Hex Head Sems Screw

A hex head sems screw is a screw with a pre assembled washer. The washer is held on the screw and cannot be lost. The head is hexagonal and takes a cross recess drive.

A hex head sems screw fastens parts through a drilled hole. The captive washer spreads the load under the head. It takes a nut of the same thread and class, or it can thread into a tapped hole.

Sems screws are often made in carbon steel or stainless steel. Carbon steel is usually plated for corrosion resistance, while stainless steel is chosen for wet or outdoor use.

This is a general guide to checking this kind of part. It says nothing about any supplier's parts.

Ask for a certificate of conformance for the screw and washer. On receipt, check the drive recess, the washer retention, and that the thread runs freely.