Rotary Metal Bellow Semi-Cartridge Mechanical Seal

Product Overview; 

The BS700 is a robust semi‑cartridge rotary metal bellows mechanical seal designed for high‑temperature and hazardous liquid services such as hydrocarbons, thermic fluids and chemical process media. Its welded metal bellows element replaces conventional dynamic secondary elastomers, removing failure modes associated with O‑ring hardening, cracking or loss of elasticity at elevated temperatures and in aggressive chemistries. This makes the BS700 particularly suitable where standard pusher‑type seals cannot deliver the required thermal or chemical resistance. 

Supplied as a factory‑assembled semi‑cartridge unit, the BS700 mounts as a single piece on the shaft or sleeve and is preset to the correct working length. This configuration enables direct installation without on‑site setting, significantly reducing misalignment risk, shortening installation time and improving reliability at first start‑up. The hydraulically balanced seal geometry provides stable face loading and controlled heat generation under fluctuating pressure and temperature conditions, supporting continuous‑duty operation in demanding services. 

 

BS700 metal bellows semi‑cartridge seals are widely applied on API process pumps, thermal‑oil and hot‑oil circulation pumps, chemical and hydrocarbon transfer pumps, reactors, mixers and other rotating equipment handling hot, clear or lightly contaminated liquids. For duties requiring enhanced containment or environmental protection, the design is also available in double‑configuration cartridge assemblies, providing improved leakage control and safety in critical applications. 

 

Leveraging our extensive expertise in reconditioning metal bellows mechanical seals, we also offer cost‑effective refurbishment of BS700 and equivalent designs, restoring performance, extending seal life and reducing overall maintenance costs for high‑temperature sealing systems. 

 

Key Features; 

• Available in both metric and inch shaft sizes, ensuring global compatibility across a wide range of process and API pump designs. 

• Bi‑directional operation, independent of shaft rotation direction, offers versatile application on various pump and rotating‑equipment configurations. 

• Non‑clogging bellows construction is particularly suitable for clean and light hydrocarbon services, maintaining consistent sealing performance with minimal risk of fouling. 

• Rotary metal bellows design eliminates dynamic elastomer hang‑up and O‑ring hardening issues, providing enhanced flexibility, durability and reliability in high‑temperature and chemically aggressive services. 

• Semi‑cartridge construction, factory assembled and tested, enables simplified installation with preset working length, reduced setting errors and quick removal for maintenance, significantly cutting downtime. 

• Provision for flushing and quench connections supports improved seal cooling, lubrication and vapor suppression where required, enhancing performance in hazardous, volatile and low‑lubricity process media. 

• Hydraulically balanced seal faces minimise heat generation and stabilise face loading, improving seal life and performance under thermal cycling and pressure fluctuations typical of thermic‑fluid and hydrocarbon duties. 

 

Service Overview; 

Parameter	Value
Equipment	API process pumps, thermic fluid pumps, refinery pumps, mixers, agitators
Fluid	Thermic oils, hydrocarbons, fatty acids, solvents, hazardous chemicals
Service Nature	High temperature, hazardous, volatile, corrosive process fluids
Operating Mode	Continuous-duty industrial process service

 

Specifications; 

Item	Min	Max	Typical / Notes
Shaft Size	20 mm (0.750”)	150 mm (6.000”)	Metric & inch sizes available
Pressure	Vacuum	25 bar (362 psi)	Depending on seal size & service
Temperature	-40°C (-40°F)	+400°C (+752°F)	Metal bellow design for elevated temperatures
Speed	—	3600 RPM	Depends on shaft size and face combination

Materials; 

Component	Standard Material	Optional Material	Comment
Seal Faces	Carbon / Silicon Carbide	Tungsten Carbide / Silicon Carbide	Selected based on fluid properties
Metal Bellows	SS 316L	Hastelloy C276 / Alloy 20 / Inconel	High-temperature corrosion resistance
Metal Parts	SS 316	Duplex SS / Hastelloy / Titanium	For aggressive chemical environments
Secondary Seals	Graphite / PTFE	Flexible Graphite	Static sealing compatibility

 

Applications; 

• Chemical process pumps 

• Oil & gas process equipment 

• Thermic fluid circulation pumps 

• Petrochemical transfer systems 

• Refinery and API process services 

• Hydrocarbon and solvent handling systems 

• Hazardous and volatile liquid transfer duties 

• Fatty acid and specialty chemical processing 

• High-temperature reactor circulation systems 

 

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 3600 RPM
Size Range	20 mm to 150 mm (0.750” to 6.000”)

 

Engineering Note; 

Operating parameters and material selections shown are based on standard industry practices for rotary metal bellow semi-cartridge seals in chemical and hydrocarbon service. Final seal selection should be verified against actual process conditions, fluid compatibility, shaft dynamics, and applicable API 682 requirements before implementation. 

 

Specification; 

Application	Suitable for hot and cold process media in the chemical, petrochemical, oil and gas, and allied industries, including thermic fluids, hydrocarbons, fatty acids, and other hazardous or high‑temperature liquids.
Materials	Faces	Carbon / Silicon Carbide / Tungsten Carbide
	Secondary Seals	FKM (Viton) / EPDM / FFKM (Kalrez) / Graphite
	Hardware	SS 316 / SS 316L / Hastelloy C-276 / Alloy 20 / Duplex
	Bellow Material	AM-350 / Alloy 20 / Hastelloy C / Inconel 625
Operating Limits	Size	25.0 mm to 100.0 mm (1.000” to 4.000”)
	Pressure	25 bars (363 psi)
	Temperature	-40 °C to +220 °C (-40 °F +428 °F)
	Speed	2900 rpm