Tuesday, 02 September 2014

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John McKenna, Editor

Shell advances intelligent valve technology at Singapore site

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London –  Shell’s largest petrochemicals investment to date, the Houdini project in Singapore, features the use of controllers that tap into the intelligence and diagnostics potential of pneumatically operated on/off valves.

Around 2,500 instrumentation valves have been installed at the Shell Eastern Petrochemicals site. These include  around 1,300 control valves and 1,000 process safety valves – ranging in size from 2 inches to 72 inches.

Metso was awarded the umbrella contract for all pneumatically operated on/off valves in the new parts of the plant. All pneumatically operated on/off valves in the project are equipped with intelligent safety valve controllers.

The valve controllers – Metso’s Neles VG9F ValvGuards for Foundation Fieldbus – were selected instead of conventional solenoid-operated valves (SOVs) and limit switches  – in-line with a Shell philosophy to increase diagnostics availability in the control room.

Using ValvGuards for the first time did requires us to overcome a couple of issues, according to Peter Beerepoot, Shell ECC Project, manager process automation group and instrumentation.

“For example, the delivery times did create some challenges for the module fabricators,” he said. “And when we came to wire up the ValvGuards with extra proximity switches, we discovered that we could only use three of the four ports.

“However, by selecting an alternative type of cable, we were able to solve the problem. We passed this information on to Metso, and in fact, I understand they are already implementing design changes based on our feedback.”

According to the Shell manager, fitting the controllers to all the pneumatically operated on/off valves simplified installation, commissioning and operation of the valves. It also, he said, reduced the initial engineering burden associated with partial stroke testing.

In the past, explained Beerepoot, partial stroke testing would mean an extra engineering task, namely determining which valves need to be fitted with that capability. But, with the controllers fitted to all pneumatic valves, the team knows it can run partial stroke testing on all of them.

With regards to cost, Beerepoot said: “Emergency shut-down valves, for example, normally require a solenoid, a proximity switch, a mounting bracket and more, which together would have cost about the same as the valve controller.

“Moreover, we do believe the units will help us control valve maintenance costs, as well as maintain plant safety.”

Metso provided its pneumatically operated instrumentation valves factory-fitted with the controllers. They were also fitted to those valves, which were sourced from third-party suppliers.

However, the Shell expert said: “My personal recommendation is to purchase actuators and ancillary equipment, such as valve controllers from a single source in order to avoid any interface problems.” 

Each controller is essentially wired up twice: firstly to the plant’s safety systems, and secondly to the Foundation Fieldbus DCS system.

“What this means is that the traditional solenoid is wired up separately from the diagnostics elements. So even if there should be a problem with the ValvGuard’s electronics components, the solenoid will still continue to function as normal. Safety will therefore not be compromised in any way,” said Beerepoot.

As an advocate of using diagnostics information, the Shell manager believes that, in future, plant engineers will be able to check the condition of their valves immediately at the start of the shift.

“If they see a whole row of green lights, then they can attend to other duties,” he said. “If they should see a warning light, then they can drill deeper into the system to identify the cause of the problem.

“Then they can plan any necessary action, order spare parts, and write out a maintenance order. This takes all the guesswork out of valve maintenance and avoids having to deploy field operators to remove a valve from the line and open it up to see if there really is a problem or not.

“My rule is to always leave a valve in place, as dismantling valves invariably leads to subsequent issues. With sophisticated diagnostics information, it should also be quite possible to extend times between shutdowns, from the standard three or four years to five or even six years.”

To ensure the diagnostics information could be properly retrieved, extensive discussions were held with both Metso as well as asset management system supplier Yokogawa.

“There has since been a lot of interest for ValvGuard within Shell, and I fully expect these units will be applied in more applications,” Beerepoot concluded. “Of course, other suppliers will not lag behind, and I understand that similar products are being developed at this time.”

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