Might try milspec or milstd docs. I'll check and see if I can find some info for you but that's just a quick idea.

Sent from my HTC6545LVW using Tapatalk

 

Used to build these.... I just welded though. No help here on the Engineering side.

 

If you are unsure how to describe the weld, I would suggest you research fillet welds.

Then you can research tig welding and pipe welding and put all the information together.

 

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Thanks a lot guys
Best regards,
André Silva

I see one major flaw in this design. The large holes in each end plate are in the wrong orientation to each other. I presume this is for the cooling medium to circulate around the smaller tubes. One of them should be at the top, and the other at the bottom. Otherwise the cooling water only flows along the top layer of tubes and does not do much for the underlying ones. One of the large holes needs to be on the opposite end/side so the cooling water flows across all of the smaller tubes. One at the top and one at the bottom.

 

You're right but I can't change the desing! This part was given to me just for welding nothing else The only thing I know is that it is made of GB/T3625 titanium and I will need 300 parts! With that I need to make a in-depth report of everything to get the 300 parts corretly done



Thanks everyone for the replys but I still can't find nothing I want on google :/ Maybe because I'm from Portugal and not USA? :O
I saw that there are 2 types of weld in this type of heat exchanger (seal weld and strenght weld). The seal weld is used to seal the the connection so there's no fluid mix and the strength weld is used to give mechanical properties to the joint. In this case I assume that I will only need strength weld, but the main issue is to know the Titanium GB/T 3625 properties so I can find the best fillet metal rod to use in the TIG weld and because both the pipes and the plate have 5mm thick I should use a joint preparation...
My idea is to make a chamfer in the holes of the tube-sheet and then weld it to make sure we have full penetration of the weld, what do you think?
As you can see in this picture above they made a chamfer in each hole!

^


Thank you

 

The farther u stick the tubes out the harder it will be to get to them all. I'd put them flush and weld it out. Clean everything with acetone. What are ur welding skills now? Any pics of ur work?

 

Please don't laugh at this It was my 10th or 11th weld I made First weld I did was a bit fast and I started to reduce the velocity and after a couple of welds I started to find the right pace

 

This piece is only in theory, I won't be doing one like this! It's just to make a plan of welding. The main goal is to describe the complete process to obtain this piece and find the pros and cons This work has nothing pratical to do, just theory...
But saying that the tubes should be flush it's a nice idea and I'll be writing that! Thanks
I've spoke with my teacher and he told me that it's really hard to find datasheets of GB/T 3625 so he will try to find some for me and he also told me to make a chamfer on the tube-sheet, wich makes much more sense Now I need to find the parameters of welding (type of gas, pre and pos flow, current, voltage, prices etc..). Maybe I should e-mail Miller or Lincoln?

I've welded with TIG, MIG-MAG and Stick Welding! I'm pretty good with stick welding and mig-mag, but I only have a couple of hours of training (it's nothing ). I like welding but I don't know how to "start" training because I'm in college and I don't earn money, so I don't want to ask my parents to buy a welder and etc.. :/ I've a stick welder at home that belongs to my dad, but it's so basic that we can't regulate amperage It costed 50€... It says it all... But still I can do nice welds with it

 

How about the tig welds on stainless?

 

Yeah I did TIG weld on stainless with filler metal rod and without. WIthout filler metal rod it was pretty easy but when I used the filler rod it was so hard!!! Surprisingly the first try was great but the next ones I was always contaminating the electrode and I got too nervous I only tried TIG once and for 10 min or so... Unfortunetly I don't have any pitcures because that was on my class!
But what do you think of the stick weld? Not to bad for a 50€ welder, i think

I only have this of my first 2 MIG welds, first time and the 2 first weld of my life with mig welder. I had a better picture but I can't find it now, this one is with poor quality and too far from the weld, sorry

 

Doesn't look like ur ready for much of a project yet by the pics your showing. U will just mess things up sorry but it's true

 

I agree with you! This was my FIRST weld so it means I suck! And I know that... But for the first time is it too bad? My teacher said that I only need 300 more hours, but I kinda have the "gift"...
But I apreciate your sincere opinion I like to hear that, believe me... It means that I have to learn and put some effort because every welder was a "noob" once, but they practiced a lot to be better at welding

Thanks,
André

 

Titatium GB/T 3625 is a material standard for cold drawn seamless tubing to be used in heat exchangers and condensers. this will not tell you the properties of the Titanium that is to be welded. Who ever designed the heat exchanger will need to supply you with a data sheet for the material to be welded. It covers grade TA1 to TA10 in all configurations of high pressure titanium pipe including alloy mixtures. It is similar to our astm B337-B861.

