Table of Contents

  1. Introduction
  2. Scope
  3. General Procedure for flow diagram preparation
  4. The Process Flow Diagram
  5. The Pressure (P) - Temperature (T) Profile
  6. The Engineering Flow Diagrams (P&ID)
  7. The Utility Flow Diagram (UFD)
  8. The Interconnectiong Flow Diagram
  9. The Process Safeguarding Flow Diagram
  10. The Revamping Flow Diagram
  11. Check List
  12. Preparation of Line Table
  13. List of Related Red-Bag Standards
  14. List of Other Standards
  15. Typical Arrangement of Equipment Installation

1. Introduction

1.1 Purpose
The purpose of this document is to outline the procedures for the preparation of process flow diagrams, pressure-temperature profile diagrams, engineering, utility and interconnecting flow diagrams and special diagrams as revamp flow diagrams and pressure safeguarding flow diagrams.

1.2 Concept
Flow diagrams are highly specialized “language for information transfer. They represent the engineer’s concept of how plant equipment should be interconnected. The diagram is almost physical in a sense, since every piece of equipment, every pipeline, valve and instrument is shown. Diagrams are used to convey information between groups working on the project and translate the plant design into ‘real’ piping and equipment.

1.3 Use
By preparing the diagrams properly, the engineer can convey a great deal of technical information, quickly and accurately, with a Limited amount of paper work.

1.4 Tee of Diagrams There are 7 types of flow diagrams:

1.4.1 The Process Flow Diagram (PFD)
The PFD is developed by the Process Engineering Department. Final drafting by the Flow Diagram Squad. On this document are given the main process equipment, fluid flows, main control loops and critical valves. It is a tool for the process engineer(s) to convey information to project and specialist engineers to design the installation in detail (see fig: 6).

1.4.2 The Pressure Temperature Profile Diagram(PTP)
The PTP diagram is a document prepared by the Process Engineering Department with the purpose of providing project, control systems and piping engineers with the correct pressure and temperature correlations between the various piping systems, vessels, exchangers, etc. The document ensures that proper values are being used for preparation of data sheets, line tables and other documents as, e. g. painting systems, insulation, etc.

For PTP preparation procedures refer to Standard Specification BN-EG-UE-1 (Design guide for Pressure and Temperature profile).

1.4.3 The Engineering Flow Diagram (EFD)
On this document are shown all equipment connecting piping, utility piping, complete with control, loops and all other instrumentation, all valves a safety measures. It is the main tool for the project engineer to convey information to the piping design office and control systems engineering group for the detailed piping and control systems design (see fig: 13).

1.4.4. The Utilities Flow Diagram
This document. shows how utilities are generated and distributed from the source or supply point to the various parts of an installation. The diagram shows coon control loops, additional equipment that is deemed necessary to supply the utility as required and the safety measures necessary (see fig: 18). The diagrams shall be drawn in accordance with the geographical layout of the plant.

The diagrams are generally divided per generation activity, e.g. steam generation, inst air, cooling water, fuel oil, etc. The utility equipment shall be shown. Packaged units to be shown within, heavy dotted line.

1.4.5 The Interconnecting Flow Diagram (IFD)
These diagrams are prepared to show the interconnecting lines between various plant units and, e.g. tank farms, etc,

1.4.6 The Process Safeguarding Flow Diagram (PSFD)
This document shows the correlation of safety devices installed but indicated on separate EFD's. It “highlights” the final level of protection provided by the safety systems installed.

This document will be produced on client's request only, e.g. SIPM

1.4.7 Revamp Flow Diagram
“Revamping Flow Diagrams” shall be prepared to indicate which equipment, lines, control loops, etc. must be demolished, modified, removed or relocated, etc. in a revamping project. The existing engineering flow diagrams of a plant or unit to be revamped shall be used.

In general two sets of diagrams are to be prepared:

a) An updated existing EFD's version for demolishing purposes, RFD's.
b) New “as built” EFD's

For more details refer to Chapter 10.

1.5 Notes:

1.5.1 It must be noted that particular instructions given by client or licensor with respect to his requirements or special requirements covered by any authority decrees shall be observed.

1.5.2 If any of such rules, decrees or instructions exist, these must be mentioned in the “Project Specification”.

1.5.3 When these instruction have not been incorporated, the documents produced will be unacceptable to the client or licensor and/or authorities.

1.5.4 Where in the following text of this Engineering Procedure has been referred to other Company procedures or standards, this is only true where the Company standards are not conflicting with those mentioned under para 1.5.1.

1.5.5 To obtain maximum uniformity with regard to line thickness, lettering, symbols, etc. the drafting on vellums shall be executed by the Flow Diagram Squad.

1.5.6 There is still another flow diagram, prepared by the control systems engineering group, exclusively for use by process and control systems engineers. This flow diagram is principally a PFD on which the control system engineer indicates specific instrument physical data. The document is called; “Instrument Data Flow Sheet”. It is not further mentioned in this ‘Engineering Procedure”.

1.5.7 The examples presented in this Engineering Procedure are taken from actual jobs and include general Clients requirements. Therefore, the symbols used will not always be identical to the symbols shown on the legend sheet fig: 22.

1.5.3 On an EFD, a package unit, e.g. compressor, can be indicated with a heavy drawn block with reference to one or more vendor flow diagrams (process, lube oil, seal oil, water cooling, etc.) which can be adopted.

2. Scope

2.1 This Engineering Procedure shall be used as a standard for the preparation of process and engineer flow diagrams as outlined in para 1.4 of the Introduction.

2.2 It shall also be used to edit systematically the text for the Project Specification on the subject of flow diagram preparation.

2.3 The purpose of this Engineering Procedure is to provide the engineers with all necessary information to generate the various diagrams needed with the greatest consistency and efficiency possible.




The full procedure is available for registered users. The procedure is part of the Introduction and Basic Piping Design course at InIPED.