell, the tubes, the supports, and the tubesheets. Details of these levels are described in [1].

Separate analyses should be performed on components; these analyses are aggregated to produce an overall analysis of a component. Successive aggregations then eventually provide an analysis of the corrosion performance of the whole system.

Figure 4 Bases for the Location for Analysis Matrix (LAM) in a steam generator of a pressurized water nuclear power plant: (a) Locations for Analysis, LAi, at the left and modes, MDj and submodes, SDj, considered for each location. (b) Matrix for organizing Mode-Location cells. The abbreviations, "LP," "HP," "Ac," "Ak," and "Pb" for "SCC" and "IGC" refer to "low potential," "high potential," "acidic," "alkaline," and "lead" for "stress corrosion cracking" and "intergranular corrosion" (After Staehle1).

A format of the "Locations for Analysis Matrix" is shown in Figure 4. Here, various locations are selected along the ordinate of the matrix. As illustrated in Figure 4, these are locations that correspond to most likely failure sites along tubes in a steam generator of a pressurized water nuclear power plant. These are locations for analysis, LAi. Along the top or abscissa of this matrix is a set of modes and submodes that can be expected for at least some of these locations. The cells that are formed by the intersection of the locations and modes define the information that needs to be considered. In brief, such information may be:

However, the most important feature of this matrix is that it requires explicit consideration of each cell. The record of actions taken for each cell becomes part of the engineering design history and an agenda for action. The LAM is the framework within which the information of the CBDA fits. It is the means for focusing specific attention on issues of prediction and performance.

The steps in developing the LAM are detailed here

Lifetime Prediction, Roger W. Staehle, Adjunct Professor, Department of Chemical Engineering and Materials Science, University of Minnesota, Staehle Consulting Co.