For inconel clad pipe welding (no access from inside) must be completed with inconel E/ERNiCrMo-3 filler material.
CS filler materials shall not directly welded on inconel base/ weld metal in order to avoid dilution which will end up with micro cracks on fusion line. This is due to CS electrodes which is basically without addition of alloying elements, while welding the weld pool tends to pick up more alloying elements from inconel base or weld metal (% of dilution is very high around 60%) which is martensitic structure (susceptible microstructure) and more prone to cracking problem. However, on the other hand if we use inconel filler on CS, the % of dilution will be minimized and the final microstructure at fusion line is not in martensitic and hence it is recommended to use only inconel filler metals. Attached herewith some articles on inconel clad pipe welding and bevel preparation for clad portion of welding.
The following alternate filler metals can be proposed and qualified.
Option 1: Complete weld with inconel filler (ER/ENiCrMo-3)
Option 2: Root and second pass with ERNiCrMo-3 and rest by ENiCrFe-3
Option 3: Root and second pass with ERNiCrMo-3 and rest by E310 (super austenitic)
Your proposal is not acceptable. However, the following can be proposed and qualified with risk.
Root and second pass with ERNiCrMo-3 and next pass with pure iron electrodes and rest of the passes with E7018 or any CS electrodes. Till now there is no proven record for this case since control on weld pool and using pure iron electrodes requires high skill and even though it cannot be assured sound weld on all pipe joints.
Let me know your feedback.
From: Sundaram Elumalai <Elumalai.Sundaram@starfab.com.sa>
Sent: Mon, 17 Oct 2011 17:23:44
To: <materials-welding@googlegroups.com>
Subject: [MW:12682] CLAD MATERIALS -WELDING
Hi experts,
We have the following Clad Pipe and we are preparing WPS /PQR to weld this SPOOL. As I know we need to use ERNiCrMo3 / E NiCrMo 3 ( if GTAW+SMAW) to Complete weld. But if any one is having experience with this, please advice whether we will go with
GTAW - ER NiCrMo3 ( First four Passes- R/H/F1/F2)
SMAW – E7018-1 ( Balance Filling /Capping).
We have Pitting corrosion test as per ASTM G48 at 50 degree.
Pipe | NPS:10-Thk:45mm-PIPE-API 5L GR.X65 PSL2 - SMLS -GA-E-61036 | BW | 3mm Inconel Cladded |
Pipe | NPS:12-Thk:15.88mm-PIPE-API 5L GR.X65 PSL2 - SMLS -GA-E-61036 | BW | 3mm Inconel Cladded |
Pipe | NPS:12-Thk:45.5mm-PIPE-API 5L GR.X65 PSL2 - SMLS -GA-E-61036 | BW | 3mm Inconel Cladded |
Pipe | NPS:12-Thk:53.5mm-PIPE-API 5L GR.X65 PSL2 - SMLS -GA-E-61036 | BW | 3mm Inconel Cladded |
With Kind Regards,
S.Elumalai.
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