First, the bad news. One of my Boatamalan fairing crew guys died last Saturday morning. He was 29. Went out for beers with buddies after work the night before. Had 7~8 over the course of 6 hours…got home around midnight. At 4:30am, he called his buddy to say he wasn’t feeling well and wouldn’t be going to work. He went back to bed, but at 6:30am when his wife nudged him to wake him up…he was gone. Stone cold, but without ever having had any kind of health problems. Gus was the brother of my painter, and when we painted the boat back in 2013, the lead painter was up on the scaffolding to paint the top portions of the hull while Gus was below spraying near the chine at the bow. Gus flowed out the Awlgrip paint really well, and he was friendly, helpful, super hard worker…a good man. It’s too bad he’s gone…the second death of the year that’s affected me. 29-years old…I still can’t believe it.
With that said, at long last, I finally started welding my exhaust risers together. I tacked the risers together in July 2016 then learned that I need to purge the air from the inside of the stainless tubing before welding. Failing to purge causes oxygen to react with parts of the stainless alloy, which turns it into a crusty black crystaline form on the inside of the tubes that’s prone to rapid corrosion degradation. To purge the air, I need to have a dual regulator that can attach to my one 80cf tank of argon. They make dual regulators that sell for ~$100 and up, but I figured I’d save a buck or two by just using pipe fittings I’ve already got and adding a second el-cheapo regulator off of ebay.
Turns out that was a stupid idea. I should have just bought the off-the-shelf dual regulator.
Eventually I got it all worked out, though, and got to welding.
Don’t worry…the valve is off. I don’t have a vice to work with–I broke mine–so the bottle provides a stable base.
The way I’ve laid out the pix, you might think there was a smooth transition from risking “hurt” to myself by “unassembling” the regulator, but you’d be wrong. The argon regulator on the left in the pic above sells for $7 on ebay, and it’s advertised as having 1/4 npt threads. It was coming from China, so I had to wait three weeks. The weekend after it arrived, I tried to assemble the whole thing but failed. Turns out those aren’t NPT threads at all…they’re M14X1.5mm. After an absurd amount of wrangling with the seller, just trying (but failing) to get them to correct the ad, I got a full refund on it for misadvertising. Then I found an M14X1.5mm to 1/4″ NPT adapter in England and ordered it. Another week gone. When I finally assembled it and attached it to the argon bottle, all of the joints were gas-tight except for the 1/4″ NPT side of the damned adapter. The more I looked at the threads, the more they looked to me like flat threads, not tapered NPT. Two months had gone by getting to this point, and the only options I could think of were to buy a dual regulator and be done with it or break out the Marine Tex epoxy and glue the leaking joints together.
The gold regulator feeds the AlphaTIG, the chrome one feeds the fish tank bubbler at the end of the clear 1/8″ ID PVC hose. The bubbler will act as a diffuser for the gas inside the pipe, which they say helps smooth out the flow, avoid mixing of argon with the air in the pipe (argon is heavier than air), which helps push all of the O2 in the air out of the exhaust pipe.
It was late on that Sunday when I finally got the regulators installed and ready to go…too late to start welding. So I closed up shop and planned to come back the following weekend and get to welding. I spent the whole week “image training” how I’d do each weld, practicing smooth hand movements in the air with my hands holding pretend filler and TIG torch. When the following weekend arrived, I suited up in coveralls, went to the shop, turned on the lights, but when I went to turn on the argon I found it was already on. I’d forgotten to turn off the bottle valve the week before. Checking the gauge, the brand new bottle I’d just bought a week before was down from 1500psi to 500.
Son of a ….
After the Marine Tex had cured and I’d installed it on the argon bottle, I spritzed all of the pipe fittings with soapy water to make sure they were gas tight. But I hadn’t spritzed the main tank connection. So I spritzed it and, sure enough, a bubble started growing out of one spot. It’d been leaking all week long.
Son of a ….
So I got to purging and welding while hoping the bottle would hold out for at least one riser.
I’m using the 1/8″ NPT fitting on the flange as the port for the purge line. As the pipe fills with argon, it’ll push air out the far side of the exhaust.
Argon is heavier than air, so having the purge exhaust near the top of the opening will cause the whole pipe to fill with argon, shoving the air out the slit at the top of the pipe. It’s time to seal up the tape on the flange end and get to TIGging.
I’m not even close to being a pro-grade welder, but I’m not the worst of hobbyists, either. For all of that image training and practicing in the air, I still don’t have that smooth hand that the pros use to the a stack ‘o dimes weld. My welds may not be perfect, but I’m sure they’ll hold it together. Given the price I was quoted to have a set of risers built (>$5,000) and the amount of money I’m into the stainless tubing, flanges, and insulation thus far (~$1250, with plenty of leftover tubing), I still figure it’s been well worth it building my own. The experience, skills, and knowledge acquired alone has made it worth it!
The AlphaTIG has a post-flow function that keeps the argon flowing after I stop welding. The dial goes from 1 to 10, and cranking that up keeps argon flowing over the hot stainless so O2 in the air doesn’t oxidize the weld. Where you see color in the weld is where I got the piece too hot from traveling too slow. The post-flow wasn’t long enough, and air got to the weld while it was still hot enough to be oxidized. That’s what causes the purple and other colors in the weld area. I realized too late that I the post-flow knob goes far past the 10 mark. Cranking it fully open helped keep argon on the weld, but in the spots where I traveled too slowly and got it too hot, it was disappointing watching a beautiful, light gold colored weld turn purple in spots when the gas shut off.
The little pin I welded to the outside of the tube in the pic above is a short length of 3/32″ stainless TIG filler rod. I put those in a bunch of spots around the outside of the tube where I’ll wrap it with insulation. The pins will help keep the insulation from moving around.
I decided to weld the showerhead plates on both sides, but in retrospect it might have been fine (better, even) to just weld the outside. I was concerned about crevice corrosion if I didn’t get full penetration in the welds, especially inside the water-cooled portion of the showerhead. But the more I think about it, the exhaust will be hot even after the raw water flow to the showerhead shuts off. Any water remaining in the showerhead will drain into the exhaust hose. If no water remains in potential crevices on the backside of welds because the heat flashes it off, crevice corrosion can’t happen. The only time that corrosion could happen is when the engines are running and the showerheads are full of water. I’m thinking that it would be thousands of hours (maybe tens of thousands) before there was a problem. If I ever have to make another set, maybe I’ll just assemble the showerhead and weld the back plate and nozzle plates on the outside.
It was challenging clamping the irregularly shaped riser to my cheapo Harbor Freight welding bench so the outlet at the showerhead was pointed up. Gravity will keep the argon purge in the tube, but the aluminum plate helps with that as well as serving as a heat sink. As I’m staring at this picture now, I’m thinking there was absolutely no reason to weld the outside here. Oh well…what’s done is done.
I’ll have to run to the local welding supply again to get another bottle of argon so I can continue welding the risers together. It’s all good though. And I’ve got to say, even though I can see that my welds aren’t the best, I’m still having a good time doing this part of the job.
Next up in our 1969 Chris Craft Roamer 46 Refit: Welding the Starboard Exhaust Riser