Ceramic coating exhaust components

[Irace86.2.0]

Originally Posted by solidsnake11

I had to rework a coated header before it tig welded fine.

What do you define as fine? It looked ok from the outside? It held up for years under repeated track use, heat cycles, all while holding the weight of a T78 turbo?

People do perfect prep, while back purging pipes, and welds can still fail. Most welders would likely not want to touch such a repair job. They would want to cut the pipe at the crack and sand/prep everything then weld it back up, but because they don't have a jig, they wouldn't even want to do that. They wouldn't want to take the responsibility for it failing or not fitting.

[solidsnake11]

I mean it welded just like the raw pipe I rerouted around the steering arm, it was for a circle track truck. Kind of surprised it welded as well as it did since it was coated inside.
It was mild steel, it didn't need back purged and I don't know if he ever ran it on the track.

So some one takes a cracked header to a welder to repair then expects the welder to guarentee it will not crack like it did from the factory.

[Irace86.2.0]

Originally Posted by solidsnake11

I mean it welded just like the raw pipe I rerouted around the steering arm, it was for a circle track truck. Kind of surprised it welded as well as it did since it was coated inside.
It was mild steel, it didn't need back purged and I don't know if he ever ran it on the track.

So some one takes a cracked header to a welder to repair then expects the welder to guarentee it will not crack like it did from the factory.

Mild steel would be more forgiving than other metals, but unless you borescoped the inside, I’m sure the weld interacted with the paint/coating. If there was enough filler, enough pipe thickness and adequate prep work on the outside then the outside could look nice, but that doesn’t mean the inside would be nice.

Guarantee? No, but if a crack appeared after years of heat cycling then reappears within a few heat cycles then they probably would see that work returning out of pocket or someone complaining and taking their business somewhere else. I’ve seen it before.

[solidsnake11]

Well it welded fine. I guess you really have to actually have welded a lot of different materials to understand what welding fine means.

Since we are talking headers, i found a neat trick. I have been using ultra grey on the turbo flanges and v band connections. It turns into a chalky substance but it seals great.

[Irace86.2.0]

Originally Posted by solidsnake11

Well it welded fine. I guess you really have to actually have welded a lot of different materials to understand what welding fine means.

Since we are talking headers, i found a neat trick. I have been using ultra grey on the turbo flanges and v band connections. It turns into a chalky substance but it seals great.

I have. Welds can look fine, but have no penetration (as another example of a common weld issue), as an example of "you don't know unless you look". Again, unless you look at the back side of the weld in the pipe, you don't know. Ex: outside of the weld looks flat without pores, but as you can see, the inside gets progressively worse.





I appreciate you sharing your opinion and experience on the matter, but understand that your opinion is in the far minority. The consensus is to the contrary, that the coating will create gas and introduce contaminants that will cause porosity or weld defects. Call Jet-Hot, and see what they advise, or you can believe what this guy said when he called.

https://www.hotrodders.com/forum/can...rs-115428.html

I asked Jet-Hot this same question about 2 months ago and they said remove the coating in the area of the weld as not to contaminate the weld, then weld as normal. The headers I asked about are coated with their standard "sterling". I don't know if this applies to other coatings/companies though. They said nothing about additional health concerns but I did mine in pretty good ventilation just in case.
Good luck!

If the weld was indoor and decorative then who cares? If it was an intake on a car then it'll probably be fine. If it is pressurized or bearing some flex then a fatigue fail is more likely. If it is heat cycling like a header then a failure is more likely. If it is heat cycling while bearing load like a turbo manifold then a failure is even more likely. I get that we are talking about a header and not building code for welding for structures or aerospace engineering, but this is basic 101 of welding is to prep the weld.

Please watch.

[Wally86]

Originally Posted by Irace86.2.0

Talk about a lack of penetration!

[solidsnake11]

Are we talking about a header for a car or a space shuttle?

It was 12 years ago that I welded it but I remember it because I though man this is going to make a mess but the owner told me to weld it. Like I said it welded fine.
If it welded fine for a person like me that don't back purge and doesn't do hours of prep. Then it should weld fantastic for a more majority person like you irace86.


I also grind the inside of the pipe and polish it after I weld it if I am building a header.

