Pipe Insulation

For a hot pipe, is a vapor barrier necessary at all, or would it actually trap vapor that otherwise would move away from the pipe?

No. You do not need a vapour barrier. however one does need something to hold the glasswool together. Roll of canvas should do. Word of caution. Glass wool should only be handled with gloves and goggles preferably.

What will happen to the thermal conductivity of glasswool insulation directly buried in soil when the soil becomes wet from rain and groundwater? It would appear that the insualtion will just soak with water and loose its insulating properties???

Wise statement! The ground ambient temp at 3 feet of depth working against the heated temp of the water in the pipe, would create condensation issues despite the type of bulk fiber insulation used or the conduit/vapor barrier encasement. Gary

In non rocky soil, rain water from continuous downpour has no place to go but down at least till it will hit our insulation! If the vapor barrier has any crack the insulation will certainly soak up the water and keep it there for a long time. Would'nt this play havoc with its thermal conductivity more than the compression of insulation would?

Using glasswool for direct bury application seems risky and it would help if anyone out there could relate their experiences or share their knowledge about this matter.

Thanks

GA (Good Answer!) for a good question!!! Strangly enough!!

But buried hot pipes do need a sealing barrier to prevent water ingress.......I also wonder if even if water does not enter, what happens with the insulation factor if the glass wool is highly compressed by the weight of the earth around it? Probably works far less well......

Perhaps there is a better type of insulation for this type of installation? Its not my area of knowledge, sorry.

9000 feet of domestic hot water is about 300+ gallons in the pipe alone. So you would want to heat 300+ gallons just to get the pipe full? I would move the heater closer to the user.

quite right, glass wool is a poor insulator it is merely a suspension device to create an air gap, Glass itself actually conducts the heat and as previously noted water contact would create a heat sink, the idea of the enclosure pipe has my vote,

However the comment regarding the 9000 foot volume of hot water is the most noteworthy, at that distance it would need to be a heated pipe to constitute the word "hot", you are talking about 3 kilometers. the question is not real or the writer clueless to the task at hand

Also when you trench 3' deep through undisturbed soil you are creating a two mile long, 3' deep soft spot in the ground that will probably collect and hold water like a resevoir.

Probably encasing it in some thin walled pvc with insulation, sealed, would be the best bet. Then you can compact the heck out of the backfill to avoid attracting water in the trench.

Rockwool is another alternative as suggested. Rock wool of suitable thickness+ Vapor barrier+ Hessian cloth + Chicken wire mesh + Cement plaster may give strength to the structure in addition to the insulation.

You beat me to some of the ideas I was kicking around.

Why not Foamglas?

Foamglas® Pipe & Block Insulation by Pittsburgh Corning

Pittsburgh Corning's FOAMGLAS® pipe and block insulation is a lightweight, rigid insulating material composed of millions of completely sealed glass cells, each an insulating space.

Foamglas pipe insulation's all-glass, closed-cell structure provides an unmatched combination of physical properties, it is impermeable to moisture in any form, cannot burn and it is non-combustible. Foamglas pipe and block insulation is used most frequently in applications involving process piping, tanks, vessels and equipment which are most commonly used by the gas processing, refining, petrochemical and specialty chemical industries. Temperatures from -450°F to +900°F (-268°C to +482°C).

Uses:

• Low temperature pipe, equipment, tanks and vessels
• Medium and high temperature pipes and equipment
• Hot oil and hot asphalt storage tanks
• Heat transfer fluid systems
• Hydrocarbon processing systems
• Chemical processing systems
• Above ground and underground steam and chilled water piping
• Commercial and institutional piping and ductwork

FOAMGLAS® insulation is:

• Resistant to water in both liquid and vapor forms
• Non-corrosive and will not support corrosion
• Non-combustible - will not absorb flammable liquids or vapors - cannot burn
• Resistant to most industrial reagents
• Dimensionally stable under a variety of temperature and humidity conditions
• A material with superior compressive strength
• Foamglas pipe insulation is resistant to vermin and microbes
• Fiber, CFC and HCFC free

Looks good! I suppose Tornado would need third party testing before he could allow this recommendation to be posted. Gary

Depending, I would maybe use Cheap SDR as a "casing".

Are you crazy? The thickness and thermal conductivity of the Foamglass material are quite easy to understand as part of well known thermal transfer. Moreover, I wouldn't be surprised if it has been suitably tested. I have heard of it before, but most of my work has been with low temperature piping, so I forgot the name.

High vacuum has very low thermal conductivity (approaching zero), so a thin layer of it, as in a Dewar flask or Thermos bottle, makes for good insulation. Your claims are fantastic, but you haven't given a good rationale of how your material is supposed to work. And by halskinner's complaints, it doesn't seem that testing labs support this concept, either. To say the least, it is very unconventional.

I don't mean to me a slave to conventional thinking, but the burden of proof belongs to the person making the extraordinary assertion. It is not my homework to furnish proof of your concepts. If you think I missed out on something, fine--please give a brief and cogent explanation. Your insults are counterproductive.

