Computer-Aided Estimating for Instrumentation & Controls
Publication Date: 2012-Jun-06
The IP.com Prior Art Database
Page 01 of 10
COMPUTER-AIDED ESTIMATING OF INSTRUMENTATIONAND CONTROLS
DAVID F.DEATON, P.E.
Princi al Engineer
Houston, Texas 7'7210
The M.W. Rellogg Company
Maintainingtighter project cost control is a top priority for major engineeringand construction projects in the process industries. Owners and engineering contractors are trying to trim project costs through quality management, productivity improvement, project controls, and other measures. This trend has a special influence on the world of instrumentation, where advancing technology continually adds to the complexity of devices, systems and work processes.
It is not sur rising that computer-based estimatin tools have not kept up with instrumentation estimating process. A user is required to think in terms of rogram navigation and special keystroke combinations instead of thinking about t
R e work
process itself. The tool drives the activity, rather than reflectingor supporting it.
The various commercially-available PC-based estimating programs are strictly oriented toward line-item estimating, where a certain item is assigned a unit cost and unit construction hours. Thbs type of
equipment estimates for building
instrumentation as distributed controls, the complexities of the components and associated engineeringactivities are better suited for relational database design.
Historically, computer tools for control systems engineering have supported design and engineering of the details of plant instrumentation, rather than accurate estimation of cost and workhours. The tools have been more qualitative than quantitative.
Existing estimating tools have focused primarily on individual field instruments and bulk installation materials. These items typically represent 10 to 30 percent of overall budgets. The major portion of the budget is taken by complex components such as analyzer systems, digital controls and control valves. Estimating the capital cost of these commodities has been based on vendor quotes or limited historical data. Similarly, the complexity of the activities of engineering and designing these components has increased, requiring accurate, flexible methods for estimating task workhours.
P The spreadsheet is an out8
ated tool for attacking the
Page 02 of 10
COMPUTER-AIDED ESTlMATlNG OFINSTRUMENTATIONAND CONTROLS
A MORE PRODUCTIVEWAY
A progressive solution to these challenges has been developed and tested on many projects. Through a self-documenting process and computer rogram, an instrument engineer may produce either a detailed or factored estimate. phe program is designed to be intuitive, so that it follows the work process instead of driving it. The program, developed for in-house use only, calculates instrumentation and bulk material costs, and workhours for engineering, design, and construction. Program results have been validated against known project expenditures of cost and workhours. The results have attained improved...