Welding a steel hull

Elsewhere in another thread there were some discussions about welding procedures etc for steel hulls, more so aimed at amateurs, and I believe that this warrants its own tread and some constructive contributions may lead from this.

I am not a qualified welder per say, but a qualified boilermaker for the last 31 years and have work with every kind of welding rod (well, mostly) and different steels etc. in the fabrication and construction game. Furthermore, I am busy with my 19th steel hull, in short; being there, done that and have a badge.

Herewith my humble contribution based on personal experiences for welding mild steel hulls.

60 series;

I think the AWS E6013 is a good all rounder for the amateur, especially if a good brand is used. It strikes easily, and is good for most positions and basically, any type of welding machine can be used AC or DC, from shoebox type of transformer to inverters.

70 series

AWS E7018 - a magic electrode, but not for the amateur. It weld all positions brilliantly, very strong weld but have a few problems to the amateur.

For starters, it needs DC to performs best and needs at least an OCV (open circuit voltage) of 70 or more to weld satisfactory. And this puts it outside most amateur's range as most potable AC welders have an OCV of 50 and sometimes much less. However, it can be welded with an AC machine with the required OCV......

Secondly, E7018 needs to be stored in a hotbox to be totally dry and at the right temperature - have a whitish colour when ready to use. This electrode is also very finicky on dirty or rusted surfaces and prefer a grind clean surface. Also, this welding does not like to be cooled down fast...

AWS E7024 - again a brilliant electrode, but have no place on a boat in my view. It is used mainly in the steel fabrication world and is a perfect rod for welding fillet joints (corners) and pipe flanges in in a lesser way butt joints. The bad part is that it can only be used in a downhand flat position, and even a slight angle off the horizontal, will cause a mess with it. Not suitable for any position other that flat downhand.

MIG -

My choice of welding for a hull. Its only real draw back is that there must be no wind interference to blow the shielding gas away, and if so, porosity in the weld will be the result. It is also temperamental on dirty steel and needs a clean surface to perform best.
If well penetrated and fused, and excellent weld with the least distortion due to the speed and lower heat input to put it simply

This is my opinion of welding and perhaps our certified welders can enlighten us further on this

 

Wyland
Good idea starting a new thread on the subject.
By the way the Dix 43 your building looks great,may I ask what you welded it with ?
My opinion on welding is the end result is what counts. I have met and worked with a lot of different welders over the years, each have there preferance for one reason or another.
For someone that is just starting to learn to weld,start with any of the rods you have available and practice, try the defferent rods to see whitch rods burn better with your particular welding machine.
To me cutting is just as important, good clean cuts with good fit up, without this it doesnt matter what you weld it with you will have infierior welds with more distortion.
Mig is great if building indoors or putting up wind breaks , flux core is ok to but for someone just starting out it takes a bit more learnin. One has to be carefull you can make some pretty welds that have no strength.
Tom

 

Most tack welding done with a 200A DC inverter welding machine and all continous welding with a 200A DC inverter MIG machine.
Do not need more than this on a boat. Most of the time the welding was done at about 175 - 180A range where this baby has cycle duty of 90%.

 

MIG is my welding process of choice for boat building. I have used self shielded flux core wire, dual shield flux core wire and solid wire. Here's a few quick comments on each.

First the self shielded flux core wire (E71T-11): I hate it on the boat, love it for farm implements. It's easy to use, no need to worry about wind and when run hot for thick steel it's fairly tolerant about cow crap in hard to clean corners, perfect for an emergency solid fix. Cons, it really stinks and fumes.
My problem about it on boats is the flux. I found that at the junction between beads even if well brushed, it seems to always be a bit of flux at the end and beginning of beads which causes small pin holes or defect when joining them (apparent when the bead is ground down). I don't like that. It is also more work to clean up the root before welding the opposite side. To me, the issues caused by that white powdery flux don't do up for the less worry about the wind.

The dual shield flux core wire: E71T-1 run with 75/25 co2/argon gas. I love the speed at which it goes down (need a stable hand) and its wetting properties. From my reading about the stuff, I was expecting it to be a little more surface tolerant, at least to mil scale or red oxide primer. I've had worm track troubles with any little bit of scale left and on humid days. It's the only wire I've had some cracking troubles, maybe I should of tried E71T-2. I found the FCAW much more picky about settings, takes a machine with fine tweaking. Undercutting happens quite easily. I only used it in short arc, should maybe try spray some time. Anyway, cool stuff but picky.

