The European standard “ EN 681-2 Elastomeric gaskets - Material requirements for pipe joint gaskets used in water and drainage applications - Part 2: Thermoplastic elastomers” describes the material requirements for gaskets molded from thermoplastic elastomers (TPE) used only at the joints of the following:
This standard contains general requirements for finished joint gaskets. Additional requirements required by specific applications are specified in the relevant product standards, recognizing that the performance of pipe joints depends on the gasket material properties, gasket geometry, and pipe joint design.
For the purposes of this standard, the term thermoplastic elastomer refers to a polymer or polymer blend that does not require vulcanization or crosslinking during processing but has elastic properties at service temperature. These properties are lost at the processing temperature, allowing further processing, but they are restored when the material is returned to service temperature.
The nominal hardness of materials should be specified within the following ranges in the table titled “Hardness categories”:
Three hardness classes for pipe joint seals are specified in another table provided in the standard.
Dimensional tolerances for finished gaskets should be determined from the appropriate classes in ISO 3302-1. Gaskets should be free from defects or irregularities that could affect their function. Classification of defects should be as follows, according to ISO 9691:
Large surface imperfections in areas not involved in the sealing function may be considered defects. This must be agreed upon between the parties involved. Acceptance criteria depend on the type or design of the seals, respectively.
Internal defects may be considered defects. The compressive strength can be determined according to ISO 77431. Acceptable limit values for compressive strength must be agreed upon between the parties involved. These depend on the type or design of the seals, respectively.
Hardness in samples prepared according to the ISO 48 standard using the microtest method must meet the requirements listed in the table. If a gasket's dimensions are suitable, the standard test method specified in ISO 48 may be used, provided the microtest method is used for reference purposes. For the same gasket, the difference between the minimum and maximum hardness values must not exceed 5 IRHD. Each value must be within the specified tolerances.
Tensile strength and elongation at break should be determined using the method specified in ISO 37, preferably on barbell test pieces cut from a gasket or sample plate, perpendicular to the mold flow. Results from sample plate test pieces should be accepted. Sample plates should be prepared as specified in this standard. Tensile strength and elongation at break should comply with the requirements given in the table.
If the pressure setting is taken from a gasket, the measurement should be made in the direction of the pressure at which the gasket operates at 25 percent pressure, as far as possible. When determined using the method specified in ISO 815, using a small Type B test piece at 23 degrees and 70 degrees, the pressure die shall comply with the requirements listed in the table. When determined using the method specified in ISO 815, using a small Type B test piece at minus 10 degrees and a 30-minute recovery measurement, the pressure die for gaskets used in drainage and dewatering applications shall comply with the requirements listed in the table.
In short, EN 681-2 is a European standard that specifies the requirements for thermoplastic elastomer seals used in pipe connections in water supply, drainage, and sewerage systems. These seals are critical for maintaining leak-proof and flexible connections in plastic and metal piping systems.
The EN 681-2 standard is part of the broader EN 681 series, which specifies standards for different elastomeric sealants used in pipeline applications. While EN 681-1 covers vulcanized rubber, EN 681-2 focuses on thermoplastic elastomer compounds, which are becoming increasingly popular due to their processability, recyclability, and consistent properties.
The EN 681-2 standard applies to factory-made and on-site-assembled gaskets made from thermoplastic elastomers used in:
The gaskets are specifically designed for use in joining systems where flexibility is required to accommodate soil movement, pipe alignment errors and thermal expansion.
The EN 681-2 standard outlines physical, mechanical, and chemical performance standards for thermoplastic elastomer materials used in seals. The main parameters are:
The EN 681-2 standard includes several classes of thermoplastic elastomers designed for different applications:
The suitability of thermoplastic elastomer for hot water systems is more limited than rubber, which is covered by the EN 681-1 standard as types WB and WD.
EN 681-2 gaskets are commonly used in:
The use of thermoplastic elastomer materials allows coextrusion with plastic pipe sockets, automatic assembly and recyclability, making them attractive for modern production.
As thermoplastic elastomer technology develops, it offers advantages in terms of ease of processing, precision and recyclability, making it an increasingly popular choice, particularly for non-pressure and low-temperature applications.
Our organization, which has been serving for many years and meticulously following global developments in science and technology, employs a team of experienced professionals and a broad infrastructure to conduct testing, measurement, and analysis in a wide range of areas for businesses across all sectors. In this context, we also provide testing services in accordance with the standard "EN 681-2 Elastomeric seals - Material requirements for pipe joint seals used in water and drainage applications - Part 2: Thermoplastic elastomers."
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