Types of plastic pipes used in plumbing
Plastic pipes or PVC pipes are best choice for any types of plumbing
Both PVC-O and PVC-U have the same chemical make-up, thus it should come as no surprise that their overall qualities are of comparable too
The primary distinction is based on the mechanical qualities that are exhibited in accordance with the orientation
The incorporation of an impact modifier into PVC-M results in a composition that is distinct from that of conventional PVC-U
Furthermore, the properties of PVC-M can be differentiated from those of PVC-U in varying degrees, depending on the nature and quantity of the impact modifier
The comparison that is going to follow is of a generic nature, and its purpose is to highlight common variances that exist across pipe grade materials
Tensile Strength: The tensile strength of PVC-O can be up to twice as strong as the tensile strength of regular PVC-U
PVC-M has a tensile strength that is only somewhat inferior to that of PVC-U in its ordinary form
Toughness — PVC-O and PVC-M both exhibit a ductile behavior under any and all realistic conditions
This is true for all types of PVC
Standard PVC-U may have brittle qualities in certain unfavorable settings, such as when there is a notch or fault present in the material
Plastic pipes
Plastic made pipes are highly practical
Polyvinyl chloride is a thermoplastic material that consists of PVC resin that has been compounded with variable proportions of stabilizers, lubricants, fillers, pigments, plasticizers, and processing aids
PVC is a material that can be molded into almost any shape
Various compounds consisting of these components have been produced in order to attain particular sets of qualities for a variety of different uses
PVC resin is the primary component of each compound, notwithstanding this fact
In the field of organic chemistry, the name “PVC” refers to “poly (vinyl chloride),” which describes the substance as “a polymer,” or chained molecules of vinyl chloride
In most written material, the brackets are not utilized, and the name of the material is typically reduced to PVC
In the instances where a particular kind of PVC pipe is being discussed, that kind of pipe will be specifically named, as will be described in more depth below
In the context of a more general discussion, the phrase “PVC pipes” will be used to refer to the full range of PVC pipe pressure materials that Vinidex has available to purchase
Several Distinct Varieties of Polyvinyl Chloride
Those PVC compounds with the fewest number of compounding ingredients and the fewest amount of plasticizers also have the fewest number of compounding ingredients
These PVC compounds have the best short-term and long-term strengths
This particular variety of PVC is referred to as UPVC or PVC-U
In order to make compounds with increased impact resistance, UPVC may be combined with various other resins or modifiers (such as ABS, CPE, or acrylics, for example)
These chemical substances are referred to as modified PVC (PVC-M)
Plasticizers can be added to PVC compounds in order to make flexible or plasticized PVC, which can then be made into products with a broad variety of qualities
Other forms of PVC include oriented PVC (PVC-O), also known as chlorinated PVC (PVC-C), which is simply PVC-U in which the molecules are preferentially aligned in a particular direction, and CPVC (PVC-C), also known as chlorinated PVC, which has a higher chlorine content
PVC-U (unplasticized) is a tough and rigid material that is resistant to the majority of chemicals
It has an ultimate tensile stress of around 52 MPa when it is 20 degrees Celsius
In general, PVC-U can be utilized at temperatures up to 60 degrees Celsius; however, the actual temperature limit depends on the amount of stress as well as the characteristics of the environment
PVC-M, which stands for modified, is a rigid material that also possesses improved toughness, particularly when it comes to impact
When compared to PVC-U, the elastic modulus, yield stress, and ultimate tensile strength are often lower
These attributes change depending on the kind of modifier that is used and how much of it there is
PVC that has been plasticized is less rigid than its unplasticized counterpart, has a higher impact strength, is easier to extrude or mold, has a lower temperature resistance, is less resistant to chemical attack, and typically has a lower ultimate tensile strength
Plasticized PVC has a greater degree of variation in its properties from one compound to the next than PVC-U does
Plasticized PVC is not used in the production of pressure pipes by Vinidex
PVC-C (chlorinated), which is quite comparable to PVC-U in terms of the majority of its features, has a stronger temperature resistance than PVC-U and can continue to function up to 95 degrees Celsius
At temperatures of 80 degrees Celsius, its ultimate tensile stress is around 15 MPa, which is comparable to its ultimate compressive stress at 20 degrees Celsius
HSPVC is another name for PVC-O, which stands for oriented PVC (high strength PVC)
Pipes made of PVC-O material represent a significant step forward in the technological development of the PVC pipe sector
PVC-O is produced using a method that results in a preferential orientation of the long chain PVC molecules in the circumferential or hoop direction
This orientation is necessary for the production of PVC-O
This results in a noticeable improvement in the qualities in this particular direction
In addition to its many other advantages, PVC-O may be manufactured to have an ultimate tensile strength that is up to twice as high as that of PVC-U
There is the potential for very significant gains in strength and/or savings in materials to be made in applications such as pressure pipes, where the directionality of the stress is clearly defined
In the hoop direction, typical properties of PVC-O include the following: PVC-O has a tensile strength equal to 90 MPa
PVC-O has a modulus of elasticity of 4000 MPa
It is well knowledge that changing the orientation of molecules can improve a substance’s properties, and there have been commercial applications of this idea for more than three decades
