Ethylene Service Valves

Falcon Ethylene Service Valves: Technical Overview

Falcon Ethylene Service Valves are engineered to handle the unique challenges of ethylene production, storage, and transport. Ethylene (and its oxide form) is highly flammable, often stored at cryogenic temperatures, and requires zero-leakage performance to ensure plant safety.

1. Triple Offset Valves (TOV)

Falcon Triple Offset Valves are designed for high-cycle, tight-shutoff applications where gate or globe valves are too heavy or space-constrained.

• Design Principle: The triple offset geometry (eccentric shaft, eccentric seat, and inclined conical seat) eliminates friction between the seal and the seat during travel, providing torque-seated zero leakage.

• Ethylene Specifics:

  • Fire-Safe Design: Inherently fire-safe due to all-metal construction (Stellite® Grade 6 hard-facing on seats).

  • Materials: Bodies in WCB, LCB (for low temp), or CF8M (Stainless Steel).

  • Bi-Directional Sealing: Capable of maintaining a bubble-tight seal regardless of flow direction, crucial for ethylene manifold systems.

• Temperature Range: Rated for extreme fluctuations from -196°C to +600°C.

2. Ethylene Transfer Line Valves (TLV)

These are the most critical valves in an ethylene plant, situated at the outlet of the cracking furnace. They must manage the "cracked gas" which is extremely hot and contains abrasive coke particles.

• Construction: Heavy-duty Double Disc Gate or specialized Through-Conduit Gate designs.

• Technical Features:

  • Steam Purging: Equipped with steam-flushing ports in the body and bonnet to prevent the accumulation of coke/carbon deposits in the valve cavity.

  • High-Temperature Alloys: Typically manufactured from high-nickel alloys or heat-resistant stainless steels (e.g., HK-40 or HP-40) to prevent thermal creep.

  • Internal Hard-Facing: Critical internal parts are coated with Tungsten Carbide or Stellite to resist the high-velocity erosion of cracked gas.

• Size Range: Large bore designs typically ranging from 12" to 48".

3. Decoking Valves

Used during the furnace decoking cycle, where air and steam are blown through the furnace tubes to burn off accumulated carbon (coke).

• Operating Conditions: These valves must handle a mixture of steam, air, and abrasive coke particles at high velocities.

• Design Features:

  • Erosion Resistance: Features reinforced seating areas and specialized flow paths to minimize turbulence.

  • Rapid Actuation: Often fitted with high-torque pneumatic or hydraulic actuators to ensure fast switching between "Process" and "Decoke" modes.

  • Self-Cleaning: The movement of the valve disc or wedge is designed to "scrape" the seat surface, ensuring a clean closure even in the presence of solids.

• Sealing: Metal-to-metal seating is standard to withstand the mechanical wear of the decoking process.

4. Technical Comparison & Quality Data

5. Quality Assurance for Ethylene Service

Falcon ensures these specialized valves meet the following criteria:

• PMI (Positive Material Identification): To verify alloy integrity for high-temp furnace service.

• Fugitive Emission Testing: Compliant with ISO 15848-1, ensuring zero leakage of flammable ethylene to the atmosphere.

• High-Pressure Gas Testing: Every unit undergoes nitrogen or helium testing to confirm seal integrity at both ambient and operating temperatures.