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Mine shaft piping stress analysis
2

Mine shaft piping stress analysis

Mine shaft piping stress analysis

(OP)
The consulting firm I work for acquired a contract for the reconstruction of an underground mine pumping station. Because we are a small company we asked for the help of a piping stress analysis specialist. Although I don't know the subject so well so as to judge his work, I have some questions that I'd like to share.
- The specialist proposed anchors every 6m for the shaft's pipeline. As far as I know anchors should be placed in elbows, valves etc and not in straight pipelines. If anchors must be placed in straight lines then expansion joints are needed. When I asked him this question he said that due to the nature of the project (maintenance difficulties), any other type of support wouldn't work for the mine workers and that the only result will be a minor oversizing of the supports.
-I tried to check his results only for the shaft's entrance bend with this type http://www.engineeringtoolbox.com/forces-pipe-bend... but the number's were totally different. I imagine that is the result from the placement of the anchors. As far as I know stress analysis is checked between anchors so the resulting forces from the pipeline's weight are not calculated. The other thing that seems rather strange is that when I asked him to change the operating pressure, the resulting forces at the sustained load case didn't change that much. Probably I'm missing something fundamental here.
-Last question pipe shoes are modelled as anchors at softwares or as an other type of support.

Thank you in advance.

RE: Mine shaft piping stress analysis

It sounds to me like the confusion arises from the nomenclature being used. Did he mean "anchor" or "line stop + guide" or was a gap specified, etc? More to the point, did he mean "anchor" as would be defined as "full retraints in X, Y, Z, Rx, Ry, and Rz" or as would be defined as "something to bolt the piping to the shaft wall so it doesn't fall down"?

RE: Mine shaft piping stress analysis

(OP)
SNORGY first of all thank you for your reply. He defined anchor as full retraints in "X, Y, Z, Rx, Ry, and Rz".

RE: Mine shaft piping stress analysis

In my experience, operating pressures are not the driving cause for increasing resultant stresses in most cases - generally the highest stresses are going to occur during your Gravity+Temperature(Max,Min) cases.

RE: Mine shaft piping stress analysis

I always get a kick out of posts like this. I have contributed to a number of mine shaft pumping queries on this site. I have NEVER needed to request a stress analysis for a shaft discharge line, I would recommend supports every 3 metres not6. You need to learn what the maintenance considerations are in a shaft discharge system before you can hope to come anywhere close to an optimum design. Geographically, where is this project , is it a concrete or timber shaft, what other infrastructure has to be installed in the shaft?? All of these are critical questions.

RE: Mine shaft piping stress analysis

(OP)
Dear miningman the shaft is an existing concrete shaft.Apart from the shaft's discharge line the rest of the infrastructure will remain untouched for the time being.You recommend supports every 3 metres not 6 but my question remains unanswered. Do you mean anchors such as as full retraints in "X, Y, Z, Rx, Ry, and Rz"? Another critical question would be..how do you achieve pipe allignement in the existing shaft ?

Thanks for your help!!

RE: Mine shaft piping stress analysis

DGstavlas

The problem we have is that we have about 5% of the information to comment properly. So far we don't know
Size of the pipe
Pipe material
Pressure rating
wall thickness
orientation (horizontal / vertical/ angled)
length
temperature normal / running
pipe connection (welded / jointed / push fit
orientation of pipe (isometric)
Design code of pipe
External loads

I could go on, but I think you get the drift.

Full x,y,z,rx,ry, rz anchors every 6m sounds quite odd to me, but maybe it just made the analysis easy?

If you anchor things then you can get high stresses if you don't allow some movement, but it all depends - the pipe may be able to withstand it espevcially if it's thick and the temperature change is low.

also some aspects of your post are really quite puzzling without all the info you have e.g. "any other type of support wouldn't work for the mine workers" Eh?

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

RE: Mine shaft piping stress analysis

(OP)
Dear LittleInch thanks for your reply & your useful comments.

Size of the pipe : 12"
Pipe material : ASTM A-106 B
Pipe Pressure rating : Sch80
Max pressure: 65 bar
wall thickness : 17,48mm
orientation : vertical
length : 350m
delta T : 5 °C
pipe connection : flanged
orientation of pipe : pump,bend,horizontal 50m,bend,vertical 350m,bend,horizontal 20m,discharge tank
Design code of pipe : ASME B31.1
No external loads

RE: Mine shaft piping stress analysis

So basically we're looking at a 12" sch 80 pipe with a 350m vertical riser section with very small temperature variation.

