New Zealand Engineering 1999 March

Manufacturing

Automated Drawing - Now a Reality

System structure
Objects
Asset management system links

Over the past few years, Beca Consultants have adopted automated drawing methods for instrumentation and control systems design which has reduced CAD hours by up to 40 percent while also significantly improving the consistency of data. These techniques have also allowed us to shorten documentation delivery times for projects where drafting is on the critical path.

Beca Consultants’ first use of an automated drawing production system for instrumentation and control systems drawings was in the late 1980s. Simple CAD templates coupled to a flat database were developed in-house. Encouraged by the initial experience, we looked at what other options were available to us. A system running under Dbase IV was available from our associate company HA Simons in Vancouver and was used for the NZFP (now CHH) Kinleith modernisation project in 1989. This system worked on the mosaic tile approach, whereby a typical loop diagram was broken up into six tiles. A drawing could then be defined by specifying how tiles should be fitted together, with text fields being entered through the database. The improved quality and consistency of data endorsed our decision to use this approach.

By 1994, the need to increase the data linkages across a wider group of documentation was recognised as having the potential to provide further benefits. A review of suitable commercial packages was also made, and Beca decided to adopt the Rebis AutoPlant software package rather than continuing to support our own in-house systems.

Adoption of the Rebis auto-drawing system has been very successful and has been used on a number of projects. Industries include pulp and paper, water treatment, and a brewery. The largest completed project using the system required the production of 850 instrumentation loop drawings, linked to over 1,200 data sheets, and 47 Process and Instrumentation Diagrams (P&IDs). The use of an auto-drawing system was considered essential to achieve the timely delivery of documentation. The system enabled all drawings to be printed out with latest revisions over one weekend.

We have experienced two main advantages in this approach to drawing production. The first is with reduction in CAD hours. Our experience on these large projects indicates a saving of at least 40 percent over conventional CAD methods. For many standard drawings, the need for a CAD operator is almost eliminated, with designers entering design details via the database. For smaller projects, the time savings are less dramatic. The second and possibly more important advantage is that data is consistent across all documents, virtually eliminating the need for cross checking. It can of course mean all documents can be consistently wrong, hence normal verification is still required.

So far, the use of the package has concentrated on P&IDs and instrumentation documentation, as this was perceived to be where the largest gains were to be made. A piping package is also used, but is essentially a stand-alone package with data extracted through a read-only link. This is used for applications such as isometrics and 3D piping design.

System structure

The overall architecture of the system relies on a project-wide, central relational database with live links to applications. Changes within the database are immediately reflected in changes to the P&ID, loop diagrams and other linked documents. The system resides on standard CAD quality PCs linked over a local area network. Due to the requirements to run the large databases, 64MB of memory is preferred, especially for the larger projects.

The system data is entered directly into the database by engineers or designers without the need of the AutoCad environment. The project is initially process driven, with data entry of valves, equipment, motors, instruments and process lines defining the process. These are linked to the P&ID, which maintains a live link to the database. Reports such as motor lists and cable schedules are then easily obtained and always current.

A key table within the database is the instrument index. This maintains links to the datasheets which contain details of all instruments, and are a project deliverable. Typical loops are defined, with live links to the instrument index, loops, I/O schedules (to higher level control systems) and cable schedules. Specific loops are then generated using the defined templates, and are produced outside the AutoCad environment. Final drawings are delivered in the dwg format, and are then independent of the auto-drawing system. Clients with the auto-drawing environment can also take delivery of the database if they require it for ongoing support.

The procurement process has also been improved. The procurement status of process and instrumentation equipment is maintained in the relational database, allowing details such as supplier delivery dates, price and other key data to be queried as part of the instrument index. The possibility of ordering incorrect equipment is then significantly reduced.

It must be remembered that as documents are "live", a drawing is simply a snapshot of the design at the moment of printing. When issues for tender, construction or other milestones are required, the database must be saved at that point to produce a consistent set of drawings.

Objects
We look forward to future approaches to automated drawing production as these will see the use of ‘objects’ in P&IDs. Valves, instrumentation and pipe lines will all hold properties, which will define their appearance on drawings, including interconnection requirements. The objects will also contain the functionality of the equipment or instrument. For example, a change from an orifice plate flow meter to a magnetic flow meter will automatically change the drawing symbol, as well as the associated data sheets and loop diagrams. A pump will contain its pump curve, and a valve its flow characteristics. Even more importantly, it will allow full dynamic simulation of the process as part of the design. At present, Beca perform this simulation on an separate modelling system as such Ideas. Not all designs can afford this additional effort, but in the future it will be available at little additional cost. Preliminary control settings could readily become a deliverable as part of the control system design package.

Asset management system links
Links with asset management systems (AMS) also hold promise of improved plant maintenance and change control. The vision is to link together the design database with the AMS and plant Distributed Control System. Data such as run hours of motors will continuously update the AMS, which can automatically produce documents such as preventative maintenance work orders. It should also be possible to select a graphical symbol such as a pump on the DCS, and be provided with all relevant data such as manufacturer, agent, price paid, and usage history. Failures of equipment can then be quickly resolved by having details online.

In practice, few companies have followed this integrated path in New Zealand. For large companies, the AMS provided as part of auto-drawing packages are not comprehensive enough. Larger stand-alone asset management systems cost well into six figure sums and usually do not have the design links.

The loading of data into an asset management system can also be a daunting task. Ideally, all background plant and equipment data should be loaded and maintained. A gradual changeover, area by area, for historical plant and equipment is a sensible alternative. For new plant, the requirement from design consultants for a design database should be considered if an AMS is contemplated.

The world of industrial plant design is rapidly integrating with database technology. Promises of a reduction of design hours have been delivered, and object orientated approaches will soon gain acceptance. While integration of this data into plant operation has yet to become commonplace in New Zealand, it cannot be far away.

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Kevin Brown, systems technology manager at Beca Power, a business line of Beca Carter Hollings & Ferner Ltd Email kbrown@beca.co.nz