P&ID is the diagram which shows the interconnection of process equipment and the instrumentation used to control the process.

The uses of P&ID are as follows

• P&ID is the basis for developing the control systems in the chemical process.
• It helps in Equipment design and Piping design and also serves to estimate the capital cost.
• Hazard and Operability (HAZOP) Study is performed during the design stage with the help of P&I diagram.
• It will assist in preparing Commissioning procedure, Pre-Startup Safety Review, Standard Operating Procedures for Startup, Normal operation and Shutdown.
• It also assists in preparing Plant Operating manual
• Control narrative and Interlock narratives will be prepared by having P&ID as the basis.
• It will help to prepare the Instrument Index and other will serve as a reference for creating other datasheets.
• It acts as a beacon for newbie process engineer in a Chemical Industry.
• P& ID also helps in Incident investigations to find out What Went Wrong through root cause analysis.
• It helps in evolving maintenance procedures of equipment. It helps to visualize the interconnecting systems with the equipment and planning for proper isolation can be done.

What is the difference between P&ID and PFD?

Process Flow Diagram (PFD) is used for indicating the general flow of process and equipment. It helps to visualize the overall process of the in a chemical plant.

PFD will contain main process piping, Main equipment number, Equipment Name, Flow directions, Major bypass lines, Critical Control Valves that affects the process, Stream Number, Stream Designation, Process parameters like operating temperature, operating pressure, flow rate, Composition and heat duty of heat transfer equipment.

PFD will not contain Piping size and classification, Process control Instrumentation details like Transmitters, Control valves, Design Temperature and Pressure, Material of Construction of Equipment and piping, Mechanical Valves for isolation, Vents and Drains, Relief valves & Safety Valves.

P&ID will contain Equipment number, Equipment Name, Process and Utility piping, Piping size and classification, Instrumentation details like Transmitters, Control valves with their numbers, Control input and output, Annunciation input, SIS input, solenoid valves, On-off valves, Motorised valves, Relief valves, All Mechanical valves Miscellaneous items like strainers, Vents, drains, Silencers, standpipes etc, Vendor items and interfaces, Equipment design pressure, Temperature and Material of Construction, Free draining requirements etc. P&ID will also have general notes that will assist during Detailed Engineering, Erection and Commissioning phase. Though it is not an exhaustive list, Our P&ID Check list in the trailing part of this post will help you to explore in detail about Piping and Instrumentation Diagrams.

P&ID will not contain Operating parameters, Equipment elevation details, Elbows, MTO, etc. It is not drawn to scale and hence geometric accuracy can not be expected out of P&ID.

P&ID Symbols

The instrumentation symbols used in P&ID are as per ISA-S5.1 standard –  Instrumentation Symbols and Identification. For Symbols of chemical apparatus and equipment normally ISO, JIS, DIN or PIP standards are followed. 

What are the Softwares available to make P&ID?

There is some renowned P&ID software available that can be used online and offline. It saves time in creating a P&ID with the help of simple user-friendly tools available in them. Some of them are,

Autocad is one of the worlds leading design and drafting software used by many of the Chemical Process Design companies for preparing P&ID. 2D and 3D design drawings also can be made out of it.

MS-Visio is very useful offline software for Chemical Engineers to prepare PFD, P& ID and other diagrams in a simple way by just dragging and dropping the symbols.

Lucidchart is an online software for preparing P&I diagrams in a fast manner. Anyone can make the drawing with a drag and drop option. This simple and efficient software also has the functionality to import and export from MS- Visio.

P&ID Review Checklist

Chemical Engineer must review the P&ID before finalizing them for implementation. Our exhaustive Excel P&ID Review Checklist helps to review the P&ID to make it fit based on Safety, Erection, Commissioning and Operation aspects.

Download the P&ID Review Checklist as Excel file

If you find anything missing in our checklist, feel free to mail to us so that we will add them.

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PFD and P& ID Preparation in Visio

Process Flow Diagram (PFD) and Piping and Instrumentation diagram (P& ID) can be prepared with the help of this software easily. The available tools for creating the diagram is customized and made available as icons under the topics Equipments – General, Heat Exchangers, Pumps, Vessels, Instruments, Pipelines, valves & Fittings. Once can also use the search box to find out the needed equipment. Other simple customizations can be done like any other MS – Office software like Changing the color, Font size and Inserting symbols which is helpful in creating colorful PFD/ P& ID’s for presentation purpose. It is possible to save the diagrams as VISIO files or simple images. The other use is we can simply copy the equipments from VISIO and paste it as image wherever we need.

Other Applications of VISIO

Organization charts for the department or for an Industry can also be effectively created with the help of VISIO. Gantt Charts can be created by using MS – VISIO to schedule project tasks and communicate them visually to team members. Program Evaluation and Review Technique (PERT) chart can be prepared which is a useful tool for Project managers. Brainstorming diagrams available in MS-VISIO Swill help to conduct a brainstorming session in effectively capturing and organizing the ideas.

