After the major process design has been completed, an equipment index (also known as an equipment list or equipment schedule) is created. The equipment index is a database of information that is used to communicate with the different disciplines of the project team. For the purposes of this article, equipment index, equipment schedule and equipment list are all used interchangeably, though their definitions are all the same.
As a rule of thumb, an equipment index should include the following equipment
- Pressure Vessels
- Heat Exchangers (shell and tube, air cooled heat exchangers)
- Any piece of equipment that has a unique equipment number on the PFD or P&ID
An equipment index does not need to include
- Piping (this should be captured on a line list)
- Safety Relief Devices
Reasons for Equipment Index
An equipment index cannot exist in a vacuum. There is a lot of data that needs to be created in order to produce an up-to-date and complete equipment schedule. Accompanying documentation for an equipment index are several other documents, drawings and data sheets. There are multiple uses for an equipment index:
- Process Engineers - In general, the process engineer will be the initial author of the equipment index. Depending on their involvement with the project and the type of project, they will likely hand the index off to the mechanical engineers for completion.
- Civil & Structural Engineers - Civil engineers use the information on the equipment list to ensure the equipment layout plan is accurate and contains all the equipment needed for the project. It also starts to define requirements for foundation design.
- Mechanical Engineers - Mechanical engineers use this information to ensure equipment design is as specified. Vessel internals, process connections, code & other process requirements are all referenced on the equipment index or supporting drawings. Additionally, the equipment index helps communicate information for line sizing.
- Electrical & Instrumentation Engineers - Electrical engineers use the equipment index as a stepping stone to complete electrical design. Horsepower listed on the index will be used for the electrical one line diagrams. Instrumentation engineers use this information as a way to start planning the instrumentation design.
Equipment Index Schedule Information
Information on the equipment list should, at a minimum, be:
- Unique equipment ID Number (P-101, K-5867, etc)
- P&ID Location
- Datasheet Number
- Plant Location or Process Unit
- Specific type of equipment
- Size and/ or capacity
- Materials of construction
- Operating pressure and temperatures
- Design pressure and temperature
- Special Requirements
Equipment specific information might be:
Pressure Vessels & Tanks
- Process Requirements such as throughput, inlet & outlet temperatures, etc.
- Code Requirements
- Metallurgy requirements
- Corrosion Allowance
- Wall Thickness Calculations or document that captures the calculations
- Nozzle Configuration & sizes or document such as an appurtenance drawing that captures this information.
- Datasheet numbers
- Horsepower Ratings
- Power Factor
- Type of control (adjustable speed drive, across the line, etc)
Equipment Index Notes
- An equipment index is a living document and cannot be finalized until the design of the facility is complete. Heat exchangers and pump capacities will likely change based on the make and model of equipment available from the selected manufacturer. For example, hydraulic horsepower might be calculated to be 77hp. Since motors are not available as 77hp, the next larger size might be selected.
- An equipment list can also be used as a basis for material tracking and expediting.
- All the information listed above can be populated in an equipment index but it is not always necessary. It is up to the project team to determine what information is needed and the equipment schedule tailored to the specific needs of the team.