A single support at the top with a 350m length hanging off it would seem to be stretching things (literally), but a full anchor support every 6m would also seem to be excessive. However, it will reduce the size of the support as the vertical pipe load will be shared amongst many others and any support failure would not be catastrophic. It's the full anchor bit that surprises me - I would have thought vertical supports every 15 to 25m and horizontal guides would have been enough, but maybe the difference is not worth bothering about and makes the vertical support too big.

there is a practical aspect also - as you say this is flanged I can only assume that you're planning on building this pipe in sections so multiple supports would be safer and easier to support. Getting a multiple flanged pipe in a dead straight line is wholly dependant on how accurate you weld the flange on. It's difficult to make up any angular misalignment on a flange

Also how do you attach the support to the concrete shaft? do you have space limitations?

did you design this pipe and then ask the stress man to "stress it" or did the specialist also design the pipework?

I can't see any big issue in having full anchors in terms of stress given the low temperature variation and really quite thick pipe, so maybe the specialist did this as a worst case run, it turned out OK so he stopped doing any other runs?

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

RE: Mine shaft piping stress analysis

(OP)

You write..."I would have thought vertical supports every 15 to 25m and horizontal guides would have been enough, but maybe the difference is not worth bothering about and makes the vertical support too big.".
This is what I was trying to ask but probably I wasn't that clear when I wrote "any other type of support wouldn't work for the mine workers". I was thinking something like your proposal (anchors+guides) but he said to me that guides need maintenance and that is something that the maintenance department doesn't want.

As I can understand you think that the piping is oversized.
Finally the support to the concrete shaft is assigned to a structural engineer so I can't say really much.

Thanks again for your valuable help.

RE: Mine shaft piping stress analysis

I doubt it will change anything, but for your education (and mine) just ask him to detail what maintenance a vertical pipe guide needs and how often? I can't think of anything.

I have no idea about the piping, but full anchors every 6m looks excessive.

However, the devil is in the detail which you and the stress man have and I don't so it's difficult to be any more positive than that.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

RE: Mine shaft piping stress analysis

(OP)
As I said in my first post I don't have the experience to confront him. I'm asking those questions in order to understand as much as I can the problem. To be honest, I can't think any other detail that I'm not sharing with you.
Let me share a thought with you..
Because as I have said already the shaft is existing and we don't know its strength, full anchors every 6m will reduce the size of the support thus making its attachment to the concrete easier.

How does that sounds ?

RE: Mine shaft piping stress analysis

What are the pipe joints? Welded / flanged / mechanical / hammer union? Is the stress analyst aiming to take credit for some axial growth into the joint(s) along each segment of pipe?

Anchors every six metres, if you have any dT at all, probably hurts the system more than it helps, at least until enough of them break that you end up with the number you should have had in the first place.

RE: Mine shaft piping stress analysis

(OP)
Dear SNORGY the pipe joints are flanged. As far as I know no he doesn't aim to take credit for some axial growth into the joint and yes there will be a delta T of 5 degrees.

RE: Mine shaft piping stress analysis

I have a lot of respect for Snorgy and Littleinch, based on their oil/gas posts they know their stuff but you are all getting out of your area of expertise. The pipe will be prefabbed at nominal 20 foot lengths. It will be flanged to accomodate the approx 450psi from the hyrostatic head( plus the frictional losses that I tend to neglect on this type of job... poor engineering , yes , but its practical and works for me every time). Unless somebody screwed up big time during the shaft sinking there will be threaded concrete inserts that have been cast into the concrete during sinking. You obviously need details of the spacing to design your brackets. And I will guarantee that the miners will have to change out at least three pipes during the first few years of operation........ gaskets fail, pipes get damaged due to falling debris in the shaft etc etc.I forget the weight of a 20 foot length of sched 80 c/w flanges but as a designer do you want to volunteeer to help them if the supports are anything other than two supports per length, so when you pull out the bad one, all the other remain undisturbed. Remember wil be standing on a make shift flatform with perhaps an 800 foot vertical drop below you.

