Author Topic: Checking in...  (Read 6744 times)

Offline Ramon Wilson

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Re: Checking in...
« Reply #30 on: June 27, 2018, 10:12:46 AM »
Have to make a comment here Jo - by fluxing the whole area of the end plate (with a nice wet paste of flux) then should the temp reach that that the previous solder melts then that flux is there to cope with the situation.  If you get to that situation without flux there you 'could' make things worse in the other areas. It's always better to have flux there rather than to try to get it on as the situation deteriorates .

Worth repeating - cleanliness - flux - heat - in that order ;)

Regards - Tug
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Offline gary.a.ayres

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Re: Checking in...
« Reply #31 on: June 27, 2018, 12:32:04 PM »
Hi Jo -

very clear advice. Thanks.

I used insulation around the boiler (ceramic fibre blanket) when I was making it and did note how much more efficient it made the process. Will indeed use it or some firebricks for the repair.

As for the burrs, I'd be a liar if I said I had noticed them (too worried about other aspects  :ShakeHead:), but now you point them out, there they are as clear as can be! It will be my great pleasure to take a needle file to them once the leak is fixed...

Cheers,

gary

Offline gary.a.ayres

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Re: Checking in...
« Reply #32 on: June 27, 2018, 12:37:30 PM »
Ramon -

You and Jo both clearly know your stuff very well.

As a compromise, I'm wondering if I might flux round all the joints separately so that the flux doesn't connect the offending tube end to other joints? That way - I guess - each joint would be protected by flux but the one I'm trying to build up would have more chance of not losing its silver solder to other joints/areas of the cap.

Does that make sense...?

Thanks all for your input on this. Am blown away by how helpful you are...

gary

Offline Stuart

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Re: Checking in...
« Reply #33 on: June 27, 2018, 12:39:46 PM »
Hi -

from a somewhat non-technical perspective: I think the lead in the soft solder makes it impossible for hard solder to stick to anything it has touched. Perhaps someone more knowledgeable than me will explain the metallurgy of this...

I'm using silver solder and easi-flow flux, and my aim is to stick with this if I can rather than use soft solder for the repair..

Yes it’s the lead it poisons the joint area ,in this situation you cannot remove all traces , if the boiler construction is sound ie all calca have been done for stress and yield for the copper it’s a valid repair.

With ref to silver solder this cad free stuf is not as easy to use IMHO. Another tip is if by chance you need to silver solder a bit of aluminium bronze is to mix in a teaspoon of table salt into your flux mix ( note I only use T5 ) others hate it it’s a bit hard to clean up .

As jo has pointed out that tube has quite a lot of damage and thinning , did you use a a three roller expander with a tapered expander rolled in
My aim is for a accurate part with a good finish

Offline Jasonb

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Re: Checking in...
« Reply #34 on: June 27, 2018, 02:43:07 PM »
Ramon -


As a compromise, I'm wondering if I might flux round all the joints separately so that the flux doesn't connect the offending tube end to other joints? That way - I guess - each joint would be protected by flux but the one I'm trying to build up would have more chance of not losing its silver solder to other joints/areas of the cap.

Does that make sense...?

can't see much point in trying to separately flux each existing joint, once you start heating the flux will flow over most of the tubeplate so may as well flux up the lot from the start.

Offline gary.a.ayres

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Re: Checking in...
« Reply #35 on: June 27, 2018, 03:01:08 PM »
@ Stuart - re the thinning of the tube: yes, it worries me a bit that the inside of the end of the tube is a bit stressed due to my (possibly ill-advised) attempts to swage it. I was wondering if it might be an idea to 'tin' the inside of the tube end with silver solder to reinforce it. Would be interested in what you and/or others think about this idea.

The expanders I used have handles like pliers that open out graduated cones. Will post a picture tonight or tomorrow.

@ Jason - Not long after my post on that point that you quote above it occurred to me that the top of the boiler is so small that the flux would just run together, as you say.

