Content from XLPE
I merged some of the content from the XLPE article. However, some of it contradicts the material in this article. I do not know which is correct, so I am posting the contradictory material below. -- Kjkolb 06:31, 22 June 2007 (UTC)
- XLPE (Cross-linked polyethylene) is a kind of insulator which is used as insulation layer in underground power cables. XLPE (crosslinked polyethylene) is a thermoset material produced by the compounding of LDPE with a crosslinking agent such as dicumyl peroxide. Al Gilbert and Frank Precopio invented PEX in March 1963 in the GE Research Laboratory located in Niskayuna, New York. In this process, the long-chain polyethylene molecules cross-link during a curing (vulcanization) process to form a material that has electrical characteristics that are similar to thermoplastic polyethylene, but with better mechanical properties, particularly at high temperatures.
- I think the word "thermoset" is off-key in the quoted paragraph. Polyethylene, including cross-linked polyethylene, is a thermoplastic, not a thermoset, although the cross-linking is commonly performed on the net shape parts, not the feedstock. For thermoset plastics, think melamine and Bakelite; once molded into a shape and cured, they can't be re-molded. If you put a hot soldering iron to PEX or XLPE, it will, most definitely, melt, whereas melamine or Bakelite will char.—QuicksilverT @ 16:51, 23 June 2009 (UTC)
Damages to XLPE compound by water?
CAN ANY BODY TELL ME THAT THE FINSIHED STOCK OF XLPE COMPOUND IF COMES IN CONTACT OF WATER THAN WHAT TYPE OF DAMAGE WILL OCCUR. WETHER THE MATERIAL IS SALVAGEABLE? OR ANY APPLICATIONS —Preceding unsigned comment added by 220.127.116.11 (talk • contribs) 11:25, April 11, 2008
- First, please STOP SHOUTING. Second, this isn't a plumbing forum; this page is only for discussion of improvements to the Cross-linked polyethylene article. For answers to your questions, please visit the Web sites of the various manufacturers of PEX/XLPE plumbing systems, where you'll find specifications and FAQs. —QuicksilverT @ 16:15, 23 June 2009 (UTC)
- That would have the effect of turning the article into a link farm, in violation of WP policy. The section on Classification describes the main categories of PEX-A, -B, and -C. Knowing the class of a candidate product and the characteristics of each class should be sufficient for the curious reader. —QuicksilverT @ 16:19, 23 June 2009 (UTC)
Comparison of types
CalPipes (a pipefitters union in California) has opposed proposals to allow PEX in California potable water lines. (http://www.calpipes.org/ProtectingCalifornians_PEX.asp)
CalPipes argues that California's proposals allow inappropriate kind(s) of PEX piping. CalPipes specifically complains about contaminants (such as MTBE, which is more commonly found in gasoline) forming in hot water lines. CalPipe also complains about PEX pipes that do not contain enough antioxidants to resist both sunlight (before installation) and hot chlorinated water (during years of use).
CalPipes links to research results from Chemical Accident Reconstruction Services (Chemaxx) (http://chemaxx.com/polytube1.htm). Chemaxx states that peroxides used to make some kinds of PEX can leach into drinking water, and break down to form contaminants (such as MTBE) which are more commonly found in gasoline.
CalPipes' website includes a letter from Lubrizol (http://www.calpipes.org/pdf/Lubrizol_Letter.pdf). Lubrizol's letter points out that there are various standards for PEX pipes, some stricter than others.
Lubrizol's website (http://www.lubrizol.com/BuildingSolutions/TradeName/FlowGuardFlex/TypesPex.html) explains that Lubrizol's brand of PEX is made using the silane process. Lubrizol also points out that the silane process allows much higher levels of antioxidants in the PEX, so silane PEX can resist much more sunlight and hot chlorinated water than PEX made by either the peroxide process or the radiation process.
I corrected my previous post: SpecialChem's website (http://www.specialchem4polymers.com/tc/silane-crosslinking-agents/index.aspx?id=trigger) mentions peroxides as part of typical silane cross-linking processes.
- CalPipes' arguments are alarmist in nature, designed to create FUD and slow down or prevent the adoption of PEX in California for the benefit of union members and the general detriment of the public. (Their page URL, "ProtectingCalifornians_PEX.asp" must be some kind of twisted joke: It should have been named "ProtectingPlumbers.asp".) It's moot, anyway, since, after dragging their feet for a decade, in January 2009 the California Building Standards Commission (CBSC) unanimously approved PEX for the California Plumbing Code (CPC), effective August 1, 2009, and furthermore, permitted local jurisdictions to approve PEX in general plumbing applications, effective immediately. If there were any real health or reliability problems with PEX in plumbing systems, we'd have heard the message from Europe decades ago, where they began using it in the 1960s, well before it was introduced in Canada and the United States. However, if the different PEX processes can be shown to have advantages or disadvantages in certain applications, it may be useful to add this information, perhaps in tabular form, to this Wikipedia article in an NPOV format. However, unless one is concerned about extreme water conditions, due to chlorination, high temperature, mineral content, etc., almost any class of PEX can be used interchangeably.—QuicksilverT @ 16:42, 23 June 2009 (UTC)
Silane PEX is also known as PEX-B.
Update Dead Links
I updated 2 dead links. They have valid information but are from a site that sells PEX. The information is good but some may want to see if they can find a better non-commercial link. I only did this as it was the best one I could find to replace a dead one that is still valid but may be open to doubt.--Marlin1975 (talk) 16:18, 6 October 2009 (UTC)
it retains it's shape because of plastic deformation, not "shape memory" because plain aluminium isn't a shape memory alloy shape memory alloys have to be heat treated for permanently deform or restore original form —Preceding unsigned comment added by 18.104.22.168 (talk) 22:12, 14 January 2010 (UTC)