SDR is one of the important specifications in HDPE pipes that frequently appears in product catalogs. Understanding SDR helps in selecting the right pipe according to the requirements of a piping system.
The SDR value is closely related to pipe dimensions and its ability to withstand working pressure. This article discusses the definition of SDR, how to calculate it, and its relationship with proper pipe selection.
What Is SDR (Standard Dimension Ratio)?
SDR or Standard Dimension Ratio is a value that represents the ratio between the outside diameter of a pipe and its wall thickness. This value is one of the standard parameters used in the piping industry to classify pipe dimensions.
The function of SDR in pipes is to help determine the proportion between diameter size and wall thickness consistently. Therefore, pipes with the same SDR will have comparable dimensional characteristics even if their diameters are different.
SDR is an important parameter in pipeline design because it is directly related to the pipe’s ability to withstand internal pressure. This parameter is used together with PE material type to determine the pressure class or PN (Pressure Nominal) of a pipe.
The SDR value is directly related to pipe dimensions, especially wall thickness. Pipes with the same outside diameter but different SDR values will have different wall thicknesses and internal diameters.
How to Calculate SDR?
SDR calculation uses a simple formula, but each component must be understood correctly.
SDR Formula
The formula used to calculate SDR is:
SDR = Dn / en
Explanation of Each Component
Each symbol in the formula represents a pipe dimension component that must be identified beforehand.
- SDR (Standard Dimension Ratio):
The ratio between the outside diameter and wall thickness of the pipe, expressed without units. - Dn (nominal diameter):
The outside diameter of the pipe expressed in millimeters (mm). - en (nominal wall thickness):
The wall thickness of the pipe expressed in millimeters (mm).
Simple Calculation Example
As an illustration, assume an HDPE pipe has an outside diameter (Dn) of 110 mm and a wall thickness (en) of 10 mm. The SDR calculation is as follows:
- SDR = Dn / en
- SDR = 110 / 10
- SDR = 11
The result indicates that the pipe has an SDR 11 specification, which then becomes a reference for determining the pipe pressure class according to the type of PE material used.
What Does the SDR Value Mean in HDPE Pipes?
The SDR value has technical significance that needs to be understood before determining pipe specifications.
- The smaller the SDR number, the thicker the pipe wall relative to its diameter, meaning the pipe generally has a higher ability to withstand working pressure.
- The larger the SDR number, the thinner the pipe wall relative to its diameter, meaning the pipe is generally used for systems with lower working pressure.
- The SDR value affects the pipe’s ability to withstand internal pressure because it is directly related to the wall thickness that carries the water pressure load inside the pipe.
- SDR selection must be adjusted according to application requirements, considering that each piping system has different working pressures and operational conditions.
Relationship Between SDR, PN, and PE Material
The SDR value cannot be separated from two other parameters: pressure class (PN) and the type of PE material used.
SDR and Pressure Class (PN)
PN or Pressure Nominal indicates the maximum working pressure that a pipe can withstand. SDR and PN are closely related because the combination of SDR, PE material type, and pressure class determines the operational pressure limit of a pipe.
SDR and PE80 Material
PE80 material has a lower Minimum Required Strength (MRS) value compared to PE100. Therefore, at the same SDR value, PE80 pipes generally have a lower pressure class (PN).
SDR and PE100 Material
PE100 material has higher mechanical strength, allowing PE100 pipes with the same SDR value to withstand higher working pressure compared to PE80.
Why SDR Cannot Be Separated from Material Specifications
SDR only indicates the proportion of pipe dimensions, while the actual pressure resistance capability is determined by the combination of SDR and the type of PE material used. Both parameters must be considered together to ensure that pipe specifications match the required working pressure of the system.
How to Choose the Right SDR?
Selecting the appropriate SDR requires consideration of several factors:
- Adjust the SDR value according to the planned working pressure of the piping system.
- Consider project specifications, including technical standards required by the project owner or applicable regulations.
- Consult technical requirements with manufacturers or engineers to ensure pipe specifications match field conditions.
- Use products that comply with required standards to maintain piping system reliability.
- Do not only consider wall thickness, because PE material characteristics and pressure class (PN) must also be evaluated together.
Consult Your HDPE Pipe SDR Specifications with ALVApipe!
To ensure that a piping system operates optimally and provides long service life, SDR selection must be adjusted according to the required PE material and pressure class (PN).
PT Alpha Cikupa Makmur through the ALVApipe brand manufactures PE 100 HDPE water pipes certified with SNI 4829.2:2015, available in diameters ranging from OD 20 mm to 250 mm with various pressure classes:
- SDR 11 (PN 16)
- SDR 13.6 (PN 12.5)
- SDR 17 (PN 10)
- SDR 21 (PN 8)
- SDR 26 (PN 6.3)
With a complete range of SDR options, the technical requirements of various water distribution, irrigation, industrial, and mining projects can be fulfilled from a single source.
Not sure which SDR specification is most suitable for your project? The ALVApipe team is ready to help determine the right specifications according to your piping system conditions and requirements.
Let’s contact the ALVApipe team now via WhatsApp +6287726663295 to get the best offer for SNI-certified HDPE water pipes for your store inventory needs!
