water distribution pipe material 4

[arj00]

What pipe material is preferable to use for water transmission line Dia. range 10inch- 16 inch.
Ductile iron is costly,GRP(glass reinforced plastic) is less costly but I did not use before! Do you think GRP is acceptable .

 

[yogibear1]

Our system in central Florida allows PVC either AWWA C909 or AWWA C900 or DIP ANSI/AWWA C151/A21. GRP sounds more like fiberglass pipe, depending upon the component ratios, which we allow for gravity sewer.

 

[cr1973]

Either DIP or PVC. We use ductile iron class 53.

 

[BRIS]

I am also considering GRP for high pressure transmission pipes up to 1.7m diameter. I can't find any reason not to use it for pressure pipe up to 16 Bar.

For GRP you need to consider the added cost of bedding and backfill material. Even so I am finding it less costly than DI and PVC.

Joint flexibility is less than DI (about one degree) so you may need to use more small angle bends than you would with DI or PVC.

I have concerns over fittings and am proposing to us DI for valve complexes.

 

[cvg]

you say that DIP is costly - but have you considered long term O&M? Very little required for iron pipe. Many iron pipes still in service after 100 years. You should consider cost/ability to tap the pipe, connect, repair leaks, ability to withstand surges or construction loads, etc. and factor that into the life cycle cost. DIP begins to look more attractive when you do that.

 

[BRIS]

I am not convinced that GRP has long term O&M costs. It has no maintenance costs! It may be more difficult to tap but that is unlikely to be a consideration for a transmission line.

The argument that iron pipes have been in service for 100 years is good but will not "hold water" with my client who is looking at the cost advantages of GRP. Even if I include for replacement costs of GRP at 50 years and discount back to a NPV (Net Present Value) GRP comes out cheaper.

A concern I do have is that the pipe is flexible and relies on the backfill for its strength. For pipes through open country this is not a problem. For pipe under roads with other services there is a possibility that future excavations adjacent to or above the GRP pipe will not be backfilled to the same specification as the design backfill leading to excessive deflection, joint leakage and perhaps pipe failure. The risk could be high in congested streets.

 

[cr1973]

Just HOW much cheaper is GRP than DI? Is it cheaper than concrete pipe? It sounds like a very touchy material to work with... not much 'play' in the joints and it sounds like it will not perform well in poor soil conditions.

Do you need special adapters to go from GRP pipe to DI valves and fittings? How do you handle corrosion then, since you cannot bond the fitting to the pipe? Probably have to stick an anode on each DI fitting?

 

[cvg]

"no maintenance costs"????

Sounds like you have been hypnotized by the salesman for flowtite...

Are you in Europe or Middle East? It seems that most of this type of pipe is installed overseas, not in the US.

it sounds like with the bedding and installation issues, you will have future maintenance costs - fixing the leaks caused by poor initial installation or by future excavation/backfill near the pipe. Also by trying to connect into this transmission line.

I'm not trying to convince you to use DIP, but have no experience with GRP. It is not widely used in the US for water applications. In fact, none of the agencies I have worked for even allow it. For example, the City of Phoenix standard allows asbestos-cement or ductile iron for all lines under 16". Over 16" it allows ductile iron or concrete pressure pipe. For any other type of pipe considered, designer would have to convince the city engineers to approve it.

 

[BRIS]

I am working on two main pipeline projects one in Libya and one in Lebanon. GRP costs are very competitive because the pipe can be manufactured in country whereas ductile iron pipe has to be imported. In both cases the client is convinced that GRP is the best material. The only arguments I have against GRP are subjective from people who have never used it (including me - I am also biased to DI). I would be very interested in getting views from anyone with any experience of GRP.

GRP can be joined to DI via normal flanged joints or Dresser (Viking Johnson) type couplings.

If you need cathodic protection then you would provide it locally to the DI fittings. clearly you don't need to bond to the pipe. If corrosion is severe then I would tape wrap the fittings rather than apply cathodic protection. If very severe than stick to GRP fittings. Only the valves need be DI in which case stick on a sacrificial anode.

Brian

 

[Zambo]

HDPE can be used up to 16 bar (above that I would recommend PVC) it is easy to install and is supplied in 100m coils up to 110mm diameter (although at this diameter coils are a 'wide load') and 12m lengths from 125mm.

Petzatakis of Greece are probably your nearest manufacturer, don't know if they have a factory in North Africa.

Zambo

 

[BRIS]

Zambo - thanks but our pipes are 300mm to 4000mm diameter. We are using DI and GRP up to 1600mm, GRP and PCCP up to 2400mm and PCCP up to 4000mm. Pressures are tpically 16 to 25 bar. Also in Libya the water temperature is 35 C which means PVC pipes would have to be derated by 40%.

Brian

 

[gvanbeek]

In this instance it is necessary to be more specific than GRP (Glass Reinforced Plastic). While the plastic is typically a thermoset it could be an epoxy (sometimes call GRE), vinyl ester (sometimes called Epoxy Vinyl Ester, but is a subset of polyester), or polyester. The more broad description is FRP (fiber reinforced plastic), the most specific is GRE, but we are typically talking about fiberglass.

