Pump string jammer 4

[itsmoked]

I'm faced with extracting a submersible multi-stage pump whose lift pipe failed about 10 feet down from the top. It's set about 150ft down. I'm thinking I've seen some sort of jamming board that you slide around the pipe string and then as you lower the pipe the weight of the pump string jams the jamming board holding the whole stack against the top rim of the well casing.

Am I just imagining this or does it exist? What's it called?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[1503-44]

See it here?

https://duckduckgo.com/?q=fishing+for+pipe+and+tools&t=brave&page=1&sexp={&iax=images&ia=images

 

[bimr]

You can buy a clamping tool like this:

Link to clamping tool

One time I changed a 120 foot deep submersible residential 4-Inch well pump when the motor had burned out. I made a tripod out of pipe and used a manual winch to pull it up. The well pump was hanging on 1 or 1.5-Inch galvanized pipe. As I pulled up the 20 foot segments, I used a pipe wrench under the pipe union to keep the string from falling back into the whole. While I held the pipe string, I disconnected each 20 foot long pipe.

I also used a pipe riser clamp. While a pipe riser clamp is not as elegant as the clamping tool, a 2-Inch riser clamp is only $6. Depends on how may wells you plan to do.

The well drillers have specialized "fishing" tools that are used if the pipe string breaks.

Link

I would try to carefully pull it out using the wiring cable. If that doesn't work, you may have to contract with a well driller.

Be sure to disinfect the well string with bleach when you re-install.

 

[LittleInch]

Had the pipe broken off or just got a hole in it?

Diameter of pipe?

Is the pipe end under water or could you put a light and camera down there?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Artisi]

Failing the successful use of a recovery tool, at 10ft unless you're in rock or restricted by other means to could dig down to the level where the riser pipe is, cut off the case giving access to the riser pipe.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[itsmoked]

Thanks folks for all the advice! I was amazed by Big's "Fishing Industy" link. Who knew? It was one of those rare moments that happen less and less to old inquisitive engineers; discovering a whole field I didn't know existed.

Here's the day's scoop. Took an ancient 2,000lb ratcheting 2 speed, with a brake, hand cranked, winch up to the site. Used that on a 1/2" safety line that was properly whipped and connected to the pump. We ran that line thru a Lewmar pulley at the top of our 15" double stacked scaffold thru a Prussic knot anchored to the scaffold, with one wrap around the winch drum. Someone tailed the lead off the winch drum.

We promptly extracted 60 inches of the pipe string. This was the very first pipe joint down from the wellhead. It was precisely what I guessed the problem was going to be after hearing they'd had two other riser failures in the past. There had been other show-stopping leaks in the pipe between the pump and the wellhead. Looking in the nearby weeds I'd seen the castaways of a prior failure. They were Sch40 PVC with the standard crap® adapters of the slip-to-male thread type. I expected to see one of them broken right at the incredibly weak problematic thread/slip interface.

Sure enough!

The entire string was 10ft lengths so there were a ton of those gawd awful adapters. Two every 10 feet.

The top joint failed and the pump and the rest of the string plunged to the bottom of the well. Luckily there was that safety line. Luckily the wire and the safety line and the bubbler line and the high and low float lines were all 200 feet long - the well depth. The pump was set at 170ft. We pulled it all using only the safety line.

Every 20 feet we drilled a 3/16" hole at the well-head that drained the twenty feet above us. Then unscrewed the bottom coupling and extracted the 20ft string and unscrewed the joint in the middle. One of them snapped clean off even though we only used our hands to unscrew them. It would've been the next one to crap-out.


I may replace the pump, a Gould 10GS15. However it was new in 2016 - 5 years.
My concern is it was installed with the ground lead unconnected. So I'd guess water has completely run down that wire into the motor area.(?) The other wires we simply soldered and wrapped with some electrical tape.. :/

It also fell to bottom while in operation and sat there running for 16 hours making an in-well geyser.

I also have to figure out what to use for the riser string since there's no way in hell I'd use adapter based sch40 again!

My understanding is that sch40 'Riser' pipe is directly threaded? I haven't followed this up yet. It's also possibly 3x the price.

I may go for threaded sch80 PVC instead, though I think that will reduce the pipe ID slightly.

Maybe one piece of 170ft of poly? Lot to hassle with but no %^@#^* joints.


Keith Cress
kcress -

http://www.flaminsystems.com

 

[1503-44]

The ingenuity of the "fishing industry" is quite amazing.

I have no experience in water well design, but thought this might be useful.

https://www.rcworst.com/blog/Water-Well-Drop-Pipe-Selection-Guide

 

[LittleInch]

SO does the pump normally "hang" directly off the outlet pipe?

A flexible won't normally like that, but PVC is a horrible material if you flex it or subject it to lots of vibrations. And the screwed line and change in section don't help either.

If by Poly pipe you mean HDPE, it has a tendency to creep under constant load.

Some sort of steel pipe instead?

Are there no connectors on the pump for wires to hold it in suspension? Or does it then try to rotate? The operating manual says the pumps have left hand threads...

But I'm sure there are tens of thousands of these around so there must be some fixing tools available



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

They hang on the pipe above bottom, so they don't get buried by sand, etc. below.

 

[LittleInch]

That's kind of what I figured out / remembered, but it puts a degree of torsion onto the pipe every time it stops and starts which won't help a simple screwed together thin PVC pipe.

