Otherwise known as the "threaded fitting and pipe joint" thread.
Right then, this shouldn't take too long since we're only covering 5 types of joint and 2 or 3 different threads.
Most of the stuff I do involves more than that in any one circuit never mind in the complete machine, if you saw the sheer number of pipe end fittings and adaptors I have to stock to cover the majority of the world’s different fluid handling systems you'd break out in a cold sweat. To me this is the easy stuff.
Firstly; if you're the proud owner of a nice new roll of PTFE tape then do yourself a favour and find a bin to keep it in. Damn PTFE tape has NO PLACE on a car, certainly no place in a nitrous system and these days its usefulness is limited to pipe threads over about 3" I'm not against the "old ways" but PTFE tape has long since been replaced by modern chemical alternatives that work ten times better, for longer and can't end up contaminating a system.
Don't be too broken hearted about throwing it away, you can buy it for about 50 pence a roll in any trade plumbing outlet, they usually sell it by the stack of ten but will usually also sell it singly.
There is a certain UK based nitrous system retailer who sells it for £5 a roll, I'm feeling charitable today so I won't name and shame him but if he's making a 1000% profit on tape, he isn't exactly giving his systems away is he ? I don't see his prices reflecting the difference in exchange rates either come to think of it.
I'm going to use the terms "male" and "female" a fair bit in this thread so we'd better make it pretty clear which is which, there's no mystery to it and if I simply say a MALE thread or taper fits INSIDE a FEMALE thread or taper I’m sure you've just drawn yourself a far more graphic picture than I could manage with words. Obvious really isn't it, but you'd be surprised how long some people struggle with telling which is which.
WARNING:Leaking Nitrous can cause pretty bad "cold" burns, once you've had one you won't find the name quite so funny. If you get one then treat it as you would a normal "hot" burn.
Things that have been in contact with leaking nitrous can also cause "cold" burns, and your first reaction is to pull away which will leave a nice patch of skin left stuck to whatever it was you touched and you'll have a good reminder about cold burns for at least a week, leave it to warm up before touching it !
Finding nitrous leaksWhile big leaks are easy to find its the little buggers that'll empty your bottle when you're not looking and the best tool in your arsenal is;
An artists paintbrush
and
A cup of soapy water !
Just dip the brush in the soapy water and brush anywhere there's a joint.
*Bottle to valve.
*Valve handle.
*Valve safety disk / pressure relief valve.
*Bottle outlet adaptor.
*Outlet to pipe adaptor.
*Pipe to solenoid adaptor.
*Solenoid filter holder.
And any guages / T pieces also in the system obviously.
Tapered pipe fittingsThis is a horrible bloody fitting, but I’m afraid we're pretty much stuck with it while industry still uses it, thankfully we don't have many of them to deal with.
A tapered pipe thread fitting comprises of a normal straight parallel female thread and a slightly tapered male thread that starts off smaller than the female and gets bigger the further in you screw it, it’s also called an interference thread because the basic idea is that it jams up as you screw it tight and this provides the seal.
It’s the most common and worst place to use that horrible PTFE tape I hate so much. The place you want the best seal is where this thread is the loosest and where any stray tape can get into the system, great idea !
Quite often especially when mixing UK and USA components you'll be threading slightly different fittings together (UK BSPT and USA NPT), normally I’d say this was a bad idea but since we're talking about an interference thread and the difference is barely 1/2 of a thread over the engaged thread length we're using then it isn't a problem. It would be a different story if we were using parallel threads but we aren't so it isn't.
Fitting tapered fittings;First screw them in by hand without sealant and tighten them up with a spanner, you don't need your favourite 12" long monkey wrench for this job, if it tightens up by more than one and a half full turns without a lot of force I’d be surprised.
Now remove it and have a look at the threads, tightening them up will have cleaned any burrs off them and will have left very slight damage on the smallest thread of the male. This means it was all the way in and wasn't a totally different thread or previously damaged beyond belief.
