iso12944大气腐蚀环境

I SO / E N 1 2 9 4 4MJM/19/07/97/GDPage No. 17/31/98This standard, which is both a new International Standard and a EuropeanStandard, has been given positive votes by both the International and Europeancommittees and can now proceed to being a full published standard. It is unlikelythat this will be the case for all parts until mid 1998 at the earliest.It should be noted, that because of the approval given by the European committee,this standard will replace existing national standards such as BS5493 and DIN55928.The main problem I see at the moment is that it appears unlikely that the US basedspecifying houses will use the specification, but will continue to use SSPC andNACE guidelines.ISO 12944 states that it is designed for use by engineers who have some technicalknowledge in the area of corrosion protection, as well as knowledge of otherrelevant specifications.Many will find the durability ranges to be extremely useful - this is the estimated timeto first major maintenance. This needs to be agreed between the interested partieswith reference to ISO 4628/1 to ISO 4628/5. It should always be realised that muchless effort is required to maintain a coating which has broken down to Ri2 than onewhich has broken down to Ri3, for example.The ‘durability’ ranges considered are:-Low2-5 YearsMedium5-15 YearsHigh>15 Yearsand are assuming the coating has reached a breakdown level of Ri3.(It is emphasised that the durability range is not a guarantee time. It is purelypresent to help the owner of the structure estimate sensible maintenance times.The guarantee time is generally shorter than the durability range, and there is nosimple relationship between the two.)I S O / E N 1 2 9 4 4MJM/19/07/97/GDPage ...