The first time: the three internal angles are: 10, 10, 160 respectively.

Second time: 20, 20, 140 correct.

Third time: 30, 30, 120 correct.

Fourth time: 40, 40, 100 correct.

The fifth time: 50, 50, 80 is correct.

Sixth time: 60, 60, 60 is correct.

Seventh time: 70, 70, 40 is correct.

Eighth time: 80, 80, 20 is correct.

Ninth time: 90, 90, 0 error

So: A: You can add up to eight such steel pipes.