© 2019 by TGC Engineers.

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DIMENSIONAL CONTROL

Texas Gulf Coast Engineers is an innovative company that provides engineering services, dimensional control services and construction/turnaround field support. These services are provided on a reimbursable basis for revamp projects, grass roots facilities, plant relocation projects and dimensional verification/revision of construction packages prepared by other engineering contractors.

 

Projects utilizing these techniques are typically installed with no leave-long field fits or rework of pipe spools due to dimensional errors, regardless of dimensional complexity.

 

TGCE is the world leader in construction field support activities for dimensionally challenging projects such as FCCU turnarounds, coke drum modification/replacements and alloy piping systems. TGCE has also recently added drones high precision dimensional data capture to our service offerings.

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TGCE AIMS Technology vs. Laser Scans Alone

The dominant dimensional tool utilized in our industry today is laser scanning/point cloud technology. It is the primary measurement device employed by the major engineering companies to produce models for detail design. Even though point cloud technology dominates the market place, laser scans have proven deficiencies. Our clients contend, and our comprehensive verification/checking procedures confirm, that design documents generated with laser scans require revisions before fabrication and construction of critical fit elements. Laser scans cannot provide the precision required for zero defect design packages or design without the use of leave-long field fits.

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TGCE/AIMS Technology uses total station point shots and digital image measurement technology to provide dimensional data for detail design, fabrication checks, and construction field support. The comprehensive use of these two diverse and independent measurement systems to dimensionally monitor all project phases is part of every TGCE project. Both of these measurement systems provide significant precision advantages over laser scanning technology.

 

On projects where these methods are utilized, dimensional errors are reduced to less than one tenth of one percent (0.1%) and most projects are error free. We do not utilize leave-long field fits in the course of doing our work, regardless of dimensionally complexity (see attached case studies). This is true even of hot services and elements in motion because of low frequency vibration.

The TGCE Difference

 

TGCE has extensive experience checking design documents that have been generated with laser scans as the basis for design. Seventy percent (70%) of TGCE’s work stream today consists of checking/correcting IFC packages where laser scanning was utilized for detail design.  A partial list of the operating companies that regularly utilize this service on a multi-site basis include: Chevron, ConocoPhillips, DuPont, ExxonMobil, Flint Hills Resources, Marathon, Shell, Sunoco and Valero Energy.

 

Most of the projects checked are designed using laser scanning as the dimensional basis of design.  Clients report that TGCE’s QA/QC services provide significant positive impact to project budget and schedule. References of projects/clients can be provided upon request.

 

Our typical QA/QC scope of work for a laser scanned project is as follows:

 

  • Model elements as required for as-built condition prior to dimensional check

  • Capture temperature data as required for adjustment from thermally expanded to fabrication dimensions (as built)

  • Detail design check, correcting any dimensional errors and eliminating any leave-long field fits in the design package

  • Dimensional capture of fabricated elements for comparison to the corrected design documents and trial fitting in the model created in step one

  • Construction field support: Lay-out and check of foundations, cut-lines, tie-ins of all other elements as required for fit-up

  • Redesign of pipe spools, as required, to compensate for the “dimensional drift” associated with shop tolerances and dimensional errors in fabrication and construction layout