A lot of drillers (probably more than half) use PVC casing for most of their domestic wells. It is inexpensive, reliable, never rusts and, used within limits, will make a lifetime well. However, PVC has one major drawback: It is not as strong as steel pipe. This means that setting depths are limited, and you can't get too rough with it either. A good, clean hole helps.
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Figuring out maximum setting depth is fairly straightforward. The strength of the material times the joint weight will give you the max theoretical setting depth. 'Theoretical' is the key word. It's not a good idea to set at maximum theoretical depths, in case you have to work a tight spot or stick it. Having a little 'in your back pocket' is always a good idea. Part of the strength of any solid is called the modulus of elasticity. Within this range, a material can be bent, compressed or stretched, and return to its original shape. Beyond this limit, permanent deformation happens. Beyond that, the material fails catastrophically. With pipe, you can pull on it within limits and it will return to its original dimensions. Beyond that, it will take a permanent stretch and will be weakened or part. Imagine a rubber band. It will stretch many times and return, but over pull it and it will break. Pipe is the same.
With PVC pipe, the modulus of elasticity is much lower than steel. It will stretch more easily, but have less overall strength. This is important to water well drillers because you might not have enough rig to pull steel casing in two, but you probably have plenty of power to part PVC. It is also more elastic than steel and will stretch a lot more for a given pull.
If you are going in the hole with a string of casing and stick it off bottom, knowing the exact depth at which you are stuck will help you determine the best course of action. It's a lot different to be stuck on bottom than to have a shallow sand fall in on the hole and stick you at a shallow depth. By carefully pulling on the casing, you can get an idea of how deep you're stuck. If it doesn't stretch much at all, you are stuck fairly shallow. If you can stretch it many inches for a given pull, you are stuck much deeper.
During my fishing career, I often had to respond to a stuck pipe job. One of the first things I usually do is pull on the pipe, stretch it, note the weight and measure the stretch in inches. Then the exact dimensions of the pipe, the grade and the amount of over pull would tell me approximately how deep it had stuck. This calculation ignores friction, so it makes a difference whether you are in casing or open hole. With stuck tubing inside a string of casing, I could often calculate almost to the exact joint where I was stuck. Not so much in open hole or horizontal wells. This helps a lot when planning a back-off or pipe-cutting procedures. It saves the wireline guys a lot of time not having to work up and down the pipe to find the stuck point. Once they had confirmed the stuck point, I could plan a string-shot, back-off (usually) one full joint above. Then I could screw in a jarring assembly or prepare for a washover.
The procedure for stretch calculations is fairly simple. Pick up the pipe to the neutral point. This is the weight just before it got stuck. Pull a small amount over this and mark the pipe. Pull slightly more and mark the pipe again. Repeat this a couple times with increasing pull, and you will be able to calculate the amount of pipe you are stretching; thus, telling you how deep you are stuck. Be careful and don't pull too much. PVC can fail catastrophically, usually at a fairly shallow depth, causing a lot of iron flying around and leading to a much more complicated fishing job.
When making your calculations, it is important to know the exact dimensions of your pipe. Don't depend on the catalog dimensions. Caliper the pipe yourself. OD squared minus ID squared equals area in square inches of the pipe. This, when coupled with the modulus of elasticity, will tell you the strength of the pipe and the amount of stretch per 1,000 pounds of pull. Often, small rigs do not have weight indicators, adding to the guesswork involved. I have found that a good initial stretch can often be safely made by idling the engine all the way down. When you pull, on many mechanical rigs, it will stall the engine. This is your baseline. You can come back to it whenever you need. Then throttle up and pull a little harder. Often on jobs like this, I carry a portable weight indicator with me that I can rig up to get very accurate measurements' an invaluable tool for a fisherman.
After I have determined the depth of the problem, I can figure out how much to safely pull on it and work the pipe. If I'm making progress, I keep going. If not, further measures are called for.