It also helps to prepare Plant layout and site layout. Cause and effect diagrams which is also known as fishbone or Ishikawa diagrams can be made using VISIO. This will Show factors and causal relationships in a given situation. Fault tree analysis diagrams show and analyzes faults in processes. Basic electrical diagrams, Circuits and logic diagrams, Industrial control systems diagrams will be helpful for creation of circuit diagrams and other Interlock diagrams. These will be very useful for Electrical engineers and Instruments Engineers also.

Hope this review will be helpful to understand the uses of MS- VISIO. If so, Share this with friends

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The task of writing chemical plant manual categorized into two. One is for new plants and the other is for plants that already running. For old plants there are already established systems and procedures and for the modifications or revamps additional information has to be added, which is a simple task. But writing the operating manual for new chemical plant is a challenging task though already similar plants are running around the world. Let us will see how to write operation manual for new plants here.

Data Collection and Brainstorming

This is the preliminary task of a process engineer who is involved in preparation of Chemical Plant operation manual. PFD, P& ID, Control System, Process description from Technology provider, Equipment supplier manuals, HAZOP study recommendations, Details of legal/ regulatory requirements, Design Material & Heat balance of Process streams are to be collected before proceeding further. Then a brainstorming session is to be arranged with the colleagues/ superiors to discuss the various activities associated with the task and set Specific Measurable Attainable Relevant Time bound goal to bring up the better manual.

Contents of Chemical Plant Operating Manual

The content of a chemical plant operation manual is simplified into the following topics and the details may be added into appropriate section based on the specific requirements of the plant.
Abbreviations
Design Basis
Overview of the Process
Process Description
Procedures
Safety, Health & Environment Section
Utility and Other Systems
Appendix

Abbreviations

Abbreviations used in the manual are to be consolidated and added in this section for better understanding for beginners.

Design Basis

Design basis of the plant including Plant Capacity, Technology used, Site Climatic Data, Raw Materials, Utility & Product Specifications forms this section in the chemical plant operation manual.

Overview of the Process

Overview of the Manufacturing process with the major equipments or sections involved in sequential manner to be described to get the overall understanding of the chemical plant. Process Flow Diagram (PFD) helps in preparing this section.

Process Description

The detailed process description with Equipments and Control valves associated including tag no’s used with the design parameters and compositions at various streams in a sequential manner forms this section. Process control philosophy for various parameters in the plant like pressure, flow, level & temperature and description of various controllers and control loops available for the process control. Various Trips and Interlocks and reasons for having it along with Emergency Shutdown (ESD) system available in that section is elaborated. Piping & Instrumentation Diagram (P& ID) and Process description from Technology provider will be useful in bringing effective process description of units in the chemical plant.

Procedures

Standard operating Procedures for individual equipment and sections in plant for Normal Operation, Start up and Shutdown and then for total plant are to be established and produced in this section. Procedure for safe isolation of equipment for maintenance jobs shall also be included. This section shall also include Trouble shooting guide for various upsets. Routine schedule with incorporation of lubrication schedule, trial run of equipment, availability check of systems etc. Equipment supplier Manuals, HAZOP study recommendations will help the process engineer for preparing this important section of Chemical Plant Operating manual.

Safety, Health & Environment Section

Safety section provides overview of installed Safety Systems, Fire Fighting Facility and available safety procedures in the chemical plant. It also provides details on Zone classification, Emergency Actions, Hazards. Applicable Work permit systems related to plant like Hot Work, Confined Space Entry and procedure for issuing and authorizing the permits are to be listed for the entrants to understand the systems. Types of Personal Protective Equipment (PPE) available, issue and usage details are to be provided in this section and proper sign boards are also to be made available in plant premises.

Toxicological information of chemicals used in the manufacturing process is to be provided in the chemical plant operation manual. Chemical handling & storage and their first air measures also need to be listed for better understanding of chemical hazards.

Environment section of the Chemical Plant operation manual must contain industry specific disposal limits for various effluents generated in the plant and details on applicable laws & governing bodies.

Utility and Other Systems

Description of various other associated facilities in Chemical Plant like Water Treatment facility, Cooling Towers, Cooling Water system, Deaerators, Boiler & Steam System, Compressed Air System, Inert Gas generation & distribution systems, Effluent treatment facilities, Flare system, Electrical Power Distribution and ESD system is to be prepared and written under this section.

Appendix in Chemical Plant Operation Manual

This section contains the supporting information for better understanding of the Chemical plant operating manual. Normally it contains PFD, P& ID, Alarm & Trip set points, MSDS of Chemicals Handled, Equipment Data sheets & Curves, Further Reading – Vendor Document List etc.

Process engineer can add additional resources in this section based on specific need. One can also create his own structure based on the needs and prepare a better chemical plant operation manual.

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