As mentioned in the first section, the ultimate goal of a piping specification is to define a list of idents that are uniquely defined over the nominal diameter sizes, based on specification items.
For example, this piping component can be added to the spec:
Pipe, B36.10M, BE, A 106 GR.B, SMLS, for the size range .5 * S-XS – 2 * S-XS.
The details are displayed below.
The idents for the selected commodity code have been built using the geometric displayed below.
Each nominal diameter (NPS1) appears multiple times with different schedules, which means with different wall thicknesses, not uniquely based on the nominal diameter sizes. Based on the engineering work of a specification engineer, the schedule for each nominal size is calculated for the specification and stored in a filter table.
Working with filter tables has the advantage that the geometric tables used for the
building the idents (S.40.12 Commodity Geometrics) can be created independent of the specifications.
You can create spec filter tables using the S.40.13 Filter Geometrics screen or the S.50.20 Wallthickness Geometrics screen. The filter table represents the applicable schedule over all sizes.
A typical best practice is to create filter table codes in accordance with the specification code in order to make maintenance easier. The example in the picture above shows the SDB_2CS300_1 filter geometric, which is used for the SDB_2CS300 specification.
You can assign filter tables to the specification on the spec header level on the Spec Header Geometric tab of Window 1; with the advantage that one filter table can be used for all spec items. Or, you assign the filter table on the spec item level in the Geom1 field on Window 2, which means it will filter only that specific spec item.
Assign Filter Table to Spec Header Geometrics
The best and easiest way to filter all components like pipe, fittings, flanges, reducers, and so forth is using one filter table on the spec header level, as shown below in the picture.
The spec header filter normally filters several different specification items that
can have different allowed nominal sizes; thus, the filter only works for schedules
and not for nominal sizes. If nominal size and schedule filtering are required for
a component, the filter table must be assigned on the spec item.
Check the Filter indicator for the filter table defined in spec header geometrics. With the assigned short code %, all spec items will be filtered using this filter table.
All spec items that are to be filtered by the spec header geometric filter table
must have the Geom1 field at the spec item level EMPTY. This rule defines for any specification item an exception filter table simply by assigning
a different filter table to the specification item record.
The filter result is shown in the screenshot below.
The idents shown above are reduced by the filter table assigned to the spec to one unique ident per nominal size, and further restricted to the size range .5 – 2 by the sizes entered on the spec item level and displayed here on Window 3 in the upper block.
Assign Filter Table to Spec Item Geom1
Filtering at the spec item level is very similar to the header filter method.
Components without a schedule like gaskets or bolts must be filtered on the spec item level. For example, the picture below shows the filter table that is needed to filter the gaskets.
Instead of the schedule, it has the gasket thickness as the second filter criteria besides the NPS.
This filter table must be assigned to the gasket spec item in the Geom1 field on the spec item level, as displayed in the picture below.
The filter result is shown in the screenshot below.
