Piping Isometrics

Isometric Drawings (ISOs)

Piping isometrics are three-dimensional representations of piping systems, projected onto a two-dimensional drawing sheet. These drawings depict the complete piping line, connecting various pieces of equipment as outlined in the line list. Isometrics are essential for providing all the details necessary for fabrication and installation. Although isometric drawings are not typically drawn to scale, they should maintain proportionality to ensure clarity. Dimensions are usually given relative to the piping's centerline.

Key Information in an Isometric Drawing

1. Plant North: Ensure the north direction is selected to facilitate easy comparison between the General Arrangement (GA) and the isometric drawing.

2. Nozzle Identification: Clearly mark the identification of nozzles on connected equipment.

3. Dimensions and Angles: Provide accurate dimensions and angles for piping components.

4. Reference Information: Include the reference numbers for P&IDs, GA drawings, line numbers, flow direction, and details about insulation and heat tracing.

5. Equipment Information: Identify the location of equipment and provide its identification.

6. Flange Details: If the flange specifications differ from the connecting piping, provide the necessary flange details for the equipment.

7. Valves: Include the size and type of every valve, along with the direction of operation.

8. Control Valves: Specify the size and number of control valves where applicable.

9. Field Welds: Indicate preferred locations for field welds to accommodate site-specific variations. General notes can be used for broader guidelines.

10. High and Low Points: Mark the location of high-point vents and low-point drains, either directly or via standard arrangement notes.

11. Bill of Materials (BOM): Provide a BOM listing all components used in the piping system.

12. Special Requirements: Include any requirements related to stress relieving, seal welding, pickling, coating, or other post-fabrication treatments.

This structured approach to piping isometrics ensures that all relevant details are clearly documented, making the process of fabrication and installation efficient and error-free.