But then I hate PVC pipes.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Artisi]

PVC pipe is a disaster waiting to happen, use steel pipe and sleep easy at night.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[itsmoked]

Little: Yes they always hang from the pipe.

Sch40 PVC is good for 750 feet with a 40# pump hanging on the bottom though this is for 'drop' pvc pipe.
Steel pipe is good for a couple of thousand feet but is heavy and corrodable. You must also be very careful about the check valve used as they are often the weight limiter.

The power wiring is not to be used for support of any kind though it occasionally saves the day when everything else breaks.

A torque arrestor is used to keep the starting motor from twisting and slapping the wall.

Water proof splices are used on the motor pigtails.





Keith Cress
kcress -

http://www.flaminsystems.com

 

[LittleInch]

Well clearly the pvc pipe used wasn't good for 150ft!

There's a big difference between good for a static load when new and a variable load and torque when 5 yrs old.

Stainless might be expensive but will last for 40 years. You pays your money...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Artisi]

Would think a pump would require replacement or service before steel pipe would corrode and fail, plus if a non-return valve is required fit it on the pump inlet - if on the pump discharge it's only carrying the weight of the pump anyway. Non-return valves on deep bore pumps are a major problem in themselves, and see no reason for having one.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[bimr]

Poly pipe is not recommended over 100' deep.

Not clear from the picture what type of PVC was used for this well, but it doesn't appear to be the proper material. The length and thickness of the couplers don't look right.

PVC well casing comes in 20' lengths which are adequate for your application.

Link to well casing

On deep wells, the installer will drill a weep hole to drain the casing so that the pump doesn't have to start against the whole water column.

 

[Compositepro]

"On deep wells, the installer will drill a weep hole to drain the casing so that the pump doesn't have to start against the whole water column."

That does not sound correct. Centrifugal pumps are loaded by flow, not by pressure.

 

[EdStainless]

Mine hangs from a single piece of some kind of high density resin pipe. All that I recall is that it is very heavy and one piece. The pump is about 140' down in a 175' well. The static water level is about 65'.
The only risk with no non-return is if it is still draining back and spinning the pump backwards when it tries to start again. That will snap a shaft faster than anything.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[Artisi]

For the small domestic type submersibles the easiest way to overcome start up if running in reverse is a time delay unit in the control panel.

A drain hole thru' the casing is for drainage of the column (if no-return valve is fitted) to reduce weight if and when pump removal is required.


It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[bimr]

"On deep wells, the installer will drill a weep hole to drain the casing so that the pump doesn't have to start against the whole water column."

That does not sound correct. Centrifugal pumps are loaded by flow, not by pressure.

"Vertical pumps have air‐filled discharge columns when not running. For example, a well pump is typically submerged several hundred feet and isolated from the pipeline by a check valve mounted at ground level.
When the pump is off, the water level drops to the normal water level in the well and a large column of air collects in the pump column (Figure 1)."

Link

I can verify that I installed a 500 HP submersible in a 1200' deep well and the water drained back. There was a check valve on the pump. There was also an air release valve specifically designed for the application. The pump is not starting against zero head, water remains in the well casing at the depth of the aquifer.

Link

In freezing climates, it is also common to drill 1/8" holes in the well casing below frost depth.

The moment of inertia on submersible well pumps is much less than a normal centrifugal pump because of the smaller diameter shaft. Because of that, the submersibles start much faster than the starting time of a standard centrifugal pump. The power draw on starting is significantly reduced as well.

 

[Valvecrazy]

Glad you got it out. When only 20' down you can use a strong nylon lifting strap tapped to a piece of PVC pipe. Use the pipe to push the nylon strap down and over the drop pipe. I have pulled (fished) large and small pumps this way. When the break is deeper an overshot fishing tool is best. Make sure the wire is pulled up first as it can wedge in the well and prevent the pump from coming out. Same with so called "safety rope". Never use rope or cable in a well, it is just another opportunity for a failure. Stand offs and torque arrestors are also more stuff down a well that is not needed. Use pipe strong enough to hold the pump and you won't need any safety line. Don't let the pump cycle on/off repeatedly and you won't need torque arrestors. never glue any pipe or fittings down a well and n3ever use sch 40 PVC. Sch 80 or sch 120 threaded with metal couplings is best and will go very deep. Pumps have to be very large and very deep before steel pipe is needed. You can also set pump several hundred feet deep on poly pipe as well. Just use long barb fittings and two hose clamps each.

It is much easier for a pump, especially a submersible pump, to start against pressure. Drilling holes in the check valve on the pump is done to keep irrigation wells from freezing in the winter. But it makes it harder for the pump to start. Many of these pumps like in the cotton fields in my area are only started a couple 2-3 times a year. When they are started they run for months at a time. With such few starts the hard start from the pipe being empty is not as much an issue as if the pump started many times a day.

A check valve is needed on a submersible pump to keep it from back spinning. Drilling holes in the check poppet will let the water drain back slowly when needed. The check valve on the pump is the only one needed. Any additional check valves up the drop pipe or at the well head will cause water hammer when the water below crashes into the check above. Keeping the system pressurized with a check valve on the pump and starting the pump against a closed or almost closed valve will greatly reduce the duration of starting amps and can somewhat decrease the amplitude of the starting amps.