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Edgecam provides the right connection for deepwater Oil & Gas Extraction

From its impressive facilities in Aberdeen, Oil States Industries (UK) designs,
manufactures and tests an array of technically demanding and tightly toleranced
components for the global subsea oil & gas industry. In the transition from part design to
manufacture Planit’s advanced CAD/CAM software, Edgecam, is providing the company
with consistent and secure manufacturing programs.

Increasingly, the hydrocarbons used to power our daily lives are being extracted from deepwater fields using ingenious systems under the sea, including tension leg platforms (TLP), floating production units, vessels and remotely operated vehicles. Oil States Industries (UK) Ltd is one of the world’s leading suppliers of tubular connections required by these oil & gas extraction systems, such as its world-renowned Swift™, Leopard™, Lynx™, Puma™ and Merlin™ connectors. The different products are designed to match the varied needs of the industry.

John Coutts, CNC Programmer/Supervisor, is responsible for all machining activities. Due to the large scale parts required by the oil industry the workshop is equipped with six very large CNC machine tools operated by 16 skilled machinists. He says: “As leading manufacturers of subsea connectors and advanced tubular connection systems, we design and manufacture our own products which have an enviable reputation for quality at oil fields across the globe. Connectors simply must not fail because the down time is expensive and the damage could be catastrophic.

An hour or two of down time off shore could run into millions of US Dollars, so our products carry up time guarantees.”

While the more established products, which have simpler designs, can be produced by
subcontracted machining during busy spells, a technically demanding product like the Merlin™ will always be produced in house to meet the critical tolerances required and also protect the manufacturing process technology. “These connectors have to be machined in a certain way in order to attain the crucial taper and face contact between the two halves of the joint,” John Coutts explains. “On the high specification Merlin joints we are working to tolerances of between 1 and 1.5 micron.”

To achieve this on their large machines, Oil States Industries keeps a very tight
maintenance schedule. Along with laser alignment prior to large projects or during servicing, every machine tool is regularly checked using Renishaw’s Q10 Ball Bar. There is no manual inspection and every part produced in the machine shop is 100 per cent checked by the company’s CMM department.

The connectors are assembled using Oil States Industries Proprietary Tooling. Annular ring grooves are machined into both the male and female sides of the tapered connectors, which lock together after assembly to provide a metal-to-metal sealed joint that is stronger than the parent material of the pipe section it is welded to.

Machined from forged steel rings the connectors are cut using NC code programmed by John Coutts using Edgecam. He uses the advanced CAM software both in solid and wireframe mode. “We use the solid model, provided by our design team using Autodesk Inventor, to simulate the NC program for verification. Verifying in Edgecam prior to sending program to the shopfloor highlights any potential collision points and allows me to thoroughly check any issues before machining starts,” John Coutts says. The need for the level of CNC program security offered by Edgecam is especially important, as some components can take up to 110 hours each to machine.

All programming is done off line using Edgecam and bespoke Post-processors have been written by Planit staff for Oil States Industries machine tools. John Coutts sets all the cutting data, feeds and speeds in the software, and the program is never altered on the shopfloor.

Edgecam’s ability to turn threads and grooves is critical to the company’s products and using the pecking function minimises the buildup of swarf - forming ‘bird nests’ on the part. John Coutts also programs stop points into the code where the tool is backed away to allow the operator to remove any swarf built up on the component and carry out inspection activities. He points out: “It is much easier for our application to use Edgecam in wire frame. The design department provides the 2D DXF profile needed to generate the tapered grooved contour required on the connector.”

As the machining process for the various connectors follows similar procedures, with variation in diameter groove profile, John Coutts is looking in the long-term at using Edgecam’s PCIs to construct a macro program, which will dramatically reduce the time required to generate the CAM program.

For Tension Leg Platform applications, sections of pipe up to 40 inch diameter and up to 72m long, each with with a female Merlin™ connector on one end and a matching male Merlin™ connector on the other – called a box and pin -- are used to tether the floating oil platform to the seabed in water depths of more than 5000 feet. These tethers culminate in an Oil States Roto-Latch™ connector, which is sunk into the bed rock and provides the anchor point.

The machined Roto-Latch™ was designed and then programmed using Edgecam, with the finished program just short of 1 million lines of NC code. “Because the Oil States Connectors are holding the rig to the seabed it’s quality control is critical and each component must pass a 200 per cent inspection procedure,” says John Coutts.

“Components can't be measured for 12 hours after machining to remove thermal anomalies and it is then inspected again within a defined timeframe and the results of both CMM checks are compared to ensure the part is within tolerance. This is followed by a 200% penetrative UV dye non destructive crack test.”

New developments are driven by customers' ever-changing requirements, and new products will allow the company to target new markets. One such new product is currently at the prototyping stage, and John Coutts has programmed it on Edgecam and carried out machining trials to prove the manufacturing process.

From a small team of around 90 people just 15 years ago, Oil State Industries’ Aberdeen site has grown to 140 employees, working day and night shifts to support the global oil and gas industry. Turnover today for this highly advanced facility is around £50 million and it is one of the most profitable sites for the American-owned company.

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