It blew up

workinforwood · Mar 12, 2009

I put my molds that took a long time to make into the HF pot. Tightnend the screws down nice and tight as usual. Applied 50lbs and walked away. Not 2 minutes later and boom, the lid blew off.

! 12 ounces of resin everywhere and the molds are junk now because they have bubbly resin partially in them. The lid is perfectly fine, can't see a thing wrong with the lid. The bowl itself is shaped like an egg. Somehow the side walls expanded out. Don't know what happend, but HF won't replace it, I tried that, but the pot is 6 months old and they warrant it for 90 days. Sucks to be me.

rjwolfe3 · Mar 12, 2009

Did you have a pressure relief valve? Did the metal in the tank fail? I hope this doesn't happen often. My Harbor Freight told me the warranty ended as soon as I replaced the hardware with newer stuff on mine so I didn't buy the extended warranty. Man that sucks but I am glad you weren't standing next to it.

Draken · Mar 12, 2009

Wow, glad to hear you were not hurt. Do you have any photos of the aftermath so we can try to figure out what went wrong?

Stick Rounder · Mar 12, 2009

Wow! Sorry. Would love to see some photos. I brought my pot in last night because it so cold outside. My wife would kill me if it went off on her kitchen countertop.

NewLondon88 · Mar 12, 2009

Holy crap!
Glad you were not standing over it.

penhead · Mar 12, 2009

Holy crap that's really frightening....did the hooks that tighten down on the lid to hold it secure come all the way...or loose..?

workinforwood · Mar 12, 2009

There's not really anything to see but a gooey mess. The clamps did not break, and no I did not have a relief valve, but the pressure wouldn't have set the valve off anyhow as it was only 50lbs. The pot didn't blow across the room. The lid is in perfect condition. The bowl broke. It didn't break in half, it elongated and crushed at the same time. Basically if you pick two opposite sides inbetween the clamps, it stretched there and the two opposing sides caved which caused the lid to pop off. The entire pot probably jumped a couple inches as it landed on it's side with the lid off and all the contents oozing over everything. I wiped it all off the counter as good as I could and cleaned the lid off. The bowl is warped out of shape. All I can figure is I need to buy a new pot, then use the new reciept to get a new bowl for free? They don't stock the bowl portion of the pot, it's a 6-12 week order. I tried using a clamp to fix the bowl back to being round, but it won't go, and probably better that it doesn't.

jkeithrussell · Mar 12, 2009

Send Curtis a PM. I bet he can get you straightened out. Or Eugene.

sbell111 · Mar 12, 2009

I think that you should not concern yourself with ways to get HF to replace your pot. Realistically, the moment that we alter the pots to conform to our use, we invalidate the warranty. There is no reason for any of us to expect HF to replace a pot that was damaged by our use.

What I would concern myself with is the cause of the failure. Personally, I suspect that your regulator allowed much more pressure into the pot than you think. Since you had removed the safety valve (invalidating the warranty), the pot failed.

rej19 · Mar 12, 2009

If the pressure guage is bad and there was not relief valve you could have had a lot more pressure that you thought. Is this the first time you have pressurized it? Just a thought.

Whoops somebody beat me to the same thought.

workinforwood · Mar 12, 2009

The pot is supposed to be able to handle 80lbs. I have my compressor itself set for only 60, I have an air dryer set on 60 and the guage on the pot said 50, as I didn't pump it up to 60 which is all I had everything set too. I doubt all three guages are incorrect. I have never dropped my pot either, and I have it marked to always put the lid back on the same spot every time. I took a picture of the now deformed pot. It's tough to see being black and all, but the rivets/weld where the clamps attach on two opposite sides are bent inside the pot. Looks like they where trying to hold on but as the pot bowed out, it pulled on those two sides as they bowed inwards. I have only used my pot about 20 times. I wonder if it might have been slightly out of round to begin with and over time just got worse. It's completely possible that it was defective from day one. Nobody will probably ever truly know. No harm done anyhow.

gketell · Mar 12, 2009

Man I'm really glad you didn't get hurt!

Here's a question and a wild, hairy guess. Was it really cold when you started the pressure and had you completely sealed off the valves?

Since it seems unlikely that the pot would blow at low pressure of 50 psi then how would it get higher? A theory, cold air in a sealed container gets warmed up by the setting resin. Air expands increasing the pressure.

Seems far fetched but so does the pot blowing at 50 psi.

GK

marcruby · Mar 12, 2009

It seems to me there are only three basic sources of the problem - 1) There was more pressure than you thought there was, 2) the resin exploded, or 3) the pot was defective.