Cheers,

gary

Offline Ramon Wilson

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Re: Checking in...
« Reply #36 on: June 27, 2018, 08:52:18 PM »
Hi Gary - you've answered your own question just as Jason has commented on.

Not being able to see just how much you have affected the tube by expanding it it's difficult to say but personally, if the leak is on the join where tube meets the end plate I would just simply heat the end of the boiler as previously suggested until the solder flows around the join again. Trying to get sufficient heat inside such a small tube is not going to be easy and could quickly lead to further difficulties, Of course if it is that thin that it is leaking on the inside as well I would be looking at taking the tube right out and replacing it completely if that is possible,

Regards - Tug

"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline gary.a.ayres

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Re: Checking in...
« Reply #37 on: June 27, 2018, 11:13:31 PM »
@ Tug -

Yes, I realised after I posted the question that it would be a game and a half trying to keep the different bits of flux separate, and Jason confirmed this.

The end of the offending tube is somewhat stressed but I think it's intact and - I believe - not leaking inside. As before, I thought this through after I posted and came to the conclusion which you have just confirmed, i.e. just go ahead and solder where the outside of the tube meets the cap (in the first instance at least).
Having to take the tube be right out would be a bleak and depressing scenario (and strangely I have been through that in my head today too) but heck I would do it if I had to because I am determined to get this boiler working. It has taken far too much of my energy, time and money for me to even consider giving up on!

Thank you Sir.

@ Stuart -

Two pictures of the pipe expanding tool that I used are below. I used it to slightly flare both ends of the four outer tubes really just to hold them in place for silver soldering (and - to my mind - make a better join). I got this idea from a build log I saw for a 6 inch boiler where the guy used soft solder. I have been advised elsewhere that in my application this was not great practice though I *seem* (touch wood) to have got away with it in seven out of the eight joins. I also used them post-soldering on the problem tube when the leak became apparent during initial air testing at 15 psi. At that point I thought that had fixed it mechanically. If only!

I hope this thread may be useful to other people as it contains a great deal of valuable info from you guys of a kind which was previously quite hard for me to find as I was researching the topic a couple of months ago.

Pictures of tool:





gary

Offline gary.a.ayres

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Re: Checking in...
« Reply #38 on: June 29, 2018, 01:52:15 AM »
Hi All -

Burning the midnight oil here and - having acted on the advice of quite a few of you (Ramon deserving a special mention) there is now a large and not very pretty fillet of silver solder round the end of the offending tube. On repeated hydraulic testing the entire boiler remained bone dry, so your input on silver soldering the repair seems to have paid off.

You guys are amazing!  :LittleAngel:

However... I was mystified because the pressure gauge kept dropping despite my having looked and looked and found no leaks or bad connections. I believe I traced it to the clack, as when I lifted the entire assembly up, water was slowly dripping out of the end of the pipe that takes the water from the tank. I tried sealing the end of the tube with my finger  while keeping an eye on the gauge (it was late...) but that was inconclusive. In order to be sure that this wasn't just residual water from the pipe draining by gravity, I turned the whole lot upside down and the water was still dripping from the pipe, apparently under pressure. Now, I guess that clacks work by gravity to some degree, but assume that between 50 and 90 psi they should in theory close even if upside down. Am I right in this? If so, I conclude that the clack was leaking a little, causing the drop in pressure. Furthermore, the second clack that you can see in the picture also dripped, so I replaced it with a blanking plug a few days ago.

The picture of my testing setup is reposted below as that might make what I'm saying clearer.

Is it normal for clacks to leak a bit? And if so are they more likely to leak on steam than on water? And can they be fixed?

Meanwhile, as the boiler itself now seems ok, I'm thinking that it's time to move on to its first steam test - unless your responses convince me that I shouldn't!



Thanks for all your help.

gary

Offline crueby

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Re: Checking in...
« Reply #39 on: June 29, 2018, 02:01:26 AM »
Excellent news on the boiler leak!   :whoohoo:


Having a small leak on the ball valve back at the pump seems to be a common problem, getting the seat for the ball perfect is tough. Did you try seating the ball with a rod and hammer, and also put in a fresh ball afterwards? A seperate shutoff valve can be used too.

