Only ever been caught with hot loads 3 times (which i'm thankfull for the experience), where a semi strip of the boom was required to be stripped. But a concept here, i was thinking about the other day...we all know you cant pump the hot stuff through the boom because the fresh stuff will bleed, once its began to set, and air is practically useless.

So, what about this...and dont take this the wrong way say you were on the fringe of losing your pipeline.

Has anyone inserted 2 spongeballs and attempt to pump a hopper of water to push the hot concrete out? (being water doesnt compact, and assuming a healthy pipeline) Any truth to this theory?

I have done that , wash the hopper out ,put 2 sponge balls, fill hopper with water and keep filling, i need 2 hopper fill of water, pump slow, flow it down to about 30%, as it starts  to move , pump on and off, try not to let it get away from you , if it comes out to fast the boom jump up and down 1 to 2 meters. And no end hose!!!! straight out out of boom pipe.

Sounds like a good idea , i think it would probably work!!

Cool ive learnt something!

I had a 28 metre boom doing a pour on my own house, the hot concrete went off, the pumper could not move it with air. It took me 45 minutes to get there with a 5 inch blowout plate with a fitting to connect to his 2,500 psi waterblaster. By the time I got there the mud was 2 hours old. We reverse blew it with one sponge and the water. Pressure went to 1,500 psi, then the mud started to move an inch at a time, pressure would drop to 1,000 psi. Very shortly the stuff moved very slowly as the blaster output was only 5 gallons a minute. We got the mud to the last 45 between the deck pipe and 6 x 5 reducer. Mud stopped, water was then past the ball. We then put another ball in and blew with air the normal direction.

We now offer the water blaster blank plates. Pumpers are instructed to reduce the unloader pressure to 500 psi then increase as required. As 90% of all our line pumps and booms are fitted with water blasters, the item is a hot seller.

The safest, and maybe the best way to deal with a boom party is to strip the elbows off of a boom and hook up a pump with a good, tight cutting ring & wear plate to the straight pipes.

This pump is full of water……… but you always have a certain amount of air in the combined system unless you can figure out how to hook the system together under water.

Since there IS that air still involved, care must be taken to keep the area clear as it will not be possible to use a “catch basket” for the 5” test cylinders and ball that will come out of the pipe.

This will give you a way to exert the full 1000^psi or 1300^psi or whatever the piston face pressure is on the pump that is doing the pushing and not the 100^psi or 150^psi that your air compressor is giving you.

THIS IS NOT A SAFE PROGRAM UNLESS IT IS IMPLEMENTED BY COMPETENT PEOPLE AND IN A CONTROLLED AREA.

Unless the concrete in the pipes is as hard as woodpecker lips this program usually works. If it doesn't, you had better have a good high-pressure washer. ;~)

PS

Don't waste time trying to push the crete through any elbows. Clean them separately, by hand.

NO ELBOWS - NO HOSES on the end. Straight pipes ;~)

Bob, we did not remove the boom bends, the water blaster on our pumps are set at 2,500 psi, the mud started to move at 1,500 psi and because the water blaster is such low flow and a constant pressure the mud was "extruded" around the bends and when it was coming out the 5 inch line through the 5 x 6 reducer it ended up being a 6 inch slug. The point is that if all pumps supplied with a water blaster had the blowout in their cabin, the operator could in an instant blowout a hot load. 90% of new pumps sold here now have water blasters and 100 gallon water tanks. They clean up faster and use less water.

The best time to remove hot mud is when it happens, one does not always have access to another pump. 

 I have done that also. I did it on a job that required the pump to blow out and wash up in order to change mixes (Hwy.2 tressel, State job). Since I was able to wash out right where I was set up I'd stretch the boom out, drop the hopper, insert 2 sponge balls and fill the hopper with water to blow the boom. The contractor loved it because they could use all the mud in the boom and it saved alot of time. It became the daily routine.

  I have also used a line pump to save pipe from becoming fence posts, but like Bob said "It's gotta be tight"! It works best if you hook the pipe directly to the assend of the pump with reducers. If it's a small line pump you can switch it over to piston-side to get more pressure.

We water push to empty line pump system all the time. Takes lots of water is only problem.  Wash out hopper then open line to insert ball.  Complete control of flow and contractor gets all but a wheelbarrow of mix.

i lost the pumps one time and had a cylinder full of concrete. it was seven days later and we backed a pump up to the one with concrete and flipped both 6 to 5 reducers over and hooked them up. we filled the hopper with water and took the dog bone off. it a bit to get the seven day old concrete moving but we did it. we pushed it into the water box and chip it.

we had a operator come back with all pipe hard . pump was only 2 weeks old took all the pipe off and kept it . for what reason I did not know at the time . do now figured out a way to drill the hard concrete out. saved all the pipe .