Sealing Type A Sleeve for Transmission Pipeline Repair

The integrity of underground transmission pipelines is maintained via in-line inspection (ILI), as well as excavation that follows suit for pipe repair/replacement. Steel sleeves are often used to reinforce a pipe section where anomalies/defects are found. Type A sleeve is referring to a steel sleeve repair where two halves of the sleeve are seam welded, while the two sleeve ends are subsequently not welded to the pipe but rather sealed. There can be a gap of 1/8" between the sleeve and the pipe, especially at the seam weld areas. Sealant (e.g., epoxy) applied underneath the sleeves would interfere with seam welding, resulting in poor weld quality that does not pass NDE inspection. The heat from welding also damages the sealant, thus creating a leak path into the annulus. Epoxy or wax tape coating applied externally at the sleeve ends after seam welding would not reliably keep the moisture out. We are looking for an effective sealing approach for Type A sleeve installation.