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Submersible Well Pump Components (C) Daniel Friedman Submersible Well Pumps Torque Solutions
Stop damage & pump losses due to twisting of the submersible pump

  • SUBMERSIBLE PUMP TORQUE PROBLEMS & SOLUTIONS - CONTENTS: how to stop the pump from unscrewing itself or breaking well piping due to torque or twist forces when the submersib le pump starts and stos. Submersible Well Pumps for Drinking Water Wells - Problems & Repair Advice.
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Submersible well pump torque problems & solutions:

Here we explain how to use a torque arrestor & other methods to stop damage to well pump wiring & piping caused by twisting forces as the pump starts.

This article series describes the components of a submersible well pump water system, how the pump, well and controls work, what the well pump components look like, and what they do. We give submersible well pump troubleshooting advice and invite questions. We include definitions of water well and water well drilling terms, the typical capacity of drilled water well pumps, and we include descriptions of methods used to fish materials out of a water well if you've dropped the pipe, well pump, or tools down into the well casing.



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Submersible Pump Torque Problems: loose connections, damaged piping, damaged wiring, lost pumps & Pipes

Everbilt torque arrester (C) Daniel FriedmanQuestion: how to stop the submersible pump from un-screwing its pipe connections

2016/08/15 Rodney said:

The submersible pump keeps unscrewing itself even after I glued the threaded coupler. I have to pull it out a 3rd time now. How can I make sure this doesn't happen again. Or is there a more serious problem at hand?

It has great pressure and it works great but right about on the 3rd or 4th day the pump quits I'm sure it's the same thing. I'll know for sure when u pull it tomorrow.

This question was posted originally at PUMP PRIME, REPEATED LOSS OF

Reply: Solutions for submersible pump well piping torque problems: unscrewing the pump, piping breaks, wiring damage, casing damage, lost pumps, lost piping.

Rodney:

I suspect that a torque produced when the pump starts is the cause of this un-screwing of the coupler. The rotating torque produced when the submersible well pump turns on tends to rotate the pump in a direction that un-screws the coupling to the drop pipe. The higher the submersible pump horsepower the greater the starting torque or twist motion forces will be.

This same rotating torque can, if the well piping is not centered in the well casing an bore, abrade the well piping ultimately causing it to break or leak. A well pipe slapping around in the well will also damage electrical wiring descending to the well pump.

Finally, the torque imparted by a starting submersible pump can also twist well piping so that that force along leads to pipe breakage, especially when PVC well piping is used.

Approaches to Handling Well Pump Torque Problems

Submersible well pump centering disc and cable guard (C) InspectApedia.com Daniel FriedmanWell and plumbing experts address the well piping torque problem using several approaches. We discuss these in more detail below.

  1. Keep the well piping centered in the well using spacers like the well pump cable protector shown here. This helps avoid pipe and wire abrasion damage.
  2. Use a torque arrestor at the pump and at intervals on well piping. Depending on where you live, local plumbing codes may require the use of torque adapters on submersible pump installations.
  3. Use welded pipe sections and metal piping to resist pipe breaks and damage
  4. Watch out: If your pump is short-cycling for other reasons such as a waterlogged pressure tank, starting more often than needed, the torque problem will be multiplied, increasing the risk of repeated breaks in well piping.
  5. For high horsepower submersible well pumps, use an electrical controller that slowly spins-up the submersible pump motor to full speed.
    Watch out: some spin-up controllers may, however, cycle so frequently that that system may itself damage the well pump motor shaft or well piping.

So, Rodney, you may have to use welded iron pipe to resist pipe breakage due to torque forces.

But in the photos above and below I'm showing another possibility that will work on some submersible well pump systems: a rubber pump torque arrester produced by Everbilt (and a number of other suppliers too) and sold at plumbing and building suppliers.

This photo was taken in a New York Home Depot store where the Everbilt Torque Arrestor sells for under $15.00. The part number is 1001 098 335. Everbilt torque arrestors are made in Canada and sold across North America. Similar products are sold in other countries.

