Assessment of steel load-bearing structures - Assessment and Refurbishment of Steel Structures - page 61

• Structures for passenger cable ways
• Load-bearing structures for technical equipment in hydraulic constructions with moving
parts
• Aerials and television towers, masts, load-bearing structures for radio telescopes and
radar
• Other functionally similar load-bearing structures.
Group B
• Industrial, civil, agricultural and residential single- or multi-storey constructions
• Technical load-bearing structures for blast furnaces, boilers of thermal power plants,
mining, drilling derricks, and cooling towers;
• Masts for electricity lines, lighting towers and masts up to a height of 25 metres
• Girders of crane runways.
Group C
• Service and technical parapets;
• Staircases and railings
• Roofing, light wells and other types of auxiliary structure.
In general, preventive inspections are performed as follows:
At least once in six months (usually in spring and autumn) for structures that are
extraordinarily dynamically loaded or for which it is necessary to make sure that the
direction, height or other requirements due to operational reasons have not changed, and
on structures located on ground where there is sub-surface activity on undermined
territory (mining, underground ways, etc.)
At least once a year (usually in spring) for other structures in Group A, according to
operating conditions;
At least once in five years for structures in Groups B and C, according to their operating
conditions.
If faults and defects, that could lead to more serious threats to operation or safety are
detected during preventive inspections, a detailed diagnostic inspection should be
performed immediately.
A detailed inspection of the structure should be performed, even when there are good
results from the preventive inspection, in the following time periods:
At least once in three years for steel structures that are extraordinarily dynamically
loaded, as well as structures on ground where there is sub-surface activity
At least once in five years for other structures in Group A;
At least once in ten years for steel structures in Groups B and C, according to operating
conditions.
Periodic inspections should be performed by skilled agents who are able to identify
defects and determine their seriousness. If the identified faults and defects threaten the
reliability or operation of the structure, they should be dealt with as soon as possible.
Checking inspections of coatings and other kinds of protection against corrosion are
performed at periods corresponding to the degree of pollution—the corrosive
aggressiveness of the environment where the structure is located. The results of periodic