I will save the recovery procedures for another day, and hope that you don't stick your pipe in the meantime.
Keep 'em turning to the right and give me a call if you get in a bind.
For more Wayne Nash columns, visit www.thedriller.com/wayne.
Drillers have installed wells using PVC materials for decades. Companies make PVC casing and fittings, and even PVC screen ' the components of the whole well system. However, advancements over time have meant that PVC in the field today outperforms the materials contractors had access to when HDPE gained widespread use in the s.
Broadly, the 'recipes' companies use to make polyvinyl chloride, better known as PVC, have gone through subtle changes. Contractors may not know from just looking at the finished product, but today's PVCs tend to have more corrosion resistance and durability than earlier generations. That makes it a cost-effective option for well installations, even in harsh environments.
Modern PVC pipe can also provide more flexibility. 'Flexible' PVC is a type of PVC designed to install in wells located in difficult-to-access areas. Flexible PVC is also more resistant to breakage, which can help to prevent leaks in such wells.
Finally, there have been advancements in the methods used to join PVC pipe. Traditional methods of joining PVC pipe, such as solvent cementing, can prove time-consuming for contractors and difficult correctly execute. Newer methods of joining PVC pipe, such as mechanical joining, are faster and easier to do. Mechanical joining also provides a stronger and more reliable joint than traditional methods.
The advantages of using PVC materials in water well construction include:
Of course, every material can have trade-offs. PVC is no different and contractors should consider these factors in sourcing decisions. PVC is:
PVC pipe, casing and fittings have proven popular for contractors (and their customers) for many years. Their popularity only grows as companies develop advances in their products. Drillers have materials options when it comes to well installation. PVC has improved over time and contractors should give it another look if they haven't in a while. It could be just the thing you need to offer your customers a trouble-free water well that lasts a lifetime.
Regular PVC ( polyvinyl chloride ) is a common, strong but lightweight plastic used in construction. It is made softer and more flexible by the addition of plasticizers . If no plasticizers are added, it is known as uPVC ( unplasticized polyvinyl chloride ), rigid PVC , or vinyl siding in the U.S.
Stacked blue PVC pipes
As a flexible plastic, PVC is used to produce a wide variety of piping. Larger PVC pipes are often used in plumbing to distribute non-potable water. PVC piping can also be used to insulate electrical cables.
uPVC is used as a replacement for wood in construction, such as in double glazed window frames and window sills and in what is known as vinyl siding in the U.S. It is a versatile material that can be manufacturered in many colors or made to look like other materials (e.g., wood). uPVC is also used instead of cast iron for certain types of heavy-duty plumbing and draining.
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PVC is used as a replacement for copper and aluminum pipes and is used in waste lines, irrigation systems and pool circulation systems. It is easy to cut into smaller pieces and can be fastened with glue, making it a good alternative to metal.
uPVC is used for the majority of plastic pipes in the world, as it is incredibly resistant to chemical erosion and has smoother inner walls that help to encourage water flow. It also functions well in a wide range of temperatures and operating pressures. It is incredibly strong, stiff and cost-effective, and so is often used for sewage lines and exterior drainage pipes. Even so, uPVC piping is much less common in the U.S., where PVC piping is preferred.
Neither PVC nor uPVC is used to transmit drinking water. cPVC (chlorinated polyvinyl chloride) is used instead.
PVC is not used for window frames, although some manufacturers may use 'PVC' to refer to their uPVC windows. Instead, uPVC is used for window frames, as it does not decompose and is weather-resistant.
uPVC will not change shape under normal weather conditions, but it can be reshaped at very high temperatures. uPVC windows are more energy-efficient than those with wooden or metal frames. Moreover, uPVC can also be used for door frames and conservatories.
This video shows how a typical uPVC window is installed:
Small and slender PVC pipes are sometimes found in medical equipment. PVC is also used in leather-like or waterproof clothing materials, vinyl flooring, shoes, toys, car interiors and car cables, shower curtains, and numerous other plastic products.
