Dual Pass (Both Rotary)

Description; 

The RJ-1215 Double Pass Rotary Joint is a fixed siphon-type rotary union designed to transfer heating or cooling media into rotating rolls, cylinders, drums, and jacketed equipment while allowing condensate or return flow through the same assembly. Its double-passage construction separates inlet and return paths within a single unit, reducing external piping, supporting efficient heat transfer, and maintaining stable thermal performance with minimal leakage. 

 

In fixed siphon service, the stationary siphon pipe is positioned inside the rotating roll or dryer cylinder to continuously remove condensate or return fluid from the lowest collection point. This design is widely used in steam-heated dryers, heating and cooling rolls, calenders, jacketed drums, reactors, and other rotating process equipment where thermal stability, leakage control, and long service life are essential. 

 

Technical Key Features; 

• Multiple seal configurations available according to media, temperature, and abrasion level. 

• Field-replaceable seals and bearings for reduced maintenance downtime and cost-effective service. 

• Application-specific material options for corrosive, hygienic, high-temperature, or abrasive environments. 

• Few rotating components to minimize mechanical wear, with a stationary siphon and rotating rotor/shaft only. 

• Isolated spring systems with springs protected from process fluid to reduce corrosion, fouling, and spring hang-up. 

• Available with flanged or threaded connections for straightforward integration with common piping standards. 

• Suitable for steam, hot water, thermic fluid, and cooling water service, depending on seal face and elastomer selection. 

• Suitable for horizontal rolls where siphon geometry and minimum differential pressure support efficient condensate removal. 

• Double-pass flow arrangement for simultaneous media supply and condensate or return-fluid discharge through a single rotary joint. 

• Precision-lapped seal faces for low leakage, stable sealing, and extended operating life under steam, hot water, and thermal-fluid duty. 

• Dual-flow capability maintains controlled separation of inlet and return flow paths to improve thermal efficiency and reduce external piping. 

• High-performance bearing support for designed thrust and speed loads, providing smooth rotation and reduced vibration in high-duty applications. 

• Compact concentric, industrial construction to minimize space requirements and enable easy integration with existing roll, dryer, and process equipment layouts. 

• Fixed siphon configuration with a stationary internal siphon pipe positioned for low-point condensate collection and reliable evacuation in rotating dryers, rolls, and cylinders. 

 

Service Overview; 

Parameter	Value
Equipment	Rotary dryers, steam rolls, calenders, cooling rolls, printing cylinders, jacketed drums, process rolls
Fluid	Steam, condensate, hot water, cooling water, thermic fluid, process heating/cooling media
Service Nature	Heating, cooling, condensate removal, thermal transfer, continuous rotary service
Operating Mode	Continuous or intermittent rotation with fixed siphon condensate extraction

 

Specifications; 

Item	Min	Max	Typical / Notes
Size	12 mm (0.500”)	300 mm (12.000”)	Custom sizes available on request; confirm journal diameter and installation clearance
Pressure	Vacuum service	17 bars (247 psi)	12 bar corresponds to saturated steam ≈187°C; see P‑T derating note below
Temperature	-20°C (-4°F)	+220°C (+428°F)	Above ≈200°C, verify elastomer and face materials; factory P‑T curve required for steam at elevated temperature
Speed	Low-speed indexing	1500 RPM	Speed limit is size‑dependent; confirm with roll diameter/balance and application

 

Materials; 

Component	Standard Material	Optional Material	Comment
Body / Housing	Cast Iron / Carbon Steel	SS 304 / SS 316 / Bronze	Selected based on corrosion, hygiene, and media compatibility
Shaft / Rotor	Carbon Steel / SS 304	SS 316 / Hardened SS	Precision-machined for seal stability and concentric running
Seal Faces	Carbon (rotary) vs Ceramic (stationary)	Carbon vs SiC / SiC vs SiC / Tungsten Carbide	Face pairing selected according to steam, water, or thermic-fluid duty
Secondary Seals	FKM / Graphite Packing	EPDM / PTFE / FEP Encapsulated FKM	Based on temperature and chemical compatibility
Springs / Hardware	SS 304 / SS 316	Inconel / Hastelloy	Critical for steam service; springs should be isolated from process fluid where possible
Bearings / Support Parts	Standard industrial bearing grade	High-temperature bearing arrangement	Specify bearing type and lubrication/maintenance plan
Siphon Pipe	Carbon Steel / SS 304	SS 316 / Alloy	Fixed siphon for condensate or return fluid evacuation

 

Applications; 

• Textile finishing machines, steam cylinders, dryers, and calenders. 

• Printing and packaging cylinders, laminating machines, and coating rolls. 

• Chemical reactors, heated drums, process rolls, and thermal-fluid systems. 

• Food and beverage dryers, cooking rolls, cooling rolls, and process cylinders. 

• Pulp and paper dryer sections, felt rolls, Yankee dryers, and coating machines. 

• Steel plants, strip processing lines, galvanizing lines, and metal finishing rolls. 

• Pharmaceutical dryers, jacketed process rolls, and hygienic thermal equipment. 

• Plastic and rubber processing rolls, extrusion cooling rolls, and mixing equipment. 

• Tyre manufacturing presses, calenders, curing lines, and rubber sheet processing systems. 

 

Operating Limits; 

Parameter	Value
Pressure	Up to 17 bars (247 psi)
Temperature	-20°C to +220°C (-4°F to +428°F)
Speed	Up to 1500 RPM
Size Range	12 mm to 300 mm (0.500” to 12.000”)  Custom sizes available; provide journal drawings

 

Engineering Note; 

The operating limits and materials above are professionally inferred for a standard industrial double-pass fixed siphon rotary joint. Final selection should be verified against actual media, pressure, temperature, roll speed, connection size, siphon geometry, and installation orientation. 

 

How to order / data required from the customer; 

• Roll journal diameter and tolerance, roll wall thickness, and journal length. 

• Any site‑specific constraints for maintenance access or special testing requirements. 

• Expected media (steam, thermal oil, hot water, other) and maximum operating pressure and temperature. 

• Operating mode (continuous or intermittent), expected RPM range, and condensate load estimate if  

available. 

• Connection type and size required (thread/flange standard) and any special material or certification requirements (PED, ATEX, traceability).