ON-SITE MACHINING (OSM) CASE STUDY

Line Boring Jackup Oil Rig Platform - Chain Beam Assembly

OVERVIEW

Furmanite recently earned a contract to perform on-site line boring on the new construction of a Jackup Platform Chain Beam Assembly. In the early 1950's, the "Scorpion" designed by R. G. LeTourneau for Zapata Off-shore Company (owned by George H. W. Bush), was the first Jackup platform manufactured to provide a stable and secure floating structure  in which the entire platform could raise to a safe operating height in often treacherous open waters.  Today the Gulf Region is host to over 500 operating Jackup platforms.

SOLUTION AND IMPLEMENTATION

In setting the Jackup platform, the main assembly, at 77 feet in length and weighing in at 120,000 pounds, pays out and reels in an enormous chain which in turn lowers and raises the legs of the platform. The critical bores (being machine in photo at left) hold the shaft upon which the chain sprocket rotates. Furmanite's scope entailed machining five sets of bores, removing 2" of material diameter (1" per side) from each 3.5" long bore.

RESULTS

Furmanite was required to complete all five sets of bores in less than ten days. Furmanite scheduled a two man day crew and a two man night crew to work around the clock, completing the project in less than nine days. The customer was pleased with both the quality of the work, and the efficiency in which it was executed.

 
 

HYDROELECTRIC FIELD MACHINING PROJECT - New Turbine Installation

Overview

Furmanite was recently hired to perform in situ machining on the new construction of a three turbine hydroelectric generation power plant installation on the Ohio River. The power plant houses three horizontal 29.3-MW bulb-type turbines, and generating units, with an estimated total rated capacity of 88 MW at a gross head of 25 feet. The Stay Cone flanges and associated mating parts were manufactured and machined in the OEM's workshop facilities and transported to the site. Due to the size, configuration, mechanical handling, transportation complexity, and installation limitations the final machined finishes required precise on-site machining to correctly align the enormous mating surfaces. With a proven history of performance, Furmanite's Integrated Mechanical Services Division, a worldwide leader in large dimension field machining, was hired for the in-situ field machining of the Stay Cone Vertical Flanges.   All three bulb turbine units were to be completed with the final required 3mm to 5mm of stock removal in the mating flange faces in which the massive flanges measured 17 feet inside diameter by 19 feet outside diameter.           Solution and Implementation Furmanite was hired by the general contractor for immediate assistance to resolve the misalignment issues which were creating significant assembly delays, and was having a major effect on the entire project delivery schedule. It was Furmanite's determination that with some engineering modifications to an existing large flange facing machine the customer's machining requirements could be completed accurately. Within a 10-day timeframe Furmanite engineered the modifications for the machine, manufactured the parts, and mobilized to the site.  Watch the video, here. Results   The machine was set to known datum points using laser tracker equipment. Machining was carefully undertaken with measurements taken frequently. All three unit Stay Cone Flanges were successfully machined and completed within a 21-day period. The tolerances achieved included perpendicularity over the full 19 feet Outside Diameter to within 0.2mm (0.0078"), and the overall flatness required was +/- 0.15mm (0.0059").