Table of Contents

  1. Purpose
  2. Flow Diagrams
  3. Checking of Flow Diagrams
  4. Recording of Changes
  5. References
  6. Attachments

1. Purpose

This guide, by the application of checklists, describes the safe-guarding of quality aspects of engineering work in the development of flow diagrams. It covers the requirements to ensure that applicable specified design basis, regulatory requirements, codes and standards are correctly translated in the development of flow diagrams within the Engineering Department.

2. Flow Diagrams

2.1 The expression “ flow diagrams “ covers the following :

  1. Engineering flow diagrams ( EFD’s) and utility flow diagrams ( UFD’s ) and utility distribution diagrams ( UDD’s ).
  2. Process engineering flow diagrams (PEFS) and utility engineering flow diagrams(UEFS).
  3. P & ID’s, piping and instrument diagrams.
  4. Mechanical flow diagrams.

3. Checking of Flow Diagrams

3.1 Checklist for Administration

All changes on the flow diagrams shall be recorded properly on revision lists and the marked-up issues filed. Attachment 1 contains a checklist which covers the administrative aspects of flow diagram control.

3.2 Safety Checklist for Flow Diagrams

All questions of the safety checklist shall be verified against the flow diagrams ( refer to Attachment 2 ).

3.3 Checklist for Technical Content of Flow Diagrams

All questions of the checklist shall be verified against the flow diagrams ( refer to Attachment 3 ).

3.4 Checklist for Line Designation Tables

All questions of the checklist shall be verified against the line designation tables ( refer to Attachment 4 ).

4. Recording of Changes

The recording of changes and the filing of the associated documents shall be in accordance with the relevant sections of the “ Procedure for Production, Approval and Control of Engineering Documents “, ref. 5.1.

These files shall be maintained by the project engineers as part of the project file. To each document a “ List of Revisions “ shall be attached ( ref. 5.6 ).

5. References

Document Number Title

5.1 CM-PE-504 Approval of Engineering Documents

5.2 CM-MA-102 Document Issue Code and Change Identification

5.3 PJ-EP-200 Preparation of Flow Diagram

5.4 PC-SP-124 Safety Review of P & ID’s

5.5 CM-PE-307 Engineering Safety Program

5.6 BN-UE ( I ) - 10 List of Revisions

6. Attachments

  1. Checklist for Administration
  2. Safety Checklist for Flow Diagrams
  3. Checklist for Technical Contents of Flow Diagrams
  4. Checklist for Line Designation Tables


  1. Does a marked-up master copy exist ? It is kept up-to-date ? Are marked-up revisions identified with the originators initials?
  2. Are changes recorded on revision lists, properly referenced to flow diagrams ? Are references to potential change orders made ? Is origin of change and impact properly indicated on revision list?
  3. Are revisions properly identified on the flow sheets?
  4. Is name number of flow diagram correctly indicated?
  5. Authorized signatures? ( Refer to relevant procedure, see QA-006 ) location for “Certified” signature.
  6. Is line designation table reissued and updated with the flow diagrams?
  7. Are changes/additions/deletions to utility lines on PEFS (immediately) followed by changes to UEFS of the relevant utilities?



  1. General points:

    1.1. Hazardous nature of chemicals to be utilized
    1.2. Information available on requirements for :
    • Storage of chemicals and hydrocarbons
    • Handling of chemicals
    1.3. Type of hazards possible
    1.4. Method of prevention of same
    1.5. Possibility of dust explosion
    1.6. Possibility of low temperature flash or auto-ignition
    1.7. Prior experience on this type of plant

  2. Are there unusual hazards in the plant due to:
    2.1. High/low temperature
    2.2. High/low pressure
    2.3. Chemical reactions ( i.e. oxidation, operating within explosive limit zones )
    2.4. Excessive inventories
    2.5. Toxic or self igniting materials
    2.6. Are there any possibilities of dangerous conditions arising during plant startup and shutdown period or regeneration of catalysts
    2.7. Corrosive materials
    2.8. Radiation emission
    2.9. Utilities Failures
    2.10. Plugging of lines due to heavy oils ( asphalt ) cooled down in dead ends or near bends, strainers and block valves. This can also happen if catalyst fines are carried out from a reactor with the heavy oil into the lines.
    2.11. Plugging of reactors due to coke formation in the catalyst layer causing a rapid increase in the pressure drop across the reactor.

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