Drawing control made easy

Ensuring that your drawings are accurate and up-to-date is easier than you might expect.

By Ken Leary

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Have you ever tried to construct a model plane when the instructions are missing? Has anyone ever asked you for directions when you yourself were lost? These questions are synonymous with out-of-date or inaccurate drawings in the work place.

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Recently someone asked me to help them develop a five-year plan for managing a work area. I asked if they had an up-to-date set of drawings for this particular area. The answer was all too familiar in industry: "No, we don't have up-to-date drawings but we still need a plan."

How can anyone provide valid guidance or make reasoned recommendations without an accurate picture for that plant area? Yet, this the type of problem that management usually faces. The answer to the question affects the safety, productivity, and financial performance of any plant or company. This article deals with the issue of integrating drawings in accordance with the Process Safety Management process, OSHA 1910.119.

Some type of procedural system — better known as document control — is the key to a successful program for accurate drawings. Today, most document control systems are electronic. There are many types of computer aided design packages from which to choose. Each makes implementing and maintaining document control easy.

However, it is important to standardize on a CAD system and software package throughout the plant or corporation. If more than one CAD system is in use, then there must be software compatibility among systems or you must have software to translate CAD files.

Once the CAD software is implemented on a network, access to the drawing files must be controlled. The personnel that needs access to the drawings includes plant maintenance personnel, plant engineers, and others. Maintenance needs the drawings for troubleshooting process equipment. Engineers need access to drawings for plant expansions and renovations.

A good document control system provides access using any of several methods. The first is controlled access through a supervisor's office where the system can be monitored and kept under lock and key if necessary. This may be the least complicated and least expensive approach but it is not the preferred method. The second approach is through password-limited "read only" access to files for the majority of the employees in a plant. Only the engineers and designers have "read/write" access to the files.

The conduit of change for any drawing should be a formal procedure that requires several signatures to ensure adequate checks and balances. After updating drawings, conduct a formal review that includes the design engineer, the safety representative, relevant plant personnel, and any management representatives for the area affected by the change. If the plant is under the jurisdiction of OSHA 1910.119, then a management-of-change document must be filed and the proper signatures for this change must be documented.

Once parties agree and the change is documented, the next step in the Process Safety Management process is to complete the hazard and operability review. There are several other steps to integrate the Process Safety Management process into this change but these are beyond the scope of this article.

Drawing numbering system

Over a period of years many numbering systems for drawings have been tried. The following technique for assigning drawing numbers is the result of carefully reviewing these systems.

The drawing number itself should encode the building or area represented by the drawing, the discipline represented by the drawing content, and the equipment the drawing depicts.

Consider drawing number 114-E-105, for example. The first three numbers represent the building number--in this example, building number 114. The letter represents the discipline addressed by the drawing as in the following coding scheme:

  • E for electrical,
  • I for instrumentation,
  • A for architectural,
  • C for civil,
  • M for mechanical,
  • P for process or piping (P&ID), and
  • S for structural.

The three numbers following the letter represent the process area or equipment number. For instance, 105 may represent Furnace Number 1 or Chiller Number 3. This number should also be used in a database when filing information related to that particular equipment number. This database should contain information such as spare parts data and vendor cut-sheets on pumps, valves, and agitators, and so forth. The encoded information should also be used when purchasing equipment, troubleshooting or maintaining it, and recording information regarding equipment capacity.

Some drawing numbering systems depend upon key words in the drawing title to find the drawing in an electronic file or database. These systems are inefficient and usually require extensive effort to locate the proper drawing. Search time equates to dollars lost for those doing the searching. Most systems using this method have drawing numbers that convey absolutely nothing about the drawing itself.

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