The DIN EN 13709 1.4308 stainless steel bellows sealed globe valve is a high-performance industrial valve designed for applications requiring reliable shut-off capability, zero stem leakage, and safe handling of critical media. It combines the structural advantages of the globe valve design with the sealing performance of a metallic bellows assembly, making it highly suitable for steam systems, thermal oil systems, chemical processing, power plants, petrochemical industries, and other demanding process environments.

As industrial processes become increasingly focused on safety, environmental protection, and operational efficiency, conventional packing-sealed valves may present leakage risks after long periods of operation. Bellows sealed globe valves effectively address these concerns by introducing a welded metal bellows structure that isolates the process medium from the atmosphere and significantly reduces fugitive emissions.

DIN EN 13709 Standard Overview

DIN EN 13709 is a European standard that specifies design requirements, manufacturing criteria, dimensions, pressure-temperature ratings, testing methods, and inspection procedures for steel globe valves and globe stop-check valves. The standard ensures product consistency, safety, and interchangeability within industrial piping systems.

Valves manufactured according to DIN EN 13709 generally provide the following advantages:

• Standardized face-to-face dimensions

• Reliable pressure and temperature performance

• Strict testing requirements

• Interchangeability across systems

• Enhanced operational safety

• Compliance with international quality standards

The standard establishes clear requirements for pressure-containing parts and ensures the valve performs reliably under severe service conditions.

Material Description: Stainless Steel 1.4308

Material grade 1.4308 is a cast austenitic stainless steel equivalent to ASTM CF8. It is widely used in valve manufacturing due to its excellent combination of mechanical strength, corrosion resistance, and processability.

Typical chemical composition includes:

• Chromium (Cr): approximately 18–21%

• Nickel (Ni): approximately 8–11%

• Carbon (C): ≤0.08%

• Silicon (Si): ≤2.0%

• Manganese (Mn): ≤1.5%

The benefits of 1.4308 stainless steel include:

Excellent corrosion resistance:

The material performs effectively against water, steam, weak acids, and numerous industrial chemicals.

High temperature capability:

It maintains mechanical integrity and oxidation resistance at elevated temperatures.

Good toughness:

The austenitic structure provides excellent impact resistance even under varying temperatures.

Good weldability:

The material can be fabricated and welded efficiently without significant reduction in performance.

Long service life:

Its corrosion resistance minimizes material degradation and maintenance requirements.

Because of these characteristics, 1.4308 stainless steel is commonly selected for valve bodies, bonnets, and pressure-containing components.

Bellows Sealed Design Principle

The most distinctive feature of the bellows sealed globe valve is the metal bellows assembly positioned around the valve stem.

Traditional valves rely primarily on packing material for sealing around the stem area. Over time, repeated operation, thermal expansion, and aging of packing materials may lead to leakage.

In a bellows sealed design, the stem is enclosed within a welded stainless steel bellows element. The bellows expands and contracts during valve movement while maintaining a complete seal between the internal process medium and the external environment.

The sealing system generally consists of two levels:

Primary seal:

The welded metal bellows provides the main sealing function and eliminates stem leakage.

Secondary seal:

Conventional graphite packing acts as a backup sealing mechanism for additional safety.

This dual-sealing arrangement significantly improves operational reliability.

Construction Features

Valve Body

The valve body is designed with optimized flow geometry to minimize pressure loss and ensure effective flow regulation. Stainless steel construction enhances resistance to corrosion and high-temperature operation.

Bonnet Assembly

The bonnet supports the stem and bellows structure while maintaining pressure containment. Precision machining ensures accurate alignment between moving parts.

Metallic Bellows

The bellows is usually manufactured from corrosion-resistant stainless steel and undergoes multiple-cycle fatigue testing.

Features include:

• High flexibility

• Excellent fatigue resistance

• Leak-free operation

• Long service life

• Resistance to thermal expansion stress

Stem

The stem transfers motion from the handwheel or actuator to the valve disc. Precision machining and surface treatment improve wear resistance.

Disc and Seat

The seating surfaces are critical sealing elements. Hard-facing materials may be applied to increase wear resistance and improve sealing performance.

Handwheel or Actuator

The valve can be operated manually or integrated with automation systems such as:

• Electric actuators

• Pneumatic actuators

• Gear operators

• Hydraulic actuators

Working Principle

The operating principle of a bellows sealed globe valve is relatively simple.

When the handwheel rotates clockwise, the stem moves downward and pushes the disc toward the seat, gradually reducing the flow passage until complete shut-off occurs.

When the handwheel rotates counterclockwise, the stem rises and lifts the disc away from the seat, allowing media to flow through the valve.

During stem movement, the metal bellows expands and contracts accordingly while maintaining a sealed barrier.

The globe valve structure also allows throttling and flow regulation functions when partial opening is required.

Main Advantages

Zero External Leakage

The welded bellows structure effectively prevents leakage around the stem area, making the valve ideal for hazardous and valuable media.

Environmental Protection

Reduced fugitive emissions help facilities comply with environmental regulations and safety requirements.

Long Service Life

The dual sealing design minimizes wear and extends operational life.

Reduced Maintenance Cost

Lower leakage rates and reduced packing adjustment requirements decrease maintenance frequency.

High Temperature Performance

Stainless steel construction and metallic bellows withstand elevated operating temperatures.

Improved Safety

Bellows sealing protects operators and surrounding equipment from exposure to dangerous process fluids.

Excellent Corrosion Resistance

The 1.4308 material performs well in many corrosive environments.

Typical Technical Specifications

Typical specifications may include:

Design Standard:

DIN EN 13709

Face-to-face Standard:

DIN EN 558

Flange Standard:

DIN EN 1092-1

Testing Standard:

DIN EN 12266

Body Material:

1.4308 Stainless Steel

Nominal Size:

DN15–DN300

Pressure Rating:

PN16–PN40

Temperature Range:

-29°C to 425°C

Connection Type:

Flanged

Operation:

Manual, pneumatic, electric

Applicable Media:

• Steam

• Water

• Thermal oil

• Chemical liquids

• Gas

• Petrochemical fluids

Industrial Applications

Steam Systems

Bellows sealed globe valves are extensively used in steam pipelines because steam leakage can lead to energy loss and safety concerns.

Chemical Industry

Chemical plants frequently handle corrosive and hazardous fluids where leakage prevention is critical.

Petrochemical Industry

Oil refineries and petrochemical plants use these valves for handling high-temperature and corrosive process media.

Power Generation

Power plants require reliable shut-off performance under high-pressure and high-temperature operating conditions.

Pharmaceutical Industry

Leak-free designs help maintain cleanliness and prevent contamination.

Food Processing Industry

Stainless steel materials provide hygienic characteristics suitable for controlled processing systems.