If this is'nt adequate for you, go find an experienced shaft miner.... he doesnt need to be an engineer but he will set you straight. You have admitted to being inexperienced so this is not meant to be a major criticsm , more you are gettingg advice from the wrong people.

RE: Mine shaft piping stress analysis

Rereading some of the posts here , perhaps I need to explain that in mining, a shaft goes straight down vertically for the full depth with zero offsets at any point. This is not a tunnel in the side of a hill, nor is it a ramp at perhaps 15% grade.

RE: Mine shaft piping stress analysis

Miningman,

No problem in getting info from those who have seen the realty of life in those particular situations. I gathered it was vertical eventually, but I suppose w all have different practical aspects to deal with. I probably wouldn't have designed it to be made up of 100 or so flanged joints, but then I can't figure out why you would needs to replace sections after a few years either. As said less anchors mean bigger single ones and that may not be practical.

It might sound stupid, but do you not get access down a shaft by a wire and basket type things?

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

RE: Mine shaft piping stress analysis

Does piping in a mine shaft behave differently compared to piping strapped to the side of any other vertical structure?

FL/AE = &L(T2-T1); I get F = {insert your number} kN and an axial compressive stress between anchors (due only to the dT) of {insert your own number} MPa. Are they "Ideal Anchors", or how stiff are the anchors, and what is the stress analyst planning as mitigative measures against what I perceive might be somewhat high loads generated between them?

I'll check my own numbers again, but this is why I am asking the question.

Sadly, my experience in these fora over the years has conditioned me to not offer any calculation results, because in the event an error might be found, the numerous nay-saying "error vultures" will latch onto it and the ensuing thirty posts will degrade into attacks on the competence of the individual trying to offer help.

It actually doesn't matter if its piping in a mine shaft or anywhere else. Can the concrete (and, *especially the concrete*) accommodate the loads?

RE: Mine shaft piping stress analysis

Well in the interests of broadening everyone's general knowledge background , yes Littleinch we descend into the depths on wire and basket type things but I've never heard the systems so eloquently put. We call them cages on ropes. The ropes are typically 1-2 inches in diameter, ( and are of course steel cables) the cages hold anything up to 50 men and travel between 5 an 10 meters per second depending on depth and a few other technicalities. The entire hoisting systems are designed with F of S of 10:1 which is what you want if that 1inch rope is the only thing holding you against a very swift death. There tends to be very little clearance between the cage and infrastructure mounted on the shaft walls... often around 10mm so any movement of the pipes etc is unacceptable... regardless of temperatures. The atmosphere in the shaft is generally very wet , 100% moisture, often with H2S, NO2, sometimes acidic to the point of pH of 4 or less, sometimes with major brine concentrations leaking into the shaft.... each one is unique but you get the idea.

Maybe I'm a very poor engineer but I'm close to the end of my career and its way too late for me to even ask " what does Rx, Ry and Rz mean?? Similarily Fl and AE?? Perhaps that tells you how little structural engineering I've performed over the last 40 years but I'm pretty good with explosives, both theory and practical usage, and I do have some other knowledge which is perhaps almost unique to the underground environment so hopefully you'll cut me a bit of slack on the theory.

I would think that the inserts I would expect to find would take 0.75 inch bolts , possibly 1.0 inch. The brackets might be dedicated to a single pipe column but I would not be surprised to see "multi pipe brackets " which would hold the 12 inch pump line plus perhaps a 8 or 10 inch compressed air line plus a 4or6 inch water intake line and maybe a couple of 4160 or 13.8 kv electric feeders as well. Each shaft is unique but you should be getting the idea by now. And the concrete is nearly always sulphate resistant but perhaps what I would regard as normal deteroriation , you guys would regard as being horrendous. Its all a bit subjective I suppose.

RE: Mine shaft piping stress analysis

No disrespect intended towards anyone.
The OP asked if pipe anchors spaced 6 metres apart is a design that ought be be questioned. Pipe anchors, when specified by a piping stress specialist, have a very specific definition with very specific implications. In this very particular instance, my very rough calculations for the anchor force developed between ideal anchors by 12" SCH 80 A106B pipe came to 205 kN (46000 lbf) and a compressive stress of 12 MPa in the pipe. The pipe is fine, but the theoretical anchor force is high. My questions are centered around trying to establish what other assumptions or measures the stress analyst has taken that would suggest that the loads are really much lower than that and that, therefore, the "anchors" are fine.

