McMaster sealing washers

[xxdcmast]

Im about to order from mcmaster my silicone sealing washers but Im a little confused as to which ones. I have searched the forums and seen two part numbers listed.

99604A129
Shape
Round Hole
For Screw Size
3/4"
Rubber Material
Silicone
Inside Diameter
.74"

and

99604A127
Shape
Round Hole
For Screw Size
5/8"
Rubber Material
Silicone
Inside Diameter
.615"

I am building my weldless setup with the standard 1/2 inch fittings. I hate ordering the wrong stuff so Im hoping you all can help.

Thanks

 

[xxdcmast]

Also I have one 3/8 inch weldless sight glass I would like to get the sealing washer for. Any ideas on a part number for that?

Thanks again

 

[xxdcmast]

Bump for help.

 

[bull8042]

For standard 1/2" fittings, the one I like is http://www.mcmaster.com/itm/find.AS...DtlLink&fasttrack=False&searchstring=9396K285
It is 0.725" ID and is 3/16" wide. Keep in mind that this is the most common o-ring supplied with weldless kits and does seal well. But, if your SS nut has an "o-ring groove", the o-ring may not seat within that groove. There is a thinner o-ring which I don't happen to have the P/N for off hand that seats better with that type of nut.
This one will work just fine with a flat nut and/or washer.

 

[Bobby_M]

The ones listed as 3/4" screwsize fit over 1/2" pipe nipples and the 5/8" are for 3/8" pipe nipples.

 

[xxdcmast]

Thank you very much. I just put my order through.

Thanks