u2-Lok Twin ferrule fittings
u2-Lok Twin Ferrule Fittings
About the successful certification of u2-Lok Twin Ferrule Fittings fittings by DNV · GL (Det Norske Veritas · Germanischer Lloyd), the Schwer Fittings GmbH was delighted. The very extensive type examination included the following tests: Combined pressure pulse and vibration test, repeated assembly, leak testing, vacuum testing, pull test and a burst resistance.
Stainless steel twin ferrule fittings for the process industry and hydrogen applications
Description of a twin ferrule fittings
The u2 twin ferrule fittings is used in high-pressure and vacuum applications where the highest demands are placed on material and tightness. Areas of application include the chemical, pharmaceutical and food industries as well as plant engineering and hydrogen applications. It is suitable for liquid and gaseous media.
The fitting consists of a total of four components: The connecting piece, the union nut and the clamping ring and wedge ring. The sealing and pipe clamping functions are separated by the front wedge ring and the rear clamping ring. This principle distinguishes the compression fitting from other fitting systems such as the classic cutting ring fitting
The connection piece is available as standard in straight, elbow, T- and cross-piece versions and serves as a media-conducting base for securely holding the pipe. The specially developed, extra-long pipe guide ensures reliable centering and therefore a secure fit of the pipe.
The clamping ring cuts into the surface of the pipe and thus assumes the retaining function of the pipe. Thanks to its special, spring-like contour, it dampens vibrations from the pipe network
The wedge ring seals annularly on the contact surfaces between the fitting and the pipe. The ring is pressed onto the pipe through the cone in the bore of the socket, creating a constriction. This ensures that the pipe is clamped pressure-tight
Functional description of the Twin Ferrule Fittings:
Basically, the u2-Lok screw connection consists of 4 components or individual parts: The media-carrying base body (straight socket, elbow, T-piece or cross piece), the union nut and the two rings, also known as clamping and wedge rings.
The screw connections are used wherever gases and liquid media flow and where a high safety standard is required. It is also ideal for hydrogen applications.
The u2-Lok screw connections are mainly used:
- in chemical process technology
- in pharmaceutical and biotechnology
- in petroleum processing
- in offshore and shipbuilding
- in nuclear research
- in laboratories and institutes
- in vacuum technology
- for hydrogen applications (Hydrogen H2)
The new u2 fittings are designed according to its own production facilities in Europe. The semi-finished products are mostly from EU countries. Both the quality and the current pressure tests are carried out exclusively in the company's headquarters in Denkingen.
The design largely allows vibrations and pressure pulses to be absorbed, without any fear of leackage. This design, technical manufacturing, and quality properties ensure twin ferrule fittings a wide range of applications in industry, laboratory, and measurement system areas.
The use of high quality stainless steel guarantees a long service free life, also in the chemical industry. u2-Lok Twin Ferrule Fittings, from 316 stainless steel as standard, are supplied assembled and ready to use. Even under heavy vibration conditions couplings guarantee a safe operation at high pressure or vacuum.
The fittings are delivered ready for use. The nut and the clamping wedge rings of the screw connection do not have to be dismantled for assembly. The union nuts are tightened finger-tight with the clamping and wedge rings on the screw connection body and can therefore be used immediately for assembly. For professional assembly, the assembly instructions must be observed. Repeat assemblies are possible several times.
Even when the system is operated with high vibrations, the screw connection guarantees sufficient safety at high pressures or vacuum.
This is achieved through 4 effective design details:
- The back ferrule affords damping of tube circuit vibrations through a spring like action. Furthermore, it prevents a carry-over of tightening torque from the coupling nut to front ferrule.
- The front ferrule circumferentially seals the surface between the tube and coupling. Due to the inner taper the front ferrule is pressed into the tube so that a pressure-tight impression is formed.
- Silvering of the coupling nut thread prevents seizing of the stainless steel coupling. This allows multi-use of a coupling.
- A deep pipe bore, and entry taper, guarantees accurate positioning and centring of the tube.
On request, parts can also be supplied from Hastelloy, Titanium and other highly alloyd materials. Material certification according DIN ISO 10204, ANSI etc., available on reques. Special tests and approvals possible, if required.
Schwer Fittings Standard cleaning
As standard, the u2-Lok twin-ferrule fittings are supplied free of oil and grease (off) and individually packed in foil. A special multi-stage cleaning process with ultrasonic support removes oil and grease residues as well as loose particles, ensuring that the components meet the basic requirements of the industry.
When using oxygen, certain precautions must be taken to rule out the risk of fire. The cleanliness of the system plays an important role in preventing an oxygen fire. For such applications, we offer fittings in accordance with the "offO2" Schwer Fittings standard. This in-house standard defines the cleaning, assembly and packaging of stainless steel fittings in accordance with ASTM G93 Level C for all components in contact with media.
Please refer to our more detailed information on the various cleaning standards in the data sheets listed below.
Cleaning Standard off
Cleaning Standard offO2
Certifications
The screw connections from Schwer Fittings are certified by the certification body DNV (Det Norske Veritas). The very extensive type test included the following tests: combined pressure pulse and vibration test, repeat assembly test, leak test, vacuum test, pull-out test and a bursting pressure test.
Own European production
The fittings are manufactured in our own production facilities in Europe. Most of the semi-finished products come from EU countries. Both the quality assurance and the ongoing pressure tests are carried out exclusively at the company headquarters of Schwer Fittings in Denkingen. Pressure test requirements according to customer specifications are carried out and documented at Schwer. A test number is generally lasered into the media-carrying parts including the rings. This number hides a lot of information. In this way, the assignment to the starting material with all mechanical tests and the assignment with a 3.1 certificate can be guaranteed even after years. It is also possible to trace back when, in which production plant, on which machine and by which employee the parts were manufactured.
