Nov 2, 2026
A heat exchanger gasket seals the joints between heat exchanger components, helping prevent fluid leakage under changing pressure and temperature. Start by reviewing the equipment design and operating conditions to select the most suitable gasket material. Check the process fluids on both sides, normal and upset temperatures, test pressures, available seating stress, flange condition, gasket geometry, and expected thermal or mechanical movement. This guide focuses on bolted, flanged heat exchanger joints, such as shell-and-tube channels and covers, rather than the elastomeric gaskets used in plate-and-frame units.
Heat exchanger joints may have large diameters, pass bars, ribs, or partitioned flow paths. Even a chemically compatible material can fail if the gasket cannot be manufactured accurately or compressed uniformly. For procurement, include the drawing, material, thickness, tolerances, and revision level in the sealing specification.
Quick Guide to Selecting Chemical Resistant Gaskets
| Selection area | What to confirm | Why it matters |
|---|---|---|
| Process media | Fluid composition, concentration, contaminants, and cleaning chemicals | The gasket must remain compatible with the actual media it will contact. |
| Temperature | Normal, startup, shutdown, upset, and cleaning temperatures | Heat can change gasket properties and the load retained by the bolted joint. |
| Pressure | Operating, differential, and test pressure | Internal pressure creates forces that the assembled joint must contain. |
| Joint loading | Available bolt load, gasket seating area, and flange rigidity | The gasket needs sufficient, controlled compression without exceeding joint limits. |
| Geometry | Dimensions, thickness, pass bars, partitions, and surface condition | Complex heat exchanger joints depend on accurate fit and uniform load distribution. |
| Cycling and vibration | Frequency and severity of thermal, pressure, and mechanical changes | Repeated movement can reduce residual gasket stress and expose weak points in the assembly. |
Use this checklist to narrow the options, then confirm the selection against the Durlon Gasket Manual, current product data, equipment requirements, and application engineering advice.
Comparing Heat Exchanger Gasket Materials
No gasket material is suitable for every heat exchanger. Compare the options against the process fluids, temperature and pressure ranges, flange design, available seating stress, and thermal cycling. Consider these factors for each application:
- PTFE-based materials: assess chemical compatibility first, then verify temperature limits, creep or relaxation behavior, and whether the joint can provide adequate compression.
- Compressed non-asbestos sheet: check the specific grade against the process media, temperature and pressure range, and available joint loading.
- Flexible graphite: review temperature exposure, oxidizing-environment limitations, gasket construction, and flange requirements.
- Semi-metallic designs: confirm the proposed construction and the seating load available from the flange and fasteners. Kammprofile gaskets are a common choice for high-temperature shell-and-tube joints.
How a Gasketing Machine Improves Production
For sheet gasket designs, accurate cutting helps manufacturers maintain dimensions and repeatability from one part to the next.
Custom Heat Exchanger Gaskets and Manufacturing Precision
Precision is critical for custom heat exchanger gaskets, especially large or complex shapes. For suitable sheet materials, a gasketing machine helps produce consistent, accurate cuts. However, gasket material and design must still be evaluated against the application’s operating requirements. Other constructions need different manufacturing methods.
Manufacturing methods vary by gasket material and construction:
- Sheet materials can be converted with die cutting, CNC or flash cutting, waterjet cutting, and other suitable fabrication processes.
- Metallic and semi-metallic designs can require machining, forming, winding, or additional assembly operations.
Select the fabrication method according to the approved drawing, material, tolerances, construction, and production volume.
Dimensional Consistency Matters
Consistent cutting and fabrication help OEMs obtain replacement gaskets that fit the intended heat exchanger dimensions.
Production equipment cannot make up for incomplete drawings or missing tolerances. Confirm these details before fabrication begins.
When custom heat exchanger gaskets are required, review Durlon’s Custom Metallic Gaskets and Custom Capabilities alongside application requirements. Large partitioned gaskets often require different manufacturing methods than standard ring gaskets because of their more complex geometry. Durlon’s custom metallic gaskets can be made with common pass bar designs used in heat exchanger applications, in diameters up to 104 inches (2,642 mm).
Why Pass Partition Sealing Matters
In multi-pass heat exchangers, the gasket must also seal across the pass partition ribs. If it does not, fluid can bypass from one pass to the next. This internal leak will not show on the outside of the unit, but it can reduce thermal performance. Confirm that the partition layout, rib widths, and gasket dimensions on the drawing match the equipment, and that the joint can provide enough load across both the outer sealing area and the partition sections.
How Vibration and Thermal Cycling Affect the Joint
Vibration from rotating equipment, piping, or a skid can affect gasketed joints. Vibration control components may reduce movement when they are part of the equipment design, but they cannot make up for an unsuitable gasket, insufficient bolt load, or poor flange alignment. Thermal cycling has a similar effect: as the unit heats up and cools down, the flanges, bolts, and gasket expand and contract at different rates.
Repeated movement can lower retained gasket stress and increase the chance of leakage, especially when bolt tightening is uneven or piping loads distort the joint. Review the full assembly before attributing a leak to the gasket material.
Review the Source of Movement, Not Only the Gasket
When vibration is present, maintenance teams should inspect the full connection, including:
- Fastener condition and flange alignment;
- Support arrangement, piping strain, and joint rigidity;
- Gasket construction and the source of vibration.
If the movement continues, the replacement gasket may leak again.
Inspect the flange and support arrangement to determine whether the joint can maintain adequate compression during service.
