Ermeto screw connections made of galvanized steel are the standard

Galvanized Steel Ermeto Fittings: Functional Standards for Hydraulics and Industry

Galvanized steel Ermeto fittings are standardized pipe connections for pressurized systems in fluid technology and machine equipment. Galvanization increases corrosion resistance and extends service life compared to untreated steel, without significantly altering mechanical strength. Typical product variants in this category include threaded fittings, couplings, elbows, tees, and fitting adapters in EO and EO2 designs, which differ in dimensions, sealing concepts, and ease of assembly.

Material and Coating

The base materials are cold-drawn or forged steels with defined tensile strengths. The surface is electro-galvanized, often with an additional passivation layer (e.g., yellow passivated) for increased resistance to bases and humid environments. Galvanized Ermeto parts retain typical properties at ambient temperatures, such as permanent dimensional stability, good thread strength, and increased abrasion resistance. For aggressive media, salty air, or permanent humidity levels, the application limits of galvanized steel compared to stainless steel must be checked.

Constructive Designs and Connection Types

Ermeto fittings are designed as single- or double-sided pipe fittings. Notable features include conical or cylindrical connections, hard internal edges for pipe centering, and precisely machined surfaces for seals. Typical connections are metric thread, BSP (R), and SAE variants; for EO/EO2 parts, these are generally metric connection dimensions according to DIN requirements. The designs differ in the shape of the union nut profile, the position of the sealing surface, and the length of the fitting or pipe stub area.

Sealing Concepts and Sealing Materials

Many Ermeto connections operate with a form-fitting seal through conical seating surfaces; often, no additional seal is required there. For dynamic or vibration-prone applications, elastic seals such as NBR, FKM, or PTFE washers are used. The choice of sealing material depends on the medium (hydraulic oil, water, air), temperature range, and chemical resistance. PTFE seals offer the highest chemical resistance, NBR is standard for mineral oils, and FKM is worthwhile for higher temperatures or more oil-chemically aggressive media.

Technical Performance Data and Test Criteria

Ermeto connections are designed for defined operating pressures; the permissible pressures depend on the nominal diameter, pipe wall thickness, and design (EO versus EO2). Test procedures include leak tests under static load, pressure surge tests, and vibration tests. When selecting, attention must be paid to the combination of pipe material, wall thickness, and fitting, as overtightening the union nut on thin pipes leads to plastic deformation. Manufacturer specifications and test certificates (e.g., ISO, DIN) must be consulted.

Fields of Application

Galvanized steel Ermeto fittings are used in hydraulic power units, mechanical engineering, presses, machine tools, lubrication systems, and general industrial plants. They are intended for oil and lubricant circuits, cooling systems, and pneumatic lines, provided media compatibility is given. For installations with external corrosion loads, e.g., outdoors or in a salty atmosphere, additional protective measures or alternative materials (e.g., stainless steel) must be considered.

Assembly and Processing Guidelines

Clean pipe ends and flat ground cut surfaces are a basic prerequisite for tight connections. Slowly hand-tighten the union nut and then tighten with a defined torque to avoid plastic deformation of the pipe. For EO and EO2 systems, the correct insertion depth must be observed; incorrect insertion depths lead to leaks or premature wear. Protective caps during storage and transport prevent damage to the sealing surfaces.

Practical Examples

Example 1 – Hydraulic power unit in a factory hall: In a hydraulic supply, galvanized steel EO2 couplings are used to reroute the supply lines from pumps to manifold blocks. Pipe stubs made of welded steel pipe are cut to size, deburred, and inserted into the Ermeto fitting until they stop. Then, union nuts are assembled with a defined torque. Seal choice: NBR washers for mineral oil; Test: static pressure test at 1.5 times operating pressure before commissioning. Example 2 – Lubricating oil supply for a press line: A lubricating oil line to several lubrication points uses galvanized EO elbows and tees. Due to vibration loads, additional PTFE washers are used to reduce material fatigue and leaks. Assembly note: Pipe ends with 15° chamfers and cleaning with solvent to remove abrasive particles. Example 3 – Mobile machine with changing environmental conditions: For a mobile recycling machine, galvanized Ermeto adapters were chosen to allow switching to differently sized hydraulic hoses. For frequent disassembly, lock nuts and locking plates ensure that connections remain dimensionally stable. Recommended test: visual inspection after 50 operating hours and retightening of the union nuts after a further run-in phase.

Compatibility and Interchangeability

EO and EO2 variants are compatible with each other in many cases, as long as the thread type and insertion depth match. When replacing, the internal geometry of the connection and the physical load limits must be compared. Manufacturer specifications and standard tables serve as guidance; in case of doubt, consultation with technical service offerings or the use of technical resources such as https://maku-industrie.de/technik or specific application examples for validation is recommended.

Economic Efficiency and Spare Parts Management

Galvanized Ermeto fittings are cost-effective in standard environments and offer simple warehousing due to standard dimensions. For maintenance strategies, stocking frequently used sizes and adaptations is recommended to reduce downtime. Identification systems with material and batch marking facilitate traceability and ensure consistent replacement quality.

Quality Checks and Scope of Delivery

Typical scopes of delivery include the union nut, the pipe stub, and, if applicable, sealing kits. Test documents such as leak test certificates, material-related test certificates, and measurement protocols should be provided upon request. Quality-critical points are dimensional accuracy of the threads, freedom from counterbores, and coating quality without craters or detachments.

FAQ

1. What is the difference between EO and EO2? EO and EO2 differ mainly in internal geometry and insertion depth; EO2 often offers increased pipe retention and is designed for higher pressures or dynamically loaded applications. The selection depends on pipe diameter, wall thickness, and operating pressure specifications. 2. Are galvanized Ermeto fittings suitable for outdoor applications? Galvanized versions are suitable for moderately corrosive outdoor environments; in salty or very aggressive media, stainless steel or additional coating is preferable. Regular inspection and, if necessary, post-treatment extend the service life. 3. Which seal is recommended for hydraulic oil? For mineral oil-based hydraulic media, NBR is standardly suitable. For higher temperatures or aggressive oils, FKM is recommended; PTFE is chosen when chemical resistance is paramount. Always check manufacturer specifications and temperature/chemical resistance.