Cross-stitch it flat, using a sail needle and twine, and taking a narrow hold on each side with one stitch, then a wider hold with the next one, and so on alternately.

Asbestos Pipe Guard.

Fig. 6. Asbestos Pipe Guard.

Then it will not tear again so easily as if narrow stitches were taken all along, nor will it be likely to ruck. Temporary repairs can be made with adhesive plaster.