KSB BOA-H Bellows Gate Valve - Zero Leakage Seal

Applicable Media: Steam, heat transfer oil, hot water, cold water, compressed air, other gases, water/glycol mixtures, chemical heat transfer fluids, toxic fluids, process fluids, oils, liquefied petroleum gas, flammable and explosive media.

KSB BOA-H Bellows Gate Valve | Zero-Leakage Seal, Protecting High-Temperature and High-Pressure Pipelines

Product Overview: The BOA-H is a flanged bellows gate valve from the German KSB Group. It uses a metal bellows as 

the core sealing element, combined with packing to form a double-sealing structure, completely eliminating the risk of 

external leakage at the valve stem. This product conforms to DIN/EN standards, uses a flange connection, and is suitable 

for various harsh operating conditions, including steam, thermal oil, hot water, toxic, and flammable/explosive media.

As a critical shut-off and regulating device in pipeline systems, the BOA-H bellows gate valve is widely used in hot water

 heating systems, air conditioning equipment, boiler feedwater, boiler circulation systems, steam systems, and hot oil systems.

 It is an ideal upgrade solution to replace traditional packing-sealed gate valves.

KSB BOA-H Bellows Gate Valve - Zero Leakage Seal Model Description

The BOA-H series gate valves adopt the KSB standard naming convention. The following are typical model interpretations:

Model Example | Description

BOA-H DN25 PN16 | Nominal diameter 25mm, pressure rating PN16, straight-through type

BOA-H DN50 PN25 | Nominal diameter 50mm, pressure rating PN25, straight-through type

BOA-H DN100 PN16 | Nominal diameter 100mm, pressure rating PN16, straight-through type

Optional diameter range: DN 15 – DN 350

Pressure rating options: PN 16 / PN 25 (up to PN40)

Structure type: Straight-through / Angle type (Angle type only applicable to EN-GJL-250 material)

Core Technical Parameters

Parameter Item | Specification Range

Nominal Diameter | DN 15 – DN 350

Pressure Rating | PN 16 / PN 25 (maximum PN40)

Maximum Allowable Temperature | 350 °C (ductile iron body)

Minimum Allowable Temperature | -10 °C

Connection Method | Flange connection (DIN EN 1092-2)

Body Material | Gray cast iron (EN-GJL-250 / JL1040), ductile iron (EN-GJS-400-18-LT / JS1025)

Sealing Surface Material | Wear-resistant and corrosion-resistant chrome steel / chrome-nickel steel

Bellbell Material | Stainless steel

Design Standard | EN 13709

Pressure Testing Standard | EN 12266 / API 598

Surface Coating | Blue RAL 5002

Note: Some high-temperature models (cast steel body) can withstand 450 °C and are suitable for higher temperature applications.

KSB BOA-H Bellows Gate Valve - Zero Leakage Seal Product Features and Design Advantages

1. Zero-Leakage Double Seal

Utilizes a bellows + packing double sealing structure. The bellows forms a metal sealing barrier between the medium and the

 atmosphere. Even if the bellows fails, the packing provides a second line of defense, completely eliminating external leakage 

from the valve stem. Suitable for applications with extremely stringent leakage requirements, such as those involving steam, 

heat transfer oil, flammable, explosive, and toxic media.

2. Standard Double-Layer Bellows Design

BOA-H adopts a standard double-layer bellows design, effectively dispersing stress and significantly improving the bellows'

 fatigue life, ensuring valve reliability under long-term, high-frequency operation.

3. Bellows Protection Design

When the valve is fully open, the bellows is confined within the valve body, preventing the medium from directly scouring the 

bellows surface. This effectively resists the impact of pressure fluctuations on the bellows, extending its service life.

4. Maintenance-Free Valve Stem and Position Indicator

No-Lift Handwheel: The handwheel does not rise or fall when opening or closing the valve, saving operating space.

Valve Position Indicator: Standard position indicator with a color-coded system allows identification of the valve plate type and

 sealing surface material without removing the insulation sleeve.

Replaceable Valve Disc: Reduces maintenance costs; only the valve disc needs replacement, not the entire valve cover assembly.

5. Heat-Dissipating Valve Cover Design

Utilizes a heat-dissipating valve cover structure, effectively reducing the temperature of the stuffing box area, protecting the 

packing from high-temperature damage, and reducing heat loss during operation.

