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SOME USERS are embracing safety standards, some are confused by the terminology, some just don’t understand it at all, and some are afraid to talk about it in public. Many just turn safety issues over to process control vendors, and some work hand-in-hand with outside experts (See Figure 1 below). In this article, we’ll look at how some users and vendors are dealing with safety issues.
Making Stuff Safely
Eric Marcelo, supervisor at the Nestle Philippines coffee factory in Cagayan de Oro City, Philippines, says his plant has a positive attitude toward safety. He even understands all the safety requirements that apply to his plant. “We were given training at the start of our employment, and whenever there are changes in standards or installations,” he says. “Basically speaking, safety is everyone's concern. We have a safety officer for the whole factory, safety champions for each department, and safety experts for certain processes. The safety expert ensures that safety procedures, interlocks and safety features of equipment and processes are followed or adhered to. Any changes will have to be cleared through him and will undergo complete analysis before permission to proceed is given. In certain situations, any suggestions or problems he receives, or is made aware of, will be sent to the R&D center for more thorough analysis and testing.”
|FIGURE 1: TRANSITIONS|
The sunset of old IEC safety regulations and the dawning of new SIS and SIL rules make safety systems a real challenge for control engineers, especially at large installations, such as the Rompetrol Rafinare refinery and chemical complex in Romania.
Some users turn to automation vendors to solve their safety issues. For example, the Rompetrol Rafinare refinery and chemical complex, located on the Black Sea in Navodari, Constanta, Romania, recently installed two safety instrumented systems (SISs).
Cristian Pariza, Rompetrol’s automation/systems engineer, managed the installation of SIL 3-rated DeltaV SIS technology from Emerson Process Management to protect the refinery’s gas-fired burners for atmospheric distillation/vacuum distillation (AD/VD) heaters. In addition, SIL 3-rated SIS equipment was placed on polypropylene plastic and pyrolysis units in the facility's petrochemical plant. Configuration, startup, and post-startup activities were conducted by a team of refinery and Emerson engineers.
"Looking at the AD/VD project in particular, the safety system consists of three identical subsystems, one for each heater," says Pariza. "Each subsystem is housed in a dedicated cabinet (See Figure 2 below) containing 18 logic solvers, 270 I/O points, redundant power supplies, and redundant communications with the plant network.
|FIGURE 2: SIS EQUIPMENT|
The DeltaV safety systems at Rompetrol are housed in a dedicated cabinet containing logic solvers, I/O points, redundant power supplies, and redundant communications.
Meanwhile, the Rashtriya Chemicals and Fertilizers plant in Chembur, Mumbai, India, manufactures 900 metric tons per day of ammonia, plus quantities of urea, nitric acid, and other chemicals. When its engineers wanted to update Rashtriya’s mostly pneumatic and relay-based control systems, they decided to do the process controls and safety systems all at the same time, using an integrated system from Honeywell (See Figure 3 below).
This new system includes an Experion PKS control system and a SIL-3 rated Safety Manager, which focuses on safety-related process variables, and prevents unacceptable access or interference from operators or maintenance personnel. Safety Manager also is used for compressor-process interlocks, and initiates an emergency shutdown if unhealthy process values are detected. This prevents unsafe shutdown practices, which can cause injuries or damage plant equipment. It also limits nuisance trips.
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