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December 22, 2017
PEX Drinking Water Debate Sees Disagreements Regarding Cleanliness
A recent article in the Environmental Monitor is suggesting that plastic pipes leach chemicals into drinking water. However, the Plastics Pipe Institute has come forward with evidence pointing to the contrary. Both sides are putting everything on the table as the debate over replacing America’s aging water infrastructure rages on.
Environmental Monitor - Plastic Pipes Leaching Chemicals Into Drinking Water
According to the article published by the Environmental Monitor, public concern about the safety of drinking water is at a higher level than it has been in quite some time, with roughly 63% of those surveyed indicating a high level of worry about drinking water quality. The article also says that an estimated 63 million Americans have been exposed to unsafe water within the last decade, which represents about 20% of the population. According to research from Dr. Andrew Whelton at Purdue, the entire country is at risk in the future.
From here, the article goes over the history of plumbing pipes in the United States, from the archaic “sewage in the streets” of the 1800s to the lead-based piping commonly used in the early days of plumbing. The focus eventually turns to PEX pipe, noting several benefits to the plastic pipes. Besides environmental benefits, PEX pipe is cheaper than copper pipes and has more durability with no risk of corrosion. However, Dr. Whelton’s research as presented in the article downplays the benefits of PEX piping, citing chemicals leaching into the drinking water and subsequently affecting odors in the water. His research points to some solutions to make the pipes safer for use, including flushing out all drinking pipes before regular use. In the end, both Dr. Whelton and the author of the article suggest that even with these findings, more research is necessary to fully understand the effects of PEX pipe on drinking water.
Plastics Pipe Institute - Addressing Misleading Publications on the Safety of PEX Pipe
The Plastics Pipe Institute, however, has shown concerns about publications such as the one seen in the Environmental Monitor, considering them to be misleading and not including the full story. PPI has published and circulated a number of counterclaims on the subject, linked below. One publication, revised in January of 2017, suggests that a perceived change in taste and odor with PEX pipe could be from the change of material from copper. The organization emphasizes overall compliance with NSF/ANSI Standard 61, Drinking Water System Components - Health Effects, and notes that standard helps to ensure the safety of potable water.
Beyond just this article, PPI has laid out concerns with Dr. Whelton’s research in other publications, including a November 2017 article in the American Water Works Association Journal that suggests plastic pipes can accumulate metal, further contaminating drinking water. A formal PPI technical response to that paper raised a number of issues with the research, pointing out flawed methodology and saying that the findings do not match the hypothesis of the paper. They finish their technical response by saying that the technical standards in place help to regulate against such contamination and that Dr. Whelton should consider accepting their invitation to work alongside of the NSF to mitigate potential concerns.
Conclusion - A Tough Debate Needing Experienced Answers
Large amounts of research completed by both Dr. Whelton and the PPI have seen completely different conclusions reached regarding the safety of PEX pipes. It’s safe to say that anyone in the plumbing industry should do a diligent job of researching as well to find the best possible solution for their piping needs. That’s where the value of having an experienced plastic pipe consultant comes in. The plastics experts at Bryan Hauger Consulting can help clients fully understand the benefits and risks that come with PEX pipe, and a vast array of standards expertise will help find the perfect solution to any piping problems.
Be sure to check out these links to learn more about this debate.
From the Environmental Monitor
December 15, 2017
New ASTM pipe standard aims to reduce production contamination
The F17 committee of ASTM is currently working on a new standard to ensure cleaner and safer pipes during the manufacturing process. This proposed ASTM standard is currently listed as work item WK56697 and will provide guidance to plastic pipe manufacturers on proper methods of transportation and cleaning methods for manufacturing equipment. The completed standard will be able to be used in a plant audit where inspectors can refer to the standard to make sure new products are being done the right way.
Check out another article talking about the new standard here.
