Setting up a Reference Dimension

ISODRAFT User Guide

Design Requirements : Reference Dimensions : Setting up a Reference Dimension

The point on the Pipe can be any of the following:

•

The origin (P0) of an Elbow, Tee, Bend, Cross or OLET.

•

The origin of a Support or Comment ATTA.

•

The position of the Head or Tail of a Branch.

Note:

180 degree bends cannot be used for reference dimensions.

Piping Components and ATTAs

A reference dimension is set up by setting the DMTYPE and DMFARRAY attributes of the piping component or ATTA.

Support ATTAs and dimensioned or non-dimensioned Comment ATTAs can be used to create reference dimensions for points on tube. Split ATTAs and Flow ATTAs cannot be used.

DMTYPE is a word array attribute. It defines which component of the reference dimension is plotted. It can be set to one or two of the following:


EAST
NORT
ELEV	or
POS	for a 3D dimension

Figure 5:1.: Example plot file shows one reference dimension to a piping component with POS specified, and one reference dimension to a Datum, with ELEV specified.

DMFARRAY is a reference array attribute. It is used to set the names of the reference elements.

For example:

DMTY NORT EAST

DMFA /N.WALL /VESS2

produces two reference dimensions, one giving the distance North to the centreline of the element named /N.WALL and one giving the distance East to the centreline of the Equipment named /VESS2.

DMTY ELEV

DMFA /SITE.BASE

produces a reference dimension to the centreline of the element /SITE BASE.

The dimension will be to the centreline of the Reference element.

Branch Heads and Tails

A reference dimension is set up by setting the HDMTYPE and HDMFARRAY attributes of the Head or TDMTYPE and TDMFARRAY attributes of the Tail.

HDMTYPE and TDMTYPE are word array attributes. They can be set to one or two of the following:


EAST
NORT
ELEV	or
POS	for a 3D dimension

HDMFARRAY and TDMFARRAY are reference array attributes used to set the names of the reference elements.