Method of rebuilding a conventional tissue machine to a TAD machine

A method of rebuilding a papermaking machine, which has a conventional C-wrap type twin wire forming section, for the manufacture of a sanitary paper web, said method comprising incorporating in said machine a through air drying (TAD) section for thermally predrying the formed paper web by passing hot air through the web, said C-wrap type twin wire forming section having an endless looped inner forming fabric, a forming roll that rotates in a direction and is located inside of the inner forming fabric loop and has a portion wrapped by a portion of the inner forming fabric, an existing endless looped outer forming fabric partially wrapping said portion of the inner forming fabric, means for guiding the forming fabrics so as to form between them a converging forming throat located at a lower rising quadrant of the rotatable forming roll and curving along an upstream part of said wrapped portion of the forming roll, and a headbox for discharging a jet of papermaking furnish obliquely upwards into the forming throat, said furnish on drainage through at least the outer forming fabric being formed into a paper web sandwiched between the two forming fabrics, and said TAD section including an endless looped TAD fabric and at least one hollow TAD cylinder that rotates in the same direction as the forming roll and has a foraminous shell for the passage of hot air therethrough from the exterior to the interior of said at least one TAD cylinder in order to thermally predry the web, said at least one TAD cylinder being located inside of the TAD fabric loop and having a top portion that is wrapped by a portion of the TAD fabric, said method further comprising:

• substituting a new outer forming fabric loop for the existing outer forming fabric loop, said new outer fabric loop being of greater length than that of the existing one and having a comparatively plane web facing surface, so that on separating the two forming fabrics from each other the formed paper web will adhere to and be carried by said comparatively plane web facing surface of the new outer forming fabric, said length being sufficient for permitting the new outer forming fabric loop to extend to the TAD fabric;
• and
• providing means for guiding the new outer forming fabric with its web facing surface into contacting relationship with the TAD fabric upstream of or on the TAD cylinder and thereby transfer the web from the new outer forming fabric to the TAD fabric.