SERTO Selection

the best choice for Ultra High Purity (UHP) and High Purity (HP) applications

SERTO has developed the SERTO Selection product range to meet the highest requirements for tightness and cleanliness in stainless steel connecting components. SERTO Selection stands for ultrasonically cleaned, lubricant-free stainless steel connections with electropolished surfaces and no dead space.

The SERTO Selection consists of two product families:

  • Ultra High Purity (UHP) – Orbital welded connection / union
  • High Purity (HP) – Compression ferrule union

The UHP product range is a new development. It includes the union nut made of Nitronic®60, electropolished weld-on nipple made of stainless steel 1.4404 with PTFE or silver coating, the union body, also made of electropolished stainless steel 1.4404, as well as the electropolished weld-on elbow and tee.

The coated sealing surfaces are abrasion-free and the dead space-free design prevents dirt from building up on the components. All UHP products have a lasered production code for full traceability. The low leakage rate of 10‑11 mbar x l/s and the high resistance to pressure of up to 500 bar allow a wide range of applications.

The HP product range is based on components from the existing and proven stainless steel range. The union nut made of stainless steel 1.4571 is internally silver plated, the compression ferrule made of 1.4571 is coated with PTFE or with silver, and the union body made of 1.4404/1.4571 is electropolished.

The sealing surfaces of the HP compression ferrules are also very abrasion resistant. The leakage rate is 10‑9 mbar x l/s and the resistance to pressure reaches up to 250 bar.

The SERTO SELECTION is of interest for you if

  • the cleanliness of the components is extremely important to you.
  • you require lubricant-free stainless steel unions.
  • your application requires tightness greater than 10-9 mbar x l/s.
  • you use orbitally welded components.
  • you use internally electropolished tubes.
  • you would like to refrain from using separate sealing components.


  • SERTO UHP unions are dead space free.
  • SERTO HP unions have little dead space.
  • Coatings replace cost-intensive sealing rings.
  • All components are purified in accordance with the SERTO standard, vacuum-packed in the clean room and double packed.
  • SERTO offers bended and pre-assembled tubes, internally electropolished and cleaned.
  • Pre-assembled tubes can be orbitally welded in-house.

Comparison of features UHP and HP

UHP Orbital welded connectionHP Compression ferrule union
Dead space freeLow dead space
Leakage rate: ≤ 10-11 mbar × l/sLeakage rate: ≤ 10-9 mbar × l/s
Vacuum: up to 10-9 mbarVacuum: up to 10-7 mbar
Internal roughness (iRa): ≤ 0.25 µmInternal roughness (iRa): ≤ 0.8 µm
Operating pressure: up to 500 bar (fourfold safety)Operating pressure: up to 250 bar (fourfold safety)
Metric and inch dimensionsMetric dimensions
Marking of batch codeMarking of batch code upon request
Materials: stainless steel 1.4404 / 1.4571 / Nitronic®
Temperature range: -70°C to +260°C
Lubricant-free due to coatings (silver or PTFE)
Small dimensions with radial mounting
Easy installation without seals
Ultrasonic cleaning, vacuum-packed, double packed