How can users get skid builders to follow their electrical standards and good practices? More face-to-face discussions can help. Jacobson offers these suggestions for end users:
- Insist on a face-to-face, pre-design meeting, and/or a face-to-face meeting to review comments to submittals.
- Recognize that customization is costly and expect to pay not the lowest price, but the price that enables the skid builder to deliver the desired level of customization.
- Keep general contractors from preventing the owner's desires or the manufacturer's needs, questions and costs from being communicated to skid builders.
- Withhold payment until the system meets the specification, and write specifications that hold a percentage of payment until completion that will ensure compliance.
Drazin agrees with holding face-to-face meetings and withholding payment. “The only way to hold skid builders accountable is to have discrepancies in standards affect their bottom line,” he says. “Incorporate a contractual penalty fee for not meeting specification into every contract and then hold skid builders accountable to that contract.”
Conforming to Open Standards
Control equipment vendors have a simple solution for end users and skid builders “Use our open-architecture equipment,” they say, “and you can integrate everything easily.” Though self-serving, there is a certain amount of truth in this suggestion because fieldbus architectures are readily available these days. HART is built into just about every field instrumentation device on the market, making it easy for a skid builder to obtain diagnostic and calibration information. Though a bit more expensive, it is also possible to offer Foundation Fieldbus, Profibus and DeviceNet instruments and controls. By having a fieldbus network built into the skid equipment, integration becomes much easier. The plant’s DCS could easily control fieldbus-based devices through a simple interface.
Finally, connecting the skid’s controls to the plant network is much easier if the skid’s PLC or PC-based controller is based on an open architecture. Virtually all the controllers available from major manufacturers offer some kind of universal connection to DCSs. Also, because most open architecture PC-based controllers use Windows, it is a simple matter to create a universal database/historian that can be accessed by a DCS over an Ethernet connection.
It would be beneficial to skid builders if they could advertise the fact that their systems are easy to integrate. Skid builders could change their image overnight from that of arrogant suppliers to helpful suppliers. Besides, by working with end users, they might discover a new niche in the market and increase their sales.
Basic End User Issues
HERE ARE some the fundamental tasks skid builder need to address to collaborate successfully with end users.
Maintenance: If the skid or package is going to be maintained by plant technicians, then end users usually prefer that equipment, such as instrumentation and controls, be similar to what is already being used in the plant. This minimizes training costs and keeps spare parts inventories low.
Best Practices: Some users have developed installation and wiring standards based on long experience in their particular application or industry. They know what works and what causes problems. Therefore, they want skid builders to conform to these practices.
Regulatory: Some plants must conform to rules and regulations from the FDA, EPA, OSHA and similar agencies. They want skid systems to conform to these rules, too. “Within our customer base we see an increasing demand for integration of skid-based systems, such as clean-in-place (CIP) and batch systems that are controlled by the DCS,” says Todd Stauffer, PCS 7 marketing manager at Siemens Energy & Automation. “We have one large customer in the brewing industry that insists on tightly integrating its CIP system into the main process control system. They report that this helps minimize the chance that a CIP cycle is missed, helps create consistent reporting, and eliminates the need for specialized training on the CIP system.”
Integration: While some users treat skid systems as appliances, that is, a universal device that plugs in and does its job all by itself, many users want to integrate the skid system into an overall plant control scheme. If the skid is a closed system, then integration becomes much more difficult. “Today, it is no longer acceptable for a skid-based system to be designed and implemented without thought about the equipment with which it will be integrated,” says Stauffer. “Users are tired of the struggle and extra cost that is typically required to integrate a skid-based system into the host or supervisory control system. Ten years ago, the DCS community was happy to have a Foreign Device Interface available for connectivity. Now, they expect much more. Our market analysis has shown that ‘Ease of Integration’ is one of the top three buyer criteria for selection of a new process automation system.”