Low hydrogen Electrodes 1

[bmoorthy]

i have heard of Low hydrogen Electrodes in the SMAW paralance, is there some thing equivalent in SAW flux and in FCAW wires?

 

[IFRs]

Check with your welding supply store. I think 7015 is a low H flux rod.

 

[metengr]

Yes. Carbon steel electrodes and fluxes for SAW, SFA 5.17, or low alloy steel electrodes and fluxes for SAW, SFA 5.23 can be supplied as low hydrogen. The electrodes for low hydrogen will contain an optional supplemental diffusible hydrogen designator (HX).

For FCAW, carbon steel electrodes SFA 5.20, and low alloy steel electrodes, SFA 5.29 there are similar optional supplemental diffusible hydrogen designators (HX).

For more information, please review ASME Boiler and Pressure Vessel Code, Section II, Part C "Material Specifications - Welding Rods, Electrodes, and Filler Metals"

 

[sayee1]

Typically, Exxx6/7/8 electrodes for SMAw are LH electrodes because of the redrying which reduces the diffusible hydrogen in weld metal (by reducing moisture in coating). The AWS/ASME section IIC only specify a max level off 0.6% by weight for the misture in coating for LH consumables as per SFA 5.1 (CS electrodes)
However in case a tighter tolerance on diffusible hydrogen is desired, a supplementary designator can be used which signifies the maximum diffusible hydrogen in weld metal.
For FCAW, since the flux is in the core, the chances of moisture ingress is greatly reduced, and hence most of the wires available would give a low hydrogen weld deposit. For SAW, the basic fluxes would give low hydrogen weld metal and the acidic/rutile fluxes used for higher welding speeds generally would be with higher hydrogen levels in weld metal. Typically the specifications for oil and gas offshore platforms, give a limit on the hydrogen content upto which they would consider the weld metal as low hydrogen. Typically I have seen limits upto 15 ml/100 gm or below being designated as low hydrogen, though for specific applications like higher strength materials, the limits would be lower at around 8ml/100 gm.

Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
email: sayee_prasad@yahoo.com
If it moves, train it...if it doesn't move, calibrate it...if it isn't written down, it never happened!

 

[MachineEngr]

I like the first response you got best.

Usually if you see a callout for SMAW low hydrogen they are refering to 7018 (that is the bread and butter typical). In FCAW (dual shield) your Lincoln 71M is an excellent wire and your local welding supply folks can turn you right on. For SAW (sub arc) I've worked with Lincoln and ESAB and I think you will find that all of their SAW wire/flux packages for mild steel will get you there. Again, call your welding supply folks or factory engineers for ESAB or Lincoln to get the scoop.

What you are looking for is common though, you are not looking for anything exotic.

Tony Holt, P.E.
Machine Development Co.

 

[bmoorthy]

Why is it that low hydrogen concept is applied only to Carbon steel Welding material. Can it be extended to Alloy steel as well. Or is it foolish to ask for Low hydrogen electrodes/flux for say low alloy steel and high alloy steel welding.

Or is it always low hydrogen in case of low alloy electrode and there is no scope of using non low hydrogen electrodes. To say there will be no 8013 b2, it will always be 8018 B2.

Good Luck
B.Moorthy
moorthykar@yahoo.com

 

[Metalguy]

Low alloy steels need low-H electrodes more than plain low-carbon steels. The common electrodes are 7018, 8018, 9018 and 10018-all well baked but not overbaked.