Systems Architecture as a Basis for Requisitions of Control and Safety Systems:
One important part of Instrumentation & Control (I&C) Engineers’ roles and responsibilities during the whole lifecycle of a process plant project (and especially during Detail Design Engineering) is related to the design and implementation of required control and safety systems (DCS, ESD, PLC,…). Such activities include the preparation of required data and documents which shall be attached to relevant Material Requisitions or to be transferred to vendors of systems.
Project Systems Architecture
One of the most important documents that shall be prepared by the I&C team in Detail Design Engineering Company is the SYSTEM ARCHITECTURE DIAGRAM. This document shall be prepared by considering some rules and formats in order to be easily understood by vendors of systems. (For a better understanding of the attributes of such a document refer to mentioned reference).
Figure-1: Provided Design Document for Systems Architecture of One Realistic Industrial Project
Figure 1 shows a sample of such provided design document (in Detail Design Engineering Company) for System Architecture of one realistic industrial project. As Figure 1 shows, such a document may be very complicated and of course to be more completed and defined by other documents and data/information, especially via those items mentioned in dedicated specifications or clarified in requisition notes and Bill of Material section (inside the relevant system requisitions).
Automation System Architecture
Figure 2: Typical System Architecture Facility/ Ability Presentations in the form of SYSTEM ARCHITECTURE DIAGRAM in different Vendor Documents (YOKOGAWA)
It shall be noticed that vendors or suppliers of control and safety systems, usually explain the facilities and functionalities of their systems via publishing some documents ( catalogs, brochures, datasheets, advertisements, booklets, …), and in such documents, they use some diagrams for presenting possible system configurations.
Figure 2 shows 3 different presentations on such systems from YOKOGAWA. As they can be found from Figure 2 such diagrams generally show available system blocks and communication facilities (which may be upgraded by technology growth/ development) and which can be configured in different systems architectures.
Industrial Project
On the other hand for each industrial project, the supplier or vendor will select some of the manufacturer’s products with a predefined approach based on project requirements. Such arrangement or configuration will be checked by the I&C team of the engineering company via a comparison of VENDOR SYSTEM ARCHITECTURE with Design Document SYSTEM ARCHITECTURE.
Another important point is that vendor’s or supplier’s offers for project material requisitions (of Control and Safety Systems) are not necessarily acquired from the original manufacturer. On the other hand, some integrators or even vendors (which may be also manufacturers of some items) prepare their offers by selecting different items of project requirements from different brands or manufacturers.
Vendors
In fact, vendors for preparing their offers will consider commercial points in order to provide their offers with optimum price, so their offers can properly race with big chance in comparison game (Vendor Selection!). So we can expect to receive different vendor’s offers by some similar items which are arranged/ configured via other different items (different brands or models).
This may cause some problems in comparing different offers (during the procurement phase of the project) for checking the complete satisfaction of project requirements and preventing missing any required facility.
Of course, some vendors may prepare their offer with some enhancement or better design which is hard to detect if we receive different formats of documents for their considered SYSTEM ARCHITECTURE.
As a result, we can conclude that the vendor’s offers shall include VENDOR SYSTEMS ARCHITECTURE prepared based on the DESIGN DOCUMENT SYSTEM ARCHITECTURE. If Design Document prepared suitable and complete for all project requirements, we can expect vendors to provide their document accordingly, and hence comparison of offers during Bid Stage of Procurement Phase of Project will be done better.
Systems Architecture Document in Vendor’s Offers
As explained above, different vendors shall prepare their offers (including the SYSTEM ARCHITECTURE document) based on project requirements (Design Document). It shall be noticed that since before vendor selection vendors don’t know if their company is a winning vendor or not, they couldn’t consider a big amount of engineering work for preparation of their offers.
Vendor’s Offers usually will include SYSTEM ARCHITECTURE as a general view for considered items and so may not completely satisfy project requirements, while by Technical Query or Clarification Request (via I&C Engineers of Design Engineering Company), their documents may reach the requested standard format of the project (to simplify offers evaluation/comparison).
Figure 3 shows five sample offers received for the realistic industrial projects and its design document of System Architecture is shown in Figure-1. As can be seen in Figure 3 all vendors tried to follow the project structural format of the design document for preparation of their offered System Architecture. By reviewing the figure in more detail study we can find that:
All proposed System Architecture in vendor’s offers show a general view of considered systems (as expected based on the above description). Although they don’t have some details, but all of them can show that they will satisfy project requirements. It shall be mentioned that such similar documents were reached after some technical queries between the I&C team of Detail Design Engineering and vendors.