Blow any metal out of the joint, and spray the male and female threads with Loctite 7063 "electrical contact cleaner" to get any oil or grease off, allow to dry and then add a couple of drops of Loctite 243 "Lock and seal" or Loctite 542 "hydraulic sealant" to the male thread, it doesn't need to be swimming in the stuff it only has to fill the gap between two threads.
Assemble the fitting and use the same sort of force as you used before, no need for your favourite monkey impressions here.
Wait about 2 hours for the sealant to cure before pressurising the system.
(Cure times can be accelerated by using Loctite 7240 and if temps are below 5 degrees C it should be used anyway)
If after pressurising the system it leaks then you can either take it apart, clean it all off and try again or depressurise the system and use Loctite 290 "wicking grade sealant" wait 3 hours and try again
(Loctite 290 is also great for fixing porous castings, but don't use 7240 to accelerate it, it needs time)
Parallel pipe fittingsThese are straight threads that screw together with a washer to provide the seal, much nicer than bloody tapered threads.
The seal washer may be copper, aluminium or plastic and they shouldn't be re-used. They seal by crushing and taking out any differences between the two mating surfaces, asking them to crush twice means having to do them up twice as tight as the first time.
I live in the same real world as you so give the copper and aluminium washers a chance by cleaning the washers and seal surfaces with electrical contact cleaner and using a drop of Loctite 243 (thread lock and seal) before doing them up again, don't go mad with the spanners, if it turns more than half of one flat after finger tight then your being a bit heavy handed, I know they were tight before but that was partly the seal, not how they were done up.
Plastic washers can usually be re-used a couple of times, not a great or ideal example but can be done, if the joint "feels funny" as you do it up then the plastic washer has probably just split and will never seal, if you need the big monkey wrench to stop it leaking then its life as a seal is over.
Compression fittings. AKA "Wizards of NOS plastic pipe jointsA mystery to some, loathsome to others and lovely things to the rest of us for loads of reasons.
A compression joint comprises of the female, an olive and a male tube nut.
To make a new joint;
Cut the pipe as square as possible using a brand new craft knife or Samurai sword and cut it against a lump of wood (a cutter is available but isn't all that good, snips and pliers etc certainly won't work so get a good knife, when cutting it you'll suddenly cut through it after putting what seems like a ton of pressure on the knife, if you don't cut against something like a block of wood then be prepared for a trip to casualty about now)
Slip the pipe nut onto the pipe and now put an olive on the pipe, they can be fiddly, tight little sods, don't force it and as long as your cut was clean it will go on once you get it lined up properly.
Slide the olive at least 4mm up the pipe.
Put the pipe inside the female and make sure the pipe finds its way into the little recess, Hold it tight and slide the pipe nut into the female half, add a tiny drop of grease, just enough to help lubricate the thread, if you fill the first thread that’s almost too much. DO NOT USE SEALANT !
Push the tube nut in and turn it clockwise until it engages with the thread.
Tighten it by hand or with very light spanner pressure until you feel it stop.
Mark the female and pipe nut with a black marker across two of the flats.
For 4mm pipe tighten the 8mm pipe nut between 4 and 4.5 flats
For 5mm pipe tighten the 10mm pipe nut between 5.5 and 6 flats
About now it will have gone from "feeling stiff" to "quite hard to turn actually" in the space of the last half a turn.
This is tight. To check just undo the nut, tap the pipe with a spanner while pulling on it until it comes out.
The olive should be tightly gripping the pipe but not crushing it and the pipe should protrude from the olive by 2 or 3 mm.
Olives are cheap so have a go yourself, at least crush the pipe a few times so you really know how tight is right.
If you’re going to get a pipe coming out then it'll be the 4mm high pressure because it has less surface area for the olive to grip and is more susceptible to being under tightened. Tighten it right and it won't come undone, I've got one and its held system pressure for a year, only being depressurised when I refill the bottle, same olives.
