Pipe material 2

[dylant]

What kind of pipe material can be used to flow sea water so that it would not corrode?
What is the cost of this pipeline compared with the carbon steel pipeline?


Thanks,
Dylan

 

[pauljohn]

If your talking about exhaust and raw water supply on a boat I have seen fibreglass, stainless, flexible materials like neoprene combined with rubber and strengthened with fibers or stainless wire, a corrugated pvc and many others.

Most of these cost considerably more than mild steel.

What are you using it for?

 

[dylant]

Paul,

Thanks for responding. I'm building a school project for LNG regassification. In this process, we'd use sea water to heat the liquid methane up.

Dylan

 

[waross]

Hi dylant.
I am assuming that you're a teacher or instructor looking for help with your job related project rather than a student.
respectfully

 

[pauljohn]

Dylan

I don't know anything about this process but if you are just using it to carry seawater at ambient temp. and pressure then regular PVC from any hardware store would probably be your cheapest method.

Again, I don't know anything about how the pipe comes into contact if at all with the LNG or what happens during the interaction period so it might not be suitable for that area of the process.

Paul.

 

[mshimko]

It depends on classification/code requirements, expected service life and maintenance requirements, etc.

Personally, I strongly recommend use of CuNi for seawatwer service systems. Not sure if there are any issues with CuNi and LNG, though.

 

[sjrfc2]

Did you look at ASTM F1155? That spec calls out material based on fluid system. They have a Table for LNG warm-up piping and it calls out CRES. You wouldn't want that for seawater though.

If it was just seawater I'd agree that CuNi is the material to use (again without knowing LNG limitations) but velocities in CuNi should be limited based on pipe size to avoid turbulence/erosion. Even backing rings are avoided.

 

[arto]

look in MIL-STD-777 for Navy Piping

 

[DYV1973]

You can use CuNiFer for the seawater piping. But why don't you use a plate heat exchanger (Ti or Hasalloy) to separate the seawater from your heating water. Corrosion allowances would be much better then.

DYV

 

[kenvlach]

Lots of responses from people used to big budget$$$.

High density polyethylene has been used in Hawaii for years (e.g., a 13,000+ GPM PE pipe, 1 meter diameter, since 1988) to bring deep cold seawater to the surface for cooling.

http://www.makai.com/p-abstracts.htm

Other 55-inch diameter PE pipes used for aquaculture. Some armouring required for the surf zone.

http://www.makai.com/p-aquaculture.htm

http://www.polymoldproducts.com/PE_PIPES.htm

http://www.oxfordplasticsinc.com/marine.htm

For a 25-million gallon per day (mgd) seawater facility, such as the Tampa Bay desalination plant:
"High-density polyethylene (HDPE) was used in the Tampa plant for the 48-inch raw seawater intake piping and the 54-inch concentrate disposal piping due to the water's salinity/ chloride level and relatively low pressures in the systems."

http://ww.pennnet.com/articles/article_display.cfm?article_id=194095

Even PE as a Dredge Pipe Material:

http://www.oxfordplasticsinc.com/marine.htm

 

[seatrendgokhan]

dylant,
the answer is GRP or any other GRP like materials. Currently we are using it onboard of our vessels for ballast systems. On the other hand, while designing a pipling converying high conductive liquids, you should consider corrosion. Sometimes even SS is not a good solution for such systems, therefore all the system and the envoirement around the piping is also important, sometimes even the gasket we use. For more info please google "Corrosion Control"


GOKHAN
Naval Arc.& Marine Eng.