Importance of Pressure Testing Gaskets
Pressure testing checks the integrity of the entire gasketed joint in an assembled heat exchanger, including the gasket, flanges, and fasteners. Results depend on the sealing surfaces, fasteners, gasket, applied compression, test medium, and approved procedure.
Heat exchangers may be pressure tested during manufacturing, commissioning, maintenance, or after repair according to the applicable equipment code, OEM procedure, and site requirements. The gasket installed for the test must be suitable for the test conditions, and the assembled joint must be prepared and tightened according to the approved procedure before pressure is introduced.
Before pressure testing, verify:
| Pre-test check | What to confirm |
|---|---|
| Gasket identity | Correct material, construction, thickness, and dimensions. |
| Flange condition | Sealing surfaces are clean, aligned, and in acceptable condition. |
| Fasteners | Bolts, nuts, washers, lubrication, and tightening procedure match the approved assembly method. |
| Test medium | The gasket and equipment materials are compatible with the fluid used for the test. |
| Test procedure | Pressure, hold period, inspection method, and safety controls follow the governing procedure. |
What a Pressure Test Can and Cannot Prove
A successful pressure test confirms that the assembled joint meets the specified acceptance criteria under test conditions. However, its performance may change during operation due to thermal cycling, chemical exposure, vibration, or pressure fluctuations.
If a joint leaks during a test, first verify gasket identity and dimensions, flange condition, alignment, tightening method, and fasteners.
How OEM Specification Improves Heat Exchanger Gasket Performance
For OEM heat exchangers, the gasket should be specified for its particular joint rather than treated as a generic replacement part. Defining the requirements early helps engineering and manufacturing teams work to consistent design and performance criteria.
Durlon’s Sealing Solutions for OEM Services identifies heat exchangers among the equipment supported through custom and special sealing solutions. Durlon works with OEMs to review gasket designs, select suitable materials, and confirm dimensions and performance requirements for specific equipment. Early coordination helps resolve drawing and fabrication questions before production begins.
Specify Each Joint on an OEM Skid Separately
An OEM skid may include a heat exchanger alongside compressors, exhaust equipment, and other bolted joints. Specify each gasket separately. A compressor gasket may need to handle pulsation and vibration, while a metal exhaust gasket may suit a high-temperature exhaust joint. A heat exchanger gasket may instead have to manage two different process fluids, thermal gradients, and partitioned geometry. Confirm the material, construction, and drawing for each joint rather than copying one gasket specification to another.
Establish a Consistent Gasket Specification Workflow
A standardized gasket specification workflow gives engineering, manufacturing, procurement, and maintenance teams a common set of technical requirements. Include:
- Equipment identification, joint location, and the latest approved drawing;
- Process media, operating temperature range, and operating and test pressures;
- Gasket material or approved alternatives, dimensions, thickness, partition layout, and tolerances;
- Quantity and documentation requirements.
For replacement applications, document the reason for changing the gasket. Routine maintenance may involve different considerations than replacing a gasket after leakage, flange damage, or changes in operating conditions. If a gasket has failed, review and record the relevant installation and inspection findings to help prevent similar problems.
For custom heat exchanger gaskets, consistent specifications help ensure replacement parts meet the approved design and operating requirements.
Frequently Asked Questions About Heat Exchanger Gaskets
What Information Is Needed to Select a Heat Exchanger Gasket?
Work from the approved drawing wherever possible. Confirm the inside and outside dimensions, thickness, and the position and width of any pass partition ribs. A used gasket may be compressed or distorted, so measuring it alone may not give the original dimensions. Learn more about how gaskets are measured.
What Gasket Material Is Best for a Heat Exchanger?
No single gasket material is best for every heat exchanger. Compressed non-asbestos sheet, PTFE-based materials, flexible graphite, and semi-metallic designs such as Durlon® Durtec® must be evaluated against the operating conditions. Use the comparison above and current product data to guide selection.
Why Can a Heat Exchanger Gasket Leak After Startup?
Possible causes include insufficient or uneven gasket compression, damaged or misaligned sealing surfaces, incorrect dimensions, unsuitable material selection, fastener problems, thermal cycling, vibration, pressure changes, or chemical attack. Troubleshooting should evaluate the full bolted joint rather than assuming the gasket alone caused the leak.
Can a Used Heat Exchanger Gasket Be Reinstalled?
A used gasket should not simply be reinstalled. Compression, temperature, and service exposure change the gasket during use. Replacement should follow the equipment and gasket manufacturer’s requirements, with the flange surfaces inspected and the new gasket installed using the approved assembly procedure.
Select and Specify Your Heat Exchanger Gasket with Durlon
Reliable heat exchanger sealing depends on selecting a gasket that meets the equipment’s operating and joint requirements. Durlon supports OEM and replacement applications with custom gasket options when standard configurations do not fit the requirements.
Engineering, procurement, and maintenance teams each play a role in maintaining consistent gasket performance:
- Engineering defines service conditions, joint requirements, and the approved gasket design.
- Procurement uses the current technical specification and drawing when ordering replacements.
- Maintenance checks the joint condition and follows approved installation and testing procedures.
For complex designs, Durlon’s custom capabilities team can review fabrication and inspection requirements early in the process.
Need help specifying a heat exchanger gasket for an OEM or replacement application? Contact Durlon with your equipment drawing, process media, operating temperatures, pressures, and joint requirements so the team can discuss suitable custom gasket options.