December 8, 2017
HDPE Making Strides as an Option for Nuclear Power Plants
Joint efforts between the American Society of Mechanical Engineers and the Electric Power Research Institute are making High Density Polyethylene pipe a potential alternative to steel piping in nuclear power plants. The EPRI is currently working on a “comprehensive guide” that will outline all of the need-to-know information for using HDPE in nuclear facilities. Combining ASME’s existing code case with original research, the guide intends to answer critical questions about the safety of using HDPE as compared to steel pipes. The early results look good for HDPE, as it has been holding up well in many pressure and stress tests. Researchers are still working on new test methods to detect other potential flaws, and plan on releasing their guide sometime next year.
Check out the full article!
PEX Drinking Water Debate Sees Disagreements Regarding Cleanliness
A recent article in the Environmental Monitor is suggesting that plastic pipes leach chemicals into drinking water. However, the Plastics Pipe Institute has come forward with evidence pointing to the contrary. Both sides are putting everything on the table as the debate over replacing America’s aging water infrastructure rages on.
Environmental Monitor - Plastic Pipes Leaching Chemicals Into Drinking Water
According to the article published by the Environmental Monitor, public concern about the safety of drinking water is at a higher level than it has been in quite some time, with roughly 63% of those surveyed indicating a high level of worry about drinking water quality. The article also says that an estimated 63 million Americans have been exposed to unsafe water within the last decade, which represents about 20% of the population. According to research from Dr. Andrew Whelton at Purdue, the entire country is at risk in the future.
From here, the article goes over the history of plumbing pipes in the United States, from the archaic “sewage in the streets” of the 1800s to the lead-based piping commonly used in the early days of plumbing. The focus eventually turns to PEX pipe, noting several benefits to the plastic pipes. Besides environmental benefits, PEX pipe is cheaper than copper pipes and has more durability with no risk of corrosion. However, Dr. Whelton’s research as presented in the article downplays the benefits of PEX piping, citing chemicals leaching into the drinking water and subsequently affecting odors in the water. His research points to some solutions to make the pipes safer for use, including flushing out all drinking pipes before regular use. In the end, both Dr. Whelton and the author of the article suggest that even with these findings, more research is necessary to fully understand the effects of PEX pipe on drinking water.
Plastics Pipe Institute - Addressing Misleading Publications on the Safety of PEX Pipe
The Plastics Pipe Institute, however, has shown concerns about publications such as the one seen in the Environmental Monitor, considering them to be misleading and not including the full story. PPI has published and circulated a number of counterclaims on the subject, linked below. One publication, revised in January of 2017, suggests that a perceived change in taste and odor with PEX pipe could be from the change of material from copper. The organization emphasizes overall compliance with NSF/ANSI Standard 61, Drinking Water System Components - Health Effects, and notes that standard helps to ensure the safety of potable water.
Beyond just this article, PPI has laid out concerns with Dr. Whelton’s research in other publications, including a November 2017 article in the American Water Works Association Journal that suggests plastic pipes can accumulate metal, further contaminating drinking water. A formal PPI technical response to that paper raised a number of issues with the research, pointing out flawed methodology and saying that the findings do not match the hypothesis of the paper. They finish their technical response by saying that the technical standards in place help to regulate against such contamination and that Dr. Whelton should consider accepting their invitation to work alongside of the NSF to mitigate potential concerns.
Conclusion - A Tough Debate Needing Experienced Answers
Large amounts of research completed by both Dr. Whelton and the PPI have seen completely different conclusions reached regarding the safety of PEX pipes. It’s safe to say that anyone in the plumbing industry should do a diligent job of researching as well to find the best possible solution for their piping needs. That’s where the value of having an experienced plastic pipe consultant comes in. The plastics experts at Bryan Hauger Consulting can help clients fully understand the benefits and risks that come with PEX pipe, and a vast array of standards expertise will help find the perfect solution to any piping problems.
Be sure to check out these links to learn more about this debate.
