Types of Materials for PTFE‑Lined Equipment

2026-08-04 17:38:10

PTFE‑lined equipment serves as core special‑purpose gear for handling highly corrosive media in chemical, pharmaceutical, environmental protection and other industries. Its core working principle is to composite corrosion‑resistant fluoroplastics onto the surface of high‑strength structural substrates, combining the corrosion resistance of fluoroplastics with the mechanical strength of substrates. Manufacturing materials for such equipment fall mainly into three categories: inner‑layer fluoroplastic functional materials, outer‑layer structural substrate materials, and transitional bonding materials. Specific types and properties are detailed below:

I. Inner‑Layer Fluoroplastic Functional Materials

As the corrosion‑resistant core of PTFE‑lined equipment, the inner layer is dominated by polytetrafluoroethylene (PTFE) and its modified derivatives, mainly divided into three types:

Pure Polytetrafluoroethylene (PTFE): It features outstanding chemical stability, with a temperature resistance range of ‑200 °C to 260 °C. It hardly reacts with any known chemical media and has a low friction coefficient. Nevertheless, it exhibits mediocre mechanical strength and creep resistance, along with high molding difficulty. It is mostly applied to planar linings such as inner walls of storage tanks and straight pipes, suited for general corrosive conditions under normal temperature and pressure.

Filled‑Modified PTFE: Fillers such as glass fiber, graphite, carbon fiber or bronze powder are incorporated into pure PTFE to greatly improve its creep resistance, thermal conductivity and compressive strength while retaining its original corrosion resistance. It is suitable for dynamic friction and high‑load working conditions, e.g., linings for moving components including pump impellers and stirring paddles, delivering far longer service life than pure PTFE.

Fluoroplastic Copolymers: Mainly including fluorinated ethylene propylene (FEP/F46) and perfluoroalkoxy alkane (PFA). While inheriting the corrosion resistance of PTFE, these materials feature thermal‑fusion weldability and favorable processability, making them ideal for linings of complex‑structured items such as valves and special‑shaped reaction kettles. FEP withstands temperatures from ‑200 °C to 200 °C, whereas PFA covers ‑200 °C to 260 °C, better fitting medium‑to‑high‑temperature fine‑chemical‑industry scenarios.

II. Outer‑Layer Structural Substrate Materials

The substrate provides structural support for equipment and bears pressure and thermal loads. Three primary types are available:

Carbon Steel: A commonly‑used substrate material with low cost and high mechanical strength, fit for medium‑and‑low‑pressure working conditions and general corrosive scenarios at atmospheric or low pressure, such as conventional acid‑base storage tanks and PTFE‑lined water‑conveying pipelines. Prior to use, it shall be treated by sandblasting for roughening and degreasing to lay an adhesion foundation for subsequent transitional layers.

Stainless Steel: Widely adopted in scenarios requiring high strength and sanitary standards, for instance reaction kettles in food and pharmaceutical industries. It offers high‑temperature resistance and stress‑corrosion resistance, applicable to medium‑to‑high‑temperature and medium‑to‑high‑pressure fine‑chemical‑industry environments. Surface activity is enhanced via pickling and passivation pretreatment to strengthen bonding force with transitional layers.

Special Alloys: Titanium alloys, nickel‑based alloys and others are deployed for extreme‑corrosion working conditions such as strongly oxidizing mixed acids and high‑temperature‑high‑humidity corrosive environments. The substrate itself can resist certain aggressive media, and compounding with PTFE lining further improves corrosion resistance. Despite relatively high costs, they satisfy long‑term service requirements under special extreme‑condition operations.

III. Transitional Bonding Materials

Given the poor chemical compatibility between fluoroplastics and metal substrates, transitional materials are required to achieve firm bonding between the two layers and prevent lining detachment. Common transitional materials are dedicated bonding systems, including modified silane coupling agents (to boost metal‑surface activity), phenolic‑modified adhesives, polyamide‑imide primers, etc. After being sprayed or brushed onto metal substrates, they reinforce bonding force with both metals and fluoroplastics through physical anchoring and chemical bonding effects, constituting a key material guaranteeing the service life of lined equipment.

Material selection for PTFE‑lined equipment shall take into account working‑condition parameters including medium properties, temperature, pressure and structural requirements. Combinations of different materials enable adaptation to diverse scenarios ranging from ambient to high temperature, low to high pressure, and general to extreme corrosion, meeting core demands for special anti‑corrosion equipment across multiple industries.