How to deposit Titanum on Carbon Steel 1

[bmoorthy]

Is it possible to Overlay tuitanium on Carbon Steel?

What should be the choice of process and what should be the consumable?

can is simply take titanium wire and use it as a filler metal in GTAW process and keep building 6 mm, so that i get at least 2 mm undiluted titanium R 50400.

 

[metengr]

Is it possible to Overlay tuitanium on Carbon Steel?

No, not directly by arc welding.

 

[kenvlach]

The reason being that brittle intermetallics Fe₂Ti and FeTi form. Substantial cracking would probably occur whilst cooling.

Take a look at
Joining titanium plates to carbon by mean of friction
thread725-155305

 

[bmoorthy]

If i give a buffer weld deposit of say high nickel or high Ni alloy will it work

or if i first spray say Silver and then if i apply Titanium by GTAW, is it OK

 

[metengr]

Try explosive bonding.

 

[unclesyd]

bmoorthy,
I would like to have all the money I've seen spent on trying to bond/weld Ti to ferrous alloys.

What size piece do you need?

Can you come back with a few more details?

 

[bmoorthy]

Full Background:

Actually it is a clad Tube sheet for AES type ASME Sec VIII Div 1 exchanger ("U stamped" 2004 Ed and TEMA Class R).

Local repair is required to be made on the tube sheet face due to Disbonding detected when UT was done as per A 578.

The base Material Is A 516 Gr 60 Plate and the Clad metal is Ti R 50400 (Ti gr 2). The area that needs repair (Central disbonded Area) is about 150 mm x 150mm.

The Tube sheet is about 750mm Dia and the thickness of the base carbon steel is 150 mm.

The Ti after machining (In the gasket face, where lowest thickness is expected is 3mm pure Ti). But on the tube face the Ti thickness is over 6mm due to various steps for gasket machnining.

Shell side carbon steel and tube shide is Titanium.

Pressure is 35 bars (Both shell side and tube side).

Tubes are titanium and diamenter is 25 mm thicness 2mm.

Service Sour service (As defined in NACE MR 0175/ISO 15156-2003)

Further the Explosion bonding is done to ASTM B 898.

As per ASTM B 898 welding is permitted and the ASTM refers to procedure as per ASME Sec IX.



I am also stuck with the UNF clause that says Ti shall not be welded to any other material.

The question now is whether the Overlay on the tube sheet is Non pressure part?

(Also noting that tube to tube sheet joint is strength welded all supporting WPS and PQR between Ti and Ti available).

If i consider that tube sheet as non pressure part and go ahead with repair, then should i conclude that thetube to tube sheet joint is non pressure part welding?

Also i want to know what process is should go ahead with and what are the tests that i should undertake in PQR.

Yes i could check with my AI, but i am doing my home work. Although i have arrived at my test program, i am not sure whether i am doing the right thing, especiall when the material in question is Ti.

We have 4 more exchangers to go and this is the first one.

 

[deanc]

http://www.dynamicmaterials.com/Home

Many years ago I had a UDT buddy who always said..."There is no problem that cannot be solved with a suitable application of explosives"

 

[deanc]

I do not think you can rebond or weld repair your cladding,so....

Is the 516 part of the tubesheet adequate for the pressure?

Are the tubes expanded into the 516?

Do you have any leakage?

If the first 2 answers are yes and the last no, perhaps consider leaving the vessel as is.

 

[stanweld]

bmoorthy,
There are only two interlayer materials that can be used; pure silver and vanadium. These materials can be welded to carbon steel and Ti can then be welded to the silver or vanadium. Multiple passes of the interlayer will be required to assure very low Fe content of the interlayer material. As unclesyd implied, making these repairs are exccedingly costly and may not prove effective for your purposes.

If the disbondment is not actually harmful to the service, I suggest that you request a waiver from the UT disbondment requirement. If waiver cannot be granted, remake the clad tubesheet.

 

[bmoorthy]

The tube holes are not drilled.

The tube sheet is just come to the shop after explosion cladding.

UT was carried out to ensure that the quality of bonding.

Out of many tube sheets that are going to come these are the first ones.

And in the first lot we have this situation in 1 tube sheet.

Waiver is not an option. When we drill tube holes the disbonded area will open up.

The next option of machining out the clad and reexplosion bonding is also ruled out since the thickness of the tube sheet will go down and generally post bonding the edges are trimmed, the diameter allowance is at the border.


Welding is the option (Even if it is costly) but compared to economics of penalty on the delivery and the delay in re procuement and the rejection cost (Of CS and the TI) we are left with very few choice.

I am thinking of trying out Vanadium buffer followed by TI and parallely silver option as well.

But are silver not brazed? This is really new to me.

 

[SnTMan]

bmoorthy, I understand your cost and schedule pressures, but you have to decide if your organization is willing to take the responsibility for the repair. What are the consequences of your repair failing either in your shop or in service?

If you have a defective tubesheet from your vendor, that should be his problem, not yours. Sometimes these things happen, it's nobody's fault, but it is much better to take the time and expense now to avoid placing a piece of equipment in service only to have an early failure. Suppose you were the customer, what would you want?

Regards,

Mike

 

[metengr]

The tube sheet is just come to the shop after explosion cladding.

UT was carried out to ensure that the quality of bonding.

Out of many tube sheets that are going to come these are the first ones.

Agree completely with SnTMan. In fact, being a customer or purchaser I would require this defective sheet to be replaced immediately. Bmoorthy, is your organization prepared to deal with a defective tubesheet if this repair does not work?

 

[rmw]

What you have here is a piece of high dollar scrap. But, that is what your UT testing is for; to determine which is good material and which is not. Your vendor has delivered a defective part to you for which sadly, there is no real remedy. Your only options are to reject it or accept the consequences of using it.

If this is the first of several to come, what you let your vendor get away with on this one may well determine what kind of results you will get with the rest of them.

rmw

 

[stanweld]

If UT was in the P.O., the manufacturer is respnsible for the repair or replacement of the clad tubesheet. Do not undertake the repair yourself.

 

[bmoorthy]

Thank you all for your valuble inputs.
Tube sheets that had disbonding has been rejected.