1000m Vertical Pipeline 4

[stanier]

A project on the drawing board features a mine dewatering facility. The pumps at the base of the mine will pump vertically up to the surface into a tank.

It is proposed to use victaulic couplings of the high pressure variety. Supports will be rockbolted into the wall.

Please comment on the following rationalization.

There is a concern that the tolerance in the groove of the coupling will allow the pressure thrust to be transferred to the supports. These forces should be balanced either side of the support apart from the mass of the pipe & water. It would only be a problem if there was a pipe burst and the unbalanced forces would shear the support.

Thermal strain is yet to be determined as the mine temperature is to be assessed.

Have you any direct examples of this type of installation?

 

[zdas04]

A few hundred thousand gas and oil wells go to 1000 m and deeper. You might learn something from them. I would treat this project like an oil well and use oil field fittings (not Victolic) and oil field pumps.

David

 

[micalbrch]

I recommend to start this thread again in one of the Mining Engineers forum. Mine dewatering is a standard application in underground mines and the colleagues there should have plenty of experiences what pipe couplings are used and what are the risks (if any).

 

[dcasto]

zdas has it right. Either 8 round threads or welded pipe. Then let the pipe hang, use a stabilizing ring around the pipe that allows verticle movement and minimal side to side.

Couple the pump discharge to the pipe with a flex hose to isolate vibration and pipe movement.

 

[stanier]

Thanks for the feedback. I respect what you say and will investigate.

Unfortunately the customer has procured the pipe and couplings. My role is to certify what is an inadequate design.

The use of oil & gas techniques may have problems with code compliance as the nominated code is a process piping code.

From the safety aspect the pipe is in the mine shaft and thus needs to be considered differently to an oil well. The latter are installed in a bore . If they fail they do not present the same safety issues. I have already canvassed the idea of a separately drilled bore to the pump station to avoid safety issues.

 

[micalbrch]

Sorry decasto but are you sure about your recommendation? Do you know what pumps are used for mine dewatering for a 1000 m vertical head and a SG > 1.0? We are talking about minimum 1450 psi discharge pressure of slurry if one pump is used (and that's how I understood this thread). Pipes must be properly fixed and a flex hose on the discharge side... I don't know if this is the best way.

 

[BigInch]

I'd give you another star if I could.

**********************
"Being GREEN isn't easy" ..Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.live.com/

 

[zdas04]

This is called an "easy" pumping job in my world. I'd use a downhole pump like an ESP or PCP, with Oil Field jointed tubing (the added safety concerns above are a red herring--most wells have tubing free-floating within casing, and failures not related to rod wear are fairly rare and tend to be leaks rather than blow outs). Pressures mentioned above are pretty normal for wells.

If you just must, then you could run a large diameter conduit (maybe spoolable composite pipe?) and drop your pump and tubing inside of it. This is a really easy application if you don't lock yourself into dumb.

As to "nominated code", a person nominated it, that choice was not divinely ordained. If you are locking yourself into sub-optimal choices because of that then you have a truly sad operation.

David

 

[BigInch]

I've pumped oil, gasoline and jet fuel out of storage caverns using API 5L pipe, welded fittings, WNRF flanges on the pumps, no hoses, and pipe clamps rockbolted to the wall, but not using victalic couplings, so I don't know what to tell you about those. I think the question was about the victalic joint clamps, right?

**********************
"Being GREEN isn't easy" ..Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.live.com/

 

[cvg]

what is the tolerance in the grooved pipe / vict coupling? How many joints of pipe? How widely spaced are the supports? What is the total movement which could be expected if each pipe moved? How much movement would be expected at each support and what is the stress caused by this movement? Do the calcs and then speculate what the risk is.

 

[ColonelSanders83]

I make frequent use of victaulic couplings. This is what i think you need to concern yourself with.

1) There are 2 types of high pressure couplings, flexible and rigid. You need to specify which type is being used.

2) Flexible type groove connections will behave exactly like a tied bellows joint, the pressuse thrust developed is calculated from the pipe OD, the expansion and contraction is based on the movement limits of the victaulic coupling in question. Judging from you discription you will start at the bottom of the mine and assemble the pipe as you go up. This means you will have compressed gaps all the way up your run. For flexible couplings I would have a vertical ancor at the base (near the pump) and allow all the thremal and pressure growth to move up. I would then deal with all the expansions at the surface with either flexibilty or an expansion joint. This makes maintenece easy.

3) If the victaulic coupling are the rigid type, you can treat the expansions the same way you would treat welded pipe. You only need to evaluate thermal growths.