To refit the pipe then just poke it back into the hole and carefully do the tube nut up finger tight, you have to be careful the pipe finds its little recess before getting the spanner on the job so you don't force the olive off the pipe. Once its finger tight then use the spanner to tighten it. 4mm by 1 flat and 5mm by about 1/2 a flat, you'll feel them suddenly go tight at this point so stop. These things seal incredibly well and don't need to be "grunt" tight
When used between the same two halves of a joint they can be done up and undone hundreds of times and cost buttons to replace if they do wear out.
Thread and cone fittingsThis is the type used on braided pipe.
Make sure the male and female cone are clean with no dirt on them.
DO NOT USE sealant, the taper forms the seal and locks the joint, using sealant on the thread just makes life difficult whilst achieving nothing.
Screw the female half onto the male finger tight, hold the middle hex on the pipe with a spanner and use a spanner to tighten the nut, as soon as it feels tight it is, more of these pipe fittings are ruined by over tightening than by any other cause, depending on size and material it will turn between almost nothing and a full turn, but in both cases as soon as it feels tight with a spanner, stop.
If you don't hold the middle hex on the female then the seal will turn as you do it up, this scores and forms a ridge on the seal which will stop it sealing properly, it might seal this time but next time you'll really have to graunch on the spanner to get it to seal.
Once the seal surface is damaged you have 3 options;
A drop of Loctite 243 or 542 on the seal surface ONLY.
A conical seal if you can get them (good luck)
A new hose end or adaptor fitting.
If while leak testing braided hose you find the leak is actually coming from the joint between hose and hose end then hold the middle hex and try tightening the hose nut a little. It'll probably make the leak worse but since it was leaking anyway you had nothing to lose.
(See "How to: make or repair braided pipes" here;
http://www.noswizard.com/bboard/viewtopic.php?t=26 )
WARNING:Fuel leaks, do I really need to say any more ?
Leaking fuel will either drip or be sprayed at high pressure, either way I hope you catch it before the inevitable fire takes hold.
Most fuel fittings will have been covered above, except for;
Barbed fittings into rubber pipeCut the pipe where you want the adaptor to go, fit a hose clip the right size onto the pipe and slide it along the pipe out of the way, check the adaptor is the right size, it should be a snug or tight fit into the pipe, if it isn't then don't chance it, get one that is.
Wet the inside of the pipe with fuel and push the barbed fitting into the pipe, hopefully this will be quite hard work and will need a fair bit of force to get the fitting all the way into the pipe, repeat for the other end and rotate the adaptor until it sits where you want it.
Now slide the pipe clip along the pipe and sit it roughly in the middle of the adaptor, not right at either end.
Using a screwdriver do the clip up until the adaptor can't be rotated in the pipe then one more turn, you don't need to go mad, if you strip the clip thread or mash up the slot then you were doing it up too tight.
If the rubber bulges or looks like its splitting then get a new pipe, this one is either the wrong size or too old.
DO NOT try to use rubber pipe and clips to adapt to a plastic fuel pipe, firstly without barbs or a bulge it won't hold, secondly most hard plastic fuel lines contain fuel at about 60psi, not the more usual 40psi.
Contact Wizards for an appropriate adaptor, they make adaptors for any fuel system on the market and they'll have one for you.
After adapting a fuel system pressurise it and leave it for an hour or so before checking every joint for leaking fuel, then leave it another hour and check again. After running the engine check it again but be aware that the warmth may evaporate any leaking fuel before you see it.
After a day or so check it again, both hot and cold.
If you think I’m being paranoid go to a scrapyard and take a look at a burned out car, it isn't pretty. Fuel goes up fast and burns hot, it can make one hell of a mess in the time it takes you to reach for an extinguisher and pull the pin so don't take chances.
Here endeth the lesson on pipe fittings.
I'm certainly not above criticism, so if you have anything to add, something to say or a question to ask then look for the button below that says "post reply"
Bloody hairdressers ! :roll: 