RE: Mine shaft piping stress analysis

Miningman,

I have utmost respect for those who chooses willingly to travel to the bowels of the earth to extract things for the rest of us and as it gradually becomes clearer what and where this is used, the design becomes easier to understand and as said, the devil is in the detail. In those locations the desire is for something strong and easy to fix / replace, so doesn't lend itself to detailed design in the same way as several kms of piping / pipeline might. You also don't get solar gain down there in the depths....

Whilst this pipe is a bit longer, this type of design is fairly common on risers and shafts used for oil and gas lines, but we probably finesse it a bit more and it doesn't tend to have cages whistling up and down in close proximity many times a day.

Rx etc refers to rotation about axes. The anchor refered to doesn't allow any movement or rotation.

In reality it will probably be under axial stress due to hoop stress and poisons ratio as 5 C delta T is really small.

I still think you could use longer pipes and space the supports out more, but the design is acceptable, just could be chaeaper that's all.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

RE: Mine shaft piping stress analysis

(OP)
Dear all, thank you very much for your useful information...practical & theoritical.
As I can understand, you all agree (more or less) that the design is at least acceptable.
Miningman, I would like to give you a better picture for the installation in order to gain as much as I can of your experience.
The shaft was built somewhere in the early 80s and its diameter is 4,3m. Inside you can find the infrastructure that you described (cables, pipes etc.). Now our goal will be, to install the 12" pipe somewhere there.
This means that we need to drill some new holes and of course that SNORGY's question is very good..." Can the concrete (and, *especially the concrete*) accommodate the loads?". Now regarding the installation difficulties to be honest I can't say really much...because as I understand you are the only who was already a pretty good picture.

RE: Mine shaft piping stress analysis

Ok there seems to be considerable mutual respect developing here, so again , on the strict understanding that I will not be contributing to any discussion on stress analysis, based on the Op's description of the shaft at 4.3 metres in diameter.... which is awefull small by todays standards, plus the idea that this is a new proposed line...this will be very tricky to locate an area of shaft wall having the necessary room. I will also stick my neck out and suggest that perhaps this shaft is in Northern Saskatchewan. If so, I almost certainly have first hand knowledge of this shaft as I was sinking there in the late eighties, and there aren't that many small shafts in the world that I am aware of. If the Op confirms this I might be able to offer some more definitive suggestions again completely avoiding stress analysis considerations.

RE: Mine shaft piping stress analysis

(OP)
Dear miningman, the shaft is not located in Northern Saskatchewan. As I understand you can offer valuable information at a later stage. Now regarding the stress analysis considerations the results that I have from the specialist are : loads on restraints are 15087 N and the displacement of 0,023m. Are these results acceptable? A minor correction, we are talking about delta T of 10°C. Now after reading miningman's post for two anchors per pipe length I asked the specialist to check this proposal. The results that I got was 98752 N and the displacement of 0,013m. To be honest I could use some help with the comparison of the two solutions.

RE: Mine shaft piping stress analysis

If he has modelled full anchors, where is this displacement happening? - what direction? per 6 m pipe or the entire 350m of pipe?

Anchors in stress programs don't move regardless if you apply 1 tonne or 1000 tonnes of force so that took me by surprise - what is the max stress?

Those loads look very high for a 12" pipe support (1.5 to 10 tonnes force?) but is what happens when you "anchor" a straight piece of pipe and then add pressure or temperature difference

To be honest, without seeing all the details it's a little difficult to go much further, but perhaps if you post a "typical" support with loads, stress, deflection etc we might be able to see where this is going

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

RE: Mine shaft piping stress analysis

15 kN is not of concern to me. 205 kN concerns me.

I have no idea how the analyst has come up with 15 kN as the computed reaction force between two anchors of full (X, Y, Z, Rx, Ry, Rz) restraints with dT = 5 C for 12" A106B pipe, but it sure is a different result than I get no matter what textbook I use (LC Peng's work among them) or CAESAR II model (yes, I did run it) I create. They are other nchors, or they aren't. I have no clue. But what I WILL say is, if the computed load of 15 kN is accurate, my concerns disappear.