In more recent times, it has been utilized in the production of consumer goods like as films, high-strength waste bags, bottles for carbonated beverages, and other items of a similar nature
Types of plastic pipes
The following table provides an overview of the general characteristics of PVC compounds that are utilized in the production of pipe
The numbers that are provided here are for standard, unaltered formulas that make use of K67 PVC resin, unless otherwise specified
A few figures for other types of pipe materials are displayed below for comparison
The properties of thermoplastics are susceptible to large variations with temperature, and the relevant temperature range is stated whenever it is applicable
The application of stress for an extended period of time can have an effect on mechanical characteristics, which should more accurately be characterized by creep functions
In the area of this manual devoted to design, you will find additional data that is specifically relevant to pipe applications
Users are encouraged to get in touch with our Technical Department if they have data that falls beyond the conditions that are specified
Abbreviations
PE: Polyethylene
PP: Polypropylene
PA: Polyamide (nylon)
Cast Iron (CI):
AC: Asbestos Cement
Glass Reinforced Pipe, abbreviated as GRP
Measurement System Conversions
1MPa = 10bar = 9
81 kg/cm2 = 145lbf in2
1 Joule = 4
186 calories = 0
948 x 10-3 BTU = 0
737 ft
lbf
1 Kelvin = 1°C = 1
8°F temperature differential
Mechanical Qualities and Traits
The stress-strain response of PVC, similar to that of other thermoplastic polymers, is time and temperature dependant
The consequent behavior of strain in a plastics material under the application of a static load that remains constant is fairly complicated
There is an instantaneous elastic response, and as the load is removed, there is a complete return to its original state
In addition to this, there is a slower deformation that continues while the load is being applied indefinitely until it causes the material to burst
This behavior is referred to as creep
If the load is removed before the material fails, then the original dimensions will gradually be recovered over the course of some time
Temperature is another factor that can affect the pace of both creep and recovery
Creep rates have a tendency to increase when the temperature is raised
Plastics are considered to be viscoelastic materials due to the nature of the reaction they exhibit
Plastic pipes used in plumbing
Plastic pipes have proven much more resistance compared to metal in plumbing
Because of creep, pipes that are subjected to higher strains will fail in a shorter amount of time compared to pipes that are subjected to lower loads
This is a result of creep
For pressure pipe applications, extended life is a key requirement
Because of this, it is essential that pipes be built to function at wall stresses that will allow for extended service lives to be accomplished
In order to determine the qualities over a long period of time, a large number of test specimens are examined in pipe form until they burst
After that, each of these individual data points is plotted on a graph, and a regression analysis is carried out on the data
Extrapolating the results of a linear regression analysis allows one to determine the 97
5% lower prediction limit failure stress at the design point
This stress must be greater than a minimum needed stress (MRS)
The MRS is then multiplied by a safety factor to provide a maximum operating stress for the pipe material
This value is then used to size pipes for a variety of pressure ratings
The ISO design point of 50 years, which is equivalent to 438,000 hours, is utilized throughout in Europe and Australasia
The design milestone of 100,000 hours has traditionally been utilized in countries of the North American continent
This design point is very random, and it should not be taken as an indication of the PVC pipe’s anticipated service life in any capacity
Traditionally, the stress regression line is displayed on logarithmic axes, displaying the circumferential or hoop stress versus time to rupture
Types of plastic pipes in plumbing
The types of design for PVC and plastic pipes intended for using in applications involving pressure like plumbing requires the prediction of the pipes’ long-term qualities as well as the use of a safety factor
As is the case with every other aspect of engineering design, the amount of confidence in the ability to forecast performance is reflected in the magnitude of the safety factor
The increased confidence in the predictable behavior of the materials of the new generation, PVC-M and PVC-O, has the advantage of making it possible to employ a lower factor of safety in the design process
PVC-O and PVC-M pipes operate at a greater design stress than ordinary PVC-U pipes as a result of their reduced safety factor and, in the case of PVC-O, higher strength in the hoop direction
This is due to the fact that PVC-O has a higher strength in the hoop direction
Creep and Elasticity – The modulus of elasticity of PVC-O is up to 24 percent higher than that of ordinary PVC-U in the orientated direction, while the modulus of PVC-O is comparable to that of standard PVC-U in the other directions
PVC-M has an elastic modulus that is only moderately lower than PVC-U in its ordinary form
PVC-O has superior impact characteristics over normal PVC-U, outperforming it by a factor of at least 2 and up to 5
PVC-M also offers a stronger resilience to impact than PVC-U in its ordinary form
When testing the impact resistance of PVC-M pipes, obtaining a ductile failure characteristic is the primary goal of the tests
The features of PVC-U, PVC-M, and PVC-O do not differ significantly from one another in terms of their resistance to the effects of weathering
The joining process can be accomplished using either rubber ring joints or solvent cement joints for PVC-U and PVC-M pipes
Only pipes with rubber-ring jointed ends can be constructed from PVC-O
It is not possible to join PVC-O using solvent cement