FRP has been used in many places for water distribution, primarily in the Middle east. In the US we have an unusual situation in that items carrying potable water must have NSF approval, and food must have FDA approval. NSF approval is for a poduct only is approved, not a generic resin system. Ironically the NSF has typically not approved polyester or vinyl ester resins due to the possibility of leaching out residual styrene. Epoxy is the standard resin used for potable water systems. Ironically however FDA approves epoxy, vinyl ester and polyesters for food service (even products that are mainly water).

Therefore it is imperative to know what is the approving body for the piping system. Is it a local standard, or do they also use the NSF / FDA system?

Joining of the piping can be adhesive bonded bell and spigot, butt and strap, flanged or elastomeric gasketed bell and spigot (with or without mechanical locking). In some services they will use a gasketed bell and spigot with an FRP overwrap.

 

[Zambo]

Brian,

are you working on The Great Man Made River. I was working at Sirte Oil Company, Marsa El Brega a few years ago - not far from one of the precast concrete pipe factories. We installed a GRP fire-fighting line in the oil terminal, at the time there was no GRP production so we imported from Ameron, The Netherlands. But I guess your project is so large they can (or have) set-up a manufacturing facility there.

Zambo

 

[BRIS]

Yes I work as a consultant to Dong Ah, the main contractor, on the construction of the GMRP. The work has now moved into rehabilitation/reconstruction of piped irrigation projects. Over the next 10 years several thousands Km of distribution pipe will be installed. The requirements are sufficient to establish a GRP factory.

Some of the PCCP has suffered severe corrosion and hence there is also interest in alternative materials for the larger diameter pipes.

Brian

 

[scomil]

By GRP, I assume you mean fiberglass. Also available, but very different, are plastics - PVC or HDPE.

I have a problem with the 100 year DI performance history. I think it is a sales tactic, as the iron pipe produced 100 years ago was much thicker than what is being produced today. It's an apples to oranges comparison (yesteryears cast vs todays ductile). Besides, I doubt there are many 100 year old iron lines that have never had a corrosion failure.

Considering contemporary materials, my concerns are how to restrain fiberglass, and do they make fittings? I'm not certain if fiberglass is NSF approved for potable water either. From my experience, fiberglass has been used more for gravity sewer lines, and I would want to see a reference list of their waterline projects. On the other hand, plastics have been used for water for quite some time now (AWWA C900 for PVC was first printed in the 70's). Plastic fittings are also available and mechanical joint restraints are ready off-the-shelf.

I'm sure the pipe material debate will rage on, but I lean towards PVC.

 

[semo]

I have examined the cost difference between DI and PVC C900 in the past and found in the large diameters the DI can be cheaper than the PVC. For installation, there is little difference in weight and installation cost so it boils down to material costs. A lot of that has to do with the petroleum market, so before you decide on PVC, double check its current cost.

 

[PUMPDESIGNER]

Just curious, want to learn something.
I little or no mention of fusion welded heavy wall PE pipe.
I have become fascinated with this stuff.
Seems durable forever, flexible, easy to work with and tap into, many providers, etc.

Was on a project overseas where the stuff was being installed in solid coral rock to move all water on the site, salt water, potable, sewage, etc.

PUMPDESIGNER

 

[Rawand]

Try to consider HDPE pipes, for pressure up to 10 -12 bar,
for a small network it will be good, and for temporary network it is economical even.

 

[PUMPDESIGNER]

Thank you Rawand for your response.
10-12 bar seems to cover most of the water transmission stuff out there.
But why not for large networks?
Just curious because I know nothing about these systems.
Just to show how little I know: By my weak understanding at this point I would have to believe that HDPE is VASTLY superior to CI, C-900, and all others. Lower friction, pervious to corrosion,few or no fittings, any fittings are fusion welded anyway, less build up internally, and more.

There must be some weakness I am unaware of?

PUMPDESIGNER

 

[hydrae]

Pumpdesigner

The weakness of HDPE is you need the equipment to work on it.
Water systems have been burned in the past by HDPE when insert fittings were used. The fitting will break (most likely at 2 am Christmas morning) or the HPPE will break at the fitting. Repairs using the same type fitting become a hassle, sometimes the HDPE splits as the new fitting is inserted, or it is impossible to insert the fitting because the pipe is not round or maybe it shrank, preheating the HDPE with a torch requires skill, especially when in a ditch with water all around.
Sometimes that coil of Black pipe is not HDPE, poly butlelene? soft PVC?
To use the fusion Welded method requires the purchase or rental of the specialized cutting and heating equipment. The excavation to cut in a new tee is much larger to accommodate the equipment. The contractor has it easy, weld the pipe on top, then move into the ditch.
If you operate water system, you need to purchase the equipment because when a rock migrates next to the pipe (the contractor says he did not put that there) then wears a hole in it , the rental stores are not open, or have the equipment is rented to someone else.

Hydrae