4) Remember to check that they have enough wall thickness in the pipe. By code (B31.1, B31.3, B31.9) the groove depth must be subtracted from the pipe available wall thickness (nominal thickness minus 12.5% under thickness tolerance, corrsion allowance, and mechanical strength). The reduced value must then be compared to your minimum wall thickness required.

Just my two cents worth

A question properly stated is a problem half solved.

Always remember, free advice is worth exactly what you pay for it!

http://www.ap-dynamics.ab.ca/

 

[ColonelSanders83]

micalbrch - High pressure vic couplings are good to 4000 psi.

Looking in detail at the high pressure vic coupling style 808

http://www.victaulic.com/Docs/lit/15.01.pdf

They are the flexible type, you will have growths all the way up the shaft. I would let it grow and deal with it up top, where its easy to handle.

A question properly stated is a problem half solved.

Always remember, free advice is worth exactly what you pay for it!

http://www.ap-dynamics.ab.ca/

 

[micalbrch]

ColonelSanders83: My concerns were not about Victaulic or any other high pressure couplings. I know them and they are good. My concerns are about hoses, suppports etc.

 

[ColonelSanders83]

Micalbrch,

My apologies, I misunderstood your post.

A question properly stated is a problem half solved.

Always remember, free advice is worth exactly what you pay for it!

http://www.ap-dynamics.ab.ca/

 

[micalbrch]

Sorry, stanier. I thought my recommendation with the Mining Engineers forum was a good tip. But it seems the dwarfs are busy at the moment (or not back on surface).

ColonelSanders83: No problem. Accepted. Perhaps my post wasn't clear enough.

 

[stanier]

Sorry if I have not responded to the postings. I am having trouble with a slow ISP at this time.

The thoughts expressed by ColonelSanders83 are exactly as I was thinking.

Perhaps i did not make myself clear. I am not the designer. I have come in down the track on this job just before they start installing and they want a certification of an incomplete design. Trying to "make a silk purse out of a sow's ear".

The pipes are 5m in length. hence if there is 1mm tolerance in the couping groove the pipe could move 1m! There is something like 200t of piping here so not all the couplings are going to move to their extremety with pressure applied. I would then be concerned about column buckling at the base of the pipe.

BigInch you are right the question is about the couplings.

I would not be looking at using flexible hoses at this pressure.

Pipe is 10" so dont know if API5L tubing is the way to go.

Code has been already specified by whom do not know and I do not know if this is a company standard. i shall of course be asking.

Changing codes to make a design work is a bit like reducing safety factors to allow an aircraft design to proceed. It does not reduce risk.

 

[miningman]

This thread provides considerable amusement to myself. To all posters, please dont take my following comments as personal criticism but to me, this thread demonstrates the dangers of us engineers getting involved in areas that are not within our respective area of expertise.

Micalbrch called it correctly in suggesting that mining engineers are the go to guys for this type of exercise, and I have posted a response over there for any and all interested parties... of course being refeerred to as dwarf does not endear Mical to me but Ill get over it!!!!!!!

If the customer has already purchased sched 80 10 inch pipe then the customer better be prepared to spend some time in the shaft with the miners showing them how to bolt this material directly to the rock and still keep the pipe more or less vertical. I know exactly how to do it if the pipes are installed on the shaft steel but unless there is a major change in the design philosophy, this is a gong show in the making.

And I have used oil field technology once or twice in my career, but with all due respect to oil field engineers , I cannot for the life of me think what advantages oil field pumps might have over standard off the shelf mining submersible pumps.

Incidentally 10-12 diameter discharge lines sound about right, and this should give non mining personnel what flow rates and electrical horsepower can be anticipated during this project.

 

[cvg]

with 1mm tolerance you only have 200 mm (>8 inches) total movement.

 

[miningman]

CVG, you do realise I hope that there is a cage travelling in the shaft at around 10 metres per second containing 20 -50 miners. The clearance between this cage and the discharge pipes and/or the 4160 volt electrical cables is often less than 75 mm?? I'd be extremely concerned if I thought there was even 10 mm of potential movement in ANY of the shaft infrastructure.

 

[cvg]

ok, I get it - there are tight tolerances. this is new information that was not part of the post. I'm sure I can't verify what kind of tolerance is necessary because that information has been left out. The OP was suggesting there would be up to 1 meter of movement. I am not suggesting that 200 mm is ok or that the design should be certified and I fully agree that a dwarf should be involved in the review of this design. I find it highly suspicious or perhaps risky is a better word that the owner would purchase all the pipe and fittings and then ask somebody to design it, especially when this person may not have the proper experience.