According to the meaning of the question, if you subtract one at a time, then the bottom layer is 15, the top layer is 3, and * * * has (15-3+ 1) layers. Then, the area of trapezoid is equal to the number of steel pipes. The trapezoidal area formula can be used to calculate the number of steel pipes in this pile, and the answer can be obtained through the formula.

Solution: * * There are layers: 15-3+ 1= 13 (layers).

The number of steel pipes is (15+3)× 13÷2.

= 18× 13÷2,

=234÷2,

= 1 17 (root),

Answer: There are 1 17 steel pipes in this pile.