RE: Mine shaft piping stress analysis

(OP)
Dear SNORGY,
Let me share with you the results that I have in my hands. I will use the same terminology as it is described in the report that I have.
For the straight pipeline the computed force at an anchor node e.g 156 is, 590 kN (dT=10°C I have correct it that, at an earlier post),the load on restraint at the same node is 15 kN, the displacements are all 0.
At the two bends of the piping network (entering and exiting the shaft) the resulting force is around 750kN, the load on restraints is 700kN, the displacement is 0,17mm at the flanged joint of the bend and the straight pipeline.
The max stress intensity is 76083 kpA @ the exiting bend.
Is a modelling error possible? I mean maybe the bends, the straight pipeline should be checked separately. As I'm trying to read as much as I can these days, I see that eveyone is checking loads stresses etc. between anchors. Forgive me if I'm missing the fundamentals here but I'm starting to doubt about the specialist's abilities.
I can't understand how the anchor node resulting force is different than the load on restraint at the same node.
Maybe I didn't give him the right info?
Your thoughts...

RE: Mine shaft piping stress analysis

Don't know if this helps or not , but is the shaft upcast or downcast. If upcast I would be very surprised if delta T was even 3 degrees C. If downcast , I would need to know the geographical location and virgin rock temperature to comment.

RE: Mine shaft piping stress analysis

It is not easy to work out what is being presented, but it needs to be clear what is load on the pipe, force of the restraint / support and combined stress in the pipe.

What I think is being shown here is that the pipe is under a fairly high axial load resulting in axial stress. However apart from the bottom and top support, the rest are effectively fairly lightly loaded as all the pipe force from poissons effect / thermal expansion is being balanced by a similar force from the next pipe up the shaft - the 15kN. This force on the restraint is just for keeping it inline and allowing for the weight of the pipe between each anchor

However the last support before the bend (top and bottom) has no such balancing force being applied and hence has some high loads / forces associated with it and the restraint from the anchor to the pipe and will also include some significant bending moments absent from most of the other anchors.

Whether any of this is actually an issue should be calculated by the program for equivalent stress and reported as a %of maximum allowable stress according to your design code. This is a pretty hunky pipe for the size and pressure it is taking so has a lot spare for other stresses. It's the last support at the top and bottom which will see some fairly heavy forces and if they fail or allow any movement then the effect will ripple up the pipe.

does that make sense for you looking at the actual report / numbers?

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

RE: Mine shaft piping stress analysis

That explains a lot - LittleInch, thanks for pointing out the obvious that I (obviously) didn't see.

The net force on each anchor is balanced by opposing compressive forces imposed by piping either side of it. The high loads are NODE loads, not ANCHOR loads.

I just should have asked for a rstraint report, that would have cleared things up. My apologies for the alarm I might have caused. Now the magnitudes of the NODE loads and the actual forces on the restraints make sense to me. It looks like the stress analyst is doing things correctly - now that I realize what I should have caught on to. My bad.

RE: Mine shaft piping stress analysis

It took me a while to think about it - it's the load on the final anchors top and bottom which is quite impressive....

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

RE: Mine shaft piping stress analysis

(OP)
LittleInch thanks for clearing things out.
As I understand the proposed solution (anchors every 6m) is oversized but yet acceptable. But still I have few more questions.
The displacement 0,17mm at the bends is negligible?
Between the two anchors shouldn't be there something like an expansion joint or a spring?
At a previous post LittleInch you wrote "I would have thought vertical supports every 15 to 25m and horizontal guides would have been enough".
So as to understand why the solution is oversized..which is the maximum permissible load per anchor or the maximum displacement at the nodes.

I want to thank all of you gents for your valuable help.



RE: Mine shaft piping stress analysis

Displacement is negligible - it's the stress / loads which you need to see if you can actually supply - 70 tonnes force on the bottom support is quite a lot....

Between the anchors the pipe is acting like a spring - that's why the forces at the node / within the pipe as so high.

Permissible load will vary in each case as to what is practical / possible. I've seen anchor loads at pipelines coming into a plant in the several hundred tonne mark - needs an anchor v=block as big as a house. Totally ridiculous and unnecessary in most instances to prevent movements of 40-50mm. Allowable movement usually depends on how much pipe you can flex to reduce bending loads - depend son your piping configuration - 5mm might be too much or 50mm acceptable - it all depends....

