Трубопроводная арматура. Помогите понять смысл предложения

[ckey]

The wafer disc has been designed to clear schedule 80 piping

to clear schedule 80 piping ???

[Gaukler]

clear - прозрачный
google: clear schedule piping
...We provide clear PVC pipe in Schedule 40 & Schedule 80 and clear PVC fittings

[ckey]

Спасибо )