The utility model discloses a high strength valve for steam, including the main valve body, main valve body upper end is equipped with the valve flange that is used for controlling main valve body break -make, be equipped with a mounting flange at the main valve position below the valve flange, it has the location boss upwards to extend at a mounting flange up end, mounting flange top is equipped with sealing sleeve, the sealing sleeve lower extreme is equipped with the 2nd mounting flange with a mounting flange matched with, still be equipped with the sealing washer between a mounting flange and the 2nd mounting flange, location boss and sealing sleeve hole sliding fit, and a mounting flange all is equipped with the connecting hole that corresponds with the 2nd mounting flange, offer the mounting groove that is used for installing the sealing washer on a mounting flange, the utility model is not only simple in structure, it is with low costs, safe and reliable, long service life need not to shut down and changes, only need utilize secondary seal structure, with the whole sealed continuation and the stability that can be favorable to production once more of valve, improves production efficiency.