For most of us, two birds with one stone would seem quite enough of a stretch. But system integrator Sirio Sistemi Elettronici (SSE) of Prato, Italy, reported it had taken down three in one throw of Rockwell Automation technology when it extended the control and safety capabilities of a crude oil transfer pipeline. The application included 70 kilometers of 38-inch pipe, one onshore master control unit and four remote terminal units (RTUs), including offshore RTUs, and two onshore RTUs. The pipeline also included a variety of remote I/O data acquisition equipment and other components.
"This project was to provide integrated process controls and a supervisory control and data acquisition (SCADA) system and help establish the reliability of the existing pipeline system between two offshore terminals, an offshore maintenance terminal and the customer's main onshore terminal," said Bruno Zanotti, SSE's technical director.
Zanotti and SSE's commercial director, Cristiano Tatini, presented "Integrated Control & Safety System for Crude Oil Transfer Pipeline" today at Rockwell Automation's Process Solutions User Group (PSUG) meeting in Houston. Established in 1984, SSE is a Rockwell Automation Recognized System Integrator that typically 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," explained 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 Safety Integrity Level (SIL) 3 and comply with the IEC 61508 standard. Common environmental conditions were 5 ⁰C minimum and 50 ⁰C maximum, while maximum temperature inside the field enclosures was specified to be up to 80 ⁰C."
Zanotti added that networking for the pipeline would be mostly redundant Ethernet, but it would also use fiber optics for its especially long runs, as well as some wireless where applicable. "Our backbone communication network is based on fault-tolerant, redundant Ethernet TCP/IP and OPC protocol and with redundant communication system interfaces for each node," he said. "The communication system is based on automatic bumpless switch-over. The external, subsystem interface is also based on fault-tolerant redundant Ethernet TCP/IP and OPC."
The pipeline's software requirements were based on a three-level hierarchy: Level 1 is the high-level master terminal unit that provides 24/7 monitoring and control of all facilities; Level 2 is the mid-level RTUs that provide monitoring and control areas for operators in cooperation with Level 1; and Level 3 is the low-level subsystem that provides monitoring and control of subsystems and communicates with the RTU in each area.
"Our main challenges were that the PCS, ESD and F&G systems had to be programmable automation controller (PAC)-based and had to operate on the same PAC architecture," said Zanotti. "We also needed to use a common engineering tool for PCS, ESD and F&G controls and for the operating interfaces for monitoring functions. In addition, we had to have a strong operating and environment condition for field device system equipment, such as our remote I/O. 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:
- The functionality of a DCS system through the use of a PAC-based system with clear economic benefits;
- System scanning time lower than 500 ms;
- Better availability and reliability compared to a traditional DCS system;
- One simple programming language between systems and operator stations through the plant network;
- Easy system expansion.
"We evaluated different technologies available in the market with different system suppliers and found that Rockwell Automation's proposal was the best, and that it was the most complete solution for all of our customer's technical requirements," said Zanotti. "These included having the same supplier for all types of their required PCS, ESD and F&G systems; full integration of all installed components; a common engineering tool, in this case FactoryTalk View, for the operator interfaces; and finally worldwide commercial and technical support that would be available locally."
In short, the pipeline's PCS implemented Rockwell Automation's PlantPAx processors, power supplies, I/O modules and other components, while the ESD and F&G system implemented its AADvance processors, redundant modules and I/O components; remote I/O data acquisition on the PCS is performed on Flex I/O XT modules.
"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," explained Zanotti.
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 very cost-effective solution for our customer," Zanotti concluded. "We reduced costs and time needed for spare parts change-out and servicing, and we implemented a fully integrated plant-wide control, while reducing engineering efforts and ensuring worldwide customer support."