Can anyone explain this?

Approx 150m into the line, sheared completely yesterday afternoon. Pipe thickness was checked in February and all acceptable etc. It hasn't actually sheared on the weld, its sheared through the bend itself. Never seen anything like this before, happened to anyone else?

with such a long line the pipes will always start to move/settle a bit when pumping. Specialy if you don't secure it very well with wallbrackets etc. That way you can get unwanted forces on your elbows.

What kind of pump are you using?

Were using a Schwing 3500, with a 2800 as a back up if things go wrong!

Not sure of the pressures its being pumped at, but its only pumping slowly as supply is awful so we try to keep the concrete in the line moving for as long as possible until we have a wagon on site for a straight switchover.

I would understand a clamp blowing or even blowing on the weld, but the bend shearing like it has is very strange IMO.

I have done quite a few high rises and long line pours. I have found from my experience that when I break something, it is for two reasons. 1) The pipe was super thin and couldn't hold the pressure and broke there. 2) Mechanical loading. (I have broke almost everything due to this.) If you get the pipe line moving, it is only a matter of time before something gives. I have broken bends the same way that you have. I have done two different things to fix this. I have purchased Conforms .500 wall bends to give me a stronger bend. I have also made thrust blocks around the bend and used restraints to control excess movement. Think back, was your line moving in this area? Did you see a lot of flexation in the line near that bend? I would guess that this was the issue.

I also just noticed that you are using metric pipe as well. Metric pipe ends cannot handle the pressure of HD ends. Check the max line pressure on your pump. Metric pipe is rated at 85 BAR. The elbow looks to be a cast one in the picture. Excess movement can still crack the end of the bend and then the mechanical forces rip it off.

All pipes were tested for wear in the walls in february and all passed with flying colours, so wall thickness wasn't the issue here. All pipes are bought direct from Schwing UK and is approx 9 months old..

Remember Lewis?? When you where getting started with this project I saw the way you guys where suporting the line and made some comments about it. I even tried to sell you some heavy duty wall brackets because the line was just laying on some pins at that time. I am quite sure this bend broke because of movement causing tensions in the line.

Are you guys almost done pumping through this line or is there still a lot left to do?

Just wondering.. How easy was it to get a new bend in place where the busted one was? If it just slid in place without any problems then I am probbably wrong but if it was a fight to get it to fitt then you might get the same problem again.. Just my thoughts..

And indeed these pipes are not made for the pressure your pump is producing. With that pump you should have high pressure pipes which are A LOT stronger than what you use now. Ok when you pump slow it might not reach 85bar  but a small blockage or starting up after a longer stop and the pressure might shoot over the 85 bar and thats not good..

To be hones I wonder who sold you that pump and then delivers you these pipes to go with it

Not sure how modern your pump is but on the modern pumps you can set a maximum pressure. You could try to figure out if your pump also has this option..

Dipstick,

Thanks for the response. This is another project I am working on, the old project with the 1.3km of line went smoothly without anything like this happening.

Its an interesting point with regards to this 85bar pipeline, and something I will now investigate right away.

EDIT:

Just looked at our spec sheet for the pipe, and it has a working pressure of 85 bar (from new) and a burst pressure of 170bar. Looked at the concrete pressure the Schwing 2800 pump produces and its 106? 

Hey man!! You keep all those nice jobs for your self??

106 bar is to much for these pipes. If its a newer pump with computers you should be able to go in the menu and set the max pressure to 85. If its old you coul switch the hydro hoses on the pump cylinders to 'rod side' but then I believe you will go all the way down to 60 bar and that might be a bit low for your job. You where talking about a 3800 as main pump? That one can go up to 162bar and that is realy not good

We love a challenge ;-)

I'm not entirely sure how they work if i'm honest but if the burst pressure is 170bar, and the maximum pump pressure is 106bar, how would it burst?

You should at least consider going to the HD pipeline instead of the metric. The HD ends are rated for more pressure. The burst pressure is nice data to have but the issue here are the ends and clamps. The ends and clamps will fail before the pipe (when new). It all has to do with the ends. I would also suggest larger bends in your system line. This will help with the surge and movement. I sent you a PM, I can help and Dipstick is also a good source. I would stay away from cast pieces in your system as well.

You are really unlucky. We just sold a load off practically new HP system including loads of bend in all size and shape for a ridiculously low price.. Been trying to sell it for months but didn't get any interested. If you just would have asked me

The HD ends are also more likely to be of a higher quality and not sourced from a lower quality factory due to the lower volume using HD.  Buying the Con Forms Hevi Duty system for high pressure or high rise is going to save you in the long run.  You won't wear out the elbows near the end, they stack better for high rise applications, allow for higher pressures and are built in the US.

Conforms pipe is poor as well, trust me I know. Pipe producers have no concern regarding quality, pipes are hand welded while water quenched which inveriably leads to issues.

If you think all pipe is the same and Con Forms pipe has "no concern for pipe quality"?  I question your experiences.  Do you have any specific reference or incident?  No one is perfect in building anything but you should make a trip to Port Washington, WI and see what goes into making the Con Form pipe and elbows versus the crap coming in from overseas.  And their purchase of Esser had nothing to do with manufacturing the highest quality pipe in the world?  No one makes a higher quality product in the world than Con Forms and Esser.  And they are constantly striving to improve as well.

Elbow only as good as the pipe before and after it!