"Sealing Plug" standards question

[Lannis]

Lots of trained professionals and aero engine specialists here, so thought it would be a good place to ask.

On our motorcycles and other mechanical devices, there are a lot of drain plugs designed to hold back oil, hydraulic fluid, fuel, brake fluid, and similar.

We find that the drain plugs are sealed in MANY different ways when they come from the factory.   Copper seals, aluminum crush seals, Dowty washers, sometimes with a sealing agent, sometimes not.    And whatever was on there from the factory often gets changed by the guy doing the maintenance, either to 'improve' the seal or because it was what was on the shelf in the shop.

Are there any SAE or ISO or aircraft-type standards for specifying what kind of sealing device should be used for different materials, fluids, pressures, and applications?   There seem to be standards for almost everything else - welding, drilling, wiring, electrical terminations .... but what do people who REALLY have to do it right go by?    Like aero engines - is it up to every manufacturer and maintenance guy, or can you look up what SHOULD be used for, say, an oil sump on a Continental engine?

We've all done the "should you use it more than once, should you anneal it, does sealing material help, when do you use Dowty washers, are fiber washers OK, and when not" and all like that.

Just wondering.

Lannis

[RinkRat II]

    The short answer to the spec is YES. Now the fun part. There are approx. 30 different agencys that specify different materials and processes for all things mechanical.
There are no set standards that crosses all the agencies and applies equally on a specific item. They control the spec for their requirement but it may not coincide with another agencies criteria.   AN,ANSI,ASTM,DoD,DOT,ESA,FAA,JAXA,MS,NASA,SAE,NFPA all use independent specs for their application and some may be similar but not necessarily. General Good Engineering  practices apply.

       Paul B

[rschrum]

Glad we cleared that up. I like new copper and safety wire.

[kirby1923]

Aircraft plugs required to be safety wired. On moto engines following the specified (maintence manual) torque spects...no less..and use a torque wrench if not safety wired.

I don't have a moto w/ safety wire but follow torque specified, (and check occasionally w/ torque wrench.)

:-)

[Lannis]

Aircraft plugs required to be safety wired. On moto engines following the specified (maintence manual) torque spects...no less..and use a torque wrench if not safety wired.

I don't have a moto w/ safety wire but follow torque specified, (and check occasionally w/ torque wrench.)

:-)

Proper torque is good for anyone, although is the torque required the same whether it's an annealed copper, unannealed copper, aluminum crush, fiber, or Dowty seal?    Safety wiring is the ultimate, for airplanes and racers, then, but I guess it's up to "Good Engineering Practice" as mentioned above to say what sort of thing is used between the drain bolt and sump .....

Lannis

[kirby1923]

I have used all materials mentioned, mostly stock parts from the manufacturer (cheap by the dozen).
For the last 80K miles I have used a fiber sealing rings (auto parts store) and never had one loosen up.

For all the sealing rings (washer) the same torque applies.

As always the owner maintained machine should keep close watch on critical items!

:-)

[John Warner]

If you really don’t want something to come undone, lock-wire it!
As for what sealing method to use, that all depends on what you’re trying to stop leaking out.
Brake lines = Copper Washers. Can be Re-Annealed a couple of times, then Chuck ‘em.
Pressure Oil lines = Bonded (Dowty) Seals.
Oil fill/drain Plugs = Bonded Seal and Torque, or O-Ring, ‘nipped up’, and lock-wired.
Choose your O-Ring materials for the job in hand.
Oils need Buta-N (Nitrile), or Viton.
[url][https://www.marcorubber.com/o-ring-material-quick-reference.htm/url]

[80CX100]

I've gradually almost completely switched over to Dowty washers on the plugs to prevent leaks, for whatever reason I don't find the plugs on the newer bikes as prone to leaking.

The one problem area plugs that I struggled to seal properly are those little tiny plugs down at the bottom of the fork leg hidden inside on top of the axle assembly going up into the damper cartridge.

I think I may have read the tip here, but no matter if I use a fibre/Dowty/Aluminum crush washer, I add a small drop or two of something like Seal All/Yamabond to the base of the plug when assembling the fork leg, and let it dry well before adding any fork oil.  fwiw ymmv.

Kelly

[John Warner]

Those 'Plugs' (Bolts, usually Socket-Head Allen Bolts) screw into the Damper Assemblies, and hold them in place.
If the underside of the Bolt, and the Counterbore in the Slider (or Axle Fitting on USD Forks) is smooth and Clean, then a Bonded Seal is all you need.
If you're getting a leak when using a Bonded seal, then you have a defect somewhere.
Loctite is a good idea on those, as it's not really possible to Lock-Wire them, but the threads on the Bolt and in the Damper Assembly need to be thoroughly de-greased and dry.

[80CX100]

Those 'Plugs' (Bolts, usually Socket-Head Allen Bolts) screw into the Damper Assemblies, and hold them in place.
If the underside of the Bolt, and the Counterbore in the Slider (or Axle Fitting on USD Forks) is smooth and Clean, then a Bonded Seal is all you need.
If you're getting a leak when using a Bonded seal, then you have a defect somewhere.
Loctite is a good idea on those, as it's not really possible to Lock-Wire them, but the threads on the Bolt and in the Damper Assembly need to be thoroughly de-greased and dry.

Hey Doc, Tks for the reply, I had to google what a Bonded Seal was,lol. Realized it was what I was referring to as a Dowty Washer.

    I didn't try one in that location, I tried soft aluminum crush & then fibre washers (both required a touch of Seal All).

    I've got a collection of Bonded Seals/Dowty Washers now; not sure if I'd have anything that small, but I'll definitely keep your info in mind for the next time 

    Tks

    Kelly