Following SubMatts'June 14, 2020 article, submarine expert "S" has made some interesting comments regarding the June 12, 2020 14 hour fire on France's Rubis-classSSNPerle (S606).
S comments:
Heating of steel by fire and its cooling by water may result in significant damage of steel [1, 2]. According to submarine design experts, even apparently minor damage to submarine steel by heating and/or cooling might be extremely serious [3,4]. The degree of fire damage to the wiring/electrical system should also be precisely measured and assessed. Perle will be scrapped if damage is as severe as on USS Miami[5].
[1] https://www.steelconstruction.info/Fire_damage_assessment_of_hot_rolled_structural_steelwork
“The assessment of fire damaged hot rolled structural steel is an area in which many engineers and architects have little practical experience. On many occasions fire affected steelwork shows little or no distortion resulting in considerable uncertainty regarding its re-usability. This is particularly true in situations where fire has resulted in some parts of the structure exhibiting little or no damage alongside areas where considerable damage and distortion are clearly visible.”
[2] https://www.jstage.jst.go.jp/article/jssc/21/84/21_84_67/_pdf “Effect of heating and cooling process assuming fire of steel bridged on characteristics of welded joints of structural steel”, Steel Construction Engineering, vol.21, No84, ”Dec/2014, page 67, M. Hirohata, et. al.
“For investigating the effect of heating and cooling process assuming fire of steel bridges on characteristics of welded joints of structural steel members, a series of experiments were carried out. The heating under transformation point did not affect the joint performance regardless of cooling process. The heating over transformation point caused the softening or the hardening according to cooling rate. The degree of them was larger in the base metal rather than in the weld metal because the amount of carbon in the base metal was more than that in the weld metal. Furthermore, the change of microstructure of base metal made by TMC process was more sensitive compared with that of weld metal.”
[3] https://www.jstage.jst.go.jp/article/kyokaisi/460/0/460_KJ00002224747/_pdf “Issues on structural material and construction of submarine”, The Society of Naval Architects of Japan, No 460, Oct/1955, page 429, T. Sugimura et.al. (Technical Research and Development Institute, the Japan Defense Agency).
“USS Thresher sinking in 1963 was caused by fracture of welded parts of pipe of 10cm diameter. Risk of facture must be understood.”
- Also see https://en.wikipedia.org/wiki/USS_Thresher_(SSN-593)#Disaster_sequence_of_10_April_1963
[4] ibid, page 429
“There are two requirements in steel materials for submarine including welded parts: Standard Charpy strength at -70C and -2.2 C shall be more than 2.2kgm and 7kgm, respectively.”
[5] A USS Miami (SSN-755) was a Los Angeles-class SSN which suffering a shipyard maintenance fire in 2013, assessed as intentional sabotage. Inspectors assessed it would cost up to US$700 million to repair. Hence it was decommissioned in 2014.
S
S comments:
Heating of steel by fire and its cooling by water may result in significant damage of steel [1, 2]. According to submarine design experts, even apparently minor damage to submarine steel by heating and/or cooling might be extremely serious [3,4]. The degree of fire damage to the wiring/electrical system should also be precisely measured and assessed. Perle will be scrapped if damage is as severe as on USS Miami[5].
[1] https://www.steelconstruction.info/Fire_damage_assessment_of_hot_rolled_structural_steelwork
“The assessment of fire damaged hot rolled structural steel is an area in which many engineers and architects have little practical experience. On many occasions fire affected steelwork shows little or no distortion resulting in considerable uncertainty regarding its re-usability. This is particularly true in situations where fire has resulted in some parts of the structure exhibiting little or no damage alongside areas where considerable damage and distortion are clearly visible.”
[2] https://www.jstage.jst.go.jp/article/jssc/21/84/21_84_67/_pdf “Effect of heating and cooling process assuming fire of steel bridged on characteristics of welded joints of structural steel”, Steel Construction Engineering, vol.21, No84, ”Dec/2014, page 67, M. Hirohata, et. al.
“For investigating the effect of heating and cooling process assuming fire of steel bridges on characteristics of welded joints of structural steel members, a series of experiments were carried out. The heating under transformation point did not affect the joint performance regardless of cooling process. The heating over transformation point caused the softening or the hardening according to cooling rate. The degree of them was larger in the base metal rather than in the weld metal because the amount of carbon in the base metal was more than that in the weld metal. Furthermore, the change of microstructure of base metal made by TMC process was more sensitive compared with that of weld metal.”
[3] https://www.jstage.jst.go.jp/article/kyokaisi/460/0/460_KJ00002224747/_pdf “Issues on structural material and construction of submarine”, The Society of Naval Architects of Japan, No 460, Oct/1955, page 429, T. Sugimura et.al. (Technical Research and Development Institute, the Japan Defense Agency).
“USS Thresher sinking in 1963 was caused by fracture of welded parts of pipe of 10cm diameter. Risk of facture must be understood.”
- Also see https://en.wikipedia.org/wiki/USS_Thresher_(SSN-593)#Disaster_sequence_of_10_April_1963
[4] ibid, page 429
“There are two requirements in steel materials for submarine including welded parts: Standard Charpy strength at -70C and -2.2 C shall be more than 2.2kgm and 7kgm, respectively.”
[5] A USS Miami (SSN-755) was a Los Angeles-class SSN which suffering a shipyard maintenance fire in 2013, assessed as intentional sabotage. Inspectors assessed it would cost up to US$700 million to repair. Hence it was decommissioned in 2014.
S