Let me jump into this e-mail krub.
After I checked the maintenance responsibility between LSTH and TICON, I found that the check valve of W1/1 fire pump shall be TICON responsibility. Further as your expected damaged cause I don’ think it’s blocked by rusty but I think it may be blocked by welding slack krub.
Anyway, please you/TICON consider about this repairing responsibility again. Following figure below it absolutely be TICON responsibility. Please let know your consideration result and please let me know when will you finish repairing this part?