Graphite tapes

Graphite tapes, also known as flexible graphite tapes or expanded graphite rolls, are manufactured by processing natural flake graphite through chemical intercalation and high-temperature expansion to produce expanded graphite, which is then processed via calendering to form a continuous ribbon-shaped flexible sealing material. Depending on specific application requirements, this material can be reinforced with stainless steel foil, glass fiber backing, or impregnated PTFE emulsion. The product features a soft texture that allows for bending, easy cutting, wrapping, and mold-forming; it serves as a versatile flexible sealing substrate for flanges, valves, heat exchangers, pipe joints, and high-temperature equipment end faces. It can be used directly for wrapping applications or processed into graphite gaskets, packing strips, or sealing ring semi-finished products, making it a mainstream non-asbestos, environmentally friendly sealing material for high-temperature operating conditions.

Physical and Chemical Properties

In terms of chemical properties, graphite strips exhibit exceptional chemical inertness; they are virtually resistant to almost all acid–base solutions, organic solvents, vapors, oils, and salt-containing media except for strong oxidizing concentrated acids. When immersed for extended periods, they do not swell, decompose, or corrode under the influence of these media, nor do they undergo chemical reactions with the fluids that may lead to material contamination; furthermore, they demonstrate excellent resistance to aging, radiation, and ozone erosion, exhibiting extremely slow performance degradation when exposed to outdoor conditions or high-temperature environments over long periods, thereby ensuring a long service life.

In terms of physical properties, it exhibits outstanding high-temperature resistance: under non-oxidizing atmospheres, it can withstand long-term use at temperatures up to 650°C; in oxidizing environments, it remains stable at 450°C; and in low-temperature environments, it does not harden or crack. It demonstrates excellent compression-rebound performance, enabling it to tightly fill the irregular gaps between equipment mating surfaces upon compression, thereby compensating for machining errors and thermal expansion/contraction deformations. The material inherently possesses good self-lubrication properties with a low friction coefficient, resulting in minimal wear on shaft components when used as an dynamic seal. It also features exceptional flexibility, allowing it to be bent, wound, or wrapped around custom-shaped pipe fittings and irregular sealing surfaces, making it suitable for complex installation configurations. Additionally, it offers superior electrical and thermal conductivity, making it ideal for heat transfer and electrostatic discharge applications. The pure graphite tape possesses high flame retardancy, exhibiting no spontaneous combustion or dripping at elevated temperatures; the composite metal foil version further provides higher tensile strength, ensuring greater resistance to tearing and edge disintegration.

Application Areas and Specific Functions

In the petrochemical industry, these products are used for the sealing of reaction vessel flanges, high-temperature pipelines, and heat exchanger end faces; they effectively resist leakage from high-temperature thermal oils and corrosive chemical media, reduce raw material loss, and ensure the safety of continuous chemical production;

In the power and thermal power generation sector, these products are applied to boiler manhole doors, flue gas dampers, and sealing systems for steam turbine auxiliary equipment; they withstand high-temperature, high-pressure steam and flue gases, thereby reducing heat loss caused by steam leakage and improving the thermal efficiency of the boiler;

In the field of metallurgical high-temperature furnaces and kilns, this flexible sealing filling tape for furnace doors, flues, and hot air ducts serves to prevent the leakage of high-temperature hot gases and dust, reduce energy loss, and improve the workshop working environment;

In the field of construction machinery and pump/valve manufacturing, cutting processes are employed for producing valve packing, flange gaskets, and cylinder sealing strips, thereby addressing leakage issues caused by high-temperature hydraulic oil or high-pressure gases and enhancing the operational stability of hydraulic equipment;

In the new energy and lithium-ion battery industry, these materials leverage their high thermal and electrical conductivity to serve as thermal buffer strips for battery cells and heat dissipation backing strips for battery modules, thereby assisting in uniform temperature distribution, enhancing the operational stability and safety of the battery;

In the shipbuilding and heavy engineering sector, these products are used for marine high-temperature piping systems and diesel engine flange seals, capable of withstanding seawater salt spray and corrosion from high-temperature exhaust gases, thereby extending the replacement cycle for sealing components in marine propulsion systems;

In the food and pharmaceutical equipment industry, PTFE-impregnated high-purity graphite strips are selected for sealing applications in high-temperature sterilization equipment, as they prevent dust shedding and the release of harmful substances, thereby effectively preventing contamination of pharmaceutical products and food raw materials.

