"Because of the economy, everybody's trying to do the same thing at the same time, waiting until the last minute to commit investment and then wanting to go full speed ahead," said Robert Armstrong, chief engineer of EPC WorleyParsons, presenting to a packed room Wednesday afternoon at Emerson Global Users Exchange 2014 in Orlando, Florida. "They want the P&ID by next week when we don't even have the process information. You're already behind schedule when you start."
Trouble with attracting and retaining talent means the people there at the start aren't always there at the end, and everybody has their own ways of doing things. "Change is inevitable," Armstrong said, "and the cost of a change increases rapidly as you progress through a project, so you need to respond quickly."
Armstrong used as an example a recently completed 45,000-tonne offshore oil and gas platform for an arctic environment involving 44,000 tags, 450 P&IDs and 600 km of cable. Being totally enclosed, it had more than 100 fire zones and 50 HVAC systems.
Spacing between decks was reduced to 3 m to minimize weight and cost, and this density created problems. "Korean shipbuilders and fabricators build a bunch of small blocks at the same time and then bring them together," Armstrong said. "There's no field-run pipe; everything has to be done ahead of time and match precisely." Then many feet of cable has to be run in crowded wireways tucked away in the structure, he said. "The density of stuff inside is mind-boggling. It's a lot of trouble to pull wiring."
With 100% CHARMs for control, but hardwired safety systems, the project gave WorleyParsons a real opportunity to compare technologies. "We distributed the wiring as much as we could to minimize home-run cable, so all that would be left is the fiber," Armstrong said. "CHARMs helps us do that with electronic marshalling. We can order the controls before the design is done. It also helps us eliminate cross-wiring for less space and weight, and allows us to design for easy additions—with fiber-optics, there's no need to redesign cable trays."
In contrast, "On the SIS [safety instrumented system], if it's hardwired, much of the design comes out of the HAZOP [hazard and operability] study, late in the engineering process," Armstrong said. "It's a lot of trouble.
"Late changes are a fact of life, and electronic marshalling is a big deal. And it saves a lot of money—we estimate 2 hours per I/O point in design and more in the field."
On a recent project to engineer a methanol plant for the U.S. Gulf Coast, WorleyParsons worked with Emerson to encourage the client to use wireless technology for lower cost and more flexibility. The client was reluctant to use wireless on regulatory control, so there are 2,100 CHARMs, but 300 wireless measurement points as well. "We reviewed the 3D model and looked for places to use it, for example, the tank farm," Armstrong said. "We collaborated with Emerson to help us advance the technology and help the client see the advantages."
One of the advantages is that wireless supports Emerson's Mobile Worker offering. At 10 loops per day per team, the client's three teams of two technicians would need 100 days to check the 3,000 loops. "There was talk of hiring outside help for checkout," Armstrong said. "But with Mobile Worker, each technician is a team, so the client is able to cut the allotted time and rely on its in-house technicians."