Steel plug is very important among all the fasteners. In the pipeline system, it is used to plug some non-essential holes up.There are different types, including square head plug, hex head plug, round head plug. All the plugs are with thread, so some people call it as Threaded Plug. The nominal pipe size is from 1/8`` to 4``.
Hex head plug
As for the pressure, they maybe used for ratings up through CLASS6000 designation. About the manufacture materials, there are Carbon Steel Plug, alloy steel plug, stainless steel plug.
These plugs are with NPT thread, the material is stainless steel.
The standard of steel plug is ASME B16.11. This product is widely used in petroleum, chemical, power plant, shipbuilding etc.