Everyone would love to kill two birds with one stone, but they rarely get the chance—especially in process control and safety applications. Well, system integrator Sirio Sistemi Elettronici SpA in Prato, Italy, reports it recently accomplished precisely that goal when it integrated the control and safety capabilities of a non-European crude oil transfer pipeline. It included 70 km of 38-in. pipe, one onshore master control unit and four remote terminal units (RTUs), including two offshore and two onshore RTUs.
"This project provided integrated process controls and a SCADA system and established the reliability of the existing pipeline system between two offshore terminals, an offshore maintenance terminal and the customer's main onshore terminal," says Bruno Zanotti, SSE technical director.
Zanotti and SSE commercial director, Cristiano Tatini, presented "Integrated Control and Safety System for Crude Oil Transfer Pipeline" at Rockwell Automation's Process Solutions User Group (PSUG) on Nov. 11 in Houston. Established in 1984, SSE integrates oil and gas and power generation applications in Italy, Algeria, Kazakhstan, Brazil and Iraq.
"Our system design for this pipeline included a process control system [PCS], emergency shutdown system [ESD] and a fire and gas [F&G] system," explains Zanotti. "Common requirements for all systems included dual-redundant power supplies, processors and communication, and I/O modules, while the ESD and F&G systems needed to be SIL 3 and comply with the IEC 61508 standard." Zanotti adds that networking for the pipeline would be mostly redundant Ethernet, but it would also use fiber optics for long runs and some wireless.
"Our main challenges were that the PCS, ESD and F&G systems must be PAC-based, and must operate on the same PAC architecture. We also needed to use a common engineering tool for PCS, ESD and F&G controls and for the operating interfaces for monitoring functions. Also, we had to assure a single fault tolerance for power supply, processor and communications between the operator workstations, processors and I/O modules."
These requirements were needed so the pipeline could guarantee: DCS functions by a PAC-based system; less than 500-millisecond system scanning time; better availability and reliability than a traditional DCS; one programming language between systems and operator stations via the plant network; and easy system expansion. Consequently, the pipeline's PCS implemented Rockwell Automation's PlantPAx processors, power supplies, I/O modules and other components. The ESD and F&G system implemented their AADvance processors, redundant modules and I/O components, and its Flex XT I/O devices perform remote I/O data acquisition on the PCS.
"The master station in the main control room allows full access for monitoring and control to the data of all RTU stations. Upon the master station operator's request, under a protected password, the control of each facility can be switched to each local RTU operator," explains Zanotti. "Next, the RTU station in the main control room provides control and monitoring for its proper plant portion, while the first-platform RTU station provides control and monitoring for its section, and the second-platform RTU station provides control and monitoring for its portion.
"Likewise, the ESD system in the onshore main control room provides shutdown functions for all facilities, and the ESD systems in each RTU station provide shutdown functions of each respective facility. Also, the F&G systems in each RTU station provide fire and gas protection of their respective facilities.
"This was a cost-effective solution for our customer. We reduced costs and time needed for spare part change-out and servicing, and we implemented a fully integrated, plant-wide control, while reducing engineering efforts and ensuring worldwide customer support."