PVC is a thermoplastic derived from chlorine (from industrial grade salts) and carbon (mainly refined from oil/gas). Compared to other polymers, it is less dependent on non-renewable crude oil and natural gas, so PVC is considered a natural resource-saving plastic compared to oil-dependent plastics such as PE, PP, PET and PS. Chlorine imparts excellent fire resistance to PVC: When PVC is on fire, the flame will extinguish itself due to the self-extinguishing properties of the material.
Municipal water supply and sewer transport
drainage
Gas pipeline
Irrigation pipe
Wire conduit
Yes, research on PVC pipes manufactured and used continuously in Europe in the 1930s shows that these products have a service life of up to one hundred years or more, which often exceeds the service life of the structures they are installed in.
In addition, PVC has an impressive long-term durability record. When water utility managers and engineering companies surveyed in a study sponsored by the American Hydraulic Association Research Foundation, they used corrosion resistance, longevity and durability as the main reasons for choosing PVC. PVC is ranked first when these same water professionals are required to compare PVC to other common types of pressure pipes. [Come from: Moser, AP and Kellogg, Kenneth G., "Polyethylene (PVC) Pipeline Performance Evaluation", AWWA Research Foundation, Denver, Colorado, 1994.
Yes, they can. Due to the long service life of PVC pipe products, there are not many pipes currently in use because they are still in use. Although current standards generally do not allow recirculating used pipes to new certified pipes. PVC pipe producers can recycle almost all production waste internally. Since PVC is a thermoplastic PVC pipe, it can be simply regrind, comminuted and returned to the extrusion process to make new pipes.
Compared to many alternatives, PVC pipes are a lightweight but strong material. A length of PVC pipe will weigh one-fifth the equivalent of the equivalent size of a cast iron pipe, making it easier to install. The product is easy to assemble into a solvent welded or gasketed version, once assembled correctly, both are leak-free.
Stiffness is the property of the pipe, which defines their resistance to deformation under external loads, mainly vertical loads associated with buried pipe conditions. In non-stress applications, this is a basic property to ensure the correct performance of the installation. The allowable depth of burial is calculated according to the research test. PVC products have been successfully installed at depths of 50 feet or more.
Every day, more utility companies realize the advantages of trenchless technology. Due to cost savings, more trenchless projects are being installed than ever before. The savings are due to faster installation, faster licensing and saving design time, fewer commercial and residential disruptions, less park and tree damagement, and less interference with the road (and subsequent road maintenance).
The terms "DR(dimension ratio)" and "SDR(standard dimension ratio)" are widely used in the PVC pipe industry. Both terms refer to the same ratio, which is a parameter that is obtained by dividing the average outside diameter of the pipe by the minimum pipe wall thickness.
DR and SDR were developed out of convenience rather than out of necessity. They have been established to simplify standardization in the specification of plastic pipe on an international basis. Since these define a constant ratio between outer diameter and wall thickness, they provide a simple means of specifying product dimensions to maintain constant mechanical properties regardless of pipe size. In other words, for a given DR or SDR, pressure capacity and pipe stiffness remain constant regardless of pipe size.
Even though the terms DR and SDR are synonymous, one minor difference between them is that SDR refers only to a particular series of numbers, i.e., 51, 41, 32.5, 26, 21, etc. This series of "preferred numbers" is based on a geometric progression, and was developed by a French engineer called Charles Renard. These numbers are often called "Renard's Numbers."
The term DR became widely used in 1975, with the publication of AWWA C900, which governs production of small diameter PVC pressure pipe. AWWA allowed the desired pressure capacity to dictate wall thickness. Since the OD/t values generated did not happen to fall on any of Renard's Numbers, AWWA removed the "standard" designation from the SDR term.
It is interesting to note that the most widely used product for small diameter sanitary sewer in the U.S., ASTM D3034, SDR 35, provides an apparent contradiction in terms. While 35 is not a Renard Number, it is still referred as a standard dimension ratio. In fact, all OD/t ratios in D3034 are listed as SDRs whether they are included in Renard's "preferred numbers" or not. This was probably for convenience's sake. D3034 was written in 1972, prior to the popularization of the DR term. Accordingly, ASTM may have allowed all OD/t ratios to be called SDRs.
The bottom line is simple: the two terms are interchangeable. SDR=DR=OD/t.
