Quantifying the Influence of Air on the Capacity of Large Diameter Water Pipelines and Developing Provisional Guidelines for Effective De-Aeration Volume 2: Provisional Guidelines for the Effective De-Aeration of Large Diameter Water Pipelines
1177/2/04
March 2004

EXECUTIVE SUMMARY

1. Background and motivation

The extension of the design life of the aging water infrastructure requires an assessment of all the components that can negatively influence the hydraulic capacity and can endanger the pipeline. To ensure operational effectiveness of pipelines they must be effectively de-aerated.

The influence of air on the capacity of pipelines has long been a cause for concern. The quantification thereof was, however, unknown and required investigation. The investigation of air in pipelines required a review of available literature, experimental work, field investigations and the development of provisional guidelines for optimal design to limit the negative effects of air.

2. Aims of this study

The aims of this study were to:

• Provide a literature review with regard to aspects related to air in water pipelines
• Conduct experimental and field work to establish to influence of air in pipelines and
• Compile a provisional guideline for the design of effective de-aerated pipelines.

3. Implementation of the Research Findings

The Water Research Commission promotes the commercialisation and implementation of the research findings into practice. Based on the knowledge that was gained through the literature study, experimental and field investigations and the numerical modelling a Provisional Guideline has been developed that is intended for use by practitioners. Contained in the provisional guideline the following aspects are discussed:

• Intrusion of air into pipelines
• The consequences of air in pipelines
• Hydraulic transport of air
• Air valves
• Implementation of a new pipeline
• Sizing and positioning of air valves
• Typical installation details of air valves

These aspects will provide the designer assistance in the review of existing, and the design of new pipelines. The inclusion of utility software is a great advantage with regard to the analyses of pipe systems with regard to the locations and sizing of air valves.

4. User comments

It is envisaged that it might be possible that the use of the guidelines will highlight shortcomings and could lead to the implementation of other aspects to improve the provisional guidelines.

The incorporations of procedures to determine the location of air pockets, the practical experience of using the guidelines and the development of new products will create the opportunity for the upgrading and extension of the guideline. All users are requested to provide comments and feedback on the use of this guideline.