The Utility Flow Diagram shall be prepared as separate drawing titledas "Utilities Flow Diagram". The distribution of utilities for plant operation shall be shown on the drawing. The utilities for plant operation are generally classified as follows where applicable:
- Boiler Section;
- Condensate Recovery;
- Boiler Feed Water;
- Cooling Water;
- Raw Water;
- Plant and Potable Water;
- Fuel Tank;
- Dry and Plant Air;
- Inert Gas;
- Hot Oil & Cold Oil System;
- Flare and Blow-down;
Utility Flow Diagrams shall be presented in accordance with the requirements stipulated in Standard P&IDs where applicable.
Indication criteria of connection between P&IDs and UFDs is according to the following general philosophy:
a) The indication of isolation valve shall not be duplicated on P&ID and UFD.
b) Valve and instrument which will be used for the normal operation shall be indicated on P&ID, such as:
- Block valves for water cooler inlet and outlet;
- Block valves for snuffing steam of heater;
- Globe valve for steam injection control;
- Control valves for fuel control.
c) Valves which will be used only for start-up and shut-down shall be indicated on the UFD such as:
- Header isolation valve for steam purge connection;
- Isolation valve for fuel gas or fuel oil.
Isolation facilities shall be indicated for:
- finger areas;
- process Unit block areas;
- at position of change from pipe rack to pipe rack.
The finger area is defined as being the area that serves a particular process area which may consist of one or more process Units. In addition to the equipment that is located alongside the finger pipe rack, the finger area also includes the equipment located alongside the main pipe rack.
All equipment that is supplying a particular utility common facility either from the system (e.g., steam boilers) or from a process Unit (e.g., waste heat boilers) shall be shown in a "box" in geographical location. This "box" shall give relevant equipment number(s), Unit number and sheet
number of the drawing in which the equipment is detailed.