Tek-Tips is the largest IT community on the Internet today!
Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!
-
Congratulations MintJulep on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!
Demi water Transport
- Thread starter matay
- Start date
It depends somewhat on the water quality that you are trying to maintain. PVC may degrade the water. I have seen higher purity water systems use PVDF or stainless.
Exposure to suns rays is also an issue as PVC has a high thermal expansion. Insulation is used to lessen the consequences of exposure to sunlight.
Exposure to suns rays is also an issue as PVC has a high thermal expansion. Insulation is used to lessen the consequences of exposure to sunlight.
ABS pipes are commonly used in the electronics industry for ultra pure water. Phillips in Taiwan use it in computer monitor production where impurities are definitely not accpetable.
This is not the ABS in ASME B31.3 that caused so many problems in buildngs in the USA, but a product produced in Australia, UK, Malaysia, Indonesia and Switzerland to ISO and AS 3518 standards. It is available up to DN 800 in solvent welded or rubber ring jointed systems. It is also available with a pre insulated system.
I have used it for the last 25 years with great success.
US Filters use it for their membrane (RO UF) plants so it is certainly good enough for demin water.
This is not the ABS in ASME B31.3 that caused so many problems in buildngs in the USA, but a product produced in Australia, UK, Malaysia, Indonesia and Switzerland to ISO and AS 3518 standards. It is available up to DN 800 in solvent welded or rubber ring jointed systems. It is also available with a pre insulated system.
I have used it for the last 25 years with great success.
US Filters use it for their membrane (RO UF) plants so it is certainly good enough for demin water.
Nobody in their right mind would use solvent welded or rubber ring jointed piping systems for UPW aplications. It should be obvious to the casual reader that impurities would enter the UPW from the area of the pipe where it is solvent welded or joined with a "rubber ring". For the same reason, screwed piping is never used for UPW.
Perhaps, this type of piping may be acceptable for use in low purity demin systems, but not for UPW.
Perhaps, this type of piping may be acceptable for use in low purity demin systems, but not for UPW.
- Thread starter
- #5
PVC is probably acceptable from a materials standpoint.
However, you are probably going to be using 2" and smaller piping. The plastic piping is quite flexible and you will need supports every 4' or so. You will also have to greatly concerned regarding pipe expansion because of the high coefficient of thermal expansion of plastics.
For these reasons, the recommendation would be to go with stainless.
However, you are probably going to be using 2" and smaller piping. The plastic piping is quite flexible and you will need supports every 4' or so. You will also have to greatly concerned regarding pipe expansion because of the high coefficient of thermal expansion of plastics.
For these reasons, the recommendation would be to go with stainless.
- Thread starter
- #7
BIMR,
ABS is used extensively for UPW.
The chemical welding uses a mix of ABS and MEK. The MEK diffuses thri=ough the ABS and evaporates. It does not provide impurities as you suggest. This may occur where a OVC solvent cement is used with PVC as this is a compound not virgin PVC.
PVC has a low fracture toughness. If exposed to low temperatures , below 5C, it may be easily damaged in a bove gorund installations. If you need evidence visit the scrap heap of a plant or mine. View the PVC pipe and electrical conduit laying around the place.
Avoid PVC unless you are going to mechanically protect it.
ABS is used extensively for UPW.
The chemical welding uses a mix of ABS and MEK. The MEK diffuses thri=ough the ABS and evaporates. It does not provide impurities as you suggest. This may occur where a OVC solvent cement is used with PVC as this is a compound not virgin PVC.
PVC has a low fracture toughness. If exposed to low temperatures , below 5C, it may be easily damaged in a bove gorund installations. If you need evidence visit the scrap heap of a plant or mine. View the PVC pipe and electrical conduit laying around the place.
Avoid PVC unless you are going to mechanically protect it.
matay,
The thermal expansion is from exposure to the elements. An outside application is exposed to the sun as well as the cold. You would have to protect the piping from the sun. That is why you would have to insulate the piping, to protect it from the sun.
The pipe support issue is critical as well. PVC needs pipe supports on 3-5 foot centers. Most pipe racks do not provide that kind of support. Most industrial pipe racks are on 15-20 foot centers. The pipe may be cheap, but that is offset by the additional installation cost.
For these reasons, do not use plastic and go to 304L SS. If you want to save money, think about using sch. 10 pipe.
stanier,
First off, my recommendation is to use SS not plastic.
PVDF (polyvinylidene fluoride) has become the material of choice for UPW distribution systems, thanks to its level of purity, surface characteristics and pressure temperature capabilities. Ultrapure water—type E-1 electronic grade water is defined in ASTM D5127.
Not sure what application that you are referring to, but for a true UPW application, no one is going to use ABS pipe. Check it out yourself.
You may be mixed up with the terminology. UPW is not the same thing as demin water.
The thermal expansion is from exposure to the elements. An outside application is exposed to the sun as well as the cold. You would have to protect the piping from the sun. That is why you would have to insulate the piping, to protect it from the sun.
