Fitting difference
Fitting difference
(OP)
Can someone explain to me what is the difference between a coupling and a weldolet or threadolet, are they essentially the same things?
My actual question is in relation to welding these on to a vessel, fom that perspective are they essentially the same with just different ends? (I know a weldolet and threadolet are the same except for the end connection coming off the vessel they would be welded on to, but i just want to make sure im clear on what the difference is between these and a coupling.)
My actual question is in relation to welding these on to a vessel, fom that perspective are they essentially the same with just different ends? (I know a weldolet and threadolet are the same except for the end connection coming off the vessel they would be welded on to, but i just want to make sure im clear on what the difference is between these and a coupling.)





RE: Fitting difference
O-Let fittings are engineered, designed and made for the specific purpose of making self-reinforced nozzles on vessels or branches on pipe. The shape of the O-Let fitting has the extra bulk to replace the missing material from the vessel shell or the pipe wall. O-Let fittings are a little more expensive but cannot be used for any other purpose.
RE: Fitting difference
The O-let fitting is cast and forged to sit on the side of a pipe - which is usually relatively small bore: the O-let fitting is attached to an OD of between maybe 2.75" to to 14 or 16 inch diameter. So the base (bottom) of the O-let fitting is curved for those small diameters.
A tank or pressure vessel might be anywhere from 24 inch OD to 200+ inches OD. So the sharply curved bottom of the O-let fitting doesn't fit well over the relatively "flat" large diameter tank wall. A coupling inserted through the tank wall and fillet welded on both sides gives a better, (and faster!) double weld with less heat buildup and stress residuals than the large fill-in-the-heaping-gap weld required for a small pipe or vent on the tank.
RE: Fitting difference
There are FLAT O-Let fittings.
Check here:
http://wfi-intl.com/WFI_catalog05.pdf
RE: Fitting difference
RE: Fitting difference