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  1. #51
    Join Date
    Mar 2009
    Location
    Hazelwood Mo USA
    Posts
    462

    Default

    This a link to the Pasivation of stainless steels http://www.google.com/search?sourcei...tainless+steel

    I just googled passivation of stainless steel, there is some good reading there on the reasons for it improving corrosion resistance etc.......

    Our tanks were always passivated when any welding was performed on them as well. The article I read dealt mainly with machine parts.
    mike sr

  2. #52
    Join Date
    Mar 2007
    Location
    Deltaville, VA
    Posts
    2,239

    Default

    Pop,

    Understand fully the need for "light" (shade 8 or so).

    I'd been using an older Miller BWE for the last couple years. Mine was the non-digital and only went down to shade 9.

    When I ordered the Dynasty, I went ahead and ordered a new BWE Digital. This helmet is a "substantial" improvement over the older design. Goes to a shade 8 and has yet to flash me. The older BWE had done that a few times at very lo amps. The overall adjustment range of the BWE Digital is also a big plus. I've been using it in the grinding mode for cutting with the plasma. Uses the same headgear, but I swear it feels more comfortable.

    They're not "inexpensive" hoods, but I've always felt that quality gear to protect the eyes (only get one pair) was cheap insurance. Being around the water as much as I have over the years, I never skimped on eyeware. Always used the best optics available. It's paid off.

    Good luck with those other 30 pieces.
    Syncrowave 250 DX Tigrunner
    Dynasty 200 DX
    Miller XMT 304 w/714D Feeder & Optima Control
    Miller MM 251 w/Q300 & 30A SG
    Hobart HH187
    Dialarc 250 AC/DC
    Hypertherm PM 600 & 1250
    Wilton 7"x12" bandsaw
    PC Dry Cut Saw, Dewalt Chop Saw
    Milwaukee 8" Metal Cut Saw, Milwaukee Portaband.
    Thermco and Smith (2) Gas Mixers
    More grinders than hands

  3. #53
    Join Date
    Mar 2009
    Location
    Hazelwood Mo USA
    Posts
    462

    Default

    Sundown,

    I looked at the MWE hood, may try that one as well, mine are Speedglas, 20 years old and fixed shade 10, the other one is newer and is vari shade 9 thru 12, both have the sensitivity control but do flash me occasionally if the sensitivity isnt set just right.

    I would like the auto on as I still forget to turn mine on!

    I started this tuned pipe thing on a whim just to see if I could do it, it is causing me to be busy in my retirement years, and to be buying all sorts of new equipment ha!! I guess that isnt all bad??

    We had problems with brine (calcium cloride) lines at the dairy as well, the fix for that in their case was fibercast lines- epoxy resin composition. The problem came about due to the removal of the additive to the brine that kept it from attacking the stainless parts, due to an FDA ruling. No matter how good the weld was it would eat thru it in about six weeks, shorter time if welded too hot or the gas coverage wasnt exactly right etc.
    Point being is that when stainless is welded you loose some of the corrosion resistance.
    mike sr

  4. #54
    Join Date
    Oct 2007
    Posts
    2,949

    Default "Sensitization"

    Point being is that when stainless is welded you loose some of the corrosion resistance.[/QUOTE]

    One of 2 problems associated with welding austenitic stainless. Sensitization of the HAZ, and hot cracking of weld metal.

    Sensitization leads to intergranular corrosion in the HAZ, and is caused by chromium carbide formation and precipitation at grain boundaries in the HAZ.

    Welding naturally produces a temperature gradient in the steel. A narrow zone on each side of the weld remains in the sensitizing temperature range for sufficient time for precipitation to occur.

    It can be reduced by rapid cooling, chill bars, skip welding, etc., or sometimes use a more stabilized grade like type 321 or 347.

