On the application of FF fieldbus

I wonder how widely fieldbus systems are used these days.

When we first started the new project, I suggested to the management to use fieldbuses, but they rejected the idea as soon as they heard that it was expensive and that there were few compatible instruments available. I feel that this thing is not widely used in China at the moment; it’s not yet common. Many people agree that it will likely take another decade before it becomes widely adopted.

It remains to be determined whether the technology is mature; materials such as cables save a significant amount of money. Many companies probably don’t want to be the ones to suffer the consequences. As a technical staff member in the company, I guess many people share my desire for such a thing to be available here, but unfortunately I can’t influence the management.

Currently, the only companies in China that use the FF bus are Sinopec Shanghai Petrochemical and CNOOC Shell; however, they use it for non-critical applications, while other important control and monitoring functions still rely on DCS. Therefore, its reliability is still a matter of concern. I wonder what everyone thinks?

There have indeed been no major developments or breakthroughs in buses over the past decade, and their reliability still needs further verification.

In a side-by-side comparison, there is indeed no clear advantage, nor are there any compelling reasons to choose one over the other. As for cost savings, I’m not sure if any actual calculations have been done to determine how much can be saved on a project (on a percentage basis)

In China, there are Sinopec and CNOOC Shell; moreover, the proportion of buses does not exceed 30% of the total number of points, and I don’t think there are any others. I’m not sure where else FF is being used on a large scale.

After the application of the FF bus was promoted by SICK, there has been little activity in China; the reason is that those major domestic engineering companies no longer support it, as there are disagreements among them regarding this bus. Yet, despite this, foreign FF bus projects have continued without interruption over the past few years. Recently, an oil and gas project in the Middle East worth 2.8 billion dollars also uses the FF bus. This bus is not limited to use in less critical monitoring points – it is currently not used in safety instrumented systems, but it is employed in control circuits and even complex control systems. In the market, common instruments for measuring temperature, pressure, flow rate, as well as standard analysis instruments for measuring conductivity and pH value, all come available with FF bus connectivity； In fact, FF bus projects have not stopped in China over the past few years; it’s just that private and foreign companies use them, while state-owned enterprises use them very rarely.

Just in terms of cost, savings are indeed achieved in the initial stage. But in the later stage, the spare parts for an FF bus instrument are quite expensive. So, from the perspective of a project’s lifecycle, no cost is saved at all. There are also differences among foreign companies; Zhuhai BP used fieldbuses in the past, but the new project phase now relies on conventional instruments.

20 years ago, instruments used 4-20 milliamps; over a decade ago, they still used 4-20 milliamps along with Hart technology. Now it’s fieldbuses that are in use, and in the future, fast Ethernet and wireless technologies will dominate. The trend is for digital to replace analog signals; it’s impossible to resist this. You can only appreciate the advantages of fieldbuses after having used them. A mass flow meter allows one to view the signals for flow rate, temperature, pressure, and density at the same time. A control valve allows one to view various types of information, such as valve position feedback, air supply pressure, pressure in the actuator cylinder, and valve stem friction. This makes it possible to obtain all the information needed for preventive maintenance without having to go to the site with a manual operator. The field bus design is intended for an instrumentation engineer to maintain thousands of instruments; labor costs are high abroad, and we don’t use it because our salaries are too low. Please keep in mind that the purpose of DCS is to reduce headcount while improving efficiency; however, in China, only talk about improving efficiency and not about reducing headcount – this is what the DCS manufacturers themselves say.