For the boat I use my beloved ER70S-6 with 75/25. I know, I would get hotter arc with strait co2 but I hate spatter, even the most little bit of it. I do what ever I want with solid wire, feel I have great control on it. It talks a clear language (pops and cracks), easy to fine tweak. I get good fusion and penetration without undercutting. Don't feel any difference out of position. I'm building my hull outside and obviously I had to avoid windy days for the hull welding. Up to 10 km/h wind it's fairly easy to set up tarps to shield it. Winds are usually low early and late in the day, mid day it's too hot anyway. Once the skin is welded up most of the rest of the welding is inside the hull and not influenced by the winds. I haven't found a gas shielded wire a major inconvenient to build outside. When it comes to elements I've had more trouble with humidity and temperature changes rusting my wire. GMAW with ER70S-6 is what I like.


Murielle

 

Welding

I find enough flat welding ( Hull decks, Cabinside decks, chines, tank tops, etc) to get a lot of use out of 7024 and a slight uphand weld works well. It goes fast and makes a strong, smooth weld. It is extremeley easy for a beginer to use.
Weld a piece of 1/8th steel to a piece of 3/16th hull plate with 1/8th inch 7024 and you have more metal in the weld than in the 1/8th deck plate. Break it and it will never break on the weld. This makes a hull deck weld stronger than the deck plate and eliminates the overhead welding under the deck, drastically reducing distortion .
When you put the first weld on , the shrinkage simply pulls the decks to the hull. With the decks thus solidly anchored , when you then put a weld under the deck , it wraps the hull plate around the deck edge, causing oil canning. If one is determined to have a weld under the deck, then putting the bottom weld on first , simply pulls the decks to the hull plate. Oil caning from the second weld on top simply tries to distort the bulwark cap, which is far more solid , and able to resist oil canning, altho a destruction test will show a second weld to be irrelevant..
I once built a boat in a sheet metal shop with all kinds of wire feed welders. We found the shortness of the cable, and the need to keep moving the machine, too much trouble, so we left a gas driven stick welder outside and tacked the sheel together with it. Then we used the mig for the long welds.

 

Thanks Wynand
I am going to have to try out one of those inverter stick welders, never heard anything bad about one. Will it burn 7018 and 308 or 309 stainless rods? When I started my boat I was using my lincoln SA 250, diesel was cheap now its costing about $2.50 an hour to run it and that adds up in a hurry. I did buy a used miller dialarc 250 and been using that latley, welds good but thats a big heavy machine to move around.
Tom

 

Murielle;
The wire I used is also ER70S-6 but with an Argonshielding gas (Ash5) consisting of 93% Argon, 5% CO2 and 2% Oxygen. Expensive but magic.

Brent;
As I said before, the E7024 is a brilliant rod, providing you have flat surfaces to weld as you mentioned. Unfortunately the type of construction of the boats I build have plenty sheers etc making it a bit awkward.
Actually, it is a contact rod, making it very easy for an amateur. Just let the rod touch the plate and steer. I will burn (feed) on its own rate and yes, if the the welding machine was set properly, you will be rewarded with a super smooth weld.

Tom;
These new inverters are magic and super smooth DC. My 200A unit is rated 100% cycle duty at 165A - more than you will need on small boat building.
You have to experience welding stainless steel with these critters, so smooth and it melts like butter. Since the 200A inverter has a OCV of 70, it welds E7018 (LH - low hydrogen rod) just like any other, straight out of the box and un-heated! Not even very finicky on the strike, although an amateur may battle to get it going.
As a bonus they are very small and light - mine weights 5.8kg

BTW, for the layman, a rule of thumb method to set a welding machine to the correct amperage for any given rod; multiply the thickness of electrode (mm) by 40. Thus a 10 gauge = 3.15mm x 40 = 125 amps.
For vertical, horizontal or personal preference, the machine can just be a little tweaked /fine tuned from that setting.

 

welding process

Wynand,

What are the magic effects of that argonshielding gas? I already find welding with 75/25 mix a dream so you get me curious about something even better...are there little fairies in there that hold the gun for you?

