1.   For example, flushing the pipes would involve an extra few minutes for each delivery, adding considerably to the cost of transporting fuel, he said.

2.   However, I would not recommend flushing the pipes with an acid or other chemical to dissolve the deposits.

3.   The city is warning citizens to flush the pipes thoroughly after every shutdown and to boil water before drinking it.

4.   Even though the pipe was flushed afterward, residue may have remained inside and, all these months later, been knocked loose by the force of liftoff.