From the Environmental Monitor
December 15, 2017
New ASTM pipe standard aims to reduce production contamination
The F17 committee of ASTM is currently working on a new standard to ensure cleaner and safer pipes during the manufacturing process. This proposed ASTM standard is currently listed as work item WK56697 and will provide guidance to plastic pipe manufacturers on proper methods of transportation and cleaning methods for manufacturing equipment. The completed standard will be able to be used in a plant audit where inspectors can refer to the standard to make sure new products are being done the right way.
Check out another article talking about the new standard here.
December 8, 2017
HDPE Making Strides as an Option for Nuclear Power Plants
Joint efforts between the American Society of Mechanical Engineers and the Electric Power Research Institute are making High Density Polyethylene pipe a potential alternative to steel piping in nuclear power plants. The EPRI is currently working on a “comprehensive guide” that will outline all of the need-to-know information for using HDPE in nuclear facilities. Combining ASME’s existing code case with original research, the guide intends to answer critical questions about the safety of using HDPE as compared to steel pipes. The early results look good for HDPE, as it has been holding up well in many pressure and stress tests. Researchers are still working on new test methods to detect other potential flaws, and plan on releasing their guide sometime next year.
Check out the full article!
Jim Walker - New Board member of BHC
December 1, 2017
Jim Walker Added to Board of Directors
We're pleased to welcome Jim Walker to the Bryan Hauger Consulting Board of Directors! Jim's expertise and experience in sales and manufacturing will provide our company with another seasoned voice on our board. Mr. Walker added "I have experience on a number of fronts including as an industrial products salesman with a variety of manufacturing concerns, but none were involved with plastic. I am excited to learn about plastics and see how my experience in other businesses can benefit Bryan Hauger Consulting”. Welcome aboard, Jim!
November 28, 2017
Global Spoolable Composite Pipe Market 2017
A new marketing study is available which highlights the spoolable composite pipe market making significant inroads in energy production markets. Companies highlighted in the report include a number companies including several from North American. "The report presents a deep study of the market growth factors and drivers. In-depth research of the Spoolable Pipes Market limitations and the opportunities enable the user to make the future projection. The report also covers proceeding Market trends depends on the technological advancements, innovations and manufacturing procedure" and includes a review of various geographic markets based on product type, technology, end-users and application. The study includes information on Airborne Oil & Gas, Changchun Gaoxiang Special Pipes, Flexpipe, FlexSteel Pipeline Technologies, Future Pipe Industries, Magma Global Limited, National Oilwell Varco, Pipelife International GmbH, Polyflow LLC, and Smartpipe Technologies.
November 30, 2017
PVC Tensile Strength By Rich Geoffroy
Simply stated, tensile strength is the useful limit of a material – it is the point at which a product made of the material will break or severely distort. The tensile strength of a material is measured by pulling on the ends of a specimen of known cross-sectional area (square inches) at a constant rate (inch/minute) and measuring the force (pounds) required to stretch the material to failure. A brittle material, like glass or ceramic, will continue to increase in load or force until the material breaks suddenly. The peak load or load-at-failure divided by the original cross-sectional area of the specimen is the tensile stress-at-failure, or tensile strength of the material. A more ductile material, like copper or steel, will reach a peak load and not break immediately, but continue to extend – although less force is necessary to continue to stretch the material to failure. In this case, the peak load is termed the load-at-yield and represents the yield strength of the material, while the load-at-break is used to determine the tensile stress-at-break, or ultimate tensile strength. Other more ductile materials are capable of reorganizing their microstructure and strengthen with continued stretching or drawing. As a result, the ultimate strength can be greater than the yield strength of the material. In this situation, the higher of the two, yield or break, is considered the “tensile strength” of the material. Knowing these properties of a material, one can design products and realistically determine at what point a product made from the material will break or severely distort in use.