Otherwise, I am fairly mystified to see so much talk our days about stick welding up a hull. My husband and I have done a price analysis and pros and cons chart about welding up a hull with stick versus mig before buying good gear. We considered the welders time using the deposition rate and a practical on/off time. For materials we considered the sticks including stub wastage in stick welding; gas, wire and tips for mig. We obviously considered the equipment cost as it is more to MIG but still didn't see enough economic advantage of stick welding a hull to balance out the advantages of MIGging. My welding skills were not even a consideration as I have no issues with stick welding (with a good machine). Comfort out of position, in little nicknack holes, handling a live stick in a steel cage, the hasle of drying sticks, fumes, cleaning slag and many other considerations came in count.
Brent mentioned the freedom to move around, which we did consider and counter balance by a suit case feeder (I have 50ft leads to my case and a 20 ft gun). About the wind I already mentioned that issue in previous post, it isn't that much of a problem and I'd still rather use self shield wire than sticks.
I think the real push away factor from MIG for the backyard builder is the cost of the gear and gas (again self shield wire can be used, I don't think it's certified by Loyd's but it is by ABS). Considering the cost of equipment, a good MIG machine can be resold at fair value after a one time project.
For our shop we made the choice to go with MIG and not skimp on gear. Yes, they say that the tools don't make the carpenter but I believe that for two EVEN carpenters the one with the better tools will make the better work (or at least will do it faster).

I'd be really curious of hearing (reading) about each ones reasons to go with GMAW, FCAW or SMAW such a debate would of really hepled us when we made our expensive decisions (which turned out good for us as I don't regret them)

Murielle

 

I've never need anything but a 225 amp buzzbox.
When I jack the stern up to put the skeg on , the foreward centreline is horizontal , a good time to 7024 weld it, before jacking the bow up to put the keel on.
Brent

 

Murielle
The reason I used stick "6011".
When I first decided to build the 26 I was going to build it out at the dairy in the shop, migs. plasma the whole nine yards there. Then the wife asked me when are you planning on working on this thing and I mentioned working on it over the weekends, Then she replied well we might as well get a devorce then if your going to be gone all the time.
Thick headed me got the hint so I built it here at the house, outside on the dirt driveway. Since I,m an old time stick welder anyway I had no problem welding with stick. Funny thing is I have a cobra push pull setup, spool gun, and a linde wire feed that all hook up to my portable welder but I was running 1/8" 6011 welding rods, It just seemed a little simpler to me sense all the welds were only 1-1/2" to 2" long at a time and had to move from side to side.
The only thing I wish I would have done diferent was buy a small plasma cutter sooner. Started out using torch with 000 tip worked good on 10 gage but when I cut out the 12 gage decks they were a bit puckerd and wavey from the heat, thinking that after stiffners and beems welded under then welded in they would straiten out "wrong" I now have built in speed bumps. Thats when I bought the plasma cutter and what an improvment, used it on the rest of boat "Live and learn"
Tom

 

Welding reply from adjacent topic

Wynand thanks for the initiative to move this discussion (welding) onto its own topic.

I'm replying principally to Brent Swain's post about 6011 and its all around utility in application to metal boat building. I had remarked earlier in that topic that the whipped action of the 60 series rods seemed harder to master for the beginner than the 70 series drag rods.

Brent's point was that the overall usefulness of the 60 series made that small learning period worthwhile and noted the 7018 rod's finickiness, or sensitivity to contamination- not something the 6011 rod had problems overcoming.

I fully agree, the 6011 rod will stay molten longer and the cellulose flux cover helps the very 'runny' puddle or very 'wet' puddle to give up gas much more than 7018. The 6011 rod is more versatile in regards gap, stringers to fillet's and several other welding conditions.

My remarks were targeting the new welder, someone without the reflexes that hours of staring at the arc bring. So, while I fully and completely agree that 6010/6011 rod is much more forgiving of contamination, dampness, rod storage, and gap in a fit, as well as metal cleanliness - the fact that you can drag the rod on the joint area was the focus of my remarks.

I'm always working in doors, its always warm and the rod is stored dry, heated/cooked if the job is hydro-tested or x-rayed, and I teach at a welding table downhand to try to get someone used to looking at the toe of the weld and ignore the arc.

6010/6011 won't drag as simply, depending on the open circuit voltage it sticks, depending on angle of the drag the weld will undercut or track, and the solution for most of these issues is movement. That movement which is second nature to the practiced hand just seems more difficult for the learner. Brent knows how to do this reflexively and I believe he may be discounting the number of hours it takes to get smooth with such a technique?

Brent's point about the 'forgiveness' of the rod is right on the mark, 7018 is less tolerant of almost any thing the 6011/6010 will 'take in stride'. What I was remarking about is the complete novice, literally dragging the flux to weld a bead, downhand, on frames/stringers/brackets and jigs. Here is where I find that my students/pupils/trainees have done better with the 7018 over the 6011/6010 rods.