Interchangeability of twin ferrule fittings and individual components
Twin ferrule fittings are to be considered a complete system, which is why all components within this system are specifically matched to each other. By mixing individual parts from different manufacturers within a fitting, it can no longer be guaranteed that the functionality of the fitting system is reflective of the operating values specified in the catalogue.
Practical experience shows that mixing individual parts can work - however, it should be noted that mixing individual parts from different manufacturers within a fitting will result in the loss of all certifications for the fitting as well as the expiry of all warranty claims. Schwer Fittings therefore recommends not to mix the individual components of twin ferrule fittings from different manufacturers, and always to replace complete fittings. The technical information and specifications in our data sheets and e-shop apply.
FAQ: Stainless Steel Twin Ferrule Fittings and Clamp Ring Fittings
Description of a clamp-type wedge ring fitting
The fitting consists of a total of four components: the socket, the union nut, the clamping ring, and the wedge ring. The sealing and pipe clamping functions are separated by the front wedge ring and the rear clamping ring. This principle distinguishes the clamping ring fitting from other fitting systems, such as the classic cutting ring fitting. Even during high-vibration operation of the system, the fitting ensures sufficient safety at high pressures or under vacuum.
How does a clamp-type wedge ring fitting work?
The screw connection consists of a total of four components: the fitting, the union nut, the clamping ring, and the wedge ring. The sealing and pipe clamping functions are separated by the front wedge ring and the rear clamping ring.
The fitting is available as standard in straight, elbow, T-shaped, and cross configurations and serves as a media-base body for securely holding the pipe. The specially developed, extra-long pipe guide ensures reliable centering and thus a secure fit of the pipe.
The clamping ring cuts into the pipe surface and thus performs the function of holding the pipe in place. Thanks to its special, spring-like contour, it dampens vibrations from the pipe network.
The wedge ring provides a ring-shaped seal on the contact surfaces between the fitting and the pipe. The cone in the socket’s bore presses the ring onto the pipe, creating a constriction. This clamps the pipe securely in place, making it pressure-tight.
Where is a clamp-type wedge ring fitting used?
The u2 screw connection is used in high-pressure and vacuum applications where the highest standards for material quality and leak tightness are required. Applications include the chemical, pharmaceutical, and food industries, as well as plant engineering and hydrogen applications. It is suitable for liquid and gaseous media.
Functionally matched tolerances and consistent surface finishes in clamp-and-wedge-ring fittings ensure leak-free pipe connections in both high-pressure and vacuum applications. Vibrations and pressure surges are largely absorbed by the design without the risk of leaks.
u2-Lok fittings are primarily used:
- in chemical process engineering
- in the pharmaceutical and biotechnology industries
- in petroleum processing
- in offshore and shipbuilding
- in nuclear research
- in laboratories and research institutes
- in vacuum technology
- in hydrogen applications (Hydrogen H2)
What distinctions are there within the product range?
The u2 fittings are available in various versions, such as pipe-to-pipe, pipe-to-internal or external thread, pipe-to-shank, or weld-on connections. The product range is rounded out by various control valves with U2 connections.
What are the advantages of a clamp-type wedge ring fitting from Schwer Fittings?
Production takes place at Schwer Fittings’ manufacturing facilities in Europe. The raw materials also come from Europe. This allows us to directly influence the manufacturing processes and ensure that production always reflects the latest technical standards. All components are manufactured with the highest precision on state-of-the-art CNC turning and milling machines.
The final inspection of all items takes place in the quality assurance department at the Denkingen site. All component sizes are tested in accordance with DNV. Laser marking of all components ensures clear traceability.
What are the technical specifications (pressures, temperatures, media, etc.) of a clamp-type wedge ring fitting?
Please refer directly to the product page in the eShop for all technical specifications, including pressure ratings. Please also review the technical notes, data sheets, and installation instructions to ensure safe and proper installation of the compression fitting.
- Dimensions: metric and inch
- Sizes: 3–28 mm or 1/16″–1″
- Material: 1.4404/AISI 316L
- Pressure: max. 700 bar
- Liquid media and gases
- Leakage rate of 10^-9 mbar*l/s
How do you properly install a twin ferrule fitting?
All twin ferrule fittings are washed to remove all oil and grease and are delivered to you individually shrink-wrapped in a pre-assembled state. This means they are ready for immediate use and can be screwed onto the pipe. On-site installation training is available upon request.
Please be sure to follow our installation instructions under "→ Service → Installation Instructions".
Who should I contact if I have a technical question?
At Schwer Fittings, an experienced team of in-house and field staff is always available to provide you with expert advice. In addition, the company has specialized staff in product management who are responsible for all product areas of stainless steel pipe connection technology. The team is complemented by experts (m/f/d) in business development—particularly for hydrogen applications (H2 technology) and the process industry.
Close collaboration with our customers ensures the highest level of technical precision, efficiency, and long-term operational reliability. You can find all contact options under “„→ Worldwide Contact“”. Further information on technical services and support is available in the “„→ Technical Service“” section.
Area video
Information from our product management about product variants, function and areas of application.
Assembly Instruction: u2-Lok Twin Ferrule Fittings
The u2-Lok Twin Ferrule Fittings are delivered assembled and ready to use. The nuts and ferrules don’t need to be removed for assembly. The nuts are assembled fingertight to the body and an instant assembly is guaranteed.
Observe the generally applicable safety regulations when handling tools and machines. Wear appropriate protective clothing.
Assembly into a body:
Reassembling:
Quality Management System
In addition to national and international certifications the company Schwer Fittings is additionally certified regularly by customers. Through our own developments and solutions Schwer Fittings has numerous patents and registered designs. Furthermore, we offer the following certificates to download: