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Hallite washers

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Deric11/07/2020 15:43:49
42 forum posts
27 photos

Hello, all

I have been building Super Simplex fir a long time now and have finally got to the superheater, which is now almost finished. In order to seal the regulator output to the superheater the drawing calls for two 1/32” Hallite washers 3/4” od x 1/2” id. These washers sandwich an Oring and are fitted in the output boss on the boiler and the superheater boss when fitted and tightened compress the oring ti form the seal.

I have asked the usual suppliers if they can supply these Hallite washers and it seems no one does and doesn’t know what they are!

can anyone help me with where I can get these? and if you have built Super Simplex what did you use?




pgk pgk11/07/2020 16:02:08
1849 forum posts
288 photos

It looks like Hallite is a UK Co with website, contact phone numbers and on-line expert chat...and google throws up stockists..

Andrew Tinsley11/07/2020 16:03:23
1150 forum posts

The last time i used hallite washers was many years ago. I got them from BSS (British Steam Specialites). It is worth a try if they are still trading.


HOWARDT11/07/2020 16:58:14
569 forum posts
15 photos

Like wise have used Hallite seals in the dim and distance past, but don’t remember Hallite washers. Having done a web search seams there is Halite washers, note one l. These appear to be from gasket material referenced a few times on my search as used on Lambretta joint faces. So perhaps not a flexible seal material as such.

Robert Atkinson 211/07/2020 17:05:38
701 forum posts
16 photos

Hallite washers are fibre wahers with a wire mesh reinforcement.

Robert G8RPI.

JohnF11/07/2020 19:45:47
999 forum posts
142 photos

Hallite seems to have disappeared, I needed [wanted] some a short while back but ended up using an alternative from Ebay -- enter Hallite Gasket Material and search you should find something suitable to make your washers from - easy enough to make a couple of one use punches from the scrap box.

My recollection of Hallite is it was a paper based material with graphite impregnated and some form of reinforcement but I don't remember it as wire ? Stand to be corrected of course.


Brian Sweeting11/07/2020 20:06:33
426 forum posts
1 photos

Are these bonded seals of any use?

Bonded seals

Brian Morehen11/07/2020 20:22:48
94 forum posts
11 photos

Used to be able to buy this in a rolled up sheet which was about 1/32 thick have used this in the past for seals on steam boilers may have some ofcuts still as left overs will have to look what i have if any interest , years since i bought any..

Regards Brian

not done it yet11/07/2020 23:57:29
4743 forum posts
16 photos
Posted by Brian Sweeting on 11/07/2020 20:06:33:

Are these bonded seals of any use?

Bonded seals

You mean a Dowty washer?

Howard Lewis12/07/2020 02:17:08
3388 forum posts
2 photos

Like NDIY, I wondered if Dowty washers would do the job. Depends on the rubber insert having a high enough temperature capability.

You could make your own washers, by punching out from a sheet of gasket material. Punch the hole first, and then the OD!


David George 112/07/2020 08:06:18
1261 forum posts
438 photos

Hi there is a website for Hallite they list a roll of material.


Michael Gilligan12/07/2020 08:29:37
15883 forum posts
693 photos
Posted by not done it yet on 11/07/2020 23:57:29:
Posted by Brian Sweeting on 11/07/2020 20:06:33:

Are these bonded seals of any use?

Bonded seals


You mean a Dowty washer?


dont know ... I expect Dowty would be pleased to see that  ‘generic’ bonded seals are  not being marketed under their trade name.


Edited By Michael Gilligan on 12/07/2020 08:31:38

J Hancock12/07/2020 08:59:44
420 forum posts

Either the washers or the O-ring make the seal ?

Can't really see why you need both.

Samsaranda12/07/2020 09:05:06
940 forum posts
5 photos

Bonded seals/ Dowty washers are used to seal banjo type fittings on hydraulic systems, a particularly specialised function.
Dave W

Deric12/07/2020 09:57:29
42 forum posts
27 photos

Here is an extract from the drawing showing the superheater seal location.

i have been offered some glass impregnated PTFE to make washers which I think meant to compress and ‘protect’ the oring. Given that Super Simplex was designed in the mid 80’s Hallite washers were probably the most suitable for this application.

do you think the PTFE will do as good a job, given that it’s good for over 300DegC?

John Baguley12/07/2020 10:27:30
463 forum posts
49 photos

There really is no need for the washers but I presume that you have made the parts to the drawings so the gap for the O ring will be too big for the O ring alone. Your PTFE should be fine to make the washers or you could just make a spacer washer out of brass (put on the boiler side of the O ring) to make the gap the right width for the O ring on it's own.

I've used the O ring seal on several locos and it works very well. Much better than the threaded joints beloved by LBSC which are an absolute pain!


Brian Sweeting12/07/2020 15:57:25
426 forum posts
1 photos
Posted by not done it yet on 11/07/2020 23:57:29:
Posted by Brian Sweeting on 11/07/2020 20:06:33:

Are these bonded seals of any use?

Bonded seals

You mean a Dowty washer?

That's the name, for the life of me I couldn't remember it. It was only 40 years ago when I used them on a regular basis.

Deric12/07/2020 18:47:45
42 forum posts
27 photos

Thanks to all of who have chipped in, your comments are much appreciated.

im going to go for the PTFE solution.

Thanks again


not done it yet12/07/2020 19:49:43
4743 forum posts
16 photos
Posted by Brian Sweeting
It was only 40 years ago when I used them on a regular basis.

I know the feeling. Used extensively on hydraulics but the name is often forgotten - when one simply goes to the box of washers!

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