Boiler fittings seating washers

[modeng2000]

It seems normal to use various thicknesses of copper washers to seat boiler fittings at the wanted angle. I have seen white metal washers used here and wondered if they might be aluminium or possibly tin.
My reason for asking is that I have some thin tin sheet that could be used if this metal is suitable.

John

[circlip]

Copper is the preferred material as they can be re-annealed and used again, Alluminium are OK unless you have a water leak when they tend to rot away as a white sludge but your thin tin? Are you sure its pure tin and not tinplate? In any event you should only be using a single washer on each fitting, it's used as a seal, not as a spacer. Regards Ian.

[havoc]

Washers used for the purpose of positioning boiler fittings are mostly copper. They are soft, can stand the temperature etc. To get the thickness you need, you screw in the fitting completely, then determine what angle you need to turn back. Make a washer equal in thickness to (thread pitch * desired angle / 360).

[ron]

I would advise against aluminium, an ST boiler I bought a while back had them, they had disintegrated making it difficult to get the fittings off.
Ron

[modeng2000]

Thanks fellas, I knew there would be sensible advice.
I have been told that to make up the required thickness it was OK to use multiple washers but I can understand that that is really not the thing to do.

I'll follow Havoc's advice.

Trying to gt over this nasty type of gastric flu.

John

[kneedeepinswarf]

The melting point of pure tin is 231.9 C, saturated steam at 100psi is at 164 C: only 68 C below the melting point. At this temperature the strength of the tin would probably be greatly reduced and seals made from it might not withstand the boiler pressure.
Also tin has a UTS of 2 ton/sq.in against copper at 14 to 23 ton/sq.in (depending on hardness), these values would be reduced with increase in temperature.

[denis M]

If it helps I use, and have mentioned it before, Loctite 542 Thread sealant. You do not have to worry about washers etc just a touch of sealer and line the fitting up at the required position.

It will seal and not leak. I have used it for years.

Denis

[chris vine]

Hi Denis,

Is loctite 542 one of the ones which locks but will dismantle easily?

C

[denis M]

Chris,

Absolutely, its brilliant stuff in my view, it is not glue its a sealant so it will come apart with a little resistance. I have had it on the Baldwin for 2 years now 3 without a leak, I have used in on my Romulus over the last 17 years without a leak and I have just stripped it down with no problem.
I also did a boiler test on the Romulus at the weekend and all the blanks were sealed with it and not a leak.

My view is that if its available then use it.

Its not expensive and goes a long way.

I also use the Loctite Flange sealer, orange tackle, supplied by some suppliers in place of gaskets.

Denis

[modeng2000]

Hi Circlip,
I wasn't ignoring your input. It is just this illness that is making me think off line. Yes it is pure tin and as I see from kneedeepinswarf the melting point is far too low anyway. I'll have to find another use for the sheets that I have.

Denis, thanks for mentioning Loktite 542, that sounds the easiest way for me.

John

[ukjimoo]

I also use Loctite 542 and find it very good but beware.... i have found that it attacks and lifts paint.

Jim

[denis M]

Jim,

Yes you have to be careful that it does not get on the paintwork as my son on his Sweet Pea found to his cost but I think the for's out way the against.

Denis