While most materials have very defined tensile properties, the behavior of polymers, or plastics like PVC, is rate dependent. That means that its strength characteristics vary depending on how quickly or slowly the material is deformed – at very high rates of stretching, the material behaves like a brittle glass, while at extremely low rates of extension it has properties more like rubber. In order to compare the tensile properties of two plastic compounds, one cannot merely compare the reported tensile strengths of the materials, but must ensure that they were determined under identical test conditions – using identical specimen geometries at the same deformation rates. For PVC pressure pipe compounds, the standard conditions for establishing tensile strength are stipulated in ASTM D1784. Still, the strengths cannot be used directly to design a product unless the test conditions closely match the use conditions. For example, the tensile strength of rigid PVC, like that used in PVC pipe, is typically reported as 7800-8200 psi – that means that if held at this stress, a product will typically fail in 1 to 5 minutes – about the time it takes to run a typical tensile test. This value of tensile strength is suitable for estimating the failure stress or pressure in a one-minute quick burst test, but the value is unsuitable for determining the failure stress or pressure rating of a pipe. The stress required to cause a PVC pressure pipe to fail in 11.3 years (100,000 hours) in a product made with the same material is about half the tensile strength at 1 to 5 minutes, or 4000 psi – the value of the Hydrostatic Design Basis used for establishing the pressure rating on PVC pipe.
There are several reasons why one would want to determine the Longitudinal Tensile Strength (LTS) of a PVC pressure pipe.
Jim Walker Added to Board of Directors
We're pleased to welcome Jim Walker to the Bryan Hauger Consulting Board of Directors! Jim's expertise and experience in sales and manufacturing will provide our company with another seasoned voice on our board. Mr. Walker added "I have experience on a number of fronts including as an industrial products salesman with a variety of manufacturing concerns, but none were involved with plastic. I am excited to learn about plastics and see how my experience in other businesses can benefit Bryan Hauger Consulting”. Welcome aboard, Jim!
November 28, 2017
Global Spoolable Composite Pipe Market 2017
A new marketing study is available which highlights the spoolable composite pipe market making significant inroads in energy production markets. Companies highlighted in the report include a number companies including several from North American. "The report presents a deep study of the market growth factors and drivers. In-depth research of the Spoolable Pipes Market limitations and the opportunities enable the user to make the future projection. The report also covers proceeding Market trends depends on the technological advancements, innovations and manufacturing procedure" and includes a review of various geographic markets based on product type, technology, end-users and application. The study includes information on Airborne Oil & Gas, Changchun Gaoxiang Special Pipes, Flexpipe, FlexSteel Pipeline Technologies, Future Pipe Industries, Magma Global Limited, National Oilwell Varco, Pipelife International GmbH, Polyflow LLC, and Smartpipe Technologies.
November 30, 2017
PVC Tensile Strength By Rich Geoffroy
Simply stated, tensile strength is the useful limit of a material – it is the point at which a product made of the material will break or severely distort. The tensile strength of a material is measured by pulling on the ends of a specimen of known cross-sectional area (square inches) at a constant rate (inch/minute) and measuring the force (pounds) required to stretch the material to failure. A brittle material, like glass or ceramic, will continue to increase in load or force until the material breaks suddenly. The peak load or load-at-failure divided by the original cross-sectional area of the specimen is the tensile stress-at-failure, or tensile strength of the material. A more ductile material, like copper or steel, will reach a peak load and not break immediately, but continue to extend – although less force is necessary to continue to stretch the material to failure. In this case, the peak load is termed the load-at-yield and represents the yield strength of the material, while the load-at-break is used to determine the tensile stress-at-break, or ultimate tensile strength. Other more ductile materials are capable of reorganizing their microstructure and strengthen with continued stretching or drawing. As a result, the ultimate strength can be greater than the yield strength of the material. In this situation, the higher of the two, yield or break, is considered the “tensile strength” of the material. Knowing these properties of a material, one can design products and realistically determine at what point a product made from the material will break or severely distort in use.
