SMAW rods for boiler construction

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jlakes85
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SMAW rods for boiler construction

Postby jlakes85 » Mon Aug 21, 2017 7:03 pm

Is there any reason that a rod like 7010 couldn't be used for all passes on a welded boiler joint? My only guess would be the heating and cooling cycles that are found in a boiler are much harsher than on other types of process piping in general

Glenn Brooks
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Re: SMAW rods for boiler construction

Postby Glenn Brooks » Mon Aug 21, 2017 7:40 pm

I am certainly no expert. But have heard some people say 6010 forms better shaped root passes than 7010, and also is preferable to work because the 6010 flux produces a liquid flux, whereas 7010 is a cellulos flux product that burns with a gaseous flux - which can create lots of slag intrusion problems pretty quickly in a root pass if the rod hasn't been heated and dried properly. So Iam guessing weld pass geometry formation and potential slag intrusion/voids are the reasons.

Standard pressure vessel welding technique is to use 6010 for root passes. Then 7010 is used for making a final covering pass. Also, the 7010 puddle lays flatter and spreads better, hence might distribute expansion and shrinkage stresses on the surface of your boiler more evenly.

Hopefully some of the pressure vessel welders will comment.

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Marty_Knox
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Re: SMAW rods for boiler construction

Postby Marty_Knox » Mon Aug 21, 2017 7:52 pm

Have you run much 7010? I prefer 7018; in fact, I use Lincoln Excalibur 7018 almost exclusively.

jlakes85
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Re: SMAW rods for boiler construction

Postby jlakes85 » Mon Aug 21, 2017 8:24 pm

Hi Marty,

No, I've never run 7010. Just 6010(red) and Lincoln Excalibur 7018. I was watching some guys on YT out on the pipeline, pancake helmets and all: I think they used 6010 or other xx10 rods for all passes using downhill technique.. definitely not as pretty to look at as a 7018 fill/cap, but much faster than traditional uphill 6010/7018. I'm guessing another big advantage is not having to mess with ovens on site to keep the 7018 rods in code condition, but again I think even that 600 psi pipeline doesn't deal with nearly as severe a thermal cycling as a boiler, which is where an xx10 rod might show it's limitation in this regard

BClemens
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Re: SMAW rods for boiler construction

Postby BClemens » Tue Aug 22, 2017 8:39 am

7018 rod has an additional benefit and that is to greatly reduce hydrogen embrittlement (that is if the flux is dry). 6010 is a great tacker rod.

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cbrew
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Re: SMAW rods for boiler construction

Postby cbrew » Tue Aug 22, 2017 9:07 am

Marty, what about Tig. I know its a much slower pace.
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Marty_Knox
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Re: SMAW rods for boiler construction

Postby Marty_Knox » Tue Aug 22, 2017 9:18 am

cbrew wrote:Marty, what about Tig. I know its a much slower pace.

We do a lot of TIG. Depending on the fitup, we will do the root pass with 6010 or TIG. We use ERS70-2 for the filler with TIG. The TIG may be slower, but it makes for a smaller, neater weld with very little cleanup.

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cbrew
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Re: SMAW rods for boiler construction

Postby cbrew » Tue Aug 22, 2017 9:24 am

Marty_Knox wrote:
cbrew wrote:Marty, what about Tig. I know its a much slower pace.

We do a lot of TIG. Depending on the fitup, we will do the root pass with 6010 or TIG. We use ERS70-2 for the filler with TIG. The TIG may be slower, but it makes for a smaller, neater weld with very little cleanup.


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jlakes85
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Re: SMAW rods for boiler construction

Postby jlakes85 » Tue Aug 22, 2017 8:17 pm

Hi Marty,

Do you know if the code explicitly forbids XX10 rods for all passes on a power boiler? I can't shake this curiosity.. Thanks again.

-jlakes85

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Marty_Knox
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Re: SMAW rods for boiler construction

Postby Marty_Knox » Tue Aug 22, 2017 8:25 pm

I know you can run 6010 for all the passes. I never bothered to look up or ask about 7010.

jlakes85
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Re: SMAW rods for boiler construction

Postby jlakes85 » Tue Aug 22, 2017 9:11 pm

Hi Marty,

Sounds good..I can see it being easier to just deal with once nice size box of 6010 and call it a day, you Hough the results won't be nearly as good looking

Boiler Builder
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Re: SMAW rods for boiler construction

Postby Boiler Builder » Fri Aug 25, 2017 8:19 pm

The only difference between 6010 and 7010 is the 60xx signifies a minimum as welded tensile strength of 60,000 psi whereas the 70xx signifies a minimum as welded tensile strength of 70,000 psi.


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