DIMENSIONS

ISODRAFT Reference Manual

Command Reference Section : Alphabetical Command Reference : DIMENSIONS

Specifies dimensioning style.

The basic options for detailed dimensioning are either string or composite dimensions.

String dimensioning gives the maximum amount of detail, since it shows both the lengths of individual components and their relative positions. For assembly purposes (fabrication and erection) string dimensioning often gives more detail than is strictly necessary and composite dimensioning can be specified.

String dimensions, which are plotted by default, are measured sequentially from each relevant point to the next. The relevant points are:

•

The start or end of a branch.

•

Changes of direction (bends, elbows, etc).

Component connection points (flanges, welds, screwed and compression joints etc, excluding gaskets).

Composite dimensions ignore dimensions over which the fabricator has no control, particularly the sizes of individual components. Components which are directly connected to the each other are therefore dimensioned as though they constitute a single composite item.

Only non-flanged components, that is, those with welded, screwed or compression fittings, are considered as connected when calculating composite dimensions. Flanges are always treated as breaks in the pipeline and dimensioned separately.

Fittings which are attached to pipe only at one end are treated as composite with the fitting at the other end. Fittings which are attached to pipe at both ends are dimensioned to the arrive p-point, with two exceptions:

•

Reducers are dimensioned to the larger end;

•

Tees are dimensioned to the centreline of the off branch.

Composite dimensions are always broken at a Tee or Olet intersection point.

The user can display overall dimensions in addition to string or composite dimensions. The default standout for overall dimensions is 16mm. Overall dimensions are taken:

•

From the start of a branch to the first change of direction

•

From each change of direction to the next

•

From the last change of direction to the end of a branch

•

From the start of a falling section skew-box to the end of the skew-box.

•

Between Branch connections.

Figure 2:3.

Dimensioning Methods

Bore sizes will be marked where any confusion might otherwise arise; e.g. at reducers, reducing fittings, tees, crosses, etc.

The user can also specify:

•

Whether or not overall dimensions cross Branch connections;

•

Dimensioning to Valve centrelines.

By default, support/hanger dimensions are on the same side as string dimensions, but they can be on the opposite side. The default standout for support/hanger dimensions is 6mm.

The default settings are:

•

String dimensioning on (and, therefore, composite dimensioning off);

•

Overall dimensioning off;

•

Support dimensioning on;

•

Valve centreline dimensioning off;

Support/hanger dimensions shown alongside other pipeline dimensions.

Examples:

DIME ON

Produces isometrics which are fully annotated in string format, with both piping and support dimensions. This is the default setting.

DIME OFF

Produces isometrics with no dimensions plotted.

DIME COMP ON

Produces isometrics with composite dimensions over connected fittings.

DIME COMP OFF

Produces isometrics with string format dimensions, assuming that dimensioning is still on.

DIME OVER ON

Produces isometrics with overall dimensions on (independent of current setting of string/composite options).

DIME OVER CEN

Produces isometrics with overall dimensions to Valve centrelines and Branch connections (in addition to string dimensions).

DIME OVER CENT ONLY

Produces isometrics with overall centreline dimensions only.

DIME OVER ON STOP

Produces isometrics with overall dimensions stopping at branch connections.

DIME OVER ON ACR

Produces isometrics with overall dimensions across branch connections.

DIME OVER CENT STOP

Produces isometrics with overall dimensions to valve centrelines, stopping at branch connections.

DIME OVER CENT ACR

Produces isometrics with overall dimensions to valve centrelines and across branch connections.

DIME OVER CRIT

Produces isometrics with overall dimensions to critical components.

DIME SUPP

Produces isometrics with support dimensions only.

DIME DEFAULT

Resets the dimensioning style to its default state.

Note:

That standout distances may not be set to the same value.

Related Commands:

DIMDIST SUPPORT TRUNCATE

Restrictions:

Overall dimensioning can be specified in addition to string or composite dimensioning, but an overall dimension will not be shown if it is the same as a string or composite dimension.

Instruments Tees cannot be included within overall dimensions.

When a Tee or Olet is encountered with its arrive p-point in a branch leg, an overall dimension may not be given for the main branch.

Command Syntax:

>- DIMEnsions -+- ON -----------------------------------------------------------.
               |                                                                |
               |- OFF ----------------------------------------------------------|
               |                                                                |
               |- SUPport ------------------------------------------------------|
               |                                                                |
               |- DEFault ------------------------------------------------------|
               |                                                                |
               |- COMPosite -+- ON --.                                          |
               |             |       |                                          |
               |             ‘- OFF -+------------------------------------------|
               |                                                                |
               |- OVERall -+- ON ------------------.                            |
               |           |                       |                            |
               |           |- CENTreline -+- ONLY -|                            |
               |           |              |        |                            |
               |           |              ‘--------+- STOPping -.               |
               |           |                       |            |               |
               |           |                       |- ACRoss ---|               |
               |           |                       |            |               |
               |           |                       ‘------------+- BRANch ------|
               |           |                                    |               |
               |           |                                    |- CONNections -|
               |           |                                    |               |
               |           |                                    ‘---------------|
               |           |                                                    |
               |           |- CRITical -+- ONLY -.                              |
               |           |            |        |                              |
               |           |            ‘--------+------------------------------|
               |           |                                                    | 
               |           ‘- OFF ----------------------------------------------|
               |                                                                |
               ‘- HANGers -+- OPPosite --.                                      |
                           |             |                                      |
                           ‘- ALONgside -+- STRings ---------------------------+>

Querying:

Q DIMEnsions
Q OPTions