While most materials have very defined tensile properties, the behavior of polymers, or plastics like PVC, is rate dependent. That means that its strength characteristics vary depending on how quickly or slowly the material is deformed – at very high rates of stretching, the material behaves like a brittle glass, while at extremely low rates of extension it has properties more like rubber. In order to compare the tensile properties of two plastic compounds, one cannot merely compare the reported tensile strengths of the materials, but must ensure that they were determined under identical test conditions – using identical specimen geometries at the same deformation rates. For PVC pressure pipe compounds, the standard conditions for establishing tensile strength are stipulated in ASTM D1784. Still, the strengths cannot be used directly to design a product unless the test conditions closely match the use conditions. For example, the tensile strength of rigid PVC, like that used in PVC pipe, is typically reported as 7800-8200 psi – that means that if held at this stress, a product will typically fail in 1 to 5 minutes – about the time it takes to run a typical tensile test. This value of tensile strength is suitable for estimating the failure stress or pressure in a one-minute quick burst test, but the value is unsuitable for determining the failure stress or pressure rating of a pipe. The stress required to cause a PVC pressure pipe to fail in 11.3 years (100,000 hours) in a product made with the same material is about half the tensile strength at 1 to 5 minutes, or 4000 psi – the value of the Hydrostatic Design Basis used for establishing the pressure rating on PVC pipe.
There are several reasons why one would want to determine the Longitudinal Tensile Strength (LTS) of a PVC pressure pipe.
- For those products that are marked UL1285, a minimum LTS of 7000 psi is a requirement for UL compliance, and all UL1285 products should meet or exceed that property.
- All PVC pressure pipe standards require that the PVC 1120 material, from which the pipe is made, satisfy the cell classification requirements of 12454, stipulated in D1784. One of the cell class requirements is a minimum tensile strength of 7000 psi. Testing the LTS of the pipe ensures that the tensile strength of the material used to make the pipe was in compliance with the standard.
- To attain maximum strength, the PVC compound must be adequately processed into a homogeneous melt and formed properly into the pipe configuration by the extruder-die-sizing process. One way to assess proper homogeneity of the mixing process is by determining the LTS of the product. PVC resin begins as a fine powder, to which is added many other liquids, waxes, solids, and dispersions. While these ingredients are mixed in an intensive mixer, similar to a large home blender, the dry blend remains as a mere mixture of components and not a homogeneous composition. Final mixing into a homogeneous mass is performed in the extruder. LTS can establish if adequate blending and homogeneity has been established by at least satisfying the minimum 7000 psi value for tensile strength. Furthermore, the PVC powder particles themselves have to be adequately broken down and melted, often termed fusion, in order to achieve sufficient tensile strength of the compound. LTS can be used to detect inadequate fusion of the PVC compound. To make these assessments, the tensile specimens need to be prepared directly from the pipe wall – flattening or milling/molding the pipe before specimen preparation would add another heat history, further obscuring the likelihood of detecting the aforementioned material deficiencies.
- Ideally, the PVC extrudate exits the die in a shape very close to the final dimensions of the product – very little has to be done to the extrudate to bring it to final product dimensions. However, some manufactures when changing products to different wall thicknesses or diameters, rather than take the time to change extrusion dies due to lost down time, will manipulate the melt by drawing down the extrudate, rapidly elongating the softened plastic, or expanding the diameter just prior to the sizing/cooling sleeve. This technique saves time and money, but freezes in undesirable residual stresses in the pipe wall, and seriously compromising the physical integrity of the product. LTS is one way to determine if post-extrusion drawing or stretching has affected the physical properties of the product.To detect the presence of excessive residual stresses in the product, it is imperative that the tensile specimens be prepared directly from the pipe wall, and not after flattening or milling/molding. These additional heat histories relax residual stresses in the product, negating their detection in the product.
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