Drawings are uniquely identified by a Drawing Code. The drawing coding system is defined by the project. Obviously, there should never be two drawings with the same code.
A project’s drawing coding system defines drawing codes that consist of a series of components, each of which have meaning. Component values are frequently selected from lists of allowed values. The meanings of the each of the components define what the drawing is about (with the exception of the drawing code final component, which is normally a sequence number).
Here is an example drawing code:
In this example, the drawing code components have the following meanings:
- CC094 – Identifies the project: a hydroelectric project
- 300 – Contract number: Headrace Tunnel
- A2 – Location: Adit 2
- CV – Engineering discipline: Civil
- 0101 – Sequence number
- C1 – Revision code: Revision 1, Revision type: C – construction drawing
For each drawing component there is a list of allowed values. For example, the allowed values for engineering disciplines might be:
- CV – Civil
- EE – Electrical
- EM – Electromechanical
- GE – Geological
- ME – Mechanical
The list of allowed values for some drawing code components could also depend on the value of another drawing code component. For example the allowed locations for the headrace tunnel contract would include locations for the inlet, main tunnel, adits and pressure shaft, while the powerhouse contract locations would include the turbine hall, generator hall, control room, etc.
When defining drawing coding systems, order the drawing code components to fit the hierarchy of the project structure, with the higher-level components first. This ensures that when you sort a list of drawings codes, related drawings are grouped together. In the example, the contract number is before the location, which is before the engineering discipline. This means that all civil drawings for the headrace tunnel at adit 2 appear together in a sorted list.
The drawing code presented above, includes the revision code. The revision code identifies the revision of a drawing. Typically it’s taken from a sequence of numbers (1,2,3,..) or letters (A,B,C). The revision code sometimes includes additional information that identifies the revision type (construction, as-built, etc.) or other feature of the revision.
It’s critical that you can sort your drawing list by the revision code such that the revisions appear in the correct order. Use simple revision codes and eliminate any additional information (which you can put in separate columns in the drawing list).
Alternate Drawing Codes
Suppliers, vendors, contractors and other outside parties that deliver drawings frequently assign drawing codes based on their own coding systems.
You should always assign project drawing codes, e.g. codes based on the project’s own drawing coding system, to all externally produced drawings, and should show them in the drawing list. This ensures that when you search for the drawings associated with a particular project component you get all the relevant drawings, regardless of who produced them. It also helps you track the receipt and review of externally produced drawings.
From the project’s point of view, the foreign drawing codes of externally produced drawings are considered alternate drawing codes. Your master drawing list should also have a column for recording the alternate drawing codes. This can help reduce confusion in communication with the outside parties, who think in terms of their coding system. Ideally you can convince your external drawing producers to put project codes on the drawings they supply and use project codes in their correspondence.
Continue to (Part 3 – Classification Systems)