Long-term pro­tec­tive coat­ing suc­cess

DEMM Engineering & Manufacturing - - MOTORS AND VSDS -

Cor­ro­sion poses a threat to all in­fras­truc­ture through the degra­da­tion of struc­tures – such as build­ings, roads, bridges, pipe­lines and tow­ers – and the eco­nomic im­pact of cor­ro­sion rep­re­sents an an­nual cost of bil­lions of dol­lars to the econ­omy.

It is im­por­tant that own­ers and op­er­a­tors of high-value as­sets un­der­stand the cost im­pli­ca­tions of ig­nor­ing the ef­fects of cor­ro­sion. There are many ad­van­tages of plan­ning for cor­ro­sion con­trol and mit­i­ga­tion. Two of the main ones are: that the life of an as­set is ex­tended, thus mak­ing it more prof­itable; and main­te­nance time and costs are re­duced thus in­creas­ing the as­set’s util­i­sa­tion.

Ac­cord­ing to Justin Rigby *, coat­ings con­sul­tant at Rem­edy As­set Pro­tec­tion, there are two main ways to pro­tect an as­set from cor­ro­sion. One is to al­ter the phys­i­cal prop­er­ties of a me­tal by us­ing a tech­nol­ogy such as ca­thodic pro­tec­tion to im­press a cur­rent into a struc­ture to min­imise cor­ro­sion. The other is to phys­i­cally iso­late a struc­ture from the en­vi­ron­ment by ap­ply­ing a pro­tec­tive coat­ing.

It is im­por­tant that a pro­tec­tive coat­ing project is care­fully planned. One thing to avoid is un­der­es­ti­mat­ing the tech­ni­cal com­plex­ity of a project, es­pe­cially if the coat­ing is to be ap­plied to an ex­ist­ing struc­ture; even more so if the site is in a re­mote lo­ca­tion.

“A pro­tec­tive coat­ing is not just paint. It is an en­gi­neered prod­uct that un­der­goes rig­or­ous prod­uct de­vel­op­ment to pro­vide spe­cific prop­er­ties that will pro­tect a struc­ture from its ser­vice en­vi­ron­ment,” said Rigby. “The most im­por­tant con­sid­er­a­tions are as­sess­ment of the ser­vice en­vi­ron­ment and se­lec­tion of the re­quired coat­ings.”

There is a wide se­lec­tion of coat­ings prod­ucts avail­able to the mar­ket so it is es­sen­tial that the ap­pro­pri­ate coat­ings sys­tem is cho­sen. There is no sin­gle prod­uct that meets ev­ery coat­ing sit­u­a­tion as the de­sired at­tributes may be mu­tu­ally ex­clu­sive; so dur­ing the plan­ning of a project, a com­pro­mise may need to be made, but is im­por­tant to not be fooled by the claims made by man­u­fac­tur­ers.

Ac­cord­ing to Rigby, a good spec­i­fi­ca­tion will ref­er­ence AS/ NZ 2312 and cat­e­gorise the ser­vice en­vi­ron­ment ac­cord­ing to its cor­ro­siv­ity and then nom­i­nate a coat­ing sys­tem based on the de­sired de­sign life of the coat­ing. He rec­om­mends seek­ing ad­vice from a com­pe­tent col­league or ex­ter­nal con­sul­tant when build­ing a spec­i­fi­ca­tion and se­lect­ing the most ap­pro­pri­ate coat­ing sys­tem. The ma­jor coat­ings man­u­fac­tures, such as Akzo No­bel, Al­tex, Du­lux, Jo­tun, PPG, and Valspar, are also good sources for rep­utable ad­vice.

Tra­di­tion­ally, coat­ings pro­tect a struc­ture by be­ing a phys­i­cal bar­rier to the en­vi­ron­ment. Mod­ern tech­nol­ogy has de­vel­oped ac­tive pig­ments which are be­ing in­cor­po­rated into primers to pro­vide ad­di­tional pro­tec­tion. Ac­tive an­ti­cor­ro­sive pig­ments are added to primers which can give fur­ther pro­tec­tion for ar­eas with coat­ing dam­age in ad­di­tion to their bar­rier ef­fect. Th­ese pig­ments pre­vent cor­ro­sion of a me­tal sub­strate by build­ing up per­ma­nently pas­sive con­di­tions at the me­tal sur­face and/or by a build-up of solid com­pounds which fill the dam­aged area to the coat­ing.

Newspapers in English

Newspapers from New Zealand

© PressReader. All rights reserved.