No!, The 0818 Series Gate Valves are not Steam Rated.
A steam rated gate valve must have the Working Steam Pressure (WSP) mark molded on the valve body indicating the maximum steam pressure that the valve can withstand at the highest temperature rating. This marking is normally 125 WSP, 150 WSP or 125 SWP, 150 SWP. On some valves it may only be 125S or 150S, however this is not as common.
Without a proper stem rating marking molded on the vlave body, the valve is not steam rated!