HLT threads for heating element

[T Murph]

I'm building a new HLT from a former CO2 tank that is about 3/16 in thick. I want to cut (tap) threads to screw the element directly into the tank. My issues is finding the tapping tool to make the threads. Iv learned the threads are not typical NPT. I need info to help find the tap tool. Anyone who can help would be greatly appreciated.

 

[Joeywhat]

Do you know the thread size you need?

If not, do you own a pair of digital calipers? If you can accurately measure the threads we can have an educated guess as to the thread size.

At the very least can you list the make/model of the heating element? You might be able to ask the manufacturer what thread they are using for it.

 

[T Murph]

Do you know the thread size you need?

If not, do you own a pair of digital calipers? If you can accurately measure the threads we can have an educated guess as to the thread size.

At the very least can you list the make/model of the heating element? You might be able to ask the manufacturer what thread they are using for it.

I haven't purchased an element yet. I want to be sure to have a matching tap and element ahead of buying the 2 lements. I plan on using two identical elements that have 1 in NPSM thread. But I'm not having any luck finding the proper tap.

 

[Joeywhat]

I believe this will work: 1"-11.5 HSS 5 Flute Bright Finish NPS, Straight Pipe Tap | Fastenal

Here is a chart with thread and drill sizes for taper and straight threads.

Keep in mind that straight threads will require some form of sealant, either o-ring, pipe dope, tape, etc.

 

[T Murph]

I believe this will work: 1"-11.5 HSS 5 Flute Bright Finish NPS, Straight Pipe Tap | Fastenal

Here is a chart with thread and drill sizes for taper and straight threads.
View attachment 723568

Keep in mind that straight threads will require some form of sealant, either o-ring, pipe dope, tape, etc.

Thanks Joeywhat that's the info I was looking for. I plan on using a professional grade sealeant on the threads along with the factory o rings. I using two elements in a 3/16 in thick vessel. Not enough threads to go through to accept a nut on the inside. So it requires drilling and taping to install them.

 

[Bobby_M]

A 1" NPT tap would work just fine. You'd just thread it in all the way so that you get to the largest diameter, which turns such a thin wall into NPS. That will allow the element to thread all the way in.