What tap for 1/2″

[tiler JonesParticipant @tilerjones74981]

Hi,

Can someone help me with this please.

II need to screw a tap 1/2" BSP into a pvc pipe. The pipe wall thickness is around 5mm.

What size tap and drill bit would I need please.

I also need to do the same for a 3/8" fitting.

Thank you people

tiler

Hi

I am wondering can someone help me out please ?

I want to screw a half inch bsp tap fitting into a pvc pipe. The pipe thickness is around 5mm.

Can someone tell me what size tap and drill bit I need as I am a bit dim on the terminology.

Thank you people

tiler

Hi

I am wondering can someone help me out please ?

I want to screw a half inch bsp tap fitting into a pvc pipe. The pipe thickness is around 5mm.

Can someone tell me what size tap and drill bit I need as I am a bit dim on the terminology.

Thank you people

tiler

[tiler JonesParticipant @tilerjones74981]

[JasonBModerator @jasonb]

As the wall is quite thin and you are tapping a through hole then a taper taop will be fine.

For 1/2" BSP you want a 1/2" BSP tap and drill 47/64" or 18.7mm (19mm would probably do)

For 3/8" BSP you want a 3/8" BSP tap and drill 19/32" or 15mm

You may find it easier to use a step or cone drill on the thin wall plastic as it won't grab and will be cheaper than two specific drill bits

[tiler JonesParticipant @tilerjones74981]

You have been so helpful

Thank you

[David George 1Participant @davidgeorge1]

Are you trying to screw a metal fitting into the side of a plastic pipe or on to the end of the pipe, and is there pressure involved ie water , oil or air as if there is just screwed into the pipe is not likely to hold. You can buy fittings although bulky to do this or you can make parts which will suport and trap the plastic if nessesary.

David

[Boiler BriParticipant @boilerbri]

Hi. If you are threading PVC then you will have to have the sharpest tap,that you have. You will have to lubricate the tap more than normal as any heat build up will make the PVC stick to the tap and make the thread very poor.

Hope this helps.

Brian

[JasonBModerator @jasonb]

I've not found a problem uising my usual BSP taps to thread the wall of class C PVC Pressure pipe, the 4" stuff has a wall of about 5mm which sounds like what the OP is using. No sign of heat build up hand tapping.

I have only used it at low 0.2-0.3 bar if you are execting highter pressures then best to use an unequal tee and a female threaded insert in the small branch of the tee so you get more turns of thread engagement.

[Speedy Builder5Participant @speedybuilder5]

If you need to thicken the pipe where you need the tapped holes, cut off a couple of inches of spare pipe. Cut a 2" segment from this offset and cement it to the pipe with solvent cement where you need the tapped holes and allow to dry for 24 hours. Then drill and tap your holes.
BobH

[Author]

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