COORDINATE

1
COORDINATE ELEVATION
DIMENSIONING
2

• Plant coordinate systems use intersecting grid
  lines to locate buildings, structures,
  foundations, equipment and piping.
• Intersecting grid line
• These lines originate from a designated control
  point
• They are drawn parallel to north/south and
  east/west axes
• Control Point Benchmark
• This is a permanent marker its typically
  located in a remote area of the facility
• It is used as an origin from which intersecting
  North/South and East/West lines are labeled as
  coordinates using numerical values
• It is the primary reference point designated by
  0-0,0-0
• It establishes the elevation of piping facility
• This is the vertical distance an object is above
  sea level
• Pipe facilities use this elevation to designate
  the height above grade (Grade Ground)
• Most facilities use the arbitrary elevation of
  100-0 as grade for the plant facility.

3
In the illustration below, you see the BENCHMARK
(0-0,0-0) and the actual MATCH LINES as they
would appear in paperspace. The grid has been
arbitrarily set up at 5-0 increments and will
be removed as we progress through this tutorial.
Your finished drawing will not show the BENCHMARK
or the grid lines like the above drawing, this is
done only to show you how the initial setup of
your drawing might begin.
4
Once the North Arrow is placed on the drawing,
the use of the BENCHMARK makes more sense. It
establishes the origin of your coordinates and
how they are related.
The North Arrow on any layout drawing you make
will typically point UP toward the top of the
drawing itself. The only other acceptable
position for the North Arrow is pointed to the
RIGHT of your drawing.
5
BASIC RULES for Calculating Distance Between
Coordinates
When working around the Benchmark, you will be
dealing with 4 quadrants NE, NW, SW and SE. This
can be a little confusing when trying to solve
for distances between equipment located by
coordinates.
Page 137 in textbook.
Dont worry, its really pretty simple

• To find the distance between two coordinates in
  the same quadrant you just subtract their values
  E26-0 E12-0 14-0
• To find the distance between two coordinates
  located in different quadrants, just add their
  values W12-0 E26-0 38-0

6
In this course we will use feet/inches formatting
for the coordinates within our design project.
However, each company will have its own system of
plant coordinates ft/in, decimals of ft or
millimeters. The coordinate system within the
same facility will NEVER changemeaning that if
the plant is initially layed out as ft/in
coordinates, that it wont change to decimals of
a foot or vice versa.
7
SECTION / ELEVATION DRAWINGS
In all petro-chemical facilities, pipes are
installed both above grade and below grade.
Using the arbitrary elevation of 100-0 as a
point of reference prevents the occurrence of
negative numbers when dimensioning lines that are
below ground.
Piping section or elevation drawings have few
actual dimensions. In most instances the designer
will use callouts on the drawings to convey
elevation information for construction purposes.
Page 135 textbook
8
When you have to calculate vertical dimensions,
its a little easier than using coordinates. You
simply subtract the lower elevation from the
higher elevation to get the dimension between the
two.
Its preferable to use similar elevations
centerline to centerline or F/F to F/F, when you
are solving for dimensions. BUT thats not
always possible so, as you will learn, its
necessary to be able to do calculations using
fittings and flanges to resolve some dimensional
problems.
Questions, comments, complaints or conundrums can
be raised during the next class period or email
me.