The pipe support issue is critical as well. PVC needs pipe supports on 3-5 foot centers. Most pipe racks do not provide that kind of support. Most industrial pipe racks are on 15-20 foot centers. The pipe may be cheap, but that is offset by the additional installation cost.
For these reasons, do not use plastic and go to 304L SS. If you want to save money, think about using sch. 10 pipe.
stanier,
First off, my recommendation is to use SS not plastic.
PVDF (polyvinylidene fluoride) has become the material of choice for UPW distribution systems, thanks to its level of purity, surface characteristics and pressure temperature capabilities. Ultrapure water—type E-1 electronic grade water is defined in ASTM D5127.
Not sure what application that you are referring to, but for a true UPW application, no one is going to use ABS pipe. Check it out yourself.
You may be mixed up with the terminology. UPW is not the same thing as demin water.
BIMR,
I am certainly not confused with the difference between demin water and UPW.
I am not referring to the grade of ABS that is used in the USA for drainage. That has had its catastrophies and lawsuits. This product made in SE Asia and Europe is indeed used for UPW in the electronics industry in Taiwan, China, Malaysia.
Not everything has an ASTM reference, complies with ASME B31.3 or other matters US. There are capable technologies in the rest of the world .
For outside applications PVC is not a good choice of materials. Yes SS is a good product but that has its problems with stress corrosion cracking, corrosion in the HAZ for higher carbon grades, need for gas purging etc.
I am certainly not confused with the difference between demin water and UPW.
I am not referring to the grade of ABS that is used in the USA for drainage. That has had its catastrophies and lawsuits. This product made in SE Asia and Europe is indeed used for UPW in the electronics industry in Taiwan, China, Malaysia.
Not everything has an ASTM reference, complies with ASME B31.3 or other matters US. There are capable technologies in the rest of the world .
For outside applications PVC is not a good choice of materials. Yes SS is a good product but that has its problems with stress corrosion cracking, corrosion in the HAZ for higher carbon grades, need for gas purging etc.
Well, I don't know how to make it any clearer for you.
The Tyco reference that you listed shows ABS piping but makes no claims for the use of ABS piping in UPW applications. The Tyco reference does however show where Tyco PVDF piping is used in UPW.
From the Tyco brochure:
"Renowned as one of the toughest and high security piping systems available on the market today, ABS is used for many arduous and diverse applications. These cover Mechanical Services, Mining & Mineral Processing, Industrial & Power Generation, Water & Wastewater Infrastructure and Industrial Plumbing to name but a few."
I do not see any problem using ABS fir these applications, but ABS is not suitable for UPW applications.
You still have not given one reference for the use of ABS piping in UPW applications.
I gave you one reference that was Swiss, one that was Japanese, and the third reference that I used was from the UK. All of them are great references for the use of PVDF piping in UPW.
What do these references have to do with "Not everything has an ASTM reference, complies with ASME B31.3 or other matters US. There are capable technologies in the rest of the world." Where do you come up with that?
Stainless steel is a standard piping material used in power plants for handling demin. water. There are no issues with stress corrosion cracking, corrosion in the HAZ for higher carbon grades, need for gas purging etc. for this application and use (demin. water) in power plants.
Have you ever been to a UPW application or power plant?
The Tyco reference that you listed shows ABS piping but makes no claims for the use of ABS piping in UPW applications. The Tyco reference does however show where Tyco PVDF piping is used in UPW.
From the Tyco brochure:
"Renowned as one of the toughest and high security piping systems available on the market today, ABS is used for many arduous and diverse applications. These cover Mechanical Services, Mining & Mineral Processing, Industrial & Power Generation, Water & Wastewater Infrastructure and Industrial Plumbing to name but a few."
I do not see any problem using ABS fir these applications, but ABS is not suitable for UPW applications.
You still have not given one reference for the use of ABS piping in UPW applications.
I gave you one reference that was Swiss, one that was Japanese, and the third reference that I used was from the UK. All of them are great references for the use of PVDF piping in UPW.
What do these references have to do with "Not everything has an ASTM reference, complies with ASME B31.3 or other matters US. There are capable technologies in the rest of the world." Where do you come up with that?
Stainless steel is a standard piping material used in power plants for handling demin. water. There are no issues with stress corrosion cracking, corrosion in the HAZ for higher carbon grades, need for gas purging etc. for this application and use (demin. water) in power plants.
Have you ever been to a UPW application or power plant?
The link that Stanier provided for ABS piping shows the problems that you will encounter trying to use plastic piping:
1. Supports required every 4 feet.
2. Need for expansion loops because of the high coefficients of thermal expansion inherent to plastic piping.
3. Need for derating the pipe design pressure for piping that is operating at higher temperatures.
1. Supports required every 4 feet.
2. Need for expansion loops because of the high coefficients of thermal expansion inherent to plastic piping.
3. Need for derating the pipe design pressure for piping that is operating at higher temperatures.
- Status
Similar threads
- Question
- Locked
- Question
