Industrial valves · Клапан запорный с сильфонным уплотнением

Bellows-Sealed Globe Valve: Engineering Analysis and Application

Bellows-sealed globe valve is a precision pipeline valve assembly designed to ensure absolute tightness. The key element is a sealing unit based on a metal bellows - a multilayer corrugated membrane. This design, deforming in the axial direction synchronously with the reciprocating movement of the stem, completely isolates the working medium from the atmosphere, ensuring zero fugitive emissions.

Key Engineering Advantages of Bellows-sealed Valves from EV Group China

The technical solutions implemented in EV Group China valves surpass standard packed gland counterparts in a number of critically important parameters:

  • Absolute tightness class "A" according to GOST 9544-2015: Complete exclusion of leaks and uncontrolled emissions of toxic, aggressive, radioactive, and explosive media into the environment.
  • Increased operational life: The metal bellows isolates the stem and the packing gland unit (if it is a backup) from corrosive and abrasive effects of the flow, which significantly increases the service life of the valve.
  • Reduced operational costs (OPEX): The design does not require regular maintenance and tightening of seals, which minimizes downtime of the technological line and personnel costs.

Material Execution and Design Solutions

EV Group China's engineering solutions are based on the use of the following materials and components, certified for critical operating conditions:

  • Body: Manufactured by precision casting or hot stamping from carbon steels, austenitic stainless steels (including AISI 316, 12X18H10T), and special corrosion-resistant alloys such as Monel 400 and Hastelloy C-276 for chemically aggressive media.
  • Closing element (spool): The profile of the closing element is designed for precise flow control. For media with abrasive inclusions, the working surfaces of the seat and spool are hardfaced with Stellite or subjected to other surface hardening methods.
  • Bellows: The main sealing unit, manufactured from multilayer thin-sheet steel of Inconel 625, Hastelloy C-276, or 316Ti grades. Designed for fatigue strength up to 10,000 actuation cycles at maximum pressure and temperature parameters.
  • Stem: Polished stem, transmitting reciprocating motion from the actuator to the closing element. To reduce friction and prevent galling, the surface is processed to a high purity (Ra ≤ 0.25).
  • Sealing elements: Thermally expanded graphite (TEG) or PTFE rings are used as backup (secondary) stem seals, providing additional safety in case of unlikely damage to the main bellows unit.
  • Actuator: Possibility of aggregation with a manual handwheel, gearbox, as well as with pneumatic, hydraulic, or electric actuators for full integration into automated process control systems (APCS).

Principle of Operation and Sealing Mechanism

Rotation of the handwheel or actuation of the actuator is converted into reciprocating motion of the stem. The stem, by moving, changes the position of the closing element relative to the seat in the body, thereby regulating or completely blocking the flow of the working medium. The metal bellows, hermetically connected on one side to the body and on the other to the stem, elastically compresses or stretches, completely isolating the valve cavity. This technology, applied in EV Group China valves, guarantees zero leakage into the environment, which is a mandatory requirement for facilities of hazard classes I and II.

Key Areas of Industrial Application

Bellows-sealed valves manufactured by EV Group China are an indispensable solution for the following industries:

  • Oil and gas sector and petrochemicals: Systems for transporting and processing flammable liquids (FL), toxic gases (chlorine, ammonia, phosgene), and aggressive chemical reagents.
  • Nuclear energy: First and second circuits of nuclear power plants (NPPs), radioactive waste management systems, where requirements for tightness and radiation resistance are maximum.
  • Pharmaceutical and food production: Technological lines for the production of sterile pharmaceutical substances and aseptic food products, where any microbial or mechanical contamination of the product from outside is excluded.
  • Energy complex: High-pressure steam pipelines at thermal and power plants (TPP, CHP), systems with thermal oil (diathermic oil), where leaks lead to significant energy losses and create a fire hazard.

Engineering and Supplies from EV Group China

EV Group China provides comprehensive services for engineering and supplying bellows-sealed globe valves, compliant with API, ASME, DIN, and GOST standards. Our specialists calculate and select the optimal design and materials for the specific technological parameters of your project (pressure, temperature, medium composition). To receive a technical and commercial proposal and consultation, please contact our engineering department.