Brazing rules

Belgium (F Gas exams) took over the Dutch STEK- rule that the filler material in a brazing must penetrate 100% through the gap.
Belgium didn't think nor analyzed if this in act really needed.
I saw on the website of Tradewinds whom offers a brazing training according to the British Refr. Ass. Standards and they say We then move into the theory on the brazing process and how to make sure you work to BRA Standards and achieve 100% penetration on all joints

Why is this needed?

I'm asking this because on the copper.org website, I read Although 100% penetration and fill of the capillary space fitting is desired, a solder joint fill of 70% fill (or no greater than 30% voids) is considered satisfactory to obtain joints that can withstand the maximum recommended pressures for soldered copper tube and fitting systems.

A major difference between brazed and soldered joints is in the amount of joint overlap or fill necessary to develop full strength of the joint. In a brazed joint, full insertion of the tube to the back of the fitting cup is still highly recommended; however, complete fill of this joint space throughout this entire length is not necessary to achieve full joint strength. According to the American Welding Society (AWS), it is suggested that the brazing filler metal penetrate the capillary space at least three times the thickness of the thinnest component being joined, which is usually the tube. This is known in the industry as the AWS 3-T Rule.


I suppose the Americans have thoroughly tested this before they published it.

Link http://www.copper.org/applications/p...explained.html

Why I'm asking this; if a candidate in the Belgium F-gas makes 3 solderings with < 50% gap filling, although completely gas-tight, full strength on pressure test, he/she fails.

http://www.copper.org/applications/p...ws_3trule3.jpg

Any comments?

I recently did my brazing tests with my 2079 and we had to achieve no less than 90% penetration to pass although when I did my college CITB exams around 5 years ago 100% was the pass rate. I know when I braze large pipe i.e. 4 1/8 I get no where near 60% let alone 90-100% yet it holds a pressure test and lot lot of the time these joints will be on suction lines which are subject to heavy vibration and not had one fail (yet). In answer to your question it is probably due to men in ties making rules to make our jobs more difficult as normal.

If you look to the bends of an evaporator , they're less soldered then the AWS3-T rule and they rarely leak.
I visited ECO Italy last Thursday and >Friday and it was there that I started to think about this.

Soldering , brazing . welding

They are 3 different processes but each operative should aim for 100% every time

Think i had to get 100% fill to pass my f gas j11 thingy.

But i have seen a pipe flared, another pipe butted up to it and brazed an no leaks,

also this,

http://www.youtube.com/watch?v=e7c-d46204o

Thats a 7/8" pipe just butted together and brazed, no swaging or coupling at all, makes you think......

Jon :)

Quote:

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Originally Posted by Quality

Soldering , brazing . welding

They are 3 different processes but each operative should aim for 100% every time

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I'm sure the majority of us aim to achieve 100% in all we do not just brazing etc, but it's the regs that are being questioned when they appear to be over excessive, I would like to see the rule makers braze a 4 1/8 tube to 100% on site with an oxy/accet torch

Quote:

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Originally Posted by monkey spanners

Think i had to get 100% fill to pass my f gas j11 thingy.

But i have seen a pipe flared, another pipe butted up to it and brazed an no leaks,

also this,

http://www.youtube.com/watch?v=e7c-d46204o

Thats a 7/8" pipe just butted together and brazed, no swaging or coupling at all, makes you think......

Jon :)

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I did C&G the test I did was the one in addition to the 2079 but now I think of it the 2079 test might of been 100% but the brazing exam was only 90%:rolleyes:

Quote:

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Originally Posted by Quality

Soldering , brazing . welding

They are 3 different processes but each operative should aim for 100% every time

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Why Quality? Who says this? What prior investigation/testings says that this is really needed?
Every bend in an evaporator is perhaps 10% filled and they never leak. And in a supermarket, we then have 1000 bends all not brazed according to 'the rules'.
Is the American AW3-T rule then so fault? This rule came surely after testings.

