Boiler tube leakages in power plant

With deteriorating coal qualities in Indian coal,boiler tube leakages have become a chronic problem for boiler outages. In spite of improving flame geometry , regular soot blowing , maintaining burner condition, & watch against delayed combustion of fuel particles,boiler tube leakages are not completely avoided. Major generation loss is mainly due to this problem. Weld-overlay /coating over boiler tubes have improved the performance vis-a vis tube leakages. What is Europian / American or South East countries experience towards yearly availability of boiler with respect to Boiler tube outages?