I like several aspects of this coating, but because of your attitude, I would not authorize, purchase, or recommend it. But go ahead, keep shooting yourself in the foot. Indeed, I think your insulting tactics could be the hallmark of a fraudster.

Neither you nor your buddy has given a competent citation of the Las Vegas study. Why not?

You are correct in your assumption. I am Crazy! If I were trying to sell you something, it would be incumbent on me to prove the value of my product for your project. However, you are not the OP and I was not talking to you before you interrupted the conversation with your derogatory commentary. I don't care what you think of Hal, Me or Cerama-Tech! Either contribute to the OP's needs with your own recommended solution or stay out of my conversations. I could care less if you understand how Cerama-Tech works, as you have made no effort to understand it and you repeatedly questioned it's properties without attemptiong to gain real experience or research. As for my attitude, don't start no crap, there will be no crap! No insult intended! As for why no one has provided you with additional information, you haven't expressed a legitimate interest in any application that justifies impressing you. Nor would I ever attempt to do so!! God Bless You and Yours and I wish you a happy New Year!

Gary

You were right!

In Las Vegas no less, with w****s, slots, and mind expanding libations.

A 3rd party evaluation in Las Vegas???

Those who can't or never did pontificate.

Y'all have a good day now.

Oh, cry me a river.

You seem to have an excellent and versatile coating product, but you are making thermal claims about it that are highly unusual. Despite repeated requests for an underlying explanation or recognized testing, you have furnished nothing cogent. Instead, you have resorted to evasion and insults.

Just get an independent party to prove that this product has a consistent R-value per unit of thickness. If/when such results are in hand, you will have confirmation of your claims. But if independent testing fails to confirm the claims, discontinue them and focus instead on what can be proven.

Please get off my back! Who cares if you are convinced? Does everyone in this group care whether you approve of a product or not? Cry me a river in deed! Gary

999, I would recommend coating the pipes with Cerama-Tech coating during the installation. This will retain the heat in the lines better than exterior wraps without the moisture degradation concerns and will protect the pipes from deterioration when in contact with soils.

Warm regards,

Gary A. Coffing, Sr.

830-899-4700

www.ct-texas.com

Ceramic-enriched paint may be a superior coating, but unless its thermal conductivity is essentially zero, it can't really be much of a thermal insulator. (Unless applied really thick, like inches.) The marketing for this should focus on corrosion resistance, durability, and reflectiveness--but not insulation.

I would agree with your comment, however, you may be missing the thermal conductivity/emissivity of the product of 90%. 90 percent of the heat within the pipe is reflected back in wards toward the source. The other insulation and conduit recommendations require dry air space for the insulation to perform. The cool ground temp and the hot water in the pipe will create condensation and thus nullify the insulation values intended. A coating with high reflectivity and low emissivity is the best solution to this equation. The added protection of the pipe against corrosion/decay is a bonus. Gary

I agree that the emissivity would be a good feature of this product, but I think it is unwise to conflate it with thermal conductivity. There is a risk of underperformance on the thermal conductivity aspect, which could wipe out the successful aspects. When halskinner complains about testing labs, it places his credibility in doubt.

Help me understand your concern. If a 200 degree F heat exhaust pipe is coated with Cerama-Tech and it reduces the temp to 100 F degrees, would that not indicate that the same coating could reduce the heat loss into the relatively stable ground ambient temp soils? The outside air is the ambient and the interior pipe temperature is the source. The water pipe is heated and the ground is cooler like the air. Hal is very excited about the product and can sometimes come off as a little incredible in the way he presents it's attributes. I would not want to present the product as the cure all, however, given this extraordinary request for insulating a 9000 ft run of Hot water pipe in 3 ft deep soils, I would back this product against the other suggestions. Gary

This is underground. Air temperature is irrelevant. There is no light (or solar radiation) to be reflected. I could be wrong, but I do not believe that this material would reduce the temperature by 100°F between the inside and outside of the coating, if it anything like the normal thickness of paint-like coatings. The concept of temperature gradient times thickness is fairly simple, but you guys don't seem to address it in your presentations. Sooner or later, it may bite you.

I agree that this is underground. What part of this exercise has anything to do with solar radiation? The heat from hot water and solar radiation react the same way when they come in contact with this coating. They are repelled back to where they came from! Certainly not 100 percent, however, more than you would like to believe!! If you coat a hot water pipe with this product, it will retain far more heat than if you were to wrap it with fiber bulk insulation. Gary

I would like to see an independent lab test that confirms this. Halskinner had a weird "conspiracy theory" complaining about why this hasn't happened. Maybe there is updated news about this?

(So far all I have heard is unverified (unverifiable?) sales hype.)

The proof is in the putting! I researched the product through the Internet and made a commitment to market the product along with several others. I found studies done by the University of Las Vegas that confirm my assertions. I still can't understand what this has to do with the OP's request. If you require independent lab tests to help you understand how this product works, please investigate these on your own. In the meantime, I recommend coating the underground pipes with Cerama Tech. Gary

That didn't produce one iota of usable data. Thanks a heap.

