Threaded Fittings

Threaded fittings are primarily used in applications where there are no stringent requirements for cleanliness or the absence of dead space. Threaded fittings serve as connecting elements between pipes and systems, or simply to connect one component to another. Example: A pump connected with threaded fittings that is used to transport emulsion.

Proper installation is crucial for safe operation. The threads must be clean and free of contaminants. Tapered external threads are sealed with sealing tape or sealing thread, while a sealing ring is used for cylindrical threads. The threaded fitting is then screwed onto the corresponding component to ensure a leak-tight connection.

The thread is the primary functional element of a threaded fitting. The thread is wrapped or coated with sealing tape, sealing thread, or adhesive. The threaded fitting can then be placed on the component to be connected and screwed on to ensure a leak-tight seal.

Due to the different types of threads and sealing systems, special care must be taken when combining components. Please use internal and external threads of the same type, as this is the only way to ensure optimal fit and reliable sealing.

Threaded fittings are divided into two main groups:

• Standard fittings such as nipples, couplings, reducers, plugs, caps, nuts, locking screws, hose nipples, elbows, T-pieces, cross pieces, and bends
• Screw connections, interchangeable three-piece screw connections in straight, angled, or T-configurations.

The fittings can have either a conical or flat seal (standard: PTFE seal; other seals such as EPDM or Klingersil are available upon request).

Tapered seal:
The screw connections consist of a threaded insert, a flat gasket, an insert, and a cap nut: In conical-seal threads, the threaded surfaces are shaped so that they seal against the conical surfaces when pressed together. An additional elastomer seal is not required. This eliminates the need to rely on the media compatibility of elastic sealing materials. The medium is reliably conveyed and securely sealed.

Flat-sealing:
In flat-sealing screw connections, flat sealing surfaces, in combination with an additional sealing ring, ensure a reliable seal. When the cap nut is tightened, the sealing surfaces are brought together and the seal is compressed—regardless of the thread form. A major advantage is ease of maintenance: The fitting can be removed radially, allowing individual components to be loosened without dismantling the piping. In the event of frequent assembly, only the gasket needs to be replaced, not the entire fitting.

The threads comply with international standards, including:

• DIN EN 10226-1 (ISO 7-1): Tapered Whitworth pipe thread for thread-sealing connections
• DIN EN ISO 228-1: Cylindrical Whitworth pipe thread for non-thread-sealing connections
• NPT (ASME/ANSI B1.20.1): American tapered pipe thread for self-sealing connections.

The threaded fittings are available in various grades of stainless steel, selected for their corrosion resistance and to meet mechanical requirements:

• 1.4571 Titanium-stabilized stainless steel, highly corrosion-resistant, suitable for aggressive media
• 1.4404 Low-carbon stainless steel, particularly resistant to pitting and intergranular corrosion
• 1.4408 Precision-cast stainless steel for complex molded parts.

For three-piece screw connections, the available sealing materials are PTFE, EPDM, and Klingersil. In the e-shop, the seal part number is listed for each fitting under the “Technical Data” tab. All flat gaskets are also available to customers through the e-shop.

Please refer to the respective product listing in the eShop for exact pressure specifications.

We have increased the operating pressure ranges of all threaded fittings in quality class -7 to pressures of up to 250 bar, thereby expanding their range of applications.
This allows our customers to benefit from greater safety margins, more flexibility in component selection, and simplified standardization of their product range.

Test Parameters

• Pressure: Burst pressure
• Temperature: 20 °C
• Medium: Water

Safety

• 4-fold safety

In our video, we demonstrate the burst pressure test for the GF-140FRG38-7. The pressure test confirms the fitting’s high load-bearing capacity and forms the basis for the extended pressure ratings. The permissible operating pressures for the respective threaded fittings depend on the specific design and operating conditions.

We do not carry 3D models for -5i items. For all other materials used in threaded fittings, the 3D CAD models are otherwise available on the product pages in the eShop.

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 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.