1/4 NPT in 1" plate: through hole dia?

[racookpe1978]

I'm in the field working on a powerplant oil modification: I need to add a 1/4 NPT fitting for a instrument vent through a bearing plate 1-1/4 thick. Flow rate is not the issue, only the presence of the vent tubing itself.

Tapped hole dia = 7/16" Tapped hole depth is not in question.

But, and it may reflect too many days of 7x13 shifts, but I cannot explicitly find the through hole dia for the hole itself.

ID of a standard 1/4 pipe .540 - but is irrelevent, sicne I'm hooking up tubing. Since its a vent tube back out of the bearing assy, do I just specify a nominal 1/4" through hole, or run the 7/16 tapping drill through the plate as the through hole?

Thanks.

 

[racookpe1978]

Lest anyone worry about nuclear configuration control: This is in a gas turbine, combined cycle plant, aft (outlet) oil bearing pedestal for the CT turbine.

Not a nuclear-spec unit. 8<)

 

[hydtools]

Just specify the tap drill through, unless there is some physical reason on the other side not to.

Ted

 

[hacksaw]

instrument vents are fine with 1/4" i.d. through holes
just make sure you know what is on the other side and use a collar stop

 

[racookpe1978]

Understood.

My thanks to all. Robert