Plastic welding

rrlund

Well-known Member
I bought one of those air/electric Chicago whatever you call it plastic welders to weld up a poly sprayer saddle tank. I got the assortment of rods too. I pulled another old tank out with a piece broke out to practice on. It had a piece broken right out,but it was there,so I welded it back in.

Question is,which type rod works on that poly plastic? I'd think the green PP?

I tried the gray PVC,it turned black and looked like a pile of coon crap. The white ABS didn't seem to want to melt,but the green seemed like it melted too easy. I ended up just taking a clean screwdriver and kind of kneading the pieces of tank together and then smoothing it out. Then I layed a piece of the white in it and tried to melt it and push it in with the screwdriver. It's just kinda laying there. I didn't put any water in it so I've got no idea if it'll hold.

The temp control on that thing goes up to 12,I tried it on 8,then turned it down to 6. I had the air regulator set as near 4 pounds as I could tell on the guage. That poly is probably 1/4 to 3/16ths inch thick.

I'd just like to get it right when I try on the tank that I don't want to mess up.
 
Plastic is not user friendly aka you have to use the poly rod on poly and the abs on abs and so on. You cant mix and match. Ive got over 25 yrs in plastic injection molding and have about seen it all. It just doesnt mix.
Good Luck
Lester
 
So is the PP (polypropolene) what that sprayer tank is made of do you think? I'm no expert in this stuff by ANY means.
 
I fixed my tank with a gas tank repair kit from the parts store, and then covered it all with silicone.
 
I fixed a big crack in it with fiberglass repair,but I've got a small one that just won't seal up.
 
(quoted from post at 14:46:46 05/30/13) So is the PP (polypropolene) what that sprayer tank is made of do you think? I'm no expert in this stuff by ANY means.

Google "identifying plastic for plastic welding" and you will get a ton of websites that will show you how to figure out what your tank is made of. Its impossable for us to ID it without being in front of it. You could try to contact the company that made the tank but things could have changed and they are now using something different, and thats IF they can/will tell you.

The ABS plastic is unlikely to do anything except contaminate your repair, if its removable you may want to take it off right now before it messes things up.
 
The test for the type of plastic is to snip a small piece and burn it with a match.Polypropylene burns with no readily visible smoke. ABS burns like an acetylene torch with oxygen cut off. Vinyl- blue green flame. This is used to identify car interior plastics to order the type of paint needed.
 
Doesn't leak a drop.
a117230.jpg
 
Most sprayer tanks are polypropylene. The only alternative I know is glass fibre reinforced polyester, which is discernable by its textured surface.
HTH, Hendrik
 
It used to have a decal on it with a parrot on it and said "Poly",that's all I know. It's a Century,definately not fiberglass.
 
Only trouble is,on mine the crack is down in a 90 degree bend,then turns back in 90 degrees the other way.
 
It should be engraved in the tank within the arrow trangle if it is marked.

Your tank could be high density polyethylene or polypropylene. The two are not really compatable.

You tank does not have to be marked but could be.
Symbols for plastic
 
I used the green PP on it today. It seemed to melt at the same time as the parent material. I used a screwdriver and pushed it in to the crack,in and up a little at the same time. Looks pretty smooth,relatively speaking. I let it cool and filled it with water. So far so good. I just hope it doesn't split out in the field or on the road with a load in it.
 
Actually yes. It's right in the grove where the top "hold down" or whatever you want to call that part of the frame sits down on it. That bolts to the lower saddle. After I filled it,I whacked on that square tube frame til the pressure pushed the tank all the way out against it.

Still keeping my fingers crossed. I left it full tonight. I'll see if it's still above the crack in the morning.
 

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