Welding Clad Steel 625 (API 5L X65 + 3mm Clad 625) Filler Metal

[MrTungsten]

Hi Expert,

I Have some question regarding Clad Pipe 625, Is it possible to use 625 Filler wire (ERNiCrMo-3) on the Root and Hot Pass only , then Carbon steel Wire (i.e. ER70S-6) for the subsequent welding (Fill and Cap) ?,I there any problem with dilution? (Metallurgical perspective)

we're useing GTAW with Ar 99.997% as shielding and backing gas.
I just think , are we need bridging filler metal (ER309L) as bridging filler between 625 weld metal and Carbon Steel Weld Metal ?

Thanks

 

[metengr]

Is it possible to use 625 Filler wire (ERNiCrMo-3) on the Root and Hot Pass only , then Carbon steel Wire (i.e. ER70S-6) for the subsequent welding (Fill and Cap) ?,I there any problem with dilution? (Metallurgical perspective)

I would not recommend depositing carbon steel filler on 625 because of dilution. You will have produced harmful phases in the weld region.

 

[DVWE]

If I understand you correctly, you are trying to weld ID clad pipe from one side, correct?

If you cannot get in and back gouge the ID, then yes, I would recommend using a 309 filler as an intermediate between the carbon steel and the cladding.

 

[SJones]

https://www.nickelinstitute.org/en/...ries/10064_EngineeringWithCladSteel2ndEd.aspx

TWI in the UK did a lot of work on trying to develop welding procedures involving buffer layers and didn't really get to any useful level.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[CWEng]

If you weld carbon steel over the 625 or even 309, you will get a crack-prone martensitic weld deposit. It is not recommended. Welding 309 over 625 will produce a fully austenitic weld deposit, which can hot-crack. That is typically not recommended either. It may be possible to get enough dilution from the carbon steel to "tone down" the contribution from the 625 when welding with 309 to get some ferrite, but that would seem rather welder technique dependent, and may not be reliable.

 

[JackMats]

The simplest solution is to weld the whole joint with 625 filler. Throwing other fillers in is over complicating the matter and will cause a lot of expensive rework.

You will need to assess the ID with a boroscope at around 10mm fill. If no oxidation, suck back, miss edge etc had occurred then commence with fill.

 

[MrTungsten]

Thanks all for great response ,

Previously, I have some experience with depositing carbon steel filler above 625 weld deposit, I got solidification crack (longitudinal crack along the weld deposit) as i saw it , it's very brittle phase. Some people say it caused by NiS inclusion form which have low melting temperature (around 500 deg C).

I still confuse about this phenomena, is there anyone have some experiences with this ?
Is there any option ? , i.e using different filler metal instead of whole welding with 625 filler. 625 filler is very expensive.

 

[SJones]

In the 80s, CRC-Evans developed a procedure filling out with ER312 deposited on the first two layers of 625. I can't profess to seeing this option on today's menu.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.