Complex sentence: Mixed results have been found for all methods of protection, however this may be due to the impact of variations in local soil corrosiveness and temperature or by damage occurring during installation, which can impact effectiveness of protective coatings.
Split into simpler sentences: Mixed results have been found for all methods of protection. However, this may be due to the impact of variations in local soil corrosiveness and temperature or by damage occurring during installation, which can impact effectiveness of protective coatings.