Rotary Metal Bellow Single Cartridge Mechanical Seal

Product Overview; 

The BC720 is a precision‑engineered single cartridge mechanical seal featuring a rotary welded metal bellows design for demanding high‑temperature and hazardous fluid services. Supplied as a fully pre‑assembled, ready‑to‑install cartridge, it mounts directly over the pump shaft or sleeve with preset working length, eliminating on‑site setting and significantly reducing installation time, downtime and the risk of assembly errors. 

 

The rotary metal bellows element replaces conventional dynamic elastomer components used in pusher‑type seals, removing limitations such as O‑ring hardening, cracking and hang‑up at elevated temperatures. The welded bellows provides reliable axial movement, consistent face loading and excellent flexibility under severe thermal cycling and pressure fluctuations, making the BC720 particularly suitable for hot oils, thermic fluids, hydrocarbons and other low‑lubricity or volatile media. 

 

Designed with a hydraulically balanced sealing geometry, the BC720 minimises face distortion and heat generation while maintaining a stable fluid film at the faces, enhancing seal life and reliability in continuous‑duty operation. The robust cartridge construction is ideal for API process pumps, hot‑oil circulation pumps, condensate and boiler‑feed pumps, and chemical transfer systems used in petrochemical plants, refineries, power generation and other critical industrial environments. 

 

In addition to new manufacture, our expertise in reconditioning and refurbishment of metal bellows mechanical seals enables cost‑effective overhaul of BC720 and similar designs, restoring performance, extending seal life and reducing overall sealing costs across the pump population. 

 

Here is a single, merged Technical / Key Features section for the BC720 metal bellows single cartridge seal, written in professional language and suitable for direct use on your website or datasheet. 

 

Technical Features; 

• Available in both metric and inch shaft sizes, ensuring global compatibility with a wide range of equipment and international pump standards. 

• Bi‑directional operation, non‑dependent on shaft rotation direction, enhances installation flexibility across different pump orientations and start‑up sequences. 

• Designed for continuous‑duty refinery and petrochemical process operation, offering long service life and consistent sealing performance across severe industrial environments. 

• Hydraulically balanced seal geometry reduces face loading, lowers heat generation and improves reliability under thermal cycling, pressure transients and low‑lubricity hydrocarbon conditions. 

• Integrated flushing and quench connections provide built‑in ports for auxiliary piping plans, enabling effective seal cooling, cleaning or containment in accordance with API‑style support systems. 

• API 682 4th Edition–compliant design for use on API process pump arrangements, supporting critical oil and gas, refinery and petrochemical services where proven reliability and standardisation are essential. 

• Rotary welded metal bellows design provides superior axial flexibility and thermal stability, minimising seal face distortion and eliminating dynamic secondary elastomer wear typical of pusher‑type seals in high‑temperature service. 

• High resistance to thermal distortion and pressure fluctuations delivers excellent performance in thermic‑fluid and hot‑oil circulation systems, hazardous and volatile hydrocarbon services, and other low‑lubricity process applications. 

• Single cartridge configuration, factory assembled and factory pressure‑tested, is supplied as a preset unit for simplified installation, accurate alignment and easy removal, significantly reducing handling errors, downtime and maintenance effort. 

 

Service Overview; 

Parameter	Value
Equipment	API Process Pumps, Thermic Fluid Pumps, Chemical Transfer Pumps, Hydrocarbon Pumps
Fluid	Hot Oil, Hydrocarbon, Hazardous Liquids, Thermic Fluid, Fatty Acid, Petrochemical Fluids
Service Nature	High Temperature, Hazardous, Volatile, Continuous Duty
Operating Mode	Continuous industrial process operation

 

Specifications; 

Item	Min	Max	Typical / Notes
Shaft Size	20 mm (0.750”)	150 mm (6.000”)	Larger sizes available on request
Pressure	Vacuum	25 bar (362 psi)	Depending on operating conditions
Temperature	-40°C (-40°F)	+400°C (+752°F)	Based on bellow metallurgy
Speed	—	4500 RPM	Application dependent

 

Materials; 

Component	Standard Material	Optional Material	Comment
Seal Faces	Carbon vs Silicon Carbide	Tungsten Carbide, Silicon Carbide vs Silicon Carbide	Selected according to fluid characteristics
Metal Bellows	SS 316L	AM350, Hastelloy C276, Inconel Alloy	High-temperature resistant construction
Secondary Seals	Graphite / Flexible Graphite	PTFE	Suitable for elevated temperatures
Hardware	SS 316	Duplex SS, Hastelloy, Alloy 20	Corrosion-resistant metallurgy

 

Applications; 

• Hot oil processing systems 

• Petrochemical process pumps 

• Thermic fluid circulation pumps 

• Power plant auxiliary pump systems 

• Refinery hydrocarbon transfer systems 

• LPG and hazardous liquid handling pumps 

• API 610 and ANSI process pumping systems 

• High-temperature reactor circulation pumps 

• Fatty acid and chemical transfer applications 

• Biochemical and specialty chemical process pumps 

 

Operating Limits; 

Parameter	Value
Pressure	Up to 25 bar (362 psi)
Temperature	-40°C to +400°C (-40°F to +752°F)
Speed	Up to 4500 RPM
Size Range	20 mm to 150 mm (0.750” to 6.000”)

 

Engineering Note; 

Operating parameters shown are typical engineering limits for rotary metal bellow cartridge seals and should be verified against actual application conditions, fluid characteristics, shaft dynamics, and API piping plan selection prior to final equipment specification.