Since you've ruled out #1, and theres enough resin still in the pot to rule out #2, I would suggest never buying another HF pot or pouring it a concrete shoe if you do.

Good thing you weren't hovering over the pot when it went.

Marc

jimbob91577 · Mar 12, 2009

Man that looks egg shaped all right - it looks like you broke the yolk...

<Sorry, I had to get that one in>

great12b4ever · Mar 12, 2009

You stated that you had just put in the molds that took you a long time to make, set to 50 lbs and 2 minutes later the pot blew, resin everywhere and molds junk. I have read what everyone else has written, but I have a couple of questions to try to help get to the root to keep this from happening again.

Was this the first time to use these molds? How were they made? were they full cured? I am wondering, if these were brand new molds, if there was some sort of reaction occuring between the mold and resin. Knowing how and what the molds were like would help show or rule out this possibility.

When you tightened the lid down, did you make sure the gasket area was clean and that there wasn't anything laying or setting in the sealing area? If there was something wrong in this area, then there is the possibility that there was an overstress on one or two of the clamps causing a premature failure of the rivets/clamp.

Did you happen to notice if all the clamps tightened smoothly and evenly, or was one or two harder to tighten? If there was a noticeable difference in the tightening of one or two of the clamps, this could lead to an over/under tightening of the clamp that could lead to a failure.

There was one penturner that tried to blow up one of these pots and got it to some pretty high pressures before he had hose or connection failures, but, if I remember correctly, not a pot failure. These pots are designed with a lot more than 20 pound safety factor.

It is possible to have several reasons, all combineing into this one casting episode, such as a reaction with the mold/resin, something not allowing a complete normal seating (sealing enough to allow the pressure to build, but overstressing the clamp/rivets) of the lid to the bowl, an increase in pressure due to temp change, which is not as far fetched as you might think, or overpressure due to faulty gauge(s).

Always have a safety relief valve on your pot and piping!! Remember, this is the only thing that will keep and overpressure situation from developing.
Even your hot water heaters have a safety relief valve!!

dasimm · Mar 12, 2009

Glad your OK.

FWIW - I had a friend who could never get his HF PP to work correctly so I offered to take a look at it for him.

Took me two seconds to find the defects around the anchor points for the lid latches. Upon removing the lid it took me another two seconds to see the pot had been deformed and was no longer in-round. We pulled the gauges and piping and it's now a flower-pot. He got his next pot from Grainger and he has never had an issue with it.

Always check your equipment and make sure you have the proper safety precautions in place. As pointed out - the PRV is a critical piece.

This could have been much much worse.

Russianwolf · Mar 12, 2009

I bet the pot was deformed from the start.

A circle is a very stable shape. As long as the pressure pushes out evenly from all directions it will remain circular.

If you start with an oval, just slightly, the pressure can cause the widest point in the oval to continue to get larger. It may be a very slow process.

So I bet the pot was an oval to begin with, and just kept getting wider and wider as you did cast until critical failure occured.

workinforwood · Mar 12, 2009

I know my pressure was not high because of the three guages and then the fact that my compressor is not very big, and I did not pump air in for very long. I've seen several pots set up nice and simple like mine. The pressure valve might be important, but several people have removed them because they leak, and I know there was not too much pressure for the pot to handle. I oiled the gasket 10 minutes before I poured, as I got the pot cleaned up and ready before mixing my resins..I use alumilite and time is critical, so the pot has to be ready. The lid seemed to go on and clamp down just fine. The bowl of the pot never truly looked round to me, it looked more square round than round since day 1, but that's just what my eyes say. I never measured all the way around or even thought too. I just thought that's what it is supposed to look like. The temp in the shop was 44 when I went in, I turned on the heat to 68, I poured the resin in the same wood molds I always make and use for this particular type of pour and then I poured the resin, so the shop temp was 68 for about 5 hrs before I ever got to the pouring part. I went back in the shop, dialed down the compressor and the air dryer both to 40lbs, filled a spare tire all the way, pulled out the hose, stuck in my tire guage and read 40lbs. The air dryer is empty and the filters are clean and void of water. I think I had a bad pot, or I'm just a crazy maniac pshyco caster!

pianomanpj · Mar 12, 2009

Nothing worse than bad pot... :bulgy-eyes::hypnotized::smile-big:

MesquiteMan · Mar 12, 2009

You mention that it was a simple set up. I guess this means you have never used it for vacuum? I always wonder what effect vacuum will have over the long term life of the pot since they were not made for vacuum.

