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(Agricultural)
(OP)
27 Oct 23 19:34I am planning to install a 24 or 30" HDPE DR9 4710 line above ground, spanning 4200 linear feet over a 500' elevation. This installation is set to replace a buried steel pipe severely damaged due to landslides, which caused a kink in a 20" steel pipe. I am seeking advice on anchoring or securing the pipe to prevent excessive sliding or snaking. The pipeline will transport water up a hill with an open discharge at the top. Any suggestions on the longevity of such above-ground installations? I need this pipeline to last over 50 years. Additionally, what measures should be taken if the ground beneath the pipeline shifts? Your insights are greatly appreciated!
(Civil/Environmental)
27 Oct 23 22:17Chapter 8 in this document addresses aboveground installation:
https://usfusion.com/wp-content/uploads/2021/07/US...(Civil/Environmental)
28 Oct 23 15:35Here is the same book from the original source, and it appears to be a better PDF:
(Chemical)
30 Oct 23 06:21Hi, Take a look at this document:
(Petroleum)
30 Oct 23 08:40If you have a large (especially daily) temperature variation, generally you should not lay HDPE on the surface.
--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
(Petroleum)
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30 Oct 23 14:10Another consideration is solar gain and temperature derating above 20°C. Even if the pipeline operates continuously, it’s not feasible to guarantee performance for 50 years due to solar gain exposure, especially if the pipe is black. Any temperature above 20°C starts to require derating. I am uncertain how much SDR9 can handle, but you don't have much spare margin if you're lifting water up 500 feet (approximately 151 meters) at 15 bar at the base. Polyethylene (PE) also expands and contracts significantly more than steel (about 10 times as much), so it needs to be laid in a way that accommodates this movement, often in a serpentine pattern. However, you need to avoid the pipe taking on a Z shape. Ideally, lay the pipe at 90 degrees to the slope. Given that landslides are difficult to address, it might be better to repair the pipeline after such events rather than attempt to create an unbreakable solution. Despite being more flexible than steel and able to withstand significant movement, even UV-stabilized PE will struggle to last 50 years.
Remember - More details = better answers. Also: If you get a response, it's polite to respond to it.
(Mechanical)
31 Oct 23 19:00Attached is a photo of an above-ground HDPE installation at Richmond Power Plant in St. Croix, Virgin Islands. Although I did not design it, I had to modify the firewater system, which affected the piping. The pipe was about 300-400 feet long, laid straight, supported with clamp-type supports, and included a rubber expansion joint at each end to absorb thermal expansion. The ends of the pipe were anchored into the ground after the expansion joints.
(Mechanical)
31 Oct 23 19:05The attachment in the previous post was not opening. Here it is again:
(Mechanical)
31 Oct 23 19:15Here is a close-up of the clamp support. Note that it is relatively loose and allows the pipe to slide.
(Mechanical)
31 Oct 23 19:17Here is a close-up of an expansion joint:
(Mechanical)
31 Oct 23 19:18Here is the other side of the line from the first photo posted:
(Mechanical)
31 Oct 23 19:26Here is the above-ground piping design guide from the Plastic Pipe Institute (PPI). This can be obtained on their website along with other valuable reference material.
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HDPE pipe, also known as High-Density Polyethylene Pipe, is a robust and flexible piping system favored for various applications, including fluid and gas transportation globally. Its toughness, corrosion resistance, excellent chemical tolerance, and lightweight properties make it ideal for long-term, cost-effective piping solutions.
Unlike in the past, more companies are now choosing HDPE pipe fittings due to their cost efficiency and reliability. The eco-friendly nature of HDPE pipes further encourages their use as a green solution.
Polyethylene (PE) pipe is a general term for thermoplastic pipes made from ethylene gas. There are various types of PE pipes, including very low density, low density, cross-linked, ultra-low molecular weight, high molecular weight, medium density, ultra-high molecular weight, chlorinated, and linear low-density varieties.
HDPE pipes are denser than regular PE pipes and less flexible due to their high melting and impact points. Manufacturers may add carbon black or other colors to HDPE pipes during production to prevent UV light damage. Unlike regular PE pipes, HDPE pipes are rust-resistant and can withstand internal pressure reliably, maintaining their initial flow despite environmental factors.
The performance of HDPE pipes depends on raw materials, processing equipment, and technology. Some manufacturers add recycled materials to reduce costs and increase profits, but this compromises pipe performance. Here are seven ways to identify quality PE pipes:
High-quality pipes: Inner and outer surfaces are smooth, free from bubbles, dents, and impurities.
Inferior pipes: The surface is uneven, dull, with visible pitting.
The edge strip milled out by the welding machine should be bright in color and flexible, not breaking easily when folded repeatedly. If the strips are whitish or of varying colors, it indicates recycled materials or poor mixing.
High-quality pipes: The milled strips are bright and can withstand repeated folding.
Inferior pipes: Darker and brittle milled strips that break easily.
Qualified butt weld joints should appear smooth and symmetrical around the pipe ring, with the wrapping depth not lower than the pipe surface and a tolerance of both sides of the weld not exceeding 10% of the pipe thickness. The edge should be firm and smooth, broader at the base, without impurities, small holes, deformation, or damage from issues during the process.
High-quality pipes: The flange is flat and slightly extends under pressure.
Inferior pipes: Many pores on the weld surface, shorter wrapping under pressure.
High-quality pipes: No peculiar smell due to stable chemical properties.
Inferior pipes: Unpleasant odor or smell when heated due to unstable chemical properties.
High-quality pipes: Resistant to acid, alkali, salt, and various solvents, with anti-corrosion and aging properties.
Inferior pipes: Prone to aging phenomena like embrittlement, cracking, and molting when exposed to acid, alkali, salt, or detergents.
The elongation at break is the ratio of length at break to the original length. Higher elongation indicates better flexibility and performance.
High-quality pipes: Can extend up to 3.5 times the original length without breaking.
Inferior pipes: Poor flexibility and easy to break.
Oxidative induction time (OIT) measures how long it takes for an autocatalytic oxidation reaction to occur under high temperature and oxygen, indicating the thermal degradation resistance of PE pipes during processing, storage, welding, and usage. Longer OIT means better aging resistance.
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