[Grammar] on a length of tin drainpipe

[constantinusphilo]

catching myself only at the last moment on a length of tin drainpipe which, mercifully, held.
This is a clause from The Secret History by Donna Tartt. I think that the correct way would be: on the length of a thin drainpipe.

 

[5jj]

It's correct as it is. Drainpipe is regarded here as uncountable (you could also say drainpiping), and it's made of tin. It's not thin.