Offline gary.a.ayres

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Re: Checking in...
« Reply #40 on: June 29, 2018, 02:11:23 AM »
Cheers, crueby.

Such a relief to learn that clack leaks are common (i.e. I wasn't missing something nasty!).

I did not take the steps you mention, rookie that I am, but will certainly do so   :)

Many thanks.

Offline Kim

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Re: Checking in...
« Reply #41 on: June 29, 2018, 04:55:28 AM »
Hi Gary,
I've been through this issue recently with the boiler on my steam tractor.  You can read about my dealings and everyone's advice and comments, starting about here in my thread http://www.modelenginemaker.com/index.php/topic,5264.1005.html around post 1015.  There's a bunch of good advice there about making a good ball check valve.

I was able to improve mine, but in the end, I used a shutoff valve for my hydro testing to get past the issue. 

I figure that losing a pound of pressure every few minutes through the ball valves won't be that noticeable under working conditions.  But with the shut-off, I was able to verify the integrity of the boiler, which was the goal.

Best of luck,
Kim

Offline NickG

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Checking in...
« Reply #42 on: June 29, 2018, 06:24:29 AM »
Hi, as the others said it seems to be quite normal. I made blanking caps for the clacks on mine with an ‘o’ ring in the bottom. The boiler inspector still wanted to see them go up to the pressure to ensure their integrity. Think I may attempt to seat better them with a light tap.

On a boiler your size it won’t take much water to drop the pressure as so it’s probably nowhere near as bad as it seems.

My whistle valve was the worst culprit - it couldn’t be removed from the manifold or blanked off - it’s valve was persuaded with a hammer!!

Oh yes, forgot to add as the others pointed out a shut off valve between pump and boiler is usual on a test rig.

Boiler looks good, looking forward to seeing it in steam.


Sent from my iPhone using Tapatalk
« Last Edit: June 29, 2018, 06:27:40 AM by NickG »

Offline Stuart

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Re: Checking in...
« Reply #43 on: June 29, 2018, 07:18:59 AM »
A CAUTION TO ALL IN TESTING BOILERS

Do not do it outside in full sun at this time of year , if you pump it up to test pressure , great it does not leak , I will go and have a cuppa come back to check the pressure gauge .

You may find the boiler now is over stressed due to the heat of the sun expanding the watta in a sealed vessel

LBSC used to recomend to warm the boiler with a sprite lamp instead of a pump

Take care and have happy steam ups
My aim is for a accurate part with a good finish

Offline Ramon Wilson

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Re: Checking in...
« Reply #44 on: June 29, 2018, 07:24:21 AM »
Congratulations on a successful recovery Gary :ThumbsUp:

Yep, concur with clacks having a propensity to leak  ::) but am always wary of the 'tap with a hammer' approach. That's not to say it doesn't work but a long missed local model engineer of exceptional talent was always adamant that the best way to seal a ball was to drop the ball on the seat then screw in a mandrel to gently force the ball on its location with a twist. A bit of extra work with making the mandrel but worth it.

I have also had good success using an O ring as a seat. Indeed the clacks on the WaW boiler were treated as such. The 'seat' is recessed such to allow an O ring to sit flat and just be held by outer pressure alone. The ball just sits on the O ring. Seal is almost instantaneous once pressure comes on. Had these on my old Twin Victoria plant which ran on steam for years - never had one lift off it's seat. Nitrile ball is another route but these are limited in range O rings providing a far greater choice.

Though I have limited knowledge of operating boilers to today's standards I believe any initial test hydraulic test at 2 x WP should be done with blanks on all outlets. Subsequent test with all fittings is usually at 1.5 x WP - I think.

Another thing to note on a hydraulic test where everything is perfectly sealed is that the pressure will tend to slowly creep back a tad as things settle under pressure - not much though.

BTW one of the best indicators I have found for highlighting any tiny leak's whereabouts is the blue hand roll paper wipe. If the vessel is laid on some of this beforehand any leak is immediately obvious.

Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

 

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