Welding Tips and Tricks

This was my project over the past few days. Two carts to hold 872 pounds of vacuum pump. Every bit was welded with 3/32 6013 that's been improperly stored for six years. I used my Everlast iMIG 200, in MMA mode, 90A DCEP. It wasn't all pretty, as the flux was unpredictable, but it serves the purpose. I've got another 100 pounds to add in piping and valves, a push handle, and the controller box and it's frame. Then to paint it before bolting the pumps down. Steve S

While I'm not a fan of 6013, and refuse to use it, you did one heck of a job! As to be expected, of course.

Diesel wrote:While I'm not a fan of 6013, and refuse to use it, you did one heck of a job! As to be expected, of course.

Thank you. I didn't choose 6013. It was just what was on hand, and the only operational MIG was tied up with the guys who can't stick weld. Since I'm also a primary electrician on the new shop setup, I made a point of putting in an outlet for my personal machine.

Steve S

Made a little more progress on plumbing up these pumps. I still only have the one pump, but built parts for both as the other one is coming soon.

Here's the pump inlet section with filter: Here it is with the filter housing attached: And here it is installed, with the solenoid-operated check-valve (a standard natural gas valve), awaiting other hand-wheel valves on order for completion. Steve S

Steve,
Wow. I want one of those sintered bronze mufflers!!! I could use it in my purge chamber to really do some argon diffusion. Looks like a good little project for sure.
Jonathan

Superiorwelding wrote:Steve,
Wow. I want one of those sintered bronze mufflers!!! I could use it in my purge chamber to really do some argon diffusion. Looks like a good little project for sure.
Jonathan

I had to do a double take, I've only see the sintered mufflers in 1/4" and 1/2" size!

That muffler has 2" MNPT threads, and is about 5" long. It can handle about 1600 CFM. It's not as fine a filtration as I would have liked, but it will do and the compactness (over the 10" long 1 1/2" FNPT filters we used before) helps keep the cart's footprint small. That muffler is available from McMaster-Carr, as are a full range of sizes from 2" on down to the 1/4" ones we're all familiar with.

Steve S

The solenoid valve (for natural gas) is there to snap shut in the event of a power failure, to isolate the pump from the large volume it's pumping down, so if the pump quits the evacuated space can't suck oil out of the pump and f#@k up the whole works.

I'll be leak-testing my welds on this unit tomorrow. While I expect them to pass, I was not having a good day while welding this one out, and it looks like ass. The second unit I built looks much better.

I'll post up a couple pics when I have all the valves, and the supports in place.

I was blessed not to have to build the control boxes myself, as it's so time-consuming and our electrical contractor is already experienced with them. I only had to attach them, and wire them to the motor and solenoid valve.

Steve S

Steve,
Where did you source the NPT x FNPT Hoke (vacuum probe) valve? I can only find ones that are both male ends.

Len

Braehill wrote:Steve,
Where did you source the NPT x FNPT Hoke (vacuum probe) valve? I can only find ones that are both male ends.

Len

We get those from the Leetsdale warehouse. I'll write a note to remind myself to look for the part #, so you can get them within the company. These are good condition used ones, as the new ones are used in vacuum maintenance at retest or repair.

Steve S

Was just there this morning, it's about an hour down the river from us. I can get the number from our catalog, but thanks.

Len


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Looking good Steve! I've also never seen a bronze muffler that big...

6013 runs like butter, I don't see any issues with what you did at all. I assume your flipping the frame to keep welding flat...vertical with 6013 is not fun.

Braehill wrote:Was just there this morning, it's about an hour down the river from us. I can get the number from our catalog, but thanks.

Len

Good. I forgot to hunt the part #. They are used in every vacuum jacket vessel application I've yet encountered with your company, so should be easy to find. For the LHY trailers, search for the description "V-7". This may bring up two part #s, one is a Key-High valve, and will have a "V-7A" associated with it (as they're used in pairs). The other is the Male X Female Hoke valve. They have a different description for the atmospheric trailers, "VV-something" that I don't recall, but can find for you, if needed.

Steve S

Rick_H wrote:Looking good Steve! I've also never seen a bronze muffler that big...

6013 runs like butter, I don't see any issues with what you did at all. I assume your flipping the frame to keep welding flat...vertical with 6013 is not fun.

I did a lot of flipping, to keep the welds flat, but I did several uphill, and a few tacks downhill. 6013 up is different, but not hard.

You can have those mufflers custom built to almost any size, with any size sintering to control filtration. We were not prepared for the cost of custom pieces when the stock item from McMaster would be adequate.

