Heavy Equipment Repair Question

[Welder Dave]

7024 is a little easier to use. 7018 is stronger whether preheated or not. 1/4" 6010 isn't fun to weld with especially in the position I was using it.

 

[chidog]

The most important thing I do when welding is protect my rods. Only 2 out of the sealed container at a time. I see others just leaving the rods out to soak up moisture, 7018 is very hygroscopic and that means hydrogen. And unlike my one buddy that was the best welder ever, I've never been afraid to turn up the current, I want heat especially to keep out the porosity. The trick for all the items your welding and that end up cracking or breaking, add more plate or what ever to the area, fish plates or what ever is needed for the strength. I've welded 6 inch thick I think it was at times and have never had problems.

 

[Nige]

I mentioned this book earlier but wasn't home to take photos. The first image is the original version, my copy was published in 1978 but I think the book dates from well before that. The second is the updated & reprinted version SEBD0512-01 from 2001.

 

[Junkyard]

I just snagged one like the top pic off of eBay this morning while my boy was sitting in the orthodontist chair getting tortured lol.

 

[Welder Dave]

Ideally if you're welding something critical using low hydrogen rods you'd have a portable rod oven or even something like a cheap toaster oven to keep the rods warm enough you can't hold them with your bare hands. If you don't have a way to warm the rods doesn't mean your welds will automatically fail. If the rods have been kept dry or came from an unopened package they don't turn into a sponge soaking up moisture the second you take them out of the package/container. Typically you should use rods within about 20 minutes after taking them out of a rod oven or new package when doing code level welding. Only the most critical code level welding requires rods directly out of a portable rod oven. Those jobs will also list specific amperage ranges, preheat, interpass and post heat temperatures if slow cooling is required. Most heavy equipment repair isn't technically as critical as that. Preheat and post heat, when required, is more important than if the rods were fresh out of an oven or new package. Porosity isn't usually related to amperage as long as you're within the recommended amperage range. Striking the arc ahead of where you start the weld and moving back welding over your arc strike usually elimates porosity at the start of a weld. Generally you want to use as many amps as you can get a nice bead but as long as you get the penetration you desire is what matters. Fillet welds can benefit from higher amps but a bevel requiring 100% penetration won't be any stronger from using more amps as long as there is 100% penetration. Making sure there's no undercut or excessive build up and not leaving craters at the end of welds also helps to ensure the strongest repair. Warm rods are best but not the most critical aspect of a good repair as long as they are dry and weren't exposed to moisture. What some welders do is stick the rod on the plate for a few seconds to heat it up before welding. This will cook out any residual moisture the rods may have picked up. Not as good as rods out of an oven but a good compromise if you don't have an oven. I'd like to see a failed weld caused strictly because the rods didn't come out of an oven. I'm not talking rods that were exposed to moisture but rods kept in sealed containers. Too many people think 7018 can't be used without an oven. A friend did some tests years ago and even 7018 that had been sitting in a shop in an opened package still had more strength than other mild steel rods and passed bend tests.

I'd like to see the Cat welding booklets but I'd bet they are pretty close to established welding procedures for pressure and heavy structural welding. There are for sure certain aspects or procedures that may be unique for heavy equipment repair but I think for the most part the welding procedures are well established. That's why it's usually recommended to hire an experienced welder for more critical repairs. You can't cut corners especially when things like proper preheat and post heat is critical to the success of the repair.

 

[.RC.]

If you do an internet search for "SENR0512 - SERVICE WELDING GUIDE" you might find a pdf

I have been watching two youtube channels, icweld and onfirewelding and I have learned quite a lot from both, especially like do not root around and just lightly gouge out a crack and stick some weld in there, no they go full on to town with the oxy, plasma or air arc and are not afraid to cut out big chunks of plate and replace them. Putting in backing plates and doing big fills with welds, mostly with wire, then when they are done you do not know they were ever there.

Better then what I always seem to see where someone has tried to weld up a crack with a stick welder, usually vertical up, then it cracks again, so moare bird poo weld is the answer.

 

[BC Placer gold]

