Remplacer valeur case avec un Select Case

Sub Test()
  Dim Cel As Range
  For Each Cel In Worksheets("Document").Range("G2:G" & Worksheets("Document").Range("C65536").End(xlUp).Row)
    Select Case Cel
    Case Is = "312-Process"
      Range("M" & Cel.Row).Value = "PROCESS DESIGN"


    Case Is = "346-Electrical Design"
      Range("M" & Cel.Row).Value = "ELECTRICAL DESIGN"


    End Select
  Next Cel
End Sub

Private Sub CommandButton1_Click()
With Intersect(Me.UsedRange.EntireRow, Range("M2:M" & Rows.Count))
  .FormulaR1C1 = "=IF(COUNTIF(T_source,RC7),INDEX(T_valeur,MATCH(RC7,T_source,0)),""""&RC7)"
  .Value = .Value 'ne garde que les valeurs
End With
End Sub

Private Sub CommandButton1_Click()
Dim c As Range
Application.ScreenUpdating = False
With Intersect(Me.UsedRange.EntireRow, Range("M2:M" & Rows.Count))
  .Value = .Offset(, -6).Value
  For Each c In [T_source].SpecialCells(xlCellTypeConstants)
    .Cells.Replace "*" & c, c(, 2)
  Next
End With
End Sub

Sub Fct_Purge_Noms_Inutiles()
    ' Suppression des noms inutilisés de la feuille active
    Dim nm As Variant
    ' Suppression des noms du classeur contenant #REF
    ThisWorkbook.Activate
    For Each nm In ActiveWorkbook.Names
        If InStr(1, nm.RefersToR1C1, "#REF") <> 0 Then
            ActiveWorkbook.Names(nm.Name).Delete
        End If
    Next
End Sub

Option Explicit
Sub Quoi()
    Dim c As Range, Quoi As Range
    With Application: .ScreenUpdating = False: .Calculation = xlManual: .EnableEvents = False: End With
    Sheets("Code").Activate
    Cells.Find(What:="COLONNE G", After:=ActiveCell, LookIn:=xlValues, _
               LookAt:=xlWhole, SearchOrder:=xlByRows, SearchDirection:=xlNext, _
               MatchCase:=True, SearchFormat:=False).EntireColumn.Name = "où"
    Sheets("Document").Activate
    For Each c In Columns(7).SpecialCells(xlCellTypeConstants)
        If c <> "" Then Set Quoi = Sheets("Code").Range("où").Find(c.Value, LookIn:=xlValues)
        If Not Quoi Is Nothing Then c.Offset(0, 6) = Quoi.Offset(0, 1)
    Next
    With Application: .EnableEvents = True: .Calculation = xlAutomatic: .ScreenUpdating = True: End With
End Sub