In Brent's post he argues that worrying about the welding is "foolish" but Wynand, in a recent post here just above, gives an example of a few pin holes resulting in a cut out and re-weld. I'd say this represents two points of view about the kind of work a person is willing to accept from themselves? I come from the same school as Wynand and his welder ( but from the pictures I didn't graduate) and Brent may find my attention to these details wasted time , but I find it time well spent.

What I mean to express here is not fault-finding with Brent's point of effective time use- but that I want the lines of my designs fair, the cuts of my torch/plaz or saws to be clean, my welds to be well proportioned, evenly laid down, well fused just like every aspect of anything I build- I want to look at my work and say to my self- "nicely done". I feel my welds, and every other aspect of my work, are a reflection on my work ideals. With shaky old hands that isn't a very nice mirror but I'll still keep trying to lay down the best bead I can.

I have enough problems welding well that I don't need to lower my expectations any or it would be a complete mess.

Regarding the 7024 rod's position limitations. It was designed and advertised as a downhand flat fillet rod but, as Brent mentions, there are lots of places where a small uphill aspect (<10degrees) will float the (very heavy) flux back off the puddle enough to keep the leading edge better controlled than if the rod is vertical and dead flat- sometimes its almost like submerged arc with all that flux.

Another very positive aspect of this rod is how close to MIG welding it comes for speed of weld- they don't call it JetWeld/JetRod (Lincoln Electric Trade Mark Name & oil field welder's slang) for nothing.

cheers,

 

Welding Equipment

Another aspect of the differences we're seeing in this discussion is the impact of the welding power source or "welding machine" we're all using.

I have always had 3 phase, 240 power for all my MIG and Stick machines and until I re-read Wynand's remarks about minimum open circuit voltage for 7018- I hadn't seen the effect my shop had on my experiences.

I used the Lincoln 300 Idealarc power supply until switching to the PowCon inverters in the early 80's. All of these DC welders were run on 240 VAC 3phase power, in a dry shop, on super cleaned metal with still gas flow and no wind, rain, or any humidity.

I now use the Lincoln Power MIG 350 on single phase but its still 100 Amp 240 volt service. But all these machines make welding with 7018 like spreading butter and that is my experience.

When I pipe welded for oilfield fab shops we had the same or larger capacity machines, rod ovens, full time helpers to clean the weld with a power wheel between passes, hand you the rod and generally make the work go smooth.

If the conditions aren't perfect, I'm in the habit of building a building to get them improved enough to control so I can do the work in the controlled environment I have been taught is needed to do the work to the levels required. This could be a function of latitude effecting my attitude? In Alaska, outdoor boat building projects are a little scarce.

For general steel work I prefer ER70S with argon, as I like the extra heat and low/no-spatter results in short arc mode. For high nickel steels (L-80 pipe, A333) I like the ER80-N2 innershield with a CO2 cover, very glassy bead, absolutely clean in pulsed MIG or even pulse on pulse at depositions rates that make your strain to keep your hands up with the wire feeder.

I've always had a few Cobramatic (Push-Pull) wire feeders (all water cooled 350 Amp torches) from the MK company so I now have their new Python push-pull MIG gun in air and water cooled versions and they're very nice feeders which I only use on aluminum.

For all TIG use I prefer the OTC Dahein TIG Gun which I run on the Miller Dynasty 300DX power supply. I've used this model TIG gun for 30 years and have become quite dependent on it. I re-roll the MIG ER70S wire for this gun in 0.035", 0.030" and 0.025" hard wire for general welding. For pipe I would match the alloy to the series steel.

Before the Dynasty I used the Lincoln 300/300 TIG power supply which is a single phase AC machine- the only time I use AC for welding anything.

For stainless, pipe or plate, I rarely use anything but TIG as the wire change in the little TIG gun is as fast as rigging a stick electrode to a power supply. I have very little stainless MIG time.

Two handed (manual) TIG is only realistic for someone who welds frequently but the TIG gun allows the less talented to use this very clean and controlled method of welding more easily.

I (now) prefer to use plasma over a gas torch for most cutting in steel but have used an acetylene torch for many years for most cuts. I have never used propane instead of acetylene so I can't reflect on that gas for torch fuel.

I think Murielle's MIG versus stick value comparison exactly reflects my thinking on the issues effecting my decisions about the two methods. But, since I like to weld so much, my ideas aren't the same as those who're following Brent's minimalist path to get in the water as inexpensively as possible. If the cost of the overall project is the most critical decision factor then stick is cheaper than MIG, on the average, so it follows that it would be the cost priority choice of welding.

