Sanitary Liners & Male Parts (DIN 11851 / SMS / RJT Unions)
In high-viscosity food processing and dairy production, the union joint is a high-stress point prone to seal extrusion and crevice corrosion. Sanitary Liners and Male Parts form the core of the traditional DIN 11851 and SMS union systems. Unlike cheap cast fittings that suffer from sub-surface shrinkage porosity, Sunhyings components are forged or machined from solid 316L/304 bar stock. This structural density is critical for expanding or welding onto tubing without causing heat-induced distortion. By maintaining a strict Ra ≤ 0.8µm surface finish, we eliminate the “micro-pitting” where protein residues can bypass CIP cycles, ensuring your brewery or dairy facility remains compliant with global hygienic standards.
- Standard: Full DIN 11851 / SMS 1145 compliance.
- Material: Forged 316L prevents intergranular corrosion.
- Finish: Ra ≤ 0.8µm prevents biofilm adhesion.
- Precision: CNC-machined threads prevent nut galling.
- Versatility: Weld-on or expansion-style liners available.
- Supply: Bulk OEM manufacturing for stockists.
Technical Specifications
Product Name
Sanitary Union Parts (Liner, Male, Nut)
Standards
DIN 11851, SMS 1145, RJT (BS 4825), IDF
Material
AISI 316L (1.4404) / AISI 304 (1.4301)
Grades
Food Grade / Pharmaceutical Grade
Connection Type
Butt-weld, Expanding (Roller), or Hose Tail
Size Range
DN10 to DN150 (DIN) / 1″ to 4″ (SMS/RJT)
Surface Finish
Internal Ra ≤ 0.8µm (Standard) / 0.4µm (Optional)
Certifications
EN 10204 3.1 Material Certificates, FDA Gaskets
1. Forged Strength vs. Cast Porosity For B2B procurement, the “Total Cost of Ownership” is driven by part longevity. Our Male Parts and Liners are hot-forged. This process refines the grain structure of the stainless steel, making it significantly more resistant to stress corrosion cracking (SCC) compared to cast alternatives. This is vital in CIP systems where caustic chemicals and thermal shock (0°C to 140°C) are frequent.
2. Solving Thread Galling in SMS Unions A common engineering pain point is the “seizing” of the round nut on the male thread. We utilize precision CNC thread cutting with controlled tolerances to ensure smooth engagement. When paired with our high-quality AISI 304 nuts, the coefficient of friction is reduced, preventing the cold-welding (galling) that often ruins union fittings during routine maintenance.
3. Expansion Liner Stability For facilities using expanding (roller) joints instead of welding, the wall thickness and hardness of the liner tail are critical. Our liners are annealed to a specific hardness range to allow for clean expansion against the pipe wall without cracking or creating gaps where product could be trapped.
Note: Dimensions based on DIN 11851 Standard. Capture “DIN 11851 Liner dimensions” search intent.
| Size (DN) | Liner OD (d1) | Liner ID (d2) | Male OD (d6) | Male Thread (Rd) |
| DN 25 | 44.0 mm | 26.0 mm | 35.0 mm | 52 x 1/6″ |
| DN 40 | 56.0 mm | 38.0 mm | 48.0 mm | 65 x 1/6″ |
| DN 50 | 68.0 mm | 50.0 mm | 61.0 mm | 78 x 1/6″ |
| DN 65 | 86.0 mm | 66.0 mm | 79.0 mm | 95 x 1/6″ |
| DN 80 | 100.0 mm | 81.0 mm | 93.0 mm | 110 x 1/4″ |
| DN 100 | 121.0 mm | 100.0 mm | 114.0 mm | 130 x 1/4″ |
1. Preload and Gasket Seat
The Problem: Over-tightening the union nut can deform the D-section gasket, leading to “extrusion” into the flow path.
The Fix: Tighten until metal-to-metal contact is felt between the liner face and male shoulder. The gasket is designed to fill the hygienic cavity at this specific preload.
2. Weld Preparation
Requirement: Ensure a square cut on the process tubing. Use a high-purity orbital welder for the male part to maintain a consistent $O_2$ purge.
Anti-Galling: Apply a food-grade, metal-free lubricant to the male threads (e.g., Klüber) to ensure ease of disassembly after high-heat SIP cycles.
3. Hole Clearance (ISO 273)
When mounting male parts into manifold plates, maintain tolerances per ISO 273 to ensure the fitting is not subjected to bending moments which could lead to seal failure under vibration.
Related Products
FAQ
What is the difference between an SMS and a DIN 11851 sanitary union?
The main difference is the thread standard and the seal design. DIN 11851 uses a round thread (Rd) and a D-section gasket with a heavy cone-shaped liner. SMS 1145 uses a finer thread and a flat gasket. They are not interchangeable; always verify the regional standard of your brewery or dairy equipment before ordering.
Why is 316L preferred over 304 for sanitary liners?
316L Stainless Steel contains Molybdenum, which provides significantly higher resistance to pitting and crevice corrosion caused by chloride-heavy sanitizing agents and acids used in CIP (Clean-in-Place) cycles. While 304 is acceptable for non-contact parts, 316L is the engineering standard for wetted components.
What is an expanding liner in hygienic piping?
An expanding liner is a union part designed to be mechanically expanded (rolled) onto a pipe rather than welded. This is common in facilities where “hot work” (welding) is prohibited or for quick on-site repairs. It requires an expansion tool to press the pipe wall into the serrations of the liner tail.
Do your sanitary liners meet Ra ≤ 0.8µm requirements?
Yes. All Sunhyings hygienic male parts and liners are CNC machined and polished to a guaranteed Ra ≤ 0.8µm (32µin) internal finish as standard. We also offer Electropolishing (EP) to achieve Ra ≤ 0.4µm for high-purity pharmaceutical applications.
Can I reuse high-strength hex bolts (Grade 10.9)?
It is generally not recommended to reuse Grade 10.9 bolts in critical structural connections. Once tightened to their yield point, the bolt undergoes plastic deformation. Reusing them can result in fatigue failure or an inability to hold the correct preload.