ESW Instead of SAW 3

[shahdadf]

dear freinds,
when we can use ESW instead of SAW? what are their main differences? is it a factor of material?
regards,

 

[metengr]

I am not going to elaborate into the differences between electroslag welding (ESW) and submerged arc welding (SAW) because you can research this information yourself using Google.

Quick Comparisons;
Electroslag welding is a very high deposition rate process that is commonly used to join plates that are 5" and over in thickness. ESW does not really use an arc for melting, instead, the arc is used to being the process and molten slag that remains on top is what carries electric current while feeding filler wire. Only one single pass is required resulting in less angular distortion.

Submerged arc welding can be used on heavy plate, but it is a lower deposition process in comparison to ESW.

 

[SJones]

ESW can also be used for CRA overlay welding (even if API RP 582 misses it out!); however, contrary to stated opinion, it is a high dilution process and you may find yourself having to deposit a great deal of CRA to meet any dilution criteria.

The main consideration is that ESW deposition rates are about twice that of SAW.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[stanweld]

When making butt welds in ferritic steels, the high heat input of ESW plays havoc with toughness properties. Toughness can be somewhat restored through normalizing, normalizing and tempering and other heat treatments.

 

[gtaw]

"Stanweld" points out an important issue, and that is the large coarse grain size of the electroslag welds. The cooling rate is very slow and the grain size influences the toughness of the weld and heat affected zones.

Low temperature, as defined by your construction code, is going to limit the application of ESW when notch toughness is a consideration. Make sure you review the impact testing requirements of your fabrication/construction code to make sure you qualify the welding procedure correctly, i.e., include notch toughness testing.

As the material thickness increases, and the temperature decreases, notch testing comes into play and increases the difficulty in obtaining acceptable results.



Best regards - Al

 

[HgTX]

There's a lower-heat version out now:

Report no. FHWA-SA-96-053
Technical Information Guide for Narrow-Gap Improved Electroslag Welding

Report No. FHWA-SA-96-052
Process Operational Guide for Narrow-Gap Improved Electroslag Welding

Report No. FHWA-SA-96-051
Training Manual for Narrow-Gap Improved Electroslag Welding for Bridges


These publications are more than 10 years old, so you might want to contact the researchers (who are now at Portland State) for updates.

Hg

Eng-Tips policies: faq731-376

 

[stanweld]

ASME Section VIII, UCS-56 requires grain refining heat treatments for ESW when the thickness > 1 1/2 inches.