South America 4.6 Material 23x105mm/23X110mm Screw Spikes

The screw spike, also called a rail screw, is a threaded metal fastener used to fix the rail, base plate or fastening clip to the sleeper. Its threaded shank gives it a pull-out resistance roughly 0.5 to 1.0 times higher than a plain dog spike of the same size, which is why threaded fasteners are preferred where holding power matters. For the specific requirements of railway construction in South America, the 23×105 mm and 23×110 mm screw spikes have become a preferred fastening solution because their dimensional design matches the fastening systems used across the region and their mechanical performance holds up under tropical heat and variable load conditions.

Grade 4.6: what the numbers mean

Grade 4.6 is a property class defined by ISO 898-1. The first digit indicates a minimum tensile strength of 400 MPa, and the second digit gives the ratio of yield to tensile strength of 0.6, so the minimum yield strength is 240 MPa. This combination is deliberately modest: it is easy to form, thread-roll and galvanize, and it is ductile enough to survive the bending loads imposed during installation in uneven sleeper seats. The material is typically a high-quality low-carbon steel, processed by precise rolling and heat treatment to keep the mechanical properties consistent across the batch.

23×105 mm and 23×110 mm screw spike specifications

Why the plain oiled finish suits this market

The standard finish for these spikes is a basic anti-rust oil coating. This keeps the first cost low while giving adequate protection for storage and transport under most South American climatic conditions, from coastal humidity to highland dryness. During installation the oil film also acts as a lubricant, which helps the crew reach the specified pre-tightening torque consistently and reduces the risk of damaging the thread when driving into the dowel or sleeper. Where longer outdoor storage or coastal salt exposure is expected, hot-dip galvanizing is the recommended upgrade.

Installation and service considerations

These screw spikes are installed with a torque wrench or screw-driving machine into the pre-drilled dowel or sleeper. Because the pull-out resistance of a threaded spike is significantly higher than a plain spike, they hold gauge and resist loosening better under the vibration of passing trains. They are also used in combination with spring washers where the fastening system requires an additional elastic element. The track maintenance crew should re-check torque after the first weeks of traffic, when the sleeper and dowel settle.

FAQ

Why is grade 4.6 chosen instead of a stronger grade?

Grade 4.6 offers the best balance of cost, formability and ductility for screw spikes in timber and dowel fastening systems. Stronger grades such as 8.8 are used only when the fastening system drawing demands higher clamp force or when the sleeper material is very hard.

Can these spikes be hot-dip galvanized?

Yes. Hot-dip galvanizing is available for coastal and long-storage applications. Note that the thread fit should be verified after galvanizing, because the coating thickness affects the thread tolerance.

What is the pull-out resistance compared with a dog spike?

For the same size, a threaded screw spike typically gives about 0.5 to 1.0 times higher pull-out resistance than a plain dog spike. The holding power also depends on the dowel or timber quality.

Do I need to pre-drill timber sleepers for these spikes?

Yes. A pilot hole of the specified diameter should be drilled to the specified depth, otherwise the spike can split the sleeper or the thread may not engage evenly.

Are these spikes compatible with UIC 864-1 fastening systems?

The 23 mm diameter family is widely used in South American systems. UIC 864-1 defines screw spike requirements, and these spikes can be manufactured to that standard; confirm the head form and thread detail against the fastening system drawing.

What torque should be applied?

Use the torque specified in the fastening system documentation. As a guide for 23 mm class screws in dowels, typical values are in the range of 100-150 Nm, but the system drawing is the authority.