Allen keys 5×20 aisi 316 – code: a4-7991-05×020 – Osculati

Osculati 5×20 Allen screws in AISI 316 stainless steel (DIN 7991 / UNI 5933)

The 5×20 Allen screws in AISI 316 stainless steel Osculati are screws with countersunk head with internal hexagonal socket, designed for technical assemblies where it is important to achieve a flush surface finish on prepared seat. This geometry allows a neat and clean coupling, reducing external bulk and facilitating insertion in points where protrusions and interferences can be a limit.

The product is identified by the supplier code a4-7991-05×020 and is associated with the family “countersunk head screws with hex socket,” with reference DIN 7991 / UNI 5933. A typical choice for maintenance, replacement of small parts and assemblies in nautical and plant engineering fields, when a practical tightening with a hex key and a head that integrates into the surface is desired.

Features and construction details

Screw type: countersunk head with hex socket

These screws belong to the category of Allen screws with countersunk head. The conical head is designed to work on a countersinking countersink made in the component to be fastened, thus achieving a flush closure. The internal hexagonal socket allows tightening with a hex key, useful when lateral space is limited or when a protected drive is preferred over slotted or Phillips solutions.

Material: stainless steel AISI 316

The indicated material is AISI 316 stainless steel, frequently chosen in nautical contexts and onboard plant engineering for its suitability in applications requiring stainless steel small parts. In real applications, the choice of stainless steel is often linked to durability needs and compatibility with technical environments; however, it remains good practice to evaluate the combination of materials and the operating conditions of the system.

Reference standard: DIN 7991 / UNI 5933

The reference DIN 7991 / UNI 5933 identifies a family of countersunk head screws with recessed hexagon. This helps to recognize the type and to orient oneself during replacement or comparison with existing small parts, especially when working on assemblies already prepared for this geometry.

Product identification

• Supplier: Osculati S.r.l.
• Supplier product code: a4-7991-05×020
• SKU: oscu0000001436

These references are useful for reorders, assistance requests, and to maintain consistency in the onboard or workshop bill of materials.

Typical applications (nautical and plant engineering)

Countersunk Allen screws are used in many situations where a more linear and protrusion-free external surface is desired. In nautical and technical fields, they are often chosen for:

• Assemblies on panels and covers where a flush finish and a non-protruding head are required.
• Fastenings on components with an existing countersink, ", for example brackets, plates, and prepared accessories.
• Maintenance and replacement interventions of existing stainless steel small parts, maintaining the same type of drive and head.
• Assemblies in confined spaces, where the internal hex key can be practical compared to other drives.

In general, they are suitable when the goal is an orderly and consistent fastening with components designed for countersunk heads, avoiding solutions that could interfere with passages, covers, or movements.

Usage and operational notes

Countersunk seat check

To achieve the correct flush finish, it is important that the component to be fastened has a countersink compatible with the screw head. In the absence of an adequate seat, the head may not rest properly or be flush.

Tool selection

The hex socket requires a hex key suitable one. Using a tool in good condition helps preserve the drive and facilitates any future disassembly, especially in periodic maintenance contexts.

Fastening compatibility

When replacing, in addition to diameter and length, it is advisable to check:

• the head type (countersunk) and the presence of the related seat;
• the’drive (hex socket) to maintain the same tightening method;
• the material consistency with the rest of the small parts and with the paired components.

For specific applications or particular operating conditions, the choice of small parts should be evaluated based on the project and plant requirements.

FAQ – Frequently Asked Questions

What type of head do these Osculati Allen screws have?

They are Allen screws with countersunk head and internal hexagonal socket, designed to work on a countersunk seat and achieve a flush finish.

What is the material of the screws?

The indicated material is AISI 316 stainless steel.

Which standards do they refer to?

The product is associated with the family of countersunk head screws with hexagonal socket referring to DIN 7991 / UNI 5933.

What is the supplier code for reorder?

The supplier product code is a4-7991-05×020. For internal reference, the SKU is oscu0000001436.

In which contexts are these screws typically used?

They are often used in technical assemblies, maintenance, and replacements in nautical and onboard plant engineering, when a flush countersunk head and tightening with a hex key are desired.