Suggestions on how I should correctly seal this value

[OffshoreGas]

You'll find most pipe fitting thread forms come in both parallel and tapered variants.

With a tapered thread form it is the thread itself which forms the seal as the male and female sections tighten together. To prevent spiral leaks a small amount of thread tape is used to fill the small gaps.

On the other hand parallel thread forms are designed to seal either with a the addition of a washer or some form of sealing compound which cures anaerobically.

As far as I'm aware domestic plumbing fitting used in the UK are BSP parallel so you're always going to have problems sealing with PTFE etc.

You may get away with it on very low pressure applications such as radiators but even then weeps and seeps are quite common with time.

 

[Best]

As far as I'm aware domestic plumbing fitting used in the UK are BSP parallel so you're always going to have problems sealing with PTFE etc.

You may get away with it on very low pressure applications such as radiators but even then weeps and seeps are quite common with time.

Usually only weep through time if joints were done wrong though, - often due to not enough ptfe tape.

 

[OffshoreGas]

Parallel threads aren't designed to seal with tread tape. You need a gasket of anaerobic thread sealant of some sort. If you ever have the misfortune to do a pipe fitting course they will bore you to death with this. Have a look at the literature on pipe or tube fittings, chucking a ton of PTFE tape on is not the correct way to seal a parallel thread.

Parallel Threads vs Tapered Threads | Swagelok

 

[Best]

Parallel threads aren't designed to seal with tread tape. You need a gasket of anaerobic thread sealant of some sort. If you ever have the misfortune to do a pipe fitting course they will bore you to death with this. Have a look at the literature on pipe or tube fittings, chucking a ton of PTFE tape on is not the correct way to seal a parallel thread.

Parallel Threads vs Tapered Threads | Swagelok

On parallel threads we can still easily seal them with ptfe tape.
I see no reason to use anything else on rad tails or most other male threads.
Rads, oil boilers, copper and stainless steel cylinders, some shower valves, all are parallel threads and normally perfect seal.

 

[OffshoreGas]

On parallel threads we can still easily seal them with ptfe tape.
I see no reason to use anything else on rad tails or most other male threads.
Rads, oil boilers, copper and stainless steel cylinders, some shower valves, all are parallel threads and normally perfect seal.

Agreed, as I said you may get away with it, may leak when you fit it, it may leak in 6 months time. Why not use the right product/method from the get go?

 

[Best]

Agreed, as I said you may get away with it, may leak when you fit it, it may leak in 6 months time. Why not use the right product/method from the get go?

On most parallel threads (rad valve tails for example) I wouldn’t personally use anything other than ptfe tape and some paste. Been using that method since the 70s and never leaks if tail feels tight to turn. And I mean no weeps even after decades.
I was one of the first plumbers to embrace ptfe tape as an alternative to Hemp due to a friend of mine who worked in chemical development industry highly recommending it.

On fittings or valves with only 2 or 3 threads however, I would be concerned to use tape unless there is a shoulder joins to seal the metal to metal against.

So what is the proper seal for parallel threads (in the threads)?
Cord seal?

 

[OffshoreGas]

[QUOTE="Best, post: 1041804, member: 2832]
So what is the proper seal for parallel threads (in the threads)?
Cord seal?[/QUOTE]

PTFE is great stuff, its only really meant for tapered threads though.

Like you say you'll often get away with it on heating systems but that's largely down to them running at such low pressures.

As others have suggested Loctite 577 is a good product but I don't think its "food safe" so shouldn't be used with potable water systems.

I think Loctite 565 and 567 are suitable for use with potable water systems but you'd have to check.

Using the right stuff is only marginally more expensive and ensures no call backs.

 

[Best]

[QUOTE="Best, post: 1041804, member: 2832]
So what is the proper seal for parallel threads (in the threads)?
Cord seal?

PTFE is great stuff, its only really meant for tapered threads though.

Like you say you'll often get away with it on heating systems but that's largely down to them running at such low pressures.

As others have suggested Loctite 577 is a good product but I don't think its "food safe" so shouldn't be used with potable water systems.

I think Loctite 565 and 567 are suitable for use with potable water systems but you'd have to check.

Using the right stuff is only marginally more expensive and ensures no call backs.[/QUOTE]

The cord seal I have never used, although I do have some of it.
I suppose it is having the confidence in it, plus I would be quicker with using ptfe tape.
I also use tape on oil fittings, including 1” connections to oil tanks.
Amazing stuff ptfe (in any form, - tape, liquid or hard type ptfe). I remember researching that it was invented around WW2 period.
I hate hemp (flax as I call it) due to the joints setting solid, and it being more difficult to put on threads properly

 

[oz-plumber]

Of all the products available for sealing threads, I still use PTFE tape on just about all threaded joints.
It all about knowing how much to uses.

As the OP stated, used 10 turns and the fitting screwed all the way up.

Anyone who has been doing plumbing for anytime would realize straight away that there is a problem.
I would go as far as saying, I wouldn't have got as far as testing the joint if the finished product looked like that in the photo.