Detailed Design Specifications (DDS) are prepared for each critical utility or piece of equipment prior to the manufacturing stage. The specification provides a detailed description of the utility or piece of equipment design based on the Functional Requirement Specification (FRS) document. The DDS will take the functional requirements and detail how they will be manufactured in order to respect the requirements. The document is created in conjunction with the manufacturer to ensure that every requirement will be respected as per the customer’s requirements. A Hardware and Software Specification section can be included in the DDS or a separate document for each can be created. Either way the hardware and software specifications for the utility or piece of equipment will be detailed.

Why produce a DDS?

Detailed Design Specifications are required to protect both the end user and the manufacturer. All Requirements of the end user will be specified in the FRS prior to the manufacturing of the utility or piece of equipment, the DDS enables the manufacturer to detail the design and have it approved by the end user prior to any manufacturing being initiated. This enables the manufacturer to produce the product to the end user’s expectations once the DDS has been approved by both parties. The manufacturer has the opportunity to review the DDS and incorporate the requirements in their system or offer alternatives to meet the requirement. Some requirements may not be possible to supply and therefore will be addressed prior to the manufacturing stage eliminating possible problems before they occur. The Detailed Design Specification document may evolve with the project and is provided with a Revision History section in order to document any changes that occur throughout the project stages. The final version of the DDS will be a controlled document that can be referenced should any questions arise regarding the final product. The manufacturer must ensure that all aspects of the DDS have been understood and that all requirements can be fulfilled, or alternatives offered, in order to meet the end user’s expectations.

What does a DDS contain?

The Detailed Design Specifications include (but are not limited to) the following common sections:

Identification of Writer, Approvers:
Provides documented evidence on the personnel involved in preparing and approving the document.

Revision History:
A revision history is maintained to record any changes to the document and the date they occurred.

Introduction:
Defines the purpose and scope of the Detailed Design Specification with respect to the design of the utility or piece of equipment.

Overview:
Gives a background and objective of the utility or piece of equipment that is being considered with an overview of its functions.

Operational Requirements:
Will list the design for the function of the system which include, but are not necessarily limited to, Sequence of Operation, Cycle of Operation, and Machine Performance.

Control System Requirements:
Will list the design for the control system which include, but are not necessarily limited to, Functions, Safety, User Interfaces, Electronic Records and Signatures, Security, Alarms, and Utilities.

Hardware and Software Requirements:
Will list the specific design for the control system which include, but are not necessarily limited to, Interferences, Environment, Hardware, Operating System, and Application Software (can be included in the DDS or can have its own Hardware and Software Design Specification document).

Glossary:
Definition of all the terms that have been referenced in the document.