PVC piping for mobile system 1

[Mya44]

Hello,

I am designing a mobile water treatment system and am looking into some input into materials selection. The water we are treating is essentially brine and will be at ambient temperatures. I would like to use PVC piping as it is economical, resistant and light but I am wondering about vibration and general wear and tear encountered while traveling from site to site. Does anyone know if this is something I should concerned with and if I'm even on the right track with this or if I should be looking at totally different materials?

Thanks!

 

[moltenmetal]

As long as the service and transport conditions are not cold enough to render PVC extremely brittle, and you design your piping supports properly, PVC will stand up very well.

 

[MikeHalloran]

You need a torsionally rigid skid/trailer, or flexible connections everywhere.





Mike Halloran
Pembroke Pines, FL, USA

 

[BigInch]

Watch the mechanical wear points from transport vibration. I would think extra protection would be required in critical areas. Wind loads during transport could add to the fatigue cycles and vibration wear, if piping was not shielded and transport time vs operating time was say roughly equal. Maybe you'd want to avoid lengths of pipe with resonance periods matching windspeeds of 40-60 mph???

I always thought PVC would do better in buried or inside building conditions rather than exposed to a lot of hot-cold amabient cycles and sitting in the sun on a flat bed for awhile, then cooling off in transport wind, but maybe I'm just thinking too much there.

One thing to consider might be what kind of design life are you looking for?

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv

 

[Mya44]

Thanks for all the great input everyone!
This unit would be used in the southern and mid eastern states so I don't expect extreme cold temperatures.
I am intending to include multiple flexible connections to enable the overall system to flex with transport. Keeping short pipe lengths is definitely a good idea also.
Design life ideally will be 10+ years however if I build the system using more economical materials then having a slightly shorter design life is not critical.
We have used PVC in outdoor applications in the past (although not mobile) in Texas and found that we do need to paint it to protect from the sun.

 

[RigPiper]

I would suggest a CPVC or ABS for larger size pipes and PolyPropylene (PP) in the smaller. For mobile consideration I would be cautious with the joining methods. Cement joints would be vulnerable to vibrations however mechanical or welded joints will endure. Look a Georg Fischer Piping, they have some pretty unique items that have been proven in my industry to withstand many elements. Being used in the southern states pay close attention to the UV resistance as well as the high temperatures. The temperature of steel or other metals on the unit may reach 130 degrees in the sun.

 

[itsmoked]

Sch 80 is substantially tougher than Sch 40 too.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[europipe]

I would suggest you use HDPE.
PVC doesn't last long in the sun.

Greetings

 

[moltenmetal]

PVC is SO much easier to use than HDPE...SO much easier to build in the first place, and to fix when things go wrong or you need to alter it. Such a greater availability of valves, instruments etc. etc. compatible with the piping system without the need to go to threads...There is really no comparison between the two materials in terms of usefulness for above-ground piping systems, especially for water treatment.

Unless the service is HOT water, CPVC is just a waste of money. It is considerably more expensive than PVC and aside from temperature resistance it offers few benefits not already offered by PVC.

If it will be in direct sunlight for years on end when stored or used, put it in shade when you can, or paint the pipe with the white mastic designed for this purpose. Unpainted PVC pipe can survive for years in direct sunlight without painting- just not five or ten or twenty years... Shade or shelter is a good idea anyway, as the PVC pipe won't be the only thing on a mobile water treatment skid which can be damaged by direct sunlight for extended periods I'll wager.

 

[RigPiper]

CPVC has many different connections available. It can be socket fused, cemented, grooved, threaded, and welded. It has higher tensile, greater impact resistance. See ASTM 1784 and mentioned references. Also note; if it is applicable, is the Flame Spread which is the same for Pvc. CPVC is becoming one of the largest used industrial piping and many companies offer varieties such as heat traced and insulation at the factory. Some trade names are Corzan and Flowgard. CPVC also has many approvals for Marine, D.O.T, MIL, etc.

 

[europipe]

In Europe many potable watersystems are made of HDPE,
The only advantage of PVC is that you can glue it,
The disadvantage is you have to paint it, as you stated.
Hdpe has all the fittings you need,
just like PVC.

 

[moltenmetal]

PVC or CPVC have PLENTY of advantages for above-ground piping systems beyond being able to glue the joints- and that alone is a HUGE advantage for any company which is not anxious to spend the money on socket- or butt-fusion equipment.

CPVC is superior in a number of performance factors but costs more money. You only pay for those extra performance features if they benefit your application. Unless it's hot water, PVC is an adequate selection.

 

[Mya44]

Again, thanks for all the fantastic input everyone!
I spoke with Georg Fischer (thanks for the tip RigPiper) and they recommend either PP or PE over PVC for this application due to the vibration and stresses of constant transport and outdoor use. PP is considerably more expensive but would be the most durable and best choice in their opinion.

 

[moltenmetal]

You probably told Georg Fisher more about the details of your application than you've given to us, so I'd defer to their judgment.

Use caution, though, as polypropylene is listed as having poor UV resistance in numerous references I've seen, as well as in my own personal experience with PP items exposed directly to weather.

Much of the PP pipe and fittings sold in North America is natural (i.e without pigment), whereas in Europe the metric sizes are typically pigmented a buff colour. Pigmented versions might offer better resistance, and some formulations may, like PVC, contain UV stabilizers or other ingredients to improve resistance.