Mine shaft piping stress analysis 2

[DGStavlas]

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-bends-d_968.html

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.

 

[LittleInch]

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

 

[DGStavlas]

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 ?

 

[DGStavlas]

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.

 

[miningman]

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.

 

[LittleInch]

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