Advantages:

(1) Long working life . Under normal condition , at least 50 years of working life.
(2) Health and good performance.

(3) Smooth wall , low coefficient of friction , has good bears the friction performance .
(4) Excellent pressure resistance .
(5) Welding process is simple , low cost .
(6) Light weight , easy transportation and installation 
(7)size:20*1/2"-63*2"