I routinely use my HF pressure pot at 80 psi and occasionally at 100 psi and have not had an issue with the same pot I have been using for 3 years. Mine is so used that the areas where I tighten the clamps have started wearing thin so I need to replace the pot before they fail. Then again, I have used it thousands of times over the years with no problems at all.

workinforwood · Mar 12, 2009

I'm pretty sure my pot is exactly set up the same simple way as yours Curtis. I know I spoke with you about the setup and saw pictures of your pot which is really nice and simple. Just pressure and alumilite. I can't figure what went wrong other than something must be wrong with the bowl before it all started.

dasimm · Mar 13, 2009

Dunno - I think I leaning towards the psycho caster thing myself. :biggrin:

wolftat · Mar 13, 2009

Jeff, I would not even bother trying to reuse the lid. There is clearly something very wrong with the setup and it needs to be replaced completely. I am having a hard time believing that a perfectly good pot blew at 50#. We cast all the time over 100# with the same setup and no relief valve in site. We have also had a pot up over 200# and it didn't blow, it is not used since the testing but it did appear to be fine afterwards. There is obviously a defect in the pot and you should replace the entire setup and not take the risk of greater damage happening.

You weren't using a pot stretcher to try and get a little more in there? Did you?:biggrin:

NewLondon88 · Mar 13, 2009

wolftat said:
You weren't using a pot stretcher

Oregano? :tongue:

ngeb528 · Mar 13, 2009

workinforwood said:
The pot is supposed to be able to handle 80lbs. I have my compressor itself set for only 60, I have an air dryer set on 60 and the guage on the pot said 50, as I didn't pump it up to 60 which is all I had everything set too. I doubt all three guages are incorrect. I have never dropped my pot either, and I have it marked to always put the lid back on the same spot every time. I took a picture of the now deformed pot. It's tough to see being black and all, but the rivets/weld where the clamps attach on two opposite sides are bent inside the pot. Looks like they where trying to hold on but as the pot bowed out, it pulled on those two sides as they bowed inwards. I have only used my pot about 20 times. I wonder if it might have been slightly out of round to begin with and over time just got worse. It's completely possible that it was defective from day one. Nobody will probably ever truly know. No harm done anyhow.

Maybe aliens swapped it out when you weren't looking. Glad you weren't hurt.

workinforwood · Mar 14, 2009

Oh no worries. The lid looks fine, but it is not. It is warped pretty darn good!!! Amazing what 50lbs of pressure can do, and that's no joke!

Why can't I use a pot stretcher? Would they sell me a pot stretcher if I couldn't use it???

Darley · Mar 14, 2009

Lucky you where out of the shop won't be nice to have 50 PSI in the face, glad you're OK

Darley · Mar 14, 2009

Marc could you explain to me how the "resin EXPLODED"

never heard about this,

Rob if any foreign material is between the pot and the lid it would not cause the pot to explose as the air wil escape from the un-seal lid, resin mould got nothing to do either.

Jeff do the screws from the clamp still have all they threads??, I would sudjest to get your gauge to be checked to see if it's working well and a last thing I put my HF pot out side of the work shop when in use not by security but lack of space:biggrin: got a small shop

workinforwood · Mar 14, 2009

Guage is good and threads on clamps are fine Darley. The pot just looks like I pulled it out of the Laurentian Abyss is all. The stretching and squeezing of the pot caused the clamps to pull right over the lip of the lid. The clamps being pulled over the lip cause the inside where the clamps are attached to the pot to bend a bit. Besides...if my guage was bad, by compressor was set and my air dryer set to only pass 60lbs of air. Also, my compressor is not capable of exceeding 100 lhs of pressure ever. I'd have to hook the pot to my Semi-truck to go higher. And..I just sqeeze the trigger to fill the pot for about 20 seconds then check guage and maybe add a bit more. To pump a pot to 80 lbs with my compressor would take a good minute at least. It's a bad pot. I was in the shop, just not on that side of the shop. The shop is plenty big.

Darley · Mar 14, 2009

Jeff the best thing you can do is to trash the whole pot and get another new one and start again from square one would not event re-used any fittings life is to short to try to save $$$, hope this little incident deosn't deter you to do more casting, we do learn do we.

It blew up

Member

Member

Member

Member

Local Chapter Leader

Local Chapter Leader

Member

Member

Member

Member

Member

Attachments

Local Chapter Leader

Member

Member

Member

Member

Member

Member

Member

Retired Head Moderator

Member

Member

Product Reviews Manager

Local Chapter Leader

Member

Member

Member

Member

Member

Member