Help figuring out fitting

[mrfu]

Hi all
I have a hydraulic fitting off of a chinese wood chipper. The female end is jic 3/8 the male end is odd it is 17.75 mm in diameter. The guy at the hydraulic place couldn't figure out what it is. it is a straight thread with no taper pitch if metric is 1.5 or if english or 20 tpi if english.
It also uses a bonded washer.
Any ideas or is it within the specs for an 18mm fitting.
I am getting a fitting from the place I bought it from it would just be nice to have another source
Thanks
Tom

 

[oldnslo]

Could be M18x 1.5 or Possible that it is G3/8 - 3/8-19 BSPP British Straight Parallel Pipe thread. G3/8 should be around 16.5 -17 mm OD They both can use a bonded seal washer

 

[mrfu]

Thanks for the help. I ordered one of each, but I have a feeling it is m18 x 1.5 just with sloppy tolerences
Tom

 

[Zebrafive]

I am going to agree M18. .25mm is less than .010" probably a little undersize, but works.

 

[mrfu]

Thanks everybody for the help. it turned out to be an 18mm fitting
Tom