This point may reveal a contradiction on Brent's stance for use of the AC buzzbox since he makes so many time base weighted points. So, if saving time is such of huge importance it would follow the MIG machine would buy itself in time saved????

I can see that a 225A buzz box and some drag rod will 'work/get by/suffice' and that my commercially equipped shop point of view comes from the desire to build continually; not from a one-off then gear up and sell the equipment before you sail away- point of view.

I'm just an aluminum skiff builder and have only built one steel boat, a 52' crabber, and there I wasn't even the master carpenter just the welder/fitter.

cheers,

 

Apart from a few specialised welds, back-gouging and stainless the sticks have been replaced by MIG around here and that may be because our sticks are more expensive.

Gas mixes make a big difference to the weld too straight CO2 is cheap and gives deeper penetration in thicker sections (with more splatter).
Amateurs can produce some very nice flat looking welds that don't penetrate with supa-argon etc. Very important to get them to cut open test welds and have a look as well as the bend bash tests.

you can get certified Chinese wire now that is droping the price of the 15 kg spools from the other manufacturers but we had one batch that was variable quality on one job.

Plasma cutters are essential items they make life so easy and cost nothing to operate. Even the little ones are worth their weight in gold. They are not so good on thick plates if you want a right angle edge since they produce a beveled edge. If you get one that cuts through a painted surface it is handier.

ER70S -3 is the common cheaper wire, Murielle mentions the ER70S-6 , Still the same deposited material but has a different initial composition giving lower silicon surface deposits and is more surface tolerant wrt rust and scale. Most people don't realise that MIG wire varies like this.

Also what wire diameter do people prefer? The cheapest here is .9mm .

 

Propane gas is used quite regularly in my country as a cutting gas, especially found in scrap dealers yards etc where destructive cutting is done on big scale and economics counts. However, as Brent pointed out elsewhere, the cutting nozzle has to be replaced - an awkward to clean two piece unit and quite expensive here.

We actually have a gas called "Easy Cut", (acetylene, propane etc brew) same type of cylinder than acetylene, half the price but flame to cold to do gas welding/brazing and same nozzle can be used. However, cutting up to 4mm plate is a breeze with this gas and thicker steel a bit problematic to get started due to the lower flame temperature

I bought a small one few months ago that can cut to 10mm steel and run her with a small 7.8cfm compressor - very nice but some places you still have to use the old trusted oxy-acetylene setup.
If the cut is beveled, one of the following is wrong; 1. going to fast or 2. cutting tip is dirty or worn. Actually, if one cut to fast, believe it or not, it wears out the nozzle in an oval or larger hole, causing a crappy cut. We had this problem of premature nozzle wear and my supplier gave me that tip. Never have that problem again since cutting a little bit slower.
Always replace the cutting tip and electrode as a unit at the same time, as a worn or damaged electrode will destroy the tip in no time.

 

Well Tom this explains that. I am pretty lucky when it comes to tools as my husband and I are pretty good at justifying them and will feed each other all the best reasons to get new toys.

Mike, for most wires it seems like 1.2 mm is cheaper but I rather weld with .9mm. I found that for all wires used the results were at there best at the higher amperage of there range. The pretty flat bead with no penetration seem to rather happen when a thicker wire used at its lower range, they also seem to lose "dirty surface tolerance". To get a proper penetration with bigger wire I find I get more undercutting. So .9mm on boat and 1.2mm for farm implements.

My word about plasma cutters. We have a friend who hated his plasma as it was costing him a fortune in nozzles. This worried us but didn't seem to make sens. When we acquired our plasma we were advised to feed it with clean and dry air if we wanted to save on tips and nozzles. So we did. Our air goes first threw a water separator (home made: copper pipe threw water bucket) a 5 micron filter and finally a 1 micron filter allocated only to the cutter. This set-up has payed its value in gold, I go threw amazingly little consumables and have very tidy cuts. As mentioned by Wynand, thicker the material more it's important to slow down. For rougher work (farm) I use the tips that start cutting on angle and save the better ones for finer work.
I haven't used a drill in steel for about 4 years now, with a steady hand and a well set up cutter its possible to make very fast very neat holes (for me it's a great bonus as the big drill in steel is to strong and rips my shoulder out). Usually more precise drilling will be on smaller metal piece and I than use a drill press.
Yep, the plasma setup is not cheap but it pays for itself fast (in time, drill bits, grinding wheels, no gas...)

cheers,
murielle