How’s that again? “The system does meet the specification as written and enforced by the owners, therefore the project was signed off by the owner,” he explains. However, problems persist. The operator interfaces were designed for engineers, not for operators, so the interfaces’ operator functions aren’t simple to understand. Also, engineering management is the first responder if problems occur, but if engineering management isn’t available, then the system must be shut off.
Searles calls this project a “disjointed agglomeration,” and wishes he’d been allowed to build the system on a skid at his own shop, instead of being required to assemble it on site. “The creation of the confusion is traceable to the owners,” he says.
However, miscommunication also happens with people who are supposedly competent as communicators. For example, one would assume that engineering and procurement contractors (EPCs) would understand specifications, and communicate them to the skid builders, but this is not necessarily so. One refinery control engineer, “Bob,” who requested anonymity, explains, “The source of our problems often comes from engineering contractors we hire to manage projects, and be our primary reps to third parties. When these contractors don’t insist that the skid builder meet our specs and standards, we’re going to have issues.”
Contractors, EPCs Can Help
Michael Frey, sales engineer for Daniel Measurement & Control, a Houston-based subsidiary of Emerson Process Management, says his firm relies on engineering contractors to be their liaison with the end user. “As a metering system package supplier, Daniel interfaces with the EPCs for basic design requirements,” he explains. “These requirements are based on the application of the metering system, destination of system, fluid measured, technology applied, industry standards, etc. It is actually the EPC’s responsibility to integrate the different skids to each other. As a skid supplier, it’s necessary for us to strictly adhere to specifications provided by EPC and end user. There’s no room in our scope of supply for a ‘one size fits all’ and ‘take it or leave it’ stance.”
|FIGURE 2: SEPARATION BY A PLC|
Mobile Process Technology's ChromaSep separation process module for sulfuric acid and copper sulfate is controlled by any PLC the user chooses.
Usually, the typical skid isn’t meant to operate as a standalone module. It’s often part of a larger integrated system, which means that upstream and/or downstream interfaces have to be carefully designed. “If these interfaces don’t match, a field retrofit can be a very expensive and time-consuming affair,” adds Unitel’s Randhava.
Working Around Skid Builders
Some end users have novel ways of dealing with non-cooperation from skid builders. Eric Marcelo, a control engineer in the coffee department of Nestle Phils, Cagayan de Oro, in the Phillipines, says it just takes a little extra effort. “For the most part, I haven't had a problem with obnoxious skid builders. Most of the skids are designed by our company, and skid builders just build them to spec. These guys are the ones we've done business with for a long time, so they know how we work. This usually means they use the same PLCs we use, so communication is just a matter of laying out a cable and connecting it to the network.”
Even so, communication problems still come up. “One manufacturer neglected to tell us they could build us a skid with the same type of PLC we usually use,” adds Marcello. “So these skids became standalone, when they easily could have been tied in with our system.”
Being a big company also seems to help. “Our company has enough clout that we could threaten to blacklist a supplier that doesn't perform to our standards,” he notes. “This usually keeps them in line. However, close coordination is still the best way to ensure that everybody does what is expected of them.”
End User Needs
End user are not trying to be obnoxious, unreasonable or demanding. They have real concerns about integrating skid systems into their plants. “Skid builders should be receptive to end user stated standards and preferences, and recognize that these are desired for good reasons,” says Jacobson.
Unitel’s Randhava says, “Usually, three types of interfaces have to be taken into consideration. These include fluids, such as gases, liquids and solids; electrical; and computers and data. The correct specification of the wiring in the skid should always be of critical importance, especially if the end product will be shipped overseas. Electrical codes and explosion-proof requirements can vary significantly by country. Strange as it may seem, even within the same country, regional and local regulations can sometimes supersede national standards. In any event, rewiring in the field is always a nightmare.”
Go Face to Face