DCS System Architecture
Sample offers 1 and 2 show that two vendors provide their offers based on YOKOGAWA systems, while they used their own document format for presenting considered systems. In such cases, vendors provide their offers based on similar systems, by comparing the material take-off section of their offers we can find the differences in their offers in more detail.
Also by studying such differences the advantages (enhancements) and missed items can be easily found and so further to asking vendors to balance their offers on missed items, their enhancements can be highlighted for any future comparison.
Sample offers 3 and 4 show another two proposed offers provided based on a single platform for DCS and ESD systems (from one manufacturer) while offering 5 shows such offers provided just for the DCS system whereas another complementary offer was proposed for the ESD system (separately). In fact, the vendor of offer 5 was an integrator that proposed its offer by collection of different systems.
Figure 3: Five (Sample) Offers Received for Control Systems of Realistic Industrial Project
(Based on the Design Document System Architecture of Figure-1)
If we return to Figure-1, we can find in Design Document System Architecture there is no restrictive condition for single platform DCS and ESD or separate platform for such systems. By such consideration, the domain of available vendors on requested systems will be wider and more flexible.
Sometimes due to existing process plants (near the current project), clients may have some preference concerns on dedicated options for DCS or ESD systems (and they may prefer some known brands). In such cases, the I&C team of Detail Engineering Company may guide vendors, integrators, and suppliers to provide their offers by such preference conditions.
Design Document System Architecture Document
It is clear that all systems (including DCS and ESD) shown in Design Document System Architecture document shall have good integrity with each other, and so if vendors propose their offers based on single platform systems.
The whole integrity may be guaranteed and easily achievable, while if offers are provided based on different brands of DCS and ESD systems, it is strictly advised that both requisitions are supplied by one vendor so that such vendor will be responsible for guaranty the total integrity of both (different) systems.
Otherwise, Integrated FAT (IFAT) shall be considered in the scope of one of two vendors (preferably DCS vendor). By considering IFAT one of two systems or their real simulators (after doing FAT) shall be transferred to other system workshops for doing integrity tests (and solving any probable problems).
If the Design Document System Architecture includes some PLCs further to DCS and ESD systems, it is advised to consider such PLCs or their simulators to be available during IFAT checking. So during the bid stage, DCS/ESD vendor(s) shall be asked for such responsibility (doing integrity tests and solving any probable problems).
By studying different sample offers, it is clear that one of the main differences between them refers to considered networks and communications. So the I&C team of Detail Engineering Company shall exactly review the considered facilities of different vendors and be aware of the project specification requirements accordingly.
Final Document of Vendor Systems Architecture
After vendor selection for DCS/ESD systems, more project detail requirements shall be discussed between the vendor and the I&C team of Detail Design Engineering Company. Such cycle will be started immediately after the vendor award announcement and attending in Kick-Off Meeting (KOM) in which more detail will be transferred to the vendor and the project time schedule and correspondence procedures will be set.
However during the detailed execution of the project, the vendor documents will be reviewed by the I&C team of Detail Design Engineering Company up to reaching the final state and of course, by appearing more details, the vendor shall issue new revisions of their System Architecture with exact details.
The final revision of such document may include explanation texts, tables, referenced documents, and drawings … further to the main final System Architecture Diagram. Figure 4 shows the extracted final Vendor System Architecture Diagram for the realistic industrial project (explained in Figure 1).
As it is clear in this figure all blocks and networks and communications have specific detailed definitions (for those items of Design Document System Architecture that are relevant to DCS and ESD systems).
Figure 4: Sample of Final Vendor System Architecture for a realistic Industrial Project
Sometimes in the final document of the Vendor System Architecture Diagram still some blocks are shown schematically to reduce the complexity and business of this document, while for details of such blocks, some documents have existed (are attached).
Figure 5 shows another final Vendor System architecture Diagram for another realistic project.
Figure-5: Another sample of Final Vendor System Architecture for a realistic Industrial Project
Conclusion
For DCS and ESD systems of Industrial Projects, the vendor shall provide a System Architecture Diagram based on the Design Document System Architecture Diagram and project requirements. Such Vendor System Architecture Diagram document may be schematic and generally during the bid stage but shall be completed during the execution of the project by adding detailed information up to reaching the final design.
References:
- I&C Engineer Roles & Responsibilities
- Instrumentation Engineer Activities & Documents
- Instrumentation and Control Project Packages
- Design Document For Project System Architecture