Above ground insulator/force protection

[jartgo]

I will be piping (working pressure is 1500 psi) under a slab then coming up to the surface where the pipe will extend for 3 to 4 feet (exposed to atmosphere) and terminate at a quick connect (for a pressure washing hose). I'm looking for some suggestions on how to protect the piping from freezing and add some structural support.

The underground piping will be in a casing while traveling in the horizontal direction. When it turns to go vertical on its way out of the ground to the terminal point, I am considering using a manhole or some other form of vertical cavity...however when it gets to the surface, I'm not sure what to do with it in order to provide the protection described above.

I suppose I could abandon the idea of the manhole and just turn the stainless carrier pipe up, surround it with spiders and a pvc casing pipe, which would be encased in a concrete filled bollard?

Are there any commercially manufactured appurtenances that vaguely accomplish what I'm trying to do? The lowest air temperature will be about 25 deg F. Please feel free to make other suggestions or recommendations. Thanks in advance.

 

[BigInch]

From here I can see no reason for a manhole.
I would think that, unless you have that 25ºF temperature for very long time periods, your risk for freezing is minimal. If you see a possiblity of freezing of the water in the pipe riser, add some insulation and/or heat tracing.

Two ways to approach the mechanical strength issue. I would decide based on the effect of the incidental load on the riser pipe.

For situations where the incidental loads (with safety factor of 2 or some appropriate multiplier) will produce stresses less than 1/2 allowable stress or so, you might consider increasing the wall thickness of both the underground pipe and the riser pipe, or perhaps only the riser pipe if stress in the horizontal run remains acceptable. I'd use a XXS schedule as a minimum. For loads giving stresses greater than 1/2 allowable, I would try to eliminate those loads and consider installing guards (vehicle guardrails, barricades, etc.) I don't like concrete casing in these situations for pressure pipe, because after 1 impact, its usually gone, the pipe is scratched and then you have no mechanical protection and corrosion beginning. I don't mind concrete casing for making structural vehicle guard posts alone, but not for pressure piping.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

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

 

[jartgo]

Thanks, I like the idea of the bollards being seperate from the pipe itself, then I'll just keep the quick disconnect low to the ground and insulate it.

If I encase the XXS piping in a PVC casing while its underground, I assume I can use spiders just as in normal casing for buried piping, but any suggestions how to make the bends? The carrier piping connections would be welded in-place (again I assume IAW ASME B31.1), so I'm not sure how to make the 90's or 45's and still provide the casing for corrosion protection.

 

[BigInch]

I think everyone would like to know how to do that. The few cases I've seen that have had a "continuous" casing around the bend have had the casings connecting to a box enclosing flanged connections to the ell. Others have simply terminated the casing, using casing boots, before the bend starts and restarted the casing after the bend ended, so .. no casing on the ells, only corrosion coating wrapped on. I'd tend to do that with a riser assembly, simply terminate the casing before and after, wrapping the tee and riser with Polykin, TapeCoat, similar wrap, or a field applied epoxy, or matching whatever you're using elsewhere. If you think you need insulation in the underground part, I hear there's some waterproof types of urethane you might use to a foot or so above ground, then change to regular insulation above that, depending on how far you're going.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

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

 

[konman]

I have never considered casing for corrosion protection, but like BigInch mentioned, would use a TapeCoat or similar product. If it is any distance you are below ground, consider having your piping factory coated. For frost protection below ground (consideration where I live), we have had some luck with field applied spray foam. Heat trace and insulation would be the way to go above ground.