In plate heat exchangers, gasket reliability directly determines sealing performance, operational safety, and service life. While materials such as EPDM, NBR, and FKM are commonly specified based on temperature and chemical compatibility, the long-term performance of a gasket depends equally on manufacturing control.
Mechanical properties listed in a gasket quality certificate are not merely test numbers — they reflect compounding formulation, filler dispersion, vulcanization accuracy, and molding precision.
Tensile strength measures the maximum stress a gasket material can withstand before failure.
Base polymer grade (EPDM/NBR/FKM quality)
Carbon black and reinforcing filler content
Mixing uniformity
Vulcanization temperature and time
If vulcanization is insufficient (under-curing):
Crosslink density is low
Tensile strength decreases
Elastic recovery weakens
If vulcanization is excessive (over-curing):
Material becomes brittle
Micro-cracks may form
Structural strength may degrade
Thus, tensile strength reflects the balance of crosslink density and curing control.
Elongation indicates material flexibility and ability to absorb deformation.
Crosslink density
Plasticizer formulation
Filler proportion
Low elongation often indicates:
Over-curing
Excessive filler loading
Reduced flexibility
Excessively high elongation may suggest:
Insufficient curing
Low structural integrity
In plate heat exchangers, appropriate elongation ensures resistance to thermal cycling and compression stress.
Tear strength determines resistance to crack propagation, especially along sealing grooves.
Polymer chain uniformity
Filler dispersion
Molding pressure
Mold edge precision
Insufficient molding pressure or uneven filler distribution can create micro-voids that weaken tear resistance.
For gaskets operating under high compression, tear strength is critical to prevent edge cracking.
Hardness determines compression behavior and sealing force.
Filler ratio
Sulfur or curing agent dosage
Crosslink density control
If hardness is too high:
Gasket may not conform to plate surface
Risk of insufficient sealing line contact
If hardness is too low:
Excessive compression
Reduced structural support
Premature deformation
Proper hardness ensures uniform compression distribution in the plate pack.
Compression set measures permanent deformation after compression and heat exposure.
This is one of the most important indicators of long-term sealing performance.
Vulcanization uniformity
Crosslink network structure
Heat aging resistance
Polymer formulation stability
Under-cured materials:
Poor elastic recovery
Rapid sealing degradation
Over-cured materials:
Brittle structure
Reduced flexibility
Low compression set ensures:
Long-term sealing integrity
Stable contact pressure
Reduced leakage risk
In real industrial operation, compression set is often more critical than tensile strength.
Beyond mechanical testing, finished gasket dimensions must be tightly controlled.
Mold precision
Injection pressure
Material flow behavior
Temperature stability during curing
Thickness variation directly affects:
Compression distribution
Sealing uniformity
Plate load balance
Even small thickness inconsistencies may lead to localized leakage or uneven stress.
Visual and sectional inspection ensures:
Smooth surface finish
No burrs
No misalignment
Uniform coloration
Surface defects often originate from:
Mold contamination
Temperature fluctuation
Improper demolding
Inconsistent compound mixing
Although simple, surface quality significantly impacts early-stage sealing reliability.
| Material | Temperature Resistance | Typical Application |
|---|---|---|
| NBR | up to 110°C | HVAC and oil systems |
| EPDM | up to 150°C | Water, steam, food |
| FKM | up to 180°C | Chemical and aggressive media |
Material selection must consider:
Operating temperature
Fluid chemistry
Cleaning procedure (CIP)
Pressure cycling conditions
However, even the correct material grade cannot compensate for poor production control.
Mechanical properties are direct indicators of:
Compound formulation accuracy
Filler dispersion quality
Vulcanization precision
Dimensional molding control
Consistent production parameters ensure:
Long-term sealing stability
Reduced maintenance frequency
Lower leakage risk
Improved equipment reliability
Gasket testing is not a procedural formality — it is a reflection of production discipline and engineering responsibility.
In plate heat exchanger applications, gasket performance depends not only on material type but on the integrity of the manufacturing process.
Tensile strength, elongation, tear strength, hardness, and compression set are interconnected properties governed by formulation control, curing accuracy, and molding precision.
Properly controlled production ensures:
Stable sealing performance
Resistance to thermal and mechanical stress
Extended service life
Reduced operational risk
For industrial heat exchanger systems, gasket quality verification is a fundamental component of reliability engineering.
The most critical property is compression set, especially for long-term sealing reliability.
Low compression set ensures that the gasket maintains elastic recovery after compression and temperature exposure. Even if tensile strength is high, excessive permanent deformation can lead to leakage.
In real industrial operation, compression set often determines service life more than tensile strength.
Tensile strength reflects the structural integrity of the material and its resistance to tearing during installation and operation.
However, tensile strength alone does not guarantee sealing performance. It must be balanced with elongation and hardness to ensure flexibility and durability.
Vulcanization determines crosslink density within the rubber structure.
Under-curing leads to low strength and poor elastic recovery.
Over-curing causes brittleness and crack formation.
Proper temperature and time control during curing are essential to ensure stable mechanical properties.
Hardness (Shore A) influences compression behavior and sealing force.
If hardness is too high:
The gasket may not conform properly to the plate surface.
If hardness is too low:
Excessive compression may occur.
Structural support may weaken.
Balanced hardness ensures uniform compression and stable sealing.
Common causes include:
Improper material selection (temperature or chemical incompatibility)
Poor vulcanization control
Excessive compression set
Surface defects from molding
Thermal and pressure cycling fatigue
In many cases, failure is related to manufacturing control rather than material type alone.
Even small thickness inconsistencies can cause:
Uneven compression distribution
Localized leakage
Plate misalignment
Precision molding and strict dimensional control are essential for stable performance.
Replacement intervals depend on:
Operating temperature
Chemical exposure
Pressure cycling frequency
Compression set behavior
In high-temperature or aggressive environments, inspection during scheduled maintenance is recommended.
Not necessarily.
EPDM performs well in water and steam applications.
NBR is more suitable for oil-based fluids.
FKM is preferred for aggressive chemical environments.
Material selection must match operating conditions.
Surface defects such as burrs or molding imperfections may lead to:
Initial leakage
Stress concentration
Early crack propagation
Visual inspection is a simple but critical step in quality assurance.
