DIMENSIONAL CONTROL

Fertoing provides high-precision dimensional control survey services of large-scale industrial assets and constructions, as-built or under construction. 

This technology is actively used by the company specialists during fabrication of subsea spools within the framework of the SPU construction at Kirinskoye GCF, Sakhalin-3 Project, being the first facility of this kind in Russia.

Successful high-precision spool dimensional control has proved technological prospects for Fertoing in this field on the global market.

Dimensional control of industrial assets is performed using high-precision electronic total stations, laser trackers, and scanners together with specially designed software (like SpatialAnalyzer® (SA) developed by New River Kinematics). The above mentioned technology allows to control dimensions in all shapes and sizes.

As-built dimension control of ready fabrications or assembled structures is relatively effortless. Data from any metrology instrument, say from a total station, in a point cloud is transferred to a design management system for processing. The obtained 3D mathematical model can be compared against the original mathematical model of the asset or structure. In case there is no original model but only 2D drawings, the required model can be created on their basis. 

Dimension control of assets under construction is more complicated. However, despite all time costs during the preparatory period, the assembly itself goes quicker due to availability of as-built and designed values of the surveyed asset. First, all parts of the assembly are inspected in terms of geometrical dimensions. Then, they are marked with nominal reference points which positions are to be controlled throughout assembly. All parts with marked points are assembled in the design management system within the nominal reference system for further actual assembly on the basis of the acquired mathematical model with nominal reference points being constantly monitored for conformity.

One of the key features of this technology is that fabrication can be carried out not only on stable but moving structures such as pipe-laying barges, this was proved during our surveys on-site. However, the main part, against which all other parts will be assembled, should be stable.

To get an accurate collection of fully digital 3D coordinate data from different measuring instruments such as theodolites, total stations, laser trackers, radars and scanners the special software is used. One of such examples is SpatialAnalyzer®. 

SpatialAnalyzer® is a graphical software platform capable of data integration from multiple instruments, cross-reference of different coordinate systems based on any number of common points or geometrical elements, and determination of tolerances for each surveyed asset.

The main advantage of the offered method comparing to other methods of large-scale structure dimensional control including traditional ones using only measuring instruments are:

  • acquisition of reliable geometrical information with millimeter and sub millimeter accuracy in relatively short time;
  • applicability to assets with any geometry;
  • no need for calibration block fabrication;
  • one-man job. 

Using instruments with fitted wireless data transmitters allows online processing, mathematic modeling and tolerance determinations for further corrections, if needed (pic.1).
 

Pic. 1 SpatialAnalyzer®, asset model

SA® advanced network architecture provides simple, common interfaces with multiple instruments (total stations, laser trackers, 3D scanners, etc) and possibility to operate CAD data online (pic.2).

Pic. 2 SpatialAnalyzer®, modeling using multiple instruments

SA® allows modification of each station using 7 parameters (X, Y, Z-motion, X, Y, Z-rotation, and scale factor) with adjustment in the nominal reference system.