Jon,
another example: in Belgium we have center doing tests on copper, Centre du Cuivre in Brussels.
A friend of my is teacher and he visits each year this center with his students. He then has with him a,n expanded 7/8 -7/8 brazed connection and then also 2 pcs 7/8 tubes brazed together just put together to each other and brazed up the gap. No swaging nor expanding.
They put both in a http://www.products4engineers.nl/ind...n_6575_240.JPG
Don't know the English name for this measuring device.
Result? Exactly the same figures and strength, the weld doesn't brake but it brakes besides it.
I don't speak about resistance against vibration but it surely says everything against strength

Tensile test machine, used to break samples to ensure that they meet a minimum required strength. Most brazed joints will suffer failure in the parent metal before the brazed joint fails, mostly from the stress induced into the parent material by the large temperature changes of the brazing process.

Hi Peter,
It's because that is the standard that is set by the British Refrigeration Association. Therefore we have to teach to that level. The BRA along with other Industry bodies are responsible for writing our codes of practice and that is what has been set for the UK.
If we can train people to strive for 100% infill on every joint then we are definitely going to reduce the amount of leaks to atmosphere. Even the fact that it is being talked about in hear is a good thing.

Also, the brazed joints on the evaporator dont come under half the amount of stress, vibration, expansion and contraction as the high side of the system. Capping a joint on the high side is liable to leak whether it be in 1 month or 6 months time.

The point is that we are trying to improve our standards and taking the care to fill a joint properly is just one way that we are helping to do that. I guess the proof is also in the Strength test aswell.

Tradewinds, thanks for your good post, see that in UK the quality is as high as it is here.
You have a point when you speak about the difference between a brazing in the LP and the HP side.

I have yet to see a braze joint fail as in fracture, i've seen them leak due to actual gaps in the braze but not one that had sealed and then failed at a later date. (except on evaps due to water in the joint, freeze-melt-freeze-melt-burst)
And also ones leak due to corrosion between the pipe and filler material, the copper having been eaten away. Also porous braze due to the filler material being overheater during original brazing, think it boils off all the silver or something, anyway, reheat and melt in some new rod to dilute the bad stuff and good to go again!

But no actual metal fatigue style snappings in 25+ years....

I don't believe in standards, they were made for people who don't understand the job.

It's all about knowing the principle of good brazing, choosing the right rod for the job, tuning the torch for the best flame and patient.

Once you know these, 99.9% of your brazing work will never leak.

lennox coils on rooftop baltic units are prone to leaks,theres a 90degree bend on the discharge line with no vibration eliminators-the pipe is cut at 45degree to make a sharp 90degree bend and every time it fractures from excessive vibration when the indoor blower fan starts up!,also the evap coil rings fail on the steel edges and the only way to repair them is to pinch off at the distributor line and the previous end ring but the copper ring is really thin-like baking foil! so although we strive for 100% bomb proof brazing lets hope manufacturers find other ways of cost cutting measures

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Originally Posted by Peter_1

A major difference between brazed and soldered joints is in the amount of joint overlap or fill necessary to develop full strength of the joint.

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The difference between soldering and brazing has nothing to do with overlap??? butted joints are used in all manner of manufacture

The difference between soldering and brazing is the temperature which is created to achieve the end result

@quality..I didn't say that..it was copy/pasted from the copper.org site therefore the Italic letters.
But still my confusion remains: bends on standard evaporators are very little filled and they never leak.
I wonder what is the best practice now: brazing 20% of the gap and not overheating the connection or going for 100% filling and overheating the connection.
I think the AWS guys from the US tested this and wrote down then their specs, based on a real scientific base.

I could see it was a statment from the italic letters.
maybe a terminolgy conflict as some refer to brazing as hard soldering

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Originally Posted by monkey spanners

I have yet to see a braze joint fail as in fracture, i've seen them leak due to actual gaps in the braze but not one that had sealed and then failed at a later date. .

