5 replies to this topic

[m42364236k]

Dear colleagues:

 

I have a question about selecting a material of construction.

 

First of all I want to know the criteria of when to use galvanization.

And can we use carbon steel instead of galvanization?

 

In my project the instrument air material and also the foam inject material is galvanized.  But the contractor has used carbon steel (painted carbon steel) in some parts of this plant. 

He say that painted carbon steel can be used instead of galvanization.  I want to know if we can use the painted carbon steel instead of the mentioned galvanization material.

 

Thanks,

Mike

 

[breizh]

Hi ,

 

Consider this link : http://www.hoseandfi...-Air-Compressor

 

Good luck,

 

Breizh 

[Art Montemayor]

Mike:

 

You don’t specify WHAT area of material of construction you are dealing with.  Are you referring to structural steel?  Valves?  Piping?  Pumps?  Compressors?  Etc, etc.  without this information our members are simply guessing what your dilemma is.

 

Are you aware of what galvanization is about, how it is applied, and how it protects and is vulnerable to being defeated by oxidation?  It doesn’t appear that you are and I highly recommend you study the reasoning of applying galvanization and how it works (and is prone to failure).  Hot-dipped galvanization is the norm in protecting structural steel and some external pipe surfaces.  Galvanization cannot function as a protective coating where its coefficient of expansion is not in synchronization with the parent carbon steel material at different temperatures.  If the parent metal is heated too fast, the galvanization cracks and immediately external corrosion starts to invade the parent metal.  Properly painted piping and major equipment is almost the norm today for external protection - and this requires a routine maintenance program.

 

The proper and successful application of hot-dipped galvanization (I wouldn’t accept any other type of application) requires professional experience and expertise.  Any minor defect or pore hole in the coating allows for total defeat of the coating.  Galvanization of bolts and nuts is done - but it has to be considered as tokenism because there is no possible way to galvanize threads on both.  The galvanization of the interior surface of piping has to fall into the category of wishful dreaming.  Even if you were able to galvanize the interior pipe wall, the excessive rugosity (roughness) of the interior wall is enough to defeat it hydraulically; the expectation that the interior wall would remain impermeable to corrosion is also wishful thinking when one has to admit that any slight pore or defect in its interior surface would be total defeat against corrosion and an invitation to sudden future failure without any previous warning.

 

Please state specifically what it is that you are trying to protect with galvanization - and why you are resorting to galvanization.

[Phenol]

Hi,

 

I also have a question on similar topic.

 

Due to cost difference between stainless steel and carbon steel for large storage tanks, I would like to go for  CS Tanks with suitable inside coating for phenol storages.

 

Can some one suggest suitable paint and suggested suppliers.

 

The storage temperature is likely to be 55 to 60C

 

Please note it is pure phenol and new tanks.

 

Rajan

[breizh]

Hi ,

Consider the brochure attached , they mention Carbozinc 11.

My experience is about  SS , mainly to prevent coloration of the phenol .

Note : a lot of safety issues with this material (phenol) !

 

Good luck

Breizh

Edited by breizh, 07 January 2016 - 06:08 PM.

[Phenol]

Hi,

 

Thanks for sharing the link.

 

I also agree SS is followed as industry standard material of construction in new phenol plants(constricted in the last two decades) though old plants were designed with coated MS tanks.

 

But in some part of the world SS is still costly compared to CS and hence investors evaluate both options particularly for large final product storage tanks.

 

Carbozinc 11 seems to be a inorganic zinc silicate based paint and I have to find out available equivalents in Indian market.

 

Thanks

 

K.Rajan