Repair Welding Titanium 1

[bcd]

Hello,

The ASME Boiler and Pressure Vessel Code Section II Part D has a note that prohibits welding of cast commercially pure grade 2 (CP2) Titanium. However, the ASTM material specification allows it. Anyone know the reason why the Boiler and Pressure vessel code prohibits weld repair? Can't find anything on the internet explaining why.

 

[pradipgoswami]

Would you please refer the appropriate clause IN Sec-II, Part-D. I was unable to find it in 2013 version II-D, which I've.

If it applies to ASTM SB 367 castings, then what ASTM specification tells is this:-

9. Repair by Welding:-If repairs are required, these shall be made using a welding procedure and operators certified to quality requirements established by the producer...................................

Unalloyed titanium Grades C-2 castings shall be stress-relieved if the repair is considered capable of adding stresses that will interfere with the purpose for which the castings are intended.................

Well as you may see in ASTM this repair is subjective to a number of conditons.



Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
ca.linkedin.com/pub/pradip-goswami/5/985/299

 

[EdStainless]

This is a clause often removed when ASTM specs are moved into ASME.
We just have to live with it.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[bcd]

To pradipgoswami - It is on page 262 of the 2013 edition. Line 36. At the end, it refers to note W1, which states "not for welded construction". I'm running into a case where someone is interpreting that this means no weld repair either. Just seeking some ammunition to fight back since it is not uncommon to HIP Titanium castings and do some subsequent cosmetic weld repairs.

 

[metengr]

This note in Section II, Part D refers to joining of castings by welding and not weld repair of castings. Read the ASME SB material specification, and not the ASTM B specification regarding weld repairs.

 

[pradipgoswami]

I'm referring ASME Sec-II, Pt-B, SB-367.Clause 10 clearly specifies the guidelines for weld repair of casting. Such repairs are allowed only under extremely controlled conditions as needed for reactive materials like Titanium.

Weld repair of titanium castings must be carefully executed because titanium can become embrittled due to pickup of oxygen, hydrogen, and other contaminants during welding. GTAW is used with alloy filler rods to fill minor defects e.g. porosity, cold shuts.

Filler metals may be extra-low interstitial (ELI(Preferred) or normal interstitial to prevent excess oxygen buildup in the weld metal. Excellent quality weld deposits are routinely obtained when proper practice is used. Generally, all weld-repaired castings are stress-relief annealed after welding.

Note SB-367 10.2.1 has some exemptions about PWHT on casting repairs.

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
ca.linkedin.com/pub/pradip-goswami/5/985/299