As a point of order, while Ocean's hull structure and systems may have been built to "commercial" standards - specifically Lloyds Rules & Regulations for the Classification of Ships - T45 and QEC are not. They are built to Lloyds Rules & Regulations for the Classification of Naval Ships, which were developed by incorporating much of the military load and military structural design practices previously contained in Naval Engineering standards etc.
Because these rules use broader brush loads (ie you tend to derive a worst-case load and apply it more extensively) than the multiple iterations and piece-part load modelling previously used in NES practice, this tends to lead to simpler "heavier" structures and thicker plating, which is no bad thing. At a rough estimate using Lloyds Rules as opposed to the old NES/SSCP23 design practices puts about 5-10% on the structural weight of a ship.
That said, much of the cracking issues evident in older ships (eg T42) was directly attributable to to p1ss-poor detail design. Bulkheads not landing on bulkheads is just asking for fatigue cracking. T23's are having issues because in some cases the MoD bulk-bought steel plate without the correct rolling margin, leading to in effect thinner than designed plating, not helped by the ships being significantly heavier than they were designed to be. However, replating is always do-able, just pricy.
MSB - you ought to be careful with the Great White Turbine (WR21) aboard the T45. It has a recuperator and an intercooler and is very complex. Trouble is there are only 12 of them (unlikely to be more) and I'm led to believe that elements of their "complex bits" are supplied by Messrs Bubba and Cletus of Bumf8ck Ak, who may not be in business throughout the life of the ships.......
Those nice people at GE who offered the successful and very popular LM2500 instead were of course turned away by BuffHoon (remember him??!)