    Dave
    "Bonne journe'e mes amis"

  5. #55
    Join Date
    Mar 2009
    Location
    Hazelwood Mo USA
    Posts
    462

    Default

    Dave,
    I have always heard that if the weld area is kept over 900 degrees too long the carbides precipitate out along the edges of the weld.
    What you are saying makes sense, I made some welds with a gas lens, very well purged, weld heat just right and travel, the weld was a gold color with no carbide precipitation along the edges and the welds still ate thru, it took longer but still happened.
    The fix for it in the presses was Titanium plates, they seem to be impervious to the corrosion but were very costly.....
    I think maybe the pulse welding would help this too, I havent talked to the guys lately to see what they are doing now. The 316 tanks have brine coils in them and welded fittings on these coils, makes one wonder how long those will last?
    mike sr

  6. #56
    Join Date
    Mar 2007
    Location
    Deltaville, VA
    Posts
    2,239

    Default

    Pops,

    Just sitting here laughing at your comment. Know exactly what you're talking about, "working" in our Golden Years.

    I've "sorta" retired twice now. Once from the military at 41, and again, from the yacht sales business at 59. Let me just comment that, from my perspective, retirement is not all that it's cracked up to be.

    I weld now mainly to maintain proficieny and help friends out. My shop is at a marina service yard and the owner is a good friend of mine (I actually hired him in 1992 to run my yard). I do his welding and custom woodworking which has worked out well for both of us. He does not have to have a major capital investment in the equipment nor keep qualified help on the payroll during our off season. Frankly, most of what I make doing the welding/woodworking, over the last couple years, has gone back into upgrading equipment. Always seems to be that "latest and greatest tool" that I just have to have.

    I've welded a lot of aluminum and SS over the years. The last couple of big SS jobs were somewhat humbling. Involved replacing the bridge railings on a couple of imported trawlers. Combination of poor material (Chinese SS) to begin with, and botched mig repairs, made the jobs very challenging. Got them done, but ended up taking at least twice as long as I originally thought. Actually got a call over the weekend(referal from the first owner) from another trawler owner, that wants me to look at replacing all of his aft deck railings. I'll swing by and take a look at that this week. Probably will put it off til fall if the owner's agreeable.

    Let us know how those settings (SS + hi PPS) work for you.
    Syncrowave 250 DX Tigrunner
    Dynasty 200 DX
    Miller XMT 304 w/714D Feeder & Optima Control
    Miller MM 251 w/Q300 & 30A SG
    Hobart HH187
    Dialarc 250 AC/DC
    Hypertherm PM 600 & 1250
    Wilton 7"x12" bandsaw
    PC Dry Cut Saw, Dewalt Chop Saw
    Milwaukee 8" Metal Cut Saw, Milwaukee Portaband.
    Thermco and Smith (2) Gas Mixers
    More grinders than hands

  7. #57
    Join Date
    Oct 2007
    Posts
    2,949

    Default Carbide Sensitization

    Quote Originally Posted by popspipes View Post
    Dave,
    I have always heard that if the weld area is kept over 900 degrees too long the carbides precipitate out along the edges of the weld.
    What you are saying makes sense, I made some welds with a gas lens, very well purged, weld heat just right and travel, the weld was a gold color with no carbide precipitation along the edges and the welds still ate thru, it took longer but still happened.
    The fix for it in the presses was Titanium plates, they seem to be impervious to the corrosion but were very costly.....
    I think maybe the pulse welding would help this too, I havent talked to the guys lately to see what they are doing now. The 316 tanks have brine coils in them and welded fittings on these coils, makes one wonder how long those will last?

    Yes: Between 800-1600 degree range. 301 and 302 grades have a maximum carbon content of 0.15%, whereas 304 has a max of 0.08%.

    ELC (extra low carbon) or stabilized grades aid in reducing carbide sensitization (304L, 308L) having 0.04% max carbon content, and are often used for weldments operating in corrosive conditions, as well as "Moly" grades (316,L,-17,L-D319).