[solidsnake11]

Originally Posted by Wally86

Talk about a lack of penetration!

What she said.

[Irace86.2.0]

Originally Posted by Wally86

Talk about a lack of penetration!

Actually, porosity isn't a lack of penetration. It is a chemical reaction between contaminants that are offing gas, or it is a reaction between oxygen in the air and the metal when it is wet/molten.

Originally Posted by solidsnake11

Are we talking about a header for a car or a space shuttle?

It was 12 years ago that I welded it but I remember it because I though man this is going to make a mess but the owner told me to weld it. Like I said it welded fine.
If it welded fine for a person like me that don't back purge and doesn't do hours of prep. Then it should weld fantastic for a more majority person like you irace86.


I also grind the inside of the pipe and polish it after I weld it if I am building a header.

Car, not a space shuttle. I know that because I said this in the last post:

I get that we are talking about a header and not building code for welding for structures or aerospace engineering, but this is basic 101 of welding is to prep the weld.

How did you know it welded fine? Did you inspect the inside of the pipe? If you could see it without a borescope then you could likely have enough access it to use a grinder to remove the coating from the crack.

Again, this is about repairing a cracked header with an internal coating that can be problematic. The video I posted perfectly illustrated how simply not back purging can cause porous welds on the inside (the outside will look perfect), and now if there is also contaminants that will melt and off gases then the welds will surely be compromised. Could they last? Sure, but it is a roll of the dice like running 400+ horsepower on stock rods; weld failure is pretty much guaranteed.

[solidsnake11]

It welded just like mild steel or stainless steel. Maybe the coating shields it like the solar flux is supposed to do?

[Irace86.2.0]

Originally Posted by solidsnake11

It welded just like mild steel or stainless steel. Maybe the coating shields it like the solar flux is supposed to do?

The aluminum portion of Jet-Hot Sterlings compound starts to melt at temperatures over 1,300 degrees F, but thats OK for 90 percent of the applications out there. Cars running heavy loads of nitrous, a supercharger, or a turbo may need to move up to Jet-Hot 2000, which protects metals up to their melting point or 2,400 degrees F (whichever occurs first). The drawback is that Jet-Hot 2000 only comes in dark colors so its not as pretty. But the good news is that Jet-Hot 2000 usually eliminates the need for pricey (and hard to weld and fabricate) stainless steel tubing often specified in high-zoot nitrous or turbo applications.

https://www.hotrod.com/articles/high...amic-coatings/



304 stainless steel melts at 2600 degrees F.

http://asm.matweb.com/search/Specifi...bassnum=mq304a


TIG arc is 11k degrees F. MIG is 3-20k degrees F. Unless you were welding thick headers fast, so you had no penetration then I don’t see how the coating could survive while the metal melted. See pictures in this thread on page three. Poor penetration can happen, even on a crack or seam.

https://www.ft86club.com/forums/show...=140938&page=3

[solidsnake11]

I don't really care about everything your saying. I just know the coated header I welded welded fine.
I built the header on my 2jz corolla out of sch10 ss weld ells 16 years ago, I tried the solar flux but it just made a mess, I only used it on one weld. No back purge either. Just welded ground and sanded inside then polished the outside. I would say 40 hours of work.
The header has yet to crack, it holds a GT4508r up and has a 175 shot and 25lbs of boost. Engine has made ~1100hp on 30lbs car ran 137mph in the 1/8.
I also built the chrome moly chassis and chrome moly wheelie bars. Welded the tubs from .040 aluminum. Laid the carbon fiber up for the inside of the doors and the wing. Built the intake. Built the ecu wiring harness from scratch. Tuned the engine. It was all done in my basement.

So maybe I'm not qualified to say it welded fine.

The car was drove on the streets more than the track. It has a passenger seat and rides like a caddy.

The guy that bought it had to have surgery because of it. He was showing out on the street, put it on the brake, let go of the button, it hooked and pulled the wheels. He wasn't prepared and it messed up his neck. It's violent when it hooks.

[solidsnake11]

https://www.supraforums.com/threads/...in-1-8.603872/

[solidsnake11]

I also almost made a deal to copy my gsxr1000 turbo header I built but I didn't want to take it off and send it overseas.