 

Thanks for the tip I've spoken with me teacher and he said the same thing (He could've said it earlier.... -.- )! He will provide me a datasheet because it is hard to find this datasheets. Can you explain me that "grade" thing? How do I chose the best one?

THanks,
André

 

I never welded the tubes, but the guys that did, normally had 1/16" give or take sticking out. 1 or 2 passes. all depends. tube sheets bad a slight bevel in them. Sometimes the tubes would be expanded as well.

 

If I'm understanding this right andre is writing a thesis on how this should be done? He isn't going to be physically welding anything. This is more or less an instructional write up of step by step on the process which would include everything from the properties of the material to type of process (i.e. MIG,TIG,STICK etc..) and gases. I'm glad it's not me. Ever stop to think about what it would take to write up step by step instructions on how to do any of the welding jobs you do and make it so that whoever is reading it could understand it? Wow!

 

That's right 6Boys

I'm not doing anything physically only in theory! I have to explain what is welding and the pros and cons, explain every welding process (TIG, MIG, Stick, Plasma etc..) and choose the best process for this project and explain why it is the best, also make the table (Mounting template? I don't know how to say it in english) and explain how it works... Basically I need to write about every single detail

Actually now my teacher gave me some help and he recognised that to find the info I need is VERY hard so he gave me a push and I won't be using this forum too much, but If I come up with more problems I will post them here. In the end I will post my work here (but in PT)


Thanks, André

 

Andre,

The information you're looking for will depend in part on how the heat exchanger is going to be used. Whether the tube to tubesheet welds are fillets, partial joint penetration(PJP), or full penetration(CJP) depends on the end use. Details like how hot will the heat exchanger get? What are the mechanical properties of the materials invovled(primarily yield strength), how many thermal cycles will the heat exchanger be expected to endure.

CJP welding is the most conservative approach. However, it is also the most expensive and time consuming. Depending on the spacing between tubes and the order of assembly it may be impractical as well.

PJP or fillet welding will offer greater ease of fabrication and there fore lower cost. But the root of each weld will essentially be a crack that could propagate through the weld; resulting in failure. Operating temps, pressures, material thickness, properties, and engineered lifespan will all factor into whether or not cracking could occur and whether or not the failure happens before the engineered end of life.

Very generally speaking, yes GTAW(TIG) would be the process of choice for the general style of heat exchanger shown. BUT, I have seen heat exchangers built from 10"(250mm) diameter piping and 2"(50mm) thick plate. Such a fabrication could, and in fact was, welded using the FCAW process. GTAW would have been the wrong choice for such a large heat exchanger.

So, in closing, either you need more information to thoroughly answer the question you have been asked. Or you need to provide more information to us to help guide you to the answers.

 

Thank you so much Very nice tips!! Yeah I have very little information! The only thing my teacher gave me was the part in Solidworks, told me that the project is for 300 parts and it's made of GB/T 3625, nothing else, only this, so yeah he should have gave me more information.
Ok I will add more info to my work and see the points that I need help and I will be posting them here By the way, where can I find information about how many thermal cycles can it endure? `

Thanks a lot!!

 

Any chance you're reading too much into this assignment? Maybe the exercise is more about estimating, pricing parts and an assembly game plan. If the only requirements are the need for a heat exchanger made from 300 titanium parts, then I'd do everything possible to present an argument that involves no welding at all. Welding titanium brings in too many complications where as tube expanded joints are fast to build, fully certified and far easier to replace when they wear out. Although it may be common on some jobs, the only times I've been involved with welded tube sheets was after they had already been re-tubed a number of times and could no longer be certified by expanding alone.

 

you can check GB/T 151-2014 <HEAT EXCHANGER>, I am from china,we supply heat exchanger to power plant.

 

i cant imagine not rolling the tubes before any weld process. we just built a 3000 tube condenser for kiewit power here local and they opted for stainless over the titanium due to cost but the only change in the rolling/weld process was the weld procedure. to me not rolling the tubes first you set yourself up for failure with cracks/leaks. I'm almost certain that cleaver brooks boilers roll and weld bo matter what material is used. was nice running across this thread. alot of good reading.

Jeremy