    Dave
    "Bonne journe'e mes amis"

  8. #58
    Join Date
    Mar 2009
    Location
    Hazelwood Mo USA
    Posts
    462

    Default

    Sundown,
    I dont care for retirement either, it was OK for about six months, then I had to do something. My son uses the shop for his modifiying his motors, I did make some of his hardware but we farm that out to a CNC shop now. I limit my machine work to some R&D and small odd parts I need, or for the dairy.
    My shop has AC, Heat, is attached to my house, about 30 feet from the nap chair and the computer........... What more could a guy ask??
    I tigged for a dairy and one of our parts suppliers, the dairy sold out after 21 years and I tigged full time for almost 20 years.
    The last five years I spent working on tanks and piping for an asphalt plant, I loved the lincoln 5p rod, and the Miller Trailblazer 251........

    Dave,
    You are a wealth of information thats for sure, Im not much of a metalurgist.
    I learned something recently about platings or coatings on steel causing Hydrogen embrittlement and causing the parts to crack or break, that was a new one on me.

    this is a link to some of the video's of one of my other hobbies:

    http://www.youtube.com/profile?user=...rs&view=videos

    I believe the seventh video is of one of our engine pipe combo's in action.
    mike sr

  9. #59
    Join Date
    Mar 2007
    Location
    Deltaville, VA
    Posts
    2,239

    Default

    Mike,

    You got me laughing again.

    My shop is at a marina about .4 of a mile from my house. Same as yours except mine's air conditioned in the winter and heated in the summer.

    Seeing your hobby photos brings back good memories. Started racing outboard hydro's when I was about 6 yrs old. (8' three point hull w/ a 7 1/2 HP Wizard (Western Auto Brand). At 9 I moved to inboard hydros. Drove the 90 Cu In, 165 Cu In, and 225 Cu In boats til we got factory sponsorship from OMC in '59. Drove for them til '67 when I volunteered for the draft. Probably a good thing. Engine technology was developing a lot faster then than was hull technology. Some of the hulls back in those days had a mind all their own. They'd blow over on you even if you did everything right. Was probably a lot safer stepping out the door of a hi-performance aircraft (C 141) at 35,000' than I was in the cockpit at 120 MPH.

    Bet those scale boats can be a lot of fun. Probably just like any other boat though. Hole in the water you keep pouring money into. At least the fuel cost is probably less than I'm used to.
    Syncrowave 250 DX Tigrunner
    Dynasty 200 DX
    Miller XMT 304 w/714D Feeder & Optima Control
    Miller MM 251 w/Q300 & 30A SG
    Hobart HH187
    Dialarc 250 AC/DC
    Hypertherm PM 600 & 1250
    Wilton 7"x12" bandsaw
    PC Dry Cut Saw, Dewalt Chop Saw
    Milwaukee 8" Metal Cut Saw, Milwaukee Portaband.
    Thermco and Smith (2) Gas Mixers
    More grinders than hands

  10. #60
    Join Date
    Dec 2007
    Location
    Oklahoma
    Posts
    705

    Thumbs up

    Quote Originally Posted by popspipes View Post
    The small stainless tube was a bear to weld for me as it gets too hot too quick, I liked the 1 1/2" up to 3". Most all of the tubing I did was fusion welded (sanitary weld), cant think of the word for that now?
    It makes me wonder what it would have been like with the Dynasty type machines, some of the foreign stainless was a bear to get penetration. I liked to use Rath tubing and Ladish fittings (USA made) but that is a thing of the past now as even Ladish fittings are foreign manufactured now.........

    I used angle grinders fitted with the Three M wheels for cleanup, the 2SFN was good for tarnish removal, the 5ACRS was closer to the tubing finish.

    The salt water on those handrails will cause them to surface rust some, we used a nitric acid rinse for tanks to "passivate" them after welding.

    I had a special pair of reading glasses made, 4.0, those are working well for me so far. The steel pipes are a challenge, but they can be done.
    I need a new auto darkening hood that goes to shade eight as light is a big factor as the current goes lower.
    Autogenous may be the word you are looking for.

    Griff

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