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I also agree: I have a pack with Bitzers, made in France where all the brazings on the HP side are ..5%. The system is now 6 or 7 years old and none ever failed. I also think that once they're soldered and tight , they remain tight. My experience is that brazing very rarely leak but flares does. And if a tube cracks, then never in the brazing but besides it. This gives some arguments to braze them not to long to avoid softening of the copper.

I understand that you can set a 100% filling as a standard but then this must have some scientific background, especially we're talking about some technical, something that can be verified by testings.

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Originally Posted by install monkey

lennox coils on rooftop baltic units are prone to leaks,theres a 90degree bend on the discharge line with no vibration eliminators-the pipe is cut at 45degree to make a sharp 90degree bend and every time it fractures from excessive vibration when the indoor blower fan starts up!,also the evap coil rings fail on the steel edges and the only way to repair them is to pinch off at the distributor line and the previous end ring but the copper ring is really thin-like baking foil! so although we strive for 100% bomb proof brazing lets hope manufacturers find other ways of cost cutting measures

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Have the same experience with Leakox..sorry..Lennnox. But the reason that tubes are leaking on their feeds-through the steel edges is because they're not using the free floating coil design. Most Lennox coils comes from Thermokey.

I doubt they leak on the brazings and they leak to a faulty construction concept like eliminating vibration eliminators,...

Peter,
starting this thread and i came today to a water chiller with no less then 16 leaks on the condenser U brazed connection. Its has 3 circuits and 3 condensers and the problem was only on one of them.
As i wrote before, its only lack of understanding brazing procedure. On the other hand, it keeps my pocket from having holes....

Hi!
First of all, sorry for my lack of knowledge. In Spanish, we use the same verb for welding, soldering and brazing. (soldar)
In spite there are different methods and ways, I can't find which is each, by translating the verbs weld, solder and braze. It's just a matter of language.
Could anyone help me distinguish them?

Thanks in advance,

Regards,

Nando.

Hi Peter, I'm new to this site (which I find pretty cool), a journeyman service tech and union pipefitter and here's my 2 cents. When copper is brazed the brazing rod ( 2% silver up to 65%) molecularity bonds with copper. While solder basically just fills the gap and "sticks" to the copper. When I got certified med gas (medical gas piping) they said filling the cup of the fitting was mandatory due to bacteria that could form in the void. Now in the past due to circumstances beyond I have had to braze (with 15% sil foss) joints that were only 16th of inch fitted and had no problems with separation. I also talked with a rep from Harris once long ago and he told me that their (Harris brand) 15% brazing rod was like 4x stronger than the ACR itself when done properly.

One more thing. The parts houses out here just started selling this product called "HVAC super pro" which is a sort of glue for copper, alum, and brass. It holds up to 800psi after 8 min and says it can stand pressures up to 1200 psi after an hour. I've tested it after 12 min to 500 psi and it worked great. Not quite ready to try on the job yet but it does have potential. Hope this helps

Quote:

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Originally Posted by Fri3Oil System

Hi!
First of all, sorry for my lack of knowledge. In Spanish, we use the same verb for welding, soldering and brazing. (soldar)
In spite there are different methods and ways, I can't find which is each, by translating the verbs weld, solder and braze. It's just a matter of language.
Could anyone help me distinguish them?

Thanks in advance,

Regards,

Nando.

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Welding = With electric currant, using a coated electrode. Up to 5000°C
Brazing = With a flame of an oxy\acetyleneor propane. Up to 1500°C
Soldering = with electric soldering iron or a flame heated one. Up to 250 °C.

Heres a pic of a glycol heat exchanger that let go on a lightweight weld after 4 years . No I didnt do the original weld https://picasaweb.google.com/lh/phot...eat=directlink

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Originally Posted by chemi-cool

Welding = With electric currant, using a coated electrode. Up to 5000°C
Brazing = With a flame of an oxy\acetyleneor propane. Up to 1500°C
Soldering = with electric soldering iron or a flame heated one. Up to 250 °C.

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Cheers chemi-cool, I owe you a BCB (Big Cold Beer).
Perhaps by Oct/Nov I will be in Israel, that could be a nice chance.

Regards,

Nando.