This rubber torque arrestor device attaches around the well piping and then is expanded so that its rubber rib is just snug against the interior of the well casing.

Rubber well pump torque arrestor assembled (C) InspectApedia.com DJF The torque arrestor, by pressing against the well casing sides, is designed to absorb and dampen the twisting torque motion imparted by the submersible pump at the start of a pump-on cycle (a similar force may occur at the end of a pump on cycle too).

The rubber torque arrester shown fits inside of well casings from 4" to 8" in diameter. Below we show the submersible pump torque arrestor assembled.

Some wells may need multiple torque arrestors depending on well depth. Here is a slightly edited version of what Merrill Manufacturing™, a manufacturer of torque arrestors says about installing these devices:

The first torque arrestor should be placed no more than 3' above the pump, near the bottom of the well. Use additional rubber torque arrestors at intervals of 75' to 100' along the rising well pipe above the first torque arrestor.

Place the torque arrestor around the drop pipe so that each half is spaced evenly. Install the lower pipe clamp and tighten. Install the upper pipe clamp (leave loose) and then push down on the torque arrestor to spread the center portion so it fits the inside of the casing. Just a snug fit, do not spread it so much that it is hard to get it in the casing.

Then tighten the upper clamp. It is very important that the upper clamp is as tight as possible. This will make it easier to remove the pump at a later date. - source; "Torque Arrestor Installation", Merrill Manufacturing, 315 Flint Drive PO Box 392 Storm Lake, IA 50588-0392 800-831-6962 retrieved 2016/09/22, original source: https://www.merrillmfg.com/product/torque-arrestor-installation

Watch out: don't spread the torque arrestor so that it fits more than just snug in the well casing or you may later have trouble inserting or removing the well piping from the well.

Really? Some plumbing experts gripe that these torque arrestors don't work well and cause trouble later when you are pulling well piping. Also, bits of debris, gravel, sand, rust flakes falling down the well bore and resting on the upper rim of the torque arrestor may cause it to jam in the well casing.

A second function of the torque arrestor is to keep the well piping centered in the well. This can be a problem if the well bore is not straight or if the well piping flops around in the well casing when the pump starts. Other devices are sold for centering well piping: you don't have to use a torque arrestor just for that purpose. All well experts do advise, however, that you use centering spaces to keep well piping centered in the well casing. Otherwise movement of the well piping in the casing is likely to lead to wear, piping leaks, and possibly well casing damage.

In deeper wells or with heavier pumps welding the pipe connections may be required to manage pump torque.

Here is what Franklin Water says about pump torque:

During starting of a submersible pump, the torque developed by the motor must be supported through the pump, delivery pipe or other supports. Most pumps rotate in the direction which causes unscrewing torque on right-handed threaded pipe or pump stages.

All threaded joints, pumps and other parts of the pump support system must be capable of withstanding the maximum torque repeatedly without loosening or breaking. Unscrewing joints will break electrical cable and may cause loss of the pump-motor unit.

Now for the kicker:

To safely withstand maximum unscrewing torques with a minimum safety factor of 1.5, tightening all threaded joints to at least 13.57 N-m per motor horsepower is recommended (Table 2A). It may be necessary to tack or strap weld pipe joints on high horsepower pumps, especially at shallower settings. - Source: 50Hz Submersible Motors, Application, Installation, Maintenance [PDF], Franklin Electric Co, Tel: 800-348-2420, Retrieved 2016/08/15, original source: franklinwater.com/media/123156/50_HZ_AIM.pdf

Article Series Contents

We introduced the different types of drilled wells and bored wells
at DRILLED WELLS, STEEL CASINGS. This article discusses submersible in-well pumps - those water pumps located within the well bore or casing itself, typically close to the bottom of the well.

Rather than an in-well submersible water pump, other wells use a one line or two line jet pump (depending on well depth) - in those wells the pump is above ground rather than in the well. Those well types are discussed in more detail at
WATER PUMP, ONE LINE JET used in shallow wells
and
TWO LINE JET PUMP used in deep wells

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