Ideally if you're welding something critical using low hydrogen rods you'd have a portable rod oven or even something like a cheap toaster oven to keep the rods warm enough you can't hold them with your bare hands. If you don't have a way to warm the rods doesn't mean your welds will automatically fail. If the rods have been kept dry or came from an unopened package they don't turn into a sponge soaking up moisture the second you take them out of the package/container. Typically you should use rods within about 20 minutes after taking them out of a rod oven or new package when doing code level welding. Only the most critical code level welding requires rods directly out of a portable rod oven. Those jobs will also list specific amperage ranges, preheat, interpass and post heat temperatures if slow cooling is required. Most heavy equipment repair isn't technically as critical as that. Preheat and post heat, when required, is more important than if the rods were fresh out of an oven or new package. Porosity isn't usually related to amperage as long as you're within the recommended amperage range. Striking the arc ahead of where you start the weld and moving back welding over your arc strike usually elimates porosity at the start of a weld. Generally you want to use as many amps as you can get a nice bead but as long as you get the penetration you desire is what matters. Fillet welds can benefit from higher amps but a bevel requiring 100% penetration won't be any stronger from using more amps as long as there is 100% penetration. Making sure there's no undercut or excessive build up and not leaving craters at the end of welds also helps to ensure the strongest repair. Warm rods are best but not the most critical aspect of a good repair as long as they are dry and weren't exposed to moisture. What some welders do is stick the rod on the plate for a few seconds to heat it up before welding. This will cook out any residual moisture the rods may have picked up. Not as good as rods out of an oven but a good compromise if you don't have an oven. I'd like to see a failed weld caused strictly because the rods didn't come out of an oven. I'm not talking rods that were exposed to moisture but rods kept in sealed containers. Too many people think 7018 can't be used without an oven. A friend did some tests years ago and even 7018 that had been sitting in a shop in an opened package still had more strength than other mild steel rods and passed bend tests.

I'd like to see the Cat welding booklets but I'd bet they are pretty close to established welding procedures for pressure and heavy structural welding. There are for sure certain aspects or procedures that may be unique for heavy equipment repair but I think for the most part the welding procedures are well established. That's why it's usually recommended to hire an experienced welder for more critical repairs. You can't cut corners especially when things like proper preheat and post heat is critical to the success of the repair.

Nice info, appreciated by a ‘bush welder’

 

[Welder Dave]

Nothing wrong with stick welding but you still need 100% penetration or it's just a bandaid repair not likely to last.

 

[.RC.]

I agree but these days is how many people have the skill level to do good vertical up's with SMAW.

 

[cfherrman]

Band aid repairs are my specialty

 

[Welder Dave]

I never thought vertical up with 7018 was that difficult. You can use a smaller rod if need be.

 

[Welder Dave]

I found a Cat service welding guide online but it was really small print on my phone. I only looked at part of it. It had some mis-information that was commonly used in other welding text. It said that low hydrogen (7018) should never be weaved wider than 2 rod diameters because you would lose shielding. I've haven't seen losing shielding given as the reason before but max. weave of 2 1/2 diameters was a common reference. You don't lose shielding doing a wider weave and a wider weave is perfectly acceptable as long as there are no defects in the weld like slag inclusions. I was involved in a discussion several years ago concerning weave width. I wanted to get clarification so e-mailed Walter Sperco who is one of the main welding experts who wrote the ASME codes. His answer was interesting. He said the 2 1/2 dia. max weave is an old wife's tale that's been carried on from years back before modern electrodes. He further said he would challenge any weld specification on mild steel that limited the weave width, meaning any width. The extra heat is beneficial and as long as there is no skag inclusion you weave as wide as you like.

The other area where they were contradictory was also concerning low hydrogen/7018 rods. First they said new rods fresh out of hermetically sealed packing should be used within 4 hours. Later they said rods out of an oven should be used within 2 hours. Why would hot rods out of the oven not be at least as good out in the open as non heated new rods?? It further went on to say that rods left out of the oven past the time limit needed to be re-heated in 2 stages and the 2nd second stage was 500 deg's. Rebaking at high temps is for rods that were directly exposed to moisture or became wet. Normally rods that aren't used are just returned to the oven at the normal 200-250 deg. temperature. They don't need to baked at high temps. I think the Cat guide may have taken some of it's info from other sources that weren't necessarily the most up to date or accurate.

I worked in a few U stamp ASME certified vessel shops and none of them had extra ovens for baking rods at higher than normal temps. New packages of rods would be opened and put into an oven. Welders would take a bunch of rods to use. Any rods that weren't used were just returned to the oven. Only the most critical welds required a portable rod oven to be used at the location of the welds. It wasn't very common in a shop with a controlled environment. In the field would certainly be more crucial to have portable rod ovens to ensure the rods don't pick up moisture. For 90%+ of general repairs you don't need an oven, just dry rods from a new package or from a sealed container like the plastic rod containers that use an o-ring to seal them. There's so much debate on rod ovens it's ridiculous. Some people won't even buy or use 7018 because they don't have an oven to keep them in. Also concerning hydrogen embrittlement, it's a non issue on mild steel. It would be refreshing if someone did some controlled tests on welds done with and without an oven and with rods that had no special storage at all. Simple break tests have revealed (7018) rods out of an oven have more strength but also that rods that weren't in an oven still had superior strength to any other mild steel rods. Welds are generally stronger than the base metal so it would be good to also compare the weld tests to non welded base metal test plates. My theory is the plates welded with non heated rods would still be at least as strong as the non welded plates. On plates 3/4" and thicker preheat would be much more beneficial than heated rods.

 

[Truck Shop]

The army always stated, while on leave--the slightest penetration constitutes the act.
So keep your rod out of the oven.