6. Hard Alloy Overlay on Sealing Surface

The sealing surface is overlaid with cobalt-based hard alloy, providing excellent wear resistance, corrosion resistance, and scratch

 resistance, ensuring a good seal even after long-term use.

7. Rich Design Details

Clip spring fixing valve stem nut design ensures stable operation.

Tempered and nitrided valve stem provides excellent corrosion and friction resistance.

Asbestos-free, PCB-free, and CFC-free design meets environmental protection requirements.

KSB BOA-H Bellows Gate Valve - Zero Leakage Seal  Comparison with BOA-HV/HE Series

BOA-H belongs to the standard flange connection series. KSB also offers derivative models with other connection methods

 and higher pressure ratings:

Series Connection Method Maximum Pressure Maximum Temperature Applicable Scenarios

BOA-H Flange PN16 / PN25 350°C Standard flange connection

BOA-HE Welded End / Welded Sleeve PN25 / PN40 450°C High temperature, high pressure, permanent welded installation

BOA-HV Flange (with throttling) PN16 / PN25 350°C Conditions requiring precise flow regulation

BOA-HEV Welded End (with throttling) PN25 / PN40 450°C High temperature, high pressure + precise regulation

Selection Tips: For higher temperatures (450°C) or higher pressures (PN40), the BOA-HE/HEV series (welded connection) can be 

selected; for precise regulation, the HV/HEV series with throttling cone can be selected.

KSB BOA-H Bellows Gate Valve - Zero Leakage Seal Core Application Areas

BOA-H bellows gate valves are widely used in the following industries and scenarios:

Application Areas Typical Scenarios

Steam Systems: Steam main pipeline shut-off, steam equipment inlet, condensate system

Heat Transfer Oil Systems: Heat transfer medium circulation, heat transfer oil boilers, heating equipment inlet and outlet

Hot Water Heating: Hot water heating devices, district heating, heating stations

Air Conditioning Systems: Central air conditioning hot and cold water systems

Boiler Systems: Boiler feedwater, boiler circulation system

Petrochemical Industry: Refining equipment, chemical processes, toxic media pipelines

Pharmaceutical Industry: High-purity media, sterile process pipelines

Power Industry: Power plant steam systems, auxiliary steam pipelines

KSB BOA-H Bellows Gate Valve - Zero Leakage Seal Product Advantages Summary

Advantages | Description

✅ Zero-Leakage Sealing: Double sealing with bellows and packing, completely eliminating external leakage from the valve stem.

✅ German Quality: A century-old KSB brand, German engineering design standards.

✅ Ultra-High Temperature Resistance: Withstands media temperatures up to 350°C (450°C for some models).

✅ Double-Layer Bellows: Standard double-layer design for longer fatigue life.

✅ No-Lift Handwheel: Saves operating space and facilitates compact installation.

✅ Valve Position Indicator: With color coding system, valve plate type can be identified without removing the insulation sleeve.

✅ Replaceable Valve Disc: Reduces maintenance costs; no need to replace the entire valve cover assembly.

✅ Heat-Dissipating Valve Cover: Protects the packing from high-temperature damage.

✅ Flexible Materials: Multiple choices including gray cast iron and ductile iron to suit different working conditions.

✅ Complete Diameter Range: DN 15 – DN 350 (Full Coverage)

Installation and Maintenance Guide

Installation Precautions

Flow Direction Confirmation: During installation, ensure the flow direction arrow on the valve body matches the direction 

of the medium flow in the pipeline.

Flange Connection: Use appropriate gaskets and tightening torque to ensure a reliable flange seal.

Insulation Treatment: The short, smooth valve cover facilitates insulation, resulting in almost no heat loss.

Operating Space: The non-lifting handwheel design requires minimal installation space.

Pipeline Cleaning: Purge the pipeline before installation to prevent weld slag from damaging the sealing surface.

Maintenance Recommendations

Regular Inspection: Check the bellows sealing performance and observe for any signs of external leakage.

Valve Position Check: Confirm the valve plate position using the position indicator.

Valve Disc Replacement: After the sealing surface wears down, only the valve disc assembly needs to be replaced; complete 

replacement is not required.

Insulation Inspection: Check the insulation layer for integrity to minimize heat loss.