Simplify the following text for a Grade 9 native English-speaking person.
Original: In addition to the straight pipe or tubing , many fittings are required in plumbing systems , such as valves , elbows , tees , and unions .
Simplified: As well as the straight pipe or tubing , many fittings are required in plumbing systems , such as valves , elbows , tees , and unions .