Face-to-Back Double Cartridge Mechanical Seal

Product Overview; 

The DC670 is a robust face‑to‑back double cartridge mechanical seal developed for process pumps and critical rotating equipment that require superior leakage control, high reliability and extended equipment uptime. Supplied as a fully pre‑assembled cartridge mounted on a sleeve with an integral gland plate, the seal installs directly over the pump shaft or sleeve in a conventional stuffing box, offering straightforward, repeatable installation across a wide range of pump types and manufacturers. 

 

In a face‑to‑back configuration, the two balanced mechanical seals are arranged so that one set of faces is oriented toward the process fluid and the other toward the barrier system, combining features of back‑to‑back and face‑to‑face designs. Operated with a pressurised barrier‑fluid system in line with API 682 dual‑seal practice (Arrangement 3 concepts), the DC670 provides an enhanced pressure barrier, stable lubrication, controlled heat removal and highly effective leakage containment for hazardous, toxic, flammable and high‑temperature media. This helps prevent process contamination, reduce emissions and protect both equipment and the surrounding environment. 

 

The hydraulically balanced dual‑seal arrangement minimises face loading while the multi‑spring loading system maintains uniform face pressure and stable operation under fluctuating pressure, temperature and shaft conditions. Combined with the cartridge‑mounted construction and factory‑preset working length, this design eliminates shaft‑setting errors, simplifies alignment and reduces maintenance downtime in critical process applications. 

 

Engineered for process pumps, API 610 pumps, mixers, reactors and other rotating equipment, the DC670 is particularly well suited for petrochemical, refinery, pharmaceutical, pulp and paper, fertilizer, mining, power‑generation and other industrial sectors handling corrosive, volatile or environmentally sensitive process fluids. Its face‑to‑back configuration provides excellent pressure‑handling capability and efficient barrier‑fluid circulation, making it an ideal sealing solution wherever high integrity, safety and operational reliability are paramount. 

 

Key Features; 

• Available in both metric and inch shaft sizes, ensuring compatibility with different pump specifications and international design standards. 

• Bi‑directional operation, independent of shaft rotation direction, offering versatile application across a wide range of centrifugal pumps and rotating equipment. 

• Non‑clogging spring arrangement, located and shielded to resist fouling, suitable for clean and moderately contaminated process fluids while maintaining consistent sealing performance. 

• Face‑to‑back double cartridge configuration providing improved pressure stability and enhanced leakage containment for hazardous, volatile and environmentally sensitive process media. 

• Provision for flushing and quench connections, fully compatible with API 682‑style sealing systems and auxiliary piping plans to optimise barrier‑fluid circulation, cooling, lubrication and seal longevity. 

• Cartridge‑mounted, factory‑assembled and tested design supplied as a preset unit for quick installation and easy removal, minimising alignment and shaft‑setting errors while reducing maintenance downtime. 

• Hydraulically balanced double‑seal faces with rotating multi‑spring / wave‑spring loading ensure uniform pressure distribution, reduced heat generation and extended seal life under demanding operating conditions. 

• Heavy‑duty construction with precision‑engineered sealing geometry reduces shaft or sleeve wear and supports continuous industrial operation in petrochemical, chemical, power‑generation and other critical services. 

 

Service Overview; 

Parameter	Value
Equipment	Process Pumps, API Pumps, Agitators, Mixers, Compressors
Fluid	Hydrocarbons, Chemicals, Solvents, Light Slurries, Process Fluids
Service Nature	Hazardous, Corrosive, Volatile, High-Temperature
Operating Mode	Continuous Industrial Duty

 

Specifications; 

Item	Min	Max	Typical / Notes
Shaft Size	20 mm (0.750”)	300 mm (12.000”)	Metric & inch sizes available
Pressure	Vacuum	40 bar (580 psi)	Higher pressures on request
Temperature	-40°C (-40°F)	+220°C (+428°F)	Depends on elastomer & metallurgy
Speed	—	3600 RPM	Higher speeds available on request

 

Materials; 

Component	Standard Material	Optional Material	Comment
Seal Faces	Carbon vs Silicon Carbide	Silicon Carbide vs Silicon Carbide / Tungsten Carbide	Based on fluid lubricity & abrasiveness
Elastomers	FKM (Viton)	EPDM / PTFE / FFKM	Chemical compatibility dependent
Metal Parts	SS 316	Duplex SS / Hastelloy / Alloy 20 / Titanium	For corrosive services
Springs	SS 316	Hastelloy C	Suitable for aggressive environments

 

Applications; 

• Sugar and distillery process pumps 

• Power generation auxiliary systems 

• Steel and mining process equipment 

• Fertilizer and ammonia processing units 

• Hydrocarbon transfer and storage systems 

• Chemical processing and solvent handling systems 

• Pulp & paper stock and chemical circulation pumps 

• Pharmaceutical and hygienic processing equipment 

• Water and wastewater treatment rotating equipment 

• API process pumps in refinery and petrochemical plants 

 

Operating Limits; 

Parameter	Value
Pressure	Up to 40 bar (580 psi)
Temperature	-40°C to +220°C (-40°F to +428°F)
Speed	Up to 3600 RPM
Size Range	20 mm to 300 mm (0.750” to 12.000”)

 

Engineering Note; 

Operating limits and material combinations shown are based on standard industrial double cartridge seal configurations and typical API process applications. Final selection should be verified against actual process fluid characteristics, vapor pressure, solids content, shaft dynamics, and API piping plan requirements prior to installation.