Do your own homework, Junior. You'll thank me later. Gary

Cerama-Tech is not a Ceramic-enriched paint. It is a carefully designed coating. G

I would be curious to know whether frost is an issue and if ground water is an issue. Here in Alaska we use Arctic pipe of various types all of which are basically a pipe within a pipe using closed cell foam as an insulator layer between the two. For frost protection there is often a void for a heat trace cable to run through. This type of arrangement has proven it's superiority over all other systems for many years. Whether holding heat in, or holding cold out I think this will be your best long term solution. Almost any major pipe supplier can source this for you.

I'm a bit confused. (No hard to do at my age) Why does the OP want to run a hot water line this long? What is preventing heating the water closer to the use site? Just wondering if the cost benefit has been considered here.

The generous and rich responses have shed useful light on the subject and each one of the respondents deserve loads and heaps of gratitude.

The matter at hand is that insulatiing buried domestic hot water (supply and return) cPVC pipes is stated without any details or specific reference about the type of insulation. The long runs of these pipes to about 18 buildings from the central heating plant (storage type calorifiers in which water is heated by steam from adjacently located gas fired boilers) needs to be insulated. If we add up the circuits it adds up to a lot of pipe and insulation. The claim for a variation order did not succeed because insulating the pipes is indeed stated in the specs. Therefore any solution needs to be functional and acceptable to the client and at the same time afordable. This is why glasswool insulation instead of preinsulated HDPE (High Density Poly Ethylene) cPVC pipes is being considered. The HDPE would not absorb water (as even low density coffee cups from such material don't) so this would have been a good alternative, but once again the cost barrier cannot be broken.

How about if we encase the pipes in concrete after first insulating them with glasswool that has aluminum foil vapor barrier and polythene bags are wrapped around this assembly to seal it good to keep the water of concrete from getting in. We can then backfill above this concrete and this will eliminate the problem of compression of insulation and of water getting in?

I don't know exactly where you are located, but burying this heated pipe 3 feet down suggests to me that you're dealing with a ground frost issue there? Around these parts in upstate NY (Albany area and surrounds) we typically experience frost to at least 4 feet below grade, although I've seen it go down to no less than 8 feet below grade one winter (1994) in Amsterdam NY during a nasty cold snap when we were trying to locate a massive water main break....losing no less than 15 MGD from a 21-inch CIP main! The ground in that location was porous sand with a fairly large void structure, therefore permitting extensive frost penetration.

Typically, in this area we provide at least 5.0 Feet minimum depth of cover above the crown of water mains and 4.0 feet minimum cover atop sewers to prevent freezing. Up in the "North Country", aka Adirondack Mountains and the St. Lawrence River plain the frost depth requirements are much deeper.......so soil examinations/explorations for larger water and sewer projects are absolutely imperative, so, please keep in mind what types of soil that you're encountering in your project site as the required depth of bury may have to go deeper. Frost requirements will vary and you should investigate what is the normal or required minimum depth of bury for pipes in your area. Also, remember that typical ambient earth temps around 5 feet below grade are normal in the range of 51 to 54 F....but this may vary due to various local soil and ground water factors, and should be evaluated on a case to case basis.

If you're considering placing concrete around your pipeline I strongly suggest that you do so with a "concrete flowable fill", a low strength concrete backfill (typically having a compressive strength [f'c] = 1,500 psi or less) that can be excavated from the trench anytime in the future in the event that you must perform maintenance and/or repair activities on you pipeline.

If arctic pipe is out of the question and concrete is an acceptable alternative. then I would suggest you go to cretefoamer.com and see about using their system. You can add as much foam to the concrete as you desire and since strength isn't really an issue here you could turn it into a functional insulating layer. Anything to combat the condensation issue. Good luck to you.

There are several companies that fabricate pre insulated piping that is approved for direct burial.

Any water that makes it's way into the glass-wool insulation, will change it into a heat conductor.

One place to start is Ureacon. http://www.urecon.com/main/home.html

When this 9000ft pipe is laid, it will be something like 60°F. If it is then heated to 180°F, it will expand in length by several feet. Has the design accounted for that?

Your comment was indeed considered and the experts said expansion joints are not needed for underground pipes. This was the verdict from more than one Engineer in the field.

For example also in the case of uPVC pipes with bell and spigot joints expansion can easily be contained by simply not pushing in the pipe completely in the bell. However, the advice was that this need not be done when the pipe is laid underground, because the friction of soil will not let the pipe to move in any case.

Now your comment has cast doubt about the matter sending us back to the drawing board. Therefore feedback from experts in the field will be appreciated.

Then why does your Website read like this?:

You yourself have used the word "paint" (basically a vinyl acrylic carrier infused with "ceramic platelets." How dare you quibble with my description as "ceramic-enriched paint"?

And why does your FAQ page say that this product has no defined R-value?

I suppose they thought the site looked good as written. I quibble because this is not paint bought from Home Depot with ceramic powder mixed in, it is manufactured as a coating. They were most likely trying to explain to hard headed people that the product works differently than R-valued types of insulation. Thanks for posting the site. Gary