Demineralized Water Piping
Demineralized Water Piping
(OP)
Can someone please help solve a raging debate regarding the corrosivity of demin water and why demin systems and tankage are made of 304 stainless? Is demin water any more corrosive than fresh, aerated, potable water? Is the piping made of stainless to prevent iron pick up prior to it entering the deaerator, or because it would chew through carbon steel quickly? None of the water treatmet manuals,like Betz, really delve into this. Is this a chicken or egg type debate? Help!!





RE: Demineralized Water Piping
Calculate the LSI (langelier stability index) of demin water. You will see that the scaling tendancy is non-existant (low LSI, no surprise there), and, hence, the corrosive tendancy is very high (low, negative actually, LSI value).
Demin water loves to dissolve stuff. It is quite aggresive. Add dissolved oxygen and "say bye-bye to" carbon steel.
Iron pick-up is a practical problem in economizers, etc., due to large surface areas, but is controllable (obviously).
RE: Demineralized Water Piping
Why not use ABS piping for demin water. See www.eurapipe.com.au for details. Its more ecomomical than ss and will not contaminate your systems. It is used in the microelectronics industry for ultra pure water.
RE: Demineralized Water Piping
Materials for construction demin water tankmust be stainless steel SS 304, becouse SS 304 is very resistance with corrosive.
RE: Demineralized Water Piping
Demin water is often used for boiler MAKE-Up water. It is blended with condensate returns (to make up for losses through boiler blowdown, etc), then sent to a deaerator. Feed of oxygen scavenger and amines downstream of the deaerator "scrubber" section, that is, to the dearator storage section, is typically done to adjust water pH there, and to add amines for condensate pH/corrosion control (amines avaporate in boiler and "follow" steam to condensate lines). So, boiler feed water is DOWNSTREAM of the deaerator. Make-up water (with dissolved oxygen stil in it) and condensate returns are upstream of the deaerator.
Hope that helps.
RE: Demineralized Water Piping
May be useful to someone...
RE: Demineralized Water Piping
WTP03
RE: Demineralized Water Piping
RE: Demineralized Water Piping
Looking forward to your responses!
RE: Demineralized Water Piping
RE: Demineralized Water Piping
for the second question,i THINK there is no such specific and authorized standard.right?
we are waiting for more answers.
RE: Demineralized Water Piping
Carbon steel is used successfully to construct high pressure boilers where the oxygen level is very low and the boiler water is basically demin water.
SS is used basically for corrosion prevention, and not to prevent contamination of the water. In other process applications such as biotechnology where demin. water is used, there may be issues with contamination of water.
I am not aware of any guidelines that cover all applications.
RE: Demineralized Water Piping
RE: Demineralized Water Piping
I withstands the high corrosivity of demin water and more importantly does not contaminate the water. Water used for flush cathode ray tubes, LCD screens etc cannot toelrate on e speck of iron as this fluoresces when the elctrons are fired at the screen.
By the way it is cost effective against ss. You dont need TIG welders, X ray etc.
You can share knowledge but you cant share wisdom. Using knowledge wisely separates engineers from the enthusiastic amateurs that burden our society
RE: Demineralized Water Piping
RE: Demineralized Water Piping
ANSI B31.3 lists the properties of three grades of ABS material. I believe the manufacturer of the resin may be Uniroyal. I dont know the relevant ASME standard but it may appear in B31.3.
The reason I mention the difference in AS 3518 materials and the US materials is the high profile case of failures of ABS in the pluming industry in the US. I think this may have been settled now.
The pipe manufactured here has a different blend of acrylonitrile butadiene stryrene and is master batched differently. This results in a pipe material with different properties.
It is manufactured up to DN800 and 15 bar (at 20C)rating.
Its main applications is in mineral processing, slurries, water and waste water, effluent treatment, building services etc. It offers good corrosion resistance internally and externally.
Its low modulus mitigates waterhammer pressure transients as the celerity is reduced.
I have been designing and installing this material in applications in SE Asia for over twenty five years.
It is also available in a ready insulated system ideal for reticulating chilled water to buildings and plant.
Chek it out at the manufacturers website.http://www.eurapipe.com.au/cd/Eurapipe/default.htm
I do not have any commercial interest in this company. My interest stems from a good product that out performs legacy materials in specific applications.
Where carbon steel pipe needs repainting every five years and replacing in ten ABS keeps going. A simple NPV shows the net worth of the ABS installation.
Esso use in Malaysian offshore applications. You cant get a better recommendation that that.
You can share knowledge but you cant share wisdom. Using knowledge wisely separates engineers from the enthusiastic amateurs that burden our society
RE: Demineralized Water Piping
RE: Demineralized Water Piping
RE: Demineralized Water Piping