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3D digital versatility enhances design of subsea control systems

21st February 2013


3D digital prototyping cuts time-to-market for subsea control systems

 The oil and gas industry is one of the largest, most lucrative and fastest-growing in the world. An unprecedented demand for oil kick-started a dramatic rise in oil prices from 2003 to an all-time high in 2008 and lingering concerns over natural calamities, political events or terrorist threats - which could disrupt global oil supply - and the fact that oil production capacity is almost fully utilised, have kept prices high, and oil companies turning in record profits.

In spite of the drop in the oil price from over $100/barrel in summer 2008 to around $40/barrel in early 2009, the oil companies continue to plough much of their profits into exploration and production in ever more difficult terrain, often in areas which hitherto were considered too difficult and costly to extract.

Subsea mechanical engineering is a highly specialist business and until recently, the major oil and gas producers would have only had a handful of large specialist engineering firms to choose from.

Subsea is a large and lucrative area of the oil and gas industry. In the past, we dealt with equipment in control rooms on the surface; subsea is an area traditionally serviced only by the big companies. But the oil and gas business has changed; today there is so much work and the big companies have order books so full that they are starting to quote three to four years' delivery on sub-sea control systems.

Thinking big

Electro Flow Controls has been designing, manufacturing and installing electrical instrumentation and monitoring systems for the oil and gas industry since 1989. Its work had traditionally been for surface systems but when, in 2006, the company took on its first subsea project, it brought about a significant change in design and engineering methodologies.

"Working on surface systems, 90 percent of our drawing effort had been electrical schematics and panel arrangements. When you move to subsea, it entails a lot more mechanical and hydraulic work," says Barry Canfield, controls manager. "Subsea control systems must be contained in pressure enclosures and pressure housing so space is extremely critical. All the hydraulic manifolds and valves have to be purpose-built and the electronics have to fit exactly into the space available, so we needed to prototype them a lot better than in the past. That's why we moved to Autodesk Inventor, to give us this 3D ability to more accurately design the mechanical components," he says.

Precision and certainty in 3D

A typical surface operator station might be a stainless steel enclosure mounted on a wall in a control room, perhaps with a VDU allowing the operator to control the equipment. But because, in the past, these things could not be accurately visualised in 2D, they had to design a basic oversize box to ensure there was enough space to fit all the equipment inside.

"Today, using Inventor, we're able to produce stations that are customised and more cutting-edge," says Canfield, who comments that many of their older designs were somewhat 'agricultural' looking.

"Using 3D, we can first draw all the equipment that has to go inside - whether it's a PC, wiring, terminals, VDUs and so on - and we can assemble them in 3D so we know they will fit. If we choose, we can then modify the cabinet, perhaps slope the front to fit better or add a ledge for the buttons to sit on. Underneath we might curve it away so it doesn't interfere with the operator's knees. All these things we can do at concept stage with 3D because we can digitally build it, rotate it, refine it and even see the result in live video," he says.

"Today, we've produced a version that's very sleek-looking and is exactly the size to take the equipment inside, and we can be certain that everything will fit when it's assembled," he says.

Canfield goes on to explain that while the precision and certainty provided by 3D digital prototyping technology made it a pre-requisite in this new area of their business, the time-savings resulting from the move to 3D were an unexpected bonus. Canfield estimates that using Inventor has cut design time by at least a third, which has the knock-on effect of shorter delivery times and happier clients.

"We're only a small company and we found that 2D drawings - especially mechanical drawings - took considerable time and effort. We don't have the resources for that - we don't have large teams or a CAD department. We have engineers who are all specialists in certain areas and they do all of their own drawing work."

"While still designing in 2D, the drawing effort was laborious, partly because there was so much duplication. You're taking what you did in one projection and copying it to get the measurements across to another. Then, if we modified it, we'd have to remember to revisit all the other projections and update them. So on larger assemblies, mistakes were often made and things were missed," says Canfield.

Enhancing communications

Another problem was the communication of the designs between the various parties within the company. The switch from electrical-only through to mechanical and hydraulic operations made it more important to increase the communications between the various company disciplines.

"To be honest, if you're not a mechanical engineer, design drawings are difficult to understand," he says. "Whereas with the Inventor model, the drawings look like the finished product so our electrical engineers and project teams were able to understand them straight away. That means we can talk about the problems and solve them together."

Electro Flow Controls partnered with a larger company on an early subsea project and that company was still operating with 2D technology, which threw up some interesting comparisons. "There was a huge difference in the speed we produced our drawings," says Canfield.

They were also interested to find that when they drafted one of their partner's 2D drawings into 3D using Inventor, there were significant errors which it was able to report back to a grateful partner. "It would never have come to light if we hadn't redrawn the designs in Inventor for our own purposes!" he adds.

Driven by the demands of the subsea opportunities, Electro Flow Controls bought into Inventor with their first seat in February 2006, followed by two more within a year. The company took on a mechanical engineer with experience in 3D design to spearhead the change.

The decision to go with Inventor versus competitive 3D packages was a difficult one. The firm was already using AutoCAD Electrical and was therefore familiar with the Autodesk offering but two of the main engineers had been SolidWorks-trained.

"We made the decision to go with Inventor based on a number of criteria - overall, it simply provided the best package for us. The changeover was remarkably smooth - it was surprising how quickly we started to get usable results from it," he says.

Canfield credits part of their successful adoption of Inventor to leading Autodesk manufacturing reseller, Imass. The original software purchase was made with another reseller but Electro Flow Controls sought out Imass soon after.

"We decided we needed somebody closer - Imass is local to us which is important. I think we'll use them more in the next six months for help in setting us up with other bolt-ons like Vault."

As part of the early training on Inventor, Electro Flow Controls'w engineers decided that rather than work on a live project, they would take a project that had already been designed in 2D and redraw it into 3D, so they could document what they had built. The exercise provided some surprises.

"We re-worked one of our hydraulic power units that had already been designed in 2D and this highlighted a lot of problems we hadn't spotted before - things that didn't line up, bolt holes that weren't quite right. We'd already done 70 percent of the design in 2D and had put out most of the work to fabrication shops so it was too late to redesign with Inventor, but what started out as a training exercise ended up identifying problems on a real project that would not have been spotted until after assembly, which was a relief."

Dealing with partners and suppliers inevitably gives rise to the need to present and explain assembly procedures in a simple way. Electro Flow Controls makes extensive use of Inventor's capacity to create exploding diagrams for their suppliers to demonstrate equipment assembly.

"A picture speaks a thousand words," says Canfield, explaining how this capability enabled him to communicate to his Portsmouth machine shop not only detailed bills of materials but also the entire assembly procedure in a single diagram, saving the need to produce a detailed illustrated manual.

Could the company quantify the benefits of this software shift?

"It would be difficult to quantify simply because Inventor's letting us do new work and new projects that we couldn't do before. We've recently produced a new console layout that, a few years' ago, we could not have done - quantify that!" he says.

Barry Canfield, is Controls Manager at electrical instrumentation specialists, Electro Flow Controls, Aberdeen, UK. www.electroflowcontrols.com









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