This is a replacement inner for our Telescopic Mole post, no need to excavate the entire unit, just remove the 4 security screws, lift off top flange and pull out inner.
Insert new inner, put new top flange over and re-fit 4 new security screws (all supplied).
The basic specification for hot dip galvanized coatings on iron and steel articles is defined by a single standard, EN ISO 1461 ‘Hot dip galvanized coatings on iron and steel articles – specifications and test methods’. However, there are some exceptions to this standard (see thicker coatings below).
BS 729 was the old British galvanizing standard for hot dip galvanizing. It is now superseded by (BS) EN ISO 1461.
When hot dip galvanizing is specified, the surface of the steel is completely covered with a uniform coating whose thickness is determined principally by the thickness of the steel being galvanized (see Graph 1 below).
This is an important advantage of the galvanizing process; a standard coating thickness is applied almost automatically. The actual thickness of galvanized coating achieved varies with steel section size, surface profile and surface composition. Actual coating weights are often much more than the minimum specified in the standard. As coating life expectancy figures quoted are based on the minimum coating thickness, they are therefore usually very conservative.
Graph 1Relationship between steel thickness and surface area/tonne
Guidance on the design and performance of hot dip galvanizing is contained in EN ISO 14713 Part 1 and 2.
EN ISO 1461: coating minimum masses/ thickness on articles that are not centrifuged.
EN ISO 1461:coating minimum masses/thickness on articles that are centrifuged.
Thicker coatings than those set out in EN ISO 1461 can give additional protection for use in particularly aggressive environments and can be specified in conjunction with EN ISO 1461. It should, however, be emphasised that for most applications, thicker coatings are rarely necessary.
Grit blasting prior to galvanizing is usually the most appropriate method and a requirement for a nominal coating thickness of 1000 g/m² (140 µm) has been successfully specified for steel of 6 mm section thickness. For structural steelwork, it is advisable to ascertain whether thicker coatings could be achieved through their greater section thickness and without grit blasting.
Achieving thicker coatings through specification of a reactive steel is normally only appropriate for specific applications.