Report No FR0403

REVIEW OF WATER MAINS/SERVICE PIPE ISOLATION TECHNIQUES

Sept 1993

SUMMARY

I BENEFITS

This report gives guidance on the use and applicability of three water main and service pipe isolation techniques. A more efficient application of the techniques will enable the reduction of the number of disruptions to supply and customer interruptions necessary during maintenance, repair or alteration to the distribution system.

II OBJECTIVES

To give guidance on the selection of appropriate water main/service pipe isolation techniques for particular application.

III REASONS

The Water Mains and Services Group (WMSG) have identified a need to review isolation techniques used within the water industry and by other utilities because of the increasing need to be able to isolate areas with a minimum disruption to the customer.

IV CONCLUSIONS

Three main techniques were found; freezing, squeezing and plugging.

Freezing and squeezing are particularly applied to service pipes and less frequently on water mains.

Plugging techniques include insertion stoppers, bagging and piggable plugs. Insertion stoppers are increasing in use in the water industry whilst bagging and piggable plugs are techniques mainly used by the gas and oil industries respectively. Varying experience of these techniques illustrates some water industry concerns.

V RECOMMENDATIONS

For the appropriate situations, pipe isolating techniques can provide an effective way of avoiding the need for shut down or isolating of an area of work.

This desk study has discovered an increasing use of plugging techniques within the water industry. With this in mind and following concerns expressed by industry personnel, the WMSG should be asked to consider whether further work is necessary:

  1. to examine the structural performance of the pipe following line stopping;
  2. to assess the performance of different plugging techniques when used on mains with various linings and conditions, and under different pressures, mains sizes and materials;
  3. to examine the bagging-off technique under higher pressures using only one bag;
  4. to test the piggable plug for use in the water industry.

VI RESUME

This desk study reviews water mains and service pipe isolation techniques used within the water industry and by other UK utilities. Operating experience within the water industry is examined together with procedures for water mains isolation.

Copies of the report are available from FWR, price 15.00, less 20% to FWR Members.