Because uPVC has fewer health concerns associated with it, it is found in medical and dental pieces. For example, uPVC is sometimes used for dental retainers.
Because it is designed to be softer and more flexible than many other plastics, PVC is less durable than uPVC. However, both plastics are resistant to sunlight, oxidation, and a variety of chemicals. PVC piping's ability to withstand sunlight sometimes makes it more useful than ABS pipes.
It is very cheap to manufacture many PVC and uPVC products, which is why they are so ubiquitous in a wide variety of affordable products.
PVC pipe can be bought by length or weight. The thicker the piping, the most expensive the pipe will be. Still, PVC pipe is very affordable, with many 10-foot lengths costing less than $10.00 a piece.
PVC-coated wires can form HCl fumes in a fire, which can be a health hazard. Plasticizers may leach out of PVC into the environment.
Phthalates are what allow PVC to be flexible. Some of the phthalates used in PVC have been restricted or banned over the years, and many others are being replaced with safer phthalates. Dibutyl, benzyl butyl, and DEHP are some of the more commonly banned or restricted phthalates.
To date, there are no mainstream concerns regarding the use of uPVC, which does not use phthalates or BPA.
Neither PVC nor uPVC are biodegradable. However, uPVC is recyclable and can be reshaped into new products or pipes at very high temperatures.
Through, PVC and UPVC pipes and fittings are distinctive, these two can be confused with one another. PVC pipes are malleable, while UPVC is un-plasticized. They both are made from Polyvinyl Chloride, but some of their properties differ and therefore are fit in different applications.
Below are significant differences between PVC and UPVC pipes:
PVC is usually perplexing and sturdy because of the rigidity of polymer PVC. To burst this hardness and make PVC flexible, a plasticizing polymer is added to PVC during the manufacture of PVC pipe.
On the contrary, plasticized polymer uPVC is excluded from the pipe manufacturing process which leads UPVC pipes to be rigid and unbendable meaning that not as flexible as PVC products.
The principal application of both PVC and UPVC pipes is plumbing. You might have heard PVC piping is the best alternative to copper and aluminum pipes in irrigation, plumbing, and pool circulation structures. And that's true'
The reason behind this is the non-rigidity of PVC substance, it is easy to be amended into sought-after lengths, cuts, designs and can be fastened with glue.
On the other side, UPVC pipes are not only used for plumbing applications, they are used for wide purposes such as in heavy-duty water transportation or the construction of industry as an alternative to several stout metals. As these pipes are very tensile, they have the resistant strength to cope up with heavy-duty chemicals and corrosion.
Although uPVC pipes are strong and rigid, they are relatively easy to work with. UPVC pipes from leading manufacturers such as Skipper Limited have low weight and can be easily fitted using solvent cement.
One big perk of lightweight UPVC is that the cost involved in transportation and installation can be reduced. On the flip side, the installment of PVC is a little complex.
Both PVC and uPVC piping are designed to be durable. However, UPVC pipes are more durable in comparison to PVC. The one example behind UPVC's more durability is UPVC reduces air infiltration to keep your indoors comfortable.
PVC can introduce health hazards as PVC-coated wires can form HCl fumes in a fire due to Plasticizers that are being used in its manufacturing. Phthalates such as benzyl butyl, Dibutyl, and DEHP are one of those harmful substances that are used in PVC to make them flexible, these are restricted and banned in Pakistan over the years. To have the flexible quality endurable, many manufacturers have replaced Plasticizers with safer ones.
To date, there are no mainstream concerns regarding the use of uPVC, as it does not use phthalates or BPA while the manufacturing process. Even, UPVC is recyclable and can be reshaped into new forms at immense temperatures.
So that was all about the key Difference Between PVC and UPVC, moving next towards the advantages you can have using these pipes.
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