 Soviet armor plate plants proved incapable of producing plates of cemented armor thicker than 230 mm ( 9 @.@ 1 in ) which forced the decision to replace cemented plates thicker than 200 mm ( 7 @.@ 9 in ) with face @-@ hardened ones with less resistance in November 1940 . The plants tended to compensate by making the thicker plates harder , but this often made them more brittle and large numbers did not pass the acceptance tests . This would have significantly reduced the level of protection enjoyed by the Sovetsky Soyuz @-@ class ships in combat . 
 Soviet armor plate plants proved incapable of producing plates of cemented armor thicker than 230 mm ( 9 @.@ 1 in ) which forced the decision to replace cemented plates thicker than 200 mm ( 7 @.@ 9 in ) with face @-@ hardened ones with less resistance in November 1940 . The plants tended to compensate by making the thicker plates harder , but this often made them more brittle and large numbers did not pass <a href='None' title='1'><mark>the</mark></a>acceptance <a href='negative_concord' title='2'><mark>tests</mark></a> . This would <a href='been_done' title='3'><mark>have</mark></a> significantly reduced the level of protection enjoyed by the Sovetsky Soyuz @-@ class ships in combat . 
Soviet armor plate plants proved incapable of producing plates of cemented armor thicker den 230 mm ( 9 @.@ 1 in ) which forced da decision to replace cemented plates thicker than 200 mm ( 7 @.@ 9 in ) with face @-@ hardened ones wid less resistance in November 1940 . Tdaplants tended to compensate by wit the thicker plates harder , but this often made them more brittle and bigass numbers did not pass acceptance no tests . dis would done significantly reduced the level of protection enjoyed by the Sovetsky Soyuz @-@ class ships in combat .