Ermeto original hydraulic tube fittings made of galvanized steel

Galvanized Steel – Robust Fittings for Industrial Fluid Technology

Galvanized steel stands for high mechanical strength combined with corrosion-resistant surface protection. In the galvanized steel category, you will find pre-assembled and loose fittings according to the Ermeto standard (ermeto, eo, eo2) for oil, hydraulic, and compressed air applications in manufacturing, mechanical engineering, and maintenance. The products are designed for industrial operating conditions: fluctuating temperatures, vibrations, and dirt exposure. Material quality, galvanization depth, and the precise shaping of the sealing surfaces are crucial to prevent leaks and seizing.

Material Structure and Zinc Layer – What Matters

The base materials are hardened and unhardened steel, often specified according to DIN standards. Galvanization is carried out electrolytically, often with additional passivation to reduce white rust and improve adhesion to paints and sealants. For components such as nuts, union fittings, and screw-in studs, sufficient layer thickness is important: typical layer thicknesses range between 5 and 25 µm, depending on corrosion requirements and mechanical stress. For applications with increased corrosion risk, additional shrink or powder coatings or galvanized parts with additional paint may be useful. Pay attention to the specification: only declared zinc layers and passivations ensure the expected service life.

Ermeto Systems (ermeto, eo, eo2) – Differences and Applications

Ermeto fittings are based on standardized cone and sealing surfaces that allow for a detachable, pressure-resistant connection principle. ermeto (classic system) uses cone-shaped connections with a sealing cone; eo stands for an optimized version with improved threads and union designs; eo2 extends the series with higher pressure capability and simplified assembly properties. For low to medium pressures and standard hydraulics, ermeto/eo variants are sufficient; for higher pressures, dynamic loads, or difficult assembly conditions, eo2 is preferable. Check the pressure and temperature specifications on the product data sheets as well as compatibility with the fluids used.

Designs and Connection Variants

In this category, you will find straight and angled screw-in studs, union fittings, banjo bolts, T-pieces, reducers, and blanking plugs. Depending on the application, geometry and connection size determine flow, pressure loss, and assembly access. Conical sealing surfaces (e.g., 24° cone) create a metallic seal that seals under pressure when correctly assembled. Screw connections with flat gaskets or O-rings are useful in applications with chemically aggressive media or low pressures. For galvanized steel, tight metal seats are common; where soft seals are required, combined sealing systems are used.

Seals, Lubrication Points, and Assembly Instructions

For galvanized steel Ermeto fittings, metallic sealing surfaces are often provided. If O-rings or PTFE seals are integrated, pay attention to material compatibility with the conveyed medium and temperature resistance. Lubrication points on threads are often reduced for galvanized components, as galvanization changes friction; targeted application of assembly paste can prevent seizing and stabilize tightening torques. Recommended procedure: clean threads, apply a thin layer of assembly paste, bring the union to the cone shoulder, and tighten according to the manufacturer's torque or sequence. Note reusability: metallic sealing cones can be assembled multiple times, but elastic seals lose their dimensional stability after repeated assembly and should be replaced.

Corrosion Behavior in Practice

Electro-galvanized fittings provide protection against atmospheric corrosion and contact with non-aggressive hydraulic oils. In humid, salty, or aggressive chemical environments, the service life decreases; in such cases, alternatives such as electro-galvanized parts with an additional top coat, galvanized+passivated versions, or entirely stainless steel are advisable. Targeted material selection reduces maintenance intervals: in halls with splash water, galvanized is often sufficient; in offshore or outdoor environments, stainless steel is preferable. Document material characteristics and test results for QA and life cycle costing.

Practical Application Examples

Practical example 1: In an automated sheet metal forming plant, galvanized steel Ermeto union fittings are used as flexible connections between the hydraulic unit and line cylinders. Due to the nickel-plated surface passivation, leakage rates remained below maintenance limits for 24 months; modified assembly processes with assembly paste reduced seizing incidents by 40%. Practical example 2: In the HVAC industry, galvanized eo-2 screw-in studs connect compressors to refrigerant lines. The combination of 90° angled studs and conical seals allowed for tight installation spaces without additional sealants. Practical example 3: In the maintenance of a conveyor belt system, galvanized steel reducers were used to adapt older pipe sizes to modern pumps; documented tightening torques and recurring visual inspections reduced downtime.

Compatibility with Pipe Materials and Lubricants

Galvanized steel is mechanically compatible with steel pipes, copper lines, and various non-ferrous metals. Note potential differences when in contact with aluminum or copper in corrosive environments; galvanic corrosion can cause acceleration. Avoid direct contact of untreated aluminum parts without insulation. Choose lubricants and assembly pastes that do not attack the zinc layer; acidic products are unsuitable. Check compatibility lists from the lubricant manufacturer in conjunction with the fluids used, especially with biodegradable hydraulic oils.

Quality Features and Inspection Points for Purchasing

Pay attention to markings such as manufacturer number, material specification, galvanization standard, and test pressure. Inspection points before acceptance: visible zinc layer uniform and without flaking, thread runnability, sealing cone without grooves, and complete passivation. Request data sheets, corrosion tests (e.g., salt spray test), and information on service life. For critical systems, assembly and test protocols should be part of the scope of delivery.

Further Technical Information

For detailed technical data and application notes, please refer to the manufacturer's information and our technical pages at https://maku-industrie.de/technik. Practical applications and detailed examples can be found collected at https://maku-industrie.de/anwendungsbeispiele. The articles in the shop provide specifications for ermeto, eo, and eo2, pressure range, temperature range, and material specifications necessary for selection.

Brief Selection Guide

For quick decision-making, consider these points:

• Choose ermeto/eo for standard pressures and eo2 for higher dynamic requirements.

FAQs

1. When is galvanized steel sufficient, and when is stainless steel necessary?

Galvanized steel is sufficient for dry or moderately humid industrial environments and non-aggressive media. In salty environments, under strong chemical exposure, or for strict hygienic requirements, stainless steel is preferable. The corrosion risk, maintenance intervals, and life cycle costs are decisive.

2. Can Ermeto and eo2 fittings be assembled multiple times?

Metallic sealing cones in Ermeto and eo2 systems can be assembled multiple times, as long as the cone and threads show no damage. Elastic seals (O-rings, PTFE) should be replaced after each disassembly because their dimensional stability and surface adaptation decrease.

3. What tightening torques apply to galvanized fittings?

Tightening torques are product-specific and depend on thread size, material, and seal. Use the manufacturer's specifications from the data sheet. If data is missing, use tested reference tables and assemble with a torque wrench; an assembly paste can help ensure repeatability and tightness.