British Gas North Eastern , Scientific Services Department have had a system on trial for around seven months which has proved to be very effective in repairing joints on mains up to 12 " diameter. The Internal Anaerobic Spray System is a method of internally treating the joints of Low Pressure and Medium Pressure gas mains by spraying the sealant into the gap in the joint. Joints are located electronically then sprayed with the required volume of sealant and the system can treat 50 to 60 metres of main in each direction from one excavation.

Some problems with operating the system under no-gas conditions and without spillage of sealant have been encounterd, but these have been solved. The equipment has proved particularly effective and cost- effective when compared to alternative methods of treatment.