Steve S

Diesel wrote:While I'm not a fan of 6013, and refuse to use it, you did one heck of a job! As to be expected, of course.

If y'all would quit trying to use 6013 as // " ona them thar dragggin' rodzzz" and hold an arc with the thing you might not hate them so much. You hold an arc and crank it a bit and they'll penetrate. Go head. Up one ten-15 amps from 'normal' and hold an arc.
Drag it when welding a Nascar wing to the ol' lady's 5 color Opel GT. Then it works like a redneck MIG replacement.

For you all in the know, the Asco is energize to open in this application, what you call fail to safe engineering

DLewis0289 wrote:For you all in the know, the Asco is energize to open in this application, what you call fail to safe engineering

Exactly. The pump has a built-in anti-backflow valve, but it's not always reliable. The Asco is redundancy. If the power fails in the night, the valve closes, and the main contactor opens. Neither the valve nor the main contactor can restart on it's own when power is restored; It must be restarted manually. This protects the process from significant vacuum loss, as well as from sucking oil from the pump into the process.

The hand-wheel valves I was waiting on finally arrived, and the first pump is complete, minus some minor bracketing to store the hose used to attach it to it's service, and the paint touch-up coming from doing that. I'll post a "finished product" picture, probably tomorrow. The second pump shipped Wed. morning and I'll probably see it Monday. Round two will go much faster, as they're identical and all the issues were resolved on the first one.

I dislike designing equipment when I don't have all the information on all the parts, so there was some "adapt and overcome", but it worked well, and will repeat well.

Steve S

Finally have one done and tested. When the other pump arrives, all the components are pre-made and it will be (fairly) simple assembly and wiring.

These are hi-res shots, as my little camera ran out of battery, so I'm linking my dropbox locations for them... I won't know if they'll show until I submit the post. [Edit: whaddayaknow? It automatically resized them!]
Steve S

Damn nice job! I am guessing that is an hour meter next to the start/stop, what is a above it? Digital vacuum gauge? Do they need to pull all the way down to 29 inHg ?

Thank you. I was very pleased to have free reign to build it however I wanted it, since I'm the primary user. My design objectives were compactness (our old ones were much bulkier), low maintenance, easy hose and cord stowage, and easy to roll around (the complete pump/cart is right at 1000 pounds). The 3" pipe is mitered 18* to cant it away from the pump because there's a lifting-eye that the pipe would have been in the way of if I'd kept it straight (something no one thought of on the old pumps). If I've built it right, that eye should be at the center of gravity, though I've not tested that yet. (Sometimes, the overhead crane is the easiest way to put it where I want it.)

That is indeed an hour meter. The object behind it is actually just a rubber lined plate (the thermocouple for the vacuum gauge is sticking up behind the mated flanges). The 1 1/2" valve is obviously the main vacuum valve, the smaller valve on the left is for attaching a mass-spectrometer for helium leak detection, while the one on the right is for breaking vacuum using dry nitrogen. The plate is a safety device. The N2 is supplied through the small ball valve behind the tee, while the plate blocks the open leg of the tee. When the vessel reaches atmospheric pressure, the plate drops off, keeping anyone from accidentally creating positive pressure. In a vacuum-jacket, positive pressure in the vacuum space can crush the inner vessel.

You likely can't see in the picture, but the plate is attached to the tee with a small stainless wire, so it can't vibrate off the pump and disappear while it's not being used.

These pumps are capable of pulling to below 1 millitorr, though in our application we rarely need to get below 5 millitorr. While this is still classified as "rough" vacuum, it is almost 29.92"Hg.

Steve S

Rough at 29.92 lol, not going to get much better in our world unless you take it to theory land. Critical processes that require vacuum has no room for "just good enough", PID control for pressure is a snap with a less than perfect vessel. I used to work on vessels that required both pressure and vacuum with large agitators, which of course meant there were two back to back either John Crane or Chesterton mechanical seals rigged in the stuffing box with a 3-4" shaft running through it. This was before the split seals, an issue meant pulling the entire reduction unit to repair. One of those clients you hate, super dick, but payed well and on time, so I was on top of tanks sometimes at 2:00 am doing the work.

The semiconductor industry, research labs, and NASA are three places I can think of that go to medium and high vacuum. We don't have the coin or the need for that kind of pump. There's $25K in the one I built.

Steve S

Yeah!

Those pumps are running all weekend.

We went from sitting on our thumbs to more work than we can handle over the course of three days.

Back in the saddle!

Steve S