Comparison of core advantages against competitors

1. The raw materials are manufactured using high-purity imported flake graphite through expansion and pressing processes; they feature a high carbon content and dense structure, resulting in minimal powder shedding during use, resistance to interlayer delamination and fragmentation, and significantly superior durability compared to conventional graphite strips produced from low-cost recycled materials or low-purity graphite.

2. Supports multi-layer composite customization with single-sided or double-sided bonding; reinforced with 304 stainless steel thin sheets, significantly enhancing its tensile and tear resistance, ensuring it will not be dislodged or ruptured under high-pressure and high-speed operating conditions;

3. The material can undergo overall impregnation with a PTFE emulsion to further enhance its solvent and oil resistance, while simultaneously reducing the shedding of graphite dust and making it suitable for cleanroom production environments; however, most small manufacturers only produce single pure graphite tapes without employing an impregnation modification process.

4. The rolling process is strictly controlled, resulting in a uniform thickness across the entire coil; the surface is flat, free of holes or thickness variations; after cutting, the edges are neat; during the winding and sealing process, the force distribution is uniform, ensuring a more stable sealing effect;

5. We offer flexible customization options, including precise width and thickness cutting; we can provide various product forms such as large coil sheets, custom-length strips, and pre-formed gaskets to meet diverse processing requirements of our clients;

6. The product complies with non-asbestos environmental standards; we can provide material testing reports and specifications detailing its high-temperature and high-pressure resistance; for export orders, we can also supply complete customs declaration and certification documents; products supplied in batches exhibit consistent performance across all batches, with minimal quality variation.

Selection Guide

Based on the operating temperature and medium environment for selection, these seals are suitable for water vapor and oil applications under normal temperature and pressure conditions; in such cases, a standard flexible graphite seal can be used.

For high-temperature steam, flue gas, and thermal oil applications, stainless steel foil-reinforced graphite tape is recommended to prevent loose fracture under high-temperature conditions;

For clean environments involving strong organic solvents or materials prone to contamination, PTFE-impregnated graphite strips can be directly selected to eliminate dust fallout and medium-induced erosion.

Based on the sealing application type, for pipeline wrapping and sealing of irregular curved surfaces, pure flexible graphite tape is used, leveraging its inherent flexibility to conform to irregular surfaces;

For flat flange static sealing applications, metal-reinforced composite graphite strips are selected, offering enhanced pressure-bearing capacity;

For applications requiring thermal conductivity and anti-static properties, high-purity dense rolled graphite strips should be selected to ensure that their electrical and thermal conductivity performance meets specified standards.

Verify the critical dimensional parameters to determine the required thickness and width; the thickness determines the compression rebound amount, while the width must match the flange sealing surface width to avoid both excessive narrowing leading to crushing failure and excessive width that may occupy too much assembly space; simultaneously, confirm whether a back-coating version is required—the back-coated graphite tape can be used for temporary fixation, facilitating on-site winding and installation.

Precautions for Use

During installation of the wrapping process, the material should be moderately tightened to conform closely to the sealing surface; a small overlap should be maintained at the joint between the start and end sections. Excessive or forceful stretching must be avoided to prevent the internal structure of the graphite tape from becoming loose, which could lead to reduced resilience performance, short-term sealing failure, and increased downtime and operational losses caused by frequent replacement of sealing components; when tightening the flange, bolts should be tightened diagonally and uniformly in multiple stages to avoid excessive pressure on a single side that may compress or extrude the graphite tape, thereby ensuring long-term leak-free sealing and reducing material waste and environmental treatment costs resulting from medium leakage.

Regarding operational conditions, pure graphite seals are not recommended for long-term use in high-temperature, highly oxidative, or strongly acidic environments; in such scenarios, the PTFE impregnated variant should be used instead to slow down the oxidation and powdering rate. For dynamic sealing applications involving reciprocating friction points, the impregnated variant should be prioritized to prevent graphite powder from entering the equipment chamber, thereby reducing the risk of valve core or valve stem jamming and lowering equipment maintenance costs.

Regarding warehousing and stock management, graphite seals must be stored in dry, cool warehouses to avoid long-term heavy stacking, which could lead to permanent compression deformation and compromise their elastic sealing performance; by procuring these seals in bulk according to standardized specifications, they can be directly cut on-site during equipment maintenance, thereby reducing downtime for repairs and increasing the effective operating hours of the equipment; the long-term, stable sealing performance significantly reduces the leakage failure rate, not only minimizing the recurring procurement costs for sealing consumables but also preventing the leaking medium from corroding expensive main components such as flanges and valve bodies, thus helping customers control production costs across the entire operation and maintenance lifecycle.