Welding a steel hull

The Miller feeder you're considering would work well mounted on a jib crane, or? The 4 drive roll configuration feeds well, bird-nesting is reduced. Miller is the premier manufacturer of semi-auto processes equipment. Depending on the type of welder you will be using and the set up of your building site, however, you may find a suitcase feeder to be more versatile. Perhaps, you could be more specific?

 

thanks , feeding soft wire,ally, I nned the 11ß--120 vac as my gear is all deltaweld and megaflex, I would use a 8m gun cable with a bernard or binzel
all the newer stuff is from 12-48 volts

 

We used those ceramic backing strips on the repair of an ENSCO drilling platform. For long welds they are a time saver but we didn't use them on vertical or water tight bulkheads. Preping the plate before fitting then there is no back gouging and you can avoid the overhead procedure in the voids. Probably not the same time save on thinner plate but 6mm up there would be a benefit. Interested in the way a lot of people seem to be going towards wire feed welding. When we were looking to get certification on a vessel earlier this year anything that was watertight had to be Low Hy MMA welded. Now is that just an oil industry thing after all this was a multi million $ project not a home build? I am looking to build a boat soon and silly things like that are best got out the way early like certification and such.

I am still unsure as to alloy or steel. will have to see what design i end up with but if it was steel i was looking at MMA welding it. It is still recognized as a greater structural weld by both Lloyds and ASME, but again i haven't done small boats yet.

I was also a little alarmed at how stray arc and arc strike were dismissed as non problematic earlier in this thread after a competent welder had already explained the problems of hot spots. I can assure you as an ASME, API and CSWIP welding inspector, any vessel that is subject to pressure will fail inspection for "ARC Strike" or "stray arc". They are defects. Your hull is full of weak points due to small HAZs (heat affected zones) if you have been "ARCing up" on it. And if you still think that i'm wrong look it up on google or something.

Happy new year to you all

 

hey welder I have built many of both, if you like to pm with email address will be glad to talk,

 

holding ceramic strips

there are some mighty strong magnets with on/off switches

seems that a fixture may be mounted to 2 to 4 of them to hold the ceramic strips, could save some time and work

 

Strong magnetic fields near the weld is not good. Ark gets wild at times and the weld is not near as strong.
Tom

 

the reason for low hi on watertight areas is because of danger of asphyixiation in confined spaces if using argon or co2

 

If arc striking up had any serious effect on metal it would bend differently. It doesn't, as the arc is so brief it doesn't have time to heat the metal much.
Brent

 

Brent
Arc striking may not cause "it to bend differently"...that is not the issue at hand. The issue is that arc striking causes a metallurgical change, which can seriously affect the material properties and hence the performance of the structure. Nowt to do with any 'bending'.

 

In small metal boats, being so grossly overstrength, any change would be so small as to be totally insignificant. You would never see any measureable consequences in the middle of a plate
There are far more important issues to worry about.
Brent

 

Arc strikes are not always about their effect on the parent metal . All arc strikes should be ground to a smooth finish to create a good even surface prior to painting.

 

For those of you with poor QA and have no concern of its effects, arc strikes can reduce the strength of the parent metal to around 60~70% of its virgin state.

You can read more in
"Fatigue of Welded Structures" by TR Gurney, 1979
"Evaluation of the Fatigue Strength of welded joints with imperfections, a review" by H Petershagen, 1990

To name 2 of many hundreds of well documented soruces.

Also attached, those good poeple at TWI in the UK, also give there "simple guide" to best practice too, regarding arc strikes

 

If it reduced it by 30% it would definitely bend differently. It doesn't, as any origami boatbuilder can attest to.
Brent

 

Brent

As I, and others, including the TWI, have said before above, bending has nothing to do with it. You need to re-read #144 and #147. If your position/opinion hasn't changed, then it speaks volumes about your QA...

 

Does that mean the steel alongside your weld is 30% weaker, yet you can still expect 100% strength ? Sounds like ******** to me. How long do you have to hold the arc on the steel to weaken it 30% when dragging doesn't even warm it up.
Does that mean the dragged area in the middle of the 3/16th plate of a 36 footer may break? ********!
I've heard this one before.I was never gullible enough to believe it.
Brent