Symbol 2979 from ISO 7000 - Title/Meaning: Pressure vessel, drain Function/description: To indicate the point at which the substance contained in the pressure vessel can be drained from the vessel. Note: See also ISO 7000-2978.
pay attention to orientation of symbolAdditional information: 
See also ISO 7000-2978.
Own work using: iso.org/obp/graphics/grs/4e500fcc-349e-4c4e-a1c0-fac70e0d7df7 200.png
Vectorization:  Mrmw