At least with lots of anchors the pipe isn't going to flex or bow outwards which could happen if you have anchors too far apart.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

RE: Mine shaft piping stress analysis

(OP)
I believe that the 70 tonnes force on the bottom support will be the structural engineer's concern. LittleInch I got the general idea but I was asking for a number so as to be able to compare it at this certain case because you seem to have solved the problem from the start.


RE: Mine shaft piping stress analysis

There is no maximum figure - it all depends on your circumstances.

If you are going for multiple anchors and guides then for a 12" pipe 20-25m apart has the right "feel" with guides to limit any deflection or "bowing" to 2-3mm every 5-6m. however miningmans point about the practicality of either installing this pipe as a retrofit or replacing it in sections is also important. You are probably limited also by what the height of your crane is to get the longest section vertical before lowering it down the shaft to be fixed to the wall and to the pipes underneath it - again 20-25m sounds about as long as would want to go, but I don't know how you're able to or planning to install it.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

RE: Mine shaft piping stress analysis

Sorry Littleinch, I cant resist.. What Crane ???? That's the thing about underground in general. We don't have the headroom for cranes. And then we get into clearances at shaft stations. Sometimes we can just sneak a 30 foot member out of the shaft onto the level buts its often 20-25 feet only.

RE: Mine shaft piping stress analysis

The crane that's on top of your shaft to lower down the bits of pipe that make up your 350m long main vertical bit. That's the thing about these forums, I can't see what is in your head / desk / screen unless you tell me/us or attach a few sketches / drawings / photos. If this shaft is your only way in / out then it will become your limiting factor in getting anything built underground, but the vertical bit might be a bit different. That's probably why mining man quoted 6m lengths as being your standard sizes.

Have you though about some flexibles instead? There are plenty now in the 8" size which go to high pressure (i.e. 100 bar ish) that you could fix to the side and reel it down the shaft all the way to your pump? Usually very corrosion resistant inside and out. Search for RTP (reinforced thermo Plastic pipe manufacturers. Usually a bit more expensive than steel but you save on the installation and jointing issues.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

RE: Mine shaft piping stress analysis

the skip, headframe and hoist are in the way. no way to use a crane

RE: Mine shaft piping stress analysis

(OP)
LittleInch...just for the record I didn't ask for the crane...miningman did. Just joking..
Your idea for RTP seems quite interesting..but for a future project because for this one the specs are finalized.

RE: Mine shaft piping stress analysis

Don't I get a star??

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

RE: Mine shaft piping stress analysis

sorry,

that was late in my day when I wrote that.

If you're interested in RTP, ask in the pipeline and piping forum as there are some there who have greater experience of using it than me, but it can come in 1000m lengths and like everything has some pluses and some minuses, but might be worth looking at when installation is such an issue.

hope you understand a bit more now...

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

RE: Mine shaft piping stress analysis

(OP)
LittleInch thanks for the info.
I was checking again the report..and a question came in my mind..
The bottom bend is anchored at its curve point..when at the same time the last anchor from the top bend is 0,5m.
I mean shouldn't be anchored at the same point. One info that might help is that I have results for dT=10 & dt=-10.Is this the best way for supporting? The loads/stresses seem ok the displacements are negligible..but
isn't it a bit odd ?

RE: Mine shaft piping stress analysis

(OP)
As I was reading again all your valuable info..I came across miningman's post regarding the deltaT. In order to be sure..could you please clarify the terms ambient & operating temps.

RE: Mine shaft piping stress analysis

To me , ambient and operating mean exactly the same thing, but again this discussion is a bit theoretical for myself so others may have different definitions for these expressions. The underground environment tends to have a constant temperature. The rock acts like a massive heat sink which either adds heat to the environment or cools it. The exhaust side of the mine is nearly always warmer than the intake but once the air gets to the return shaft, the only reduction in temperature is due to the adiabatic expansion as the air gets closer to surface.

RE: Mine shaft piping stress analysis

I assume you mean a "ducks foot" support at the base bend. It's much easier to support that from the floor than it is to fix a support pointing vertically up.

Not odd at all.

Ambient / installed.com temp won't change much but operating depends on the temperature of your water flowing through it. At least down a mine you haven't got solar gain.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

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