Common applications of PTFE rods in chemical equipment

I. Introduction to PTFE Rods

PTFE rods are typically white, cylindrical, semi-finished products with diameters ranging from a few millimeters to 500 millimeters. They can be turned into components through turning, milling, and drilling. Chemical companies favor them because polytetrafluoroethylene (PTFE) is virtually inert to all industrial media, has an operating temperature range of -80°C to 260°C, and boasts an extremely low coefficient of friction. These properties make PTFE rods a versatile material commonly found in maintenance workshops.

II. Static Sealing Gaskets

Soft gaskets are commonly used to prevent leaks at the mating surfaces of pipe flanges, manholes, and pump covers. PTFE rods are sawn into rings, with sealing lips turned on both sides. The rings are then treated with sodium naphthalene to increase their surface energy, ensuring a tight fit with the metal surface. Gaskets in strong acid systems using rubber or asbestos will become brittle after just six months. However, PTFE rings can operate continuously for over five years and can be reused simply by removing, cleaning, and cleaning for maintenance.

III. Dynamic Sealing Components

Seals for agitator shafts, valve stems, and pump shafts must be both corrosion-resistant and self-lubricating. PTFE rods can be turned into V- or U-shaped rings and combined with springs or O-rings to create mechanical seals resistant to highly corrosive media. When the media contains solid particles, a PTFE scraper is often added to the outer surface of the sealing surface to keep the crystals out of the cavity and prevent wear on the sleeve.

IV. Valve Seats and Bushings

The valve seats of ball and diaphragm valves must be both chemically resistant and not exert excessive torque on the ball. The valve seats are directly turned using Dankai PTFE rods, leaving a 0.2 mm compression allowance in the inner bore. This creates a moderate springback after assembly, ensuring zero leakage and reducing operating force. The same principle can be used for the sleeves of centrifugal pumps and the slides of reciprocating pumps to completely isolate the metal substrate from the corrosive media.

V. Guide and Sliding Components

Float valves and distributors in tower internals slide up and down in high-temperature acid mist. PTFE rods are used to form guide rails and stoppers, which, when combined with stainless steel rails, eliminate metal-to-metal seizure. During maintenance, no additional lubrication is required; disassembly and flushing can restore operation. For sliding brackets in high-drop pipelines, PTFE gaskets can also reduce sticking caused by thermal expansion and contraction.

VI. Insulation and Isolation

Electrode brackets in electrolytic cells and high-frequency heating devices require both insulation and chemical resistance. PTFE rods are machined into threaded sleeves and threaded over titanium electrodes to prevent current leakage and resist electrolyte corrosion. In high-pressure liquid chromatography, short PTFE rods are processed into pipe joints to completely isolate the metal flow path from the detection signal, preventing baseline drift.