Galvanization is also known as galvanization is considered to be the technique to apply protective zinc coating for the iron or steel, for preventing rusting. Care is to be taken to the fullest extent in several services. This is actually to prevent the pipeline from getting rusted. Otherwise, it can prove to be hazardous to the personnel, may cause malfunction or damage of the instrument, equipment, etc. It is for this particular reason that piping is said to be galvanized.

Some of the commonly used techniques for the purpose of galvanization are stated to be electro-galvanizing and hot dip galvanizing.

Know the differences

If the plan is to order the same, then it is necessary to undertake proper and thorough research of the available materials in the market. This can help the person to be safe with his selection and ensure that the right and most appropriate products are purchased that meets specific needs and requirements of the business. Otherwise, it will be just merely waste of precious time and money. The professionals offering hot dip galvanizing services can help with the selection process.

Below are given some of the basic differences found between electro-galvanization and hot dipped galvanization. Also are provided the benefits offered by both over the other.

• For hot dip galvanization, a very rigid cleaning process is followed, which is generally known as the 7 bath process. Cleaning is done in alkaline solution, pickling, water rinsing, fluxing. In case, of electro-galvanization, there is not followed stringent cleaning method.

• Steel is said to be dipped in molten zinc bath @ 460 degree Celsius to achieve the coat for hot dip galvanization. But in the latter, steel is prepared in cathode in electrolytic cell, thus forming coating using electroplating process.

• Hot dip galvanization produces on steel surface Fe-Zn alloy layer, leaving behind pure zinc coating on outer surface. This alloy is quite hard. Damage is not caused to the coating by the usual abrasion, even though some damage may take place to the pure soft zinc present at the top. Electro galvanization produces Zn layer on surface that is termed to be not continuous with that of steel metallurgically.

• Electro-galvanization has very low life, ranging from several months to some years only. But, hot dip galvanization is known to have very high life averaging between 20 to 50 years.

• Electro-galvanization comes with excellent finish. However, hot dip galvanization has dull, unpleasant finish.

• The coating thickness of hot dip galvanization generally is about 80-100 µm. The coating thickness entirely depends upon the dipping duration. Also, it is affected by the steel’s roughness and composition. For electro-galvanization, coating thickness generally is about 10 to 12 µm. here, the coating thickness is determined upon the electrolyte temperature and current density.

• Hot dip galvanization is said to have normal coat thickness of about 40% much more expensive when compared to electro-galvanizing. The latter has normal coat thickness that is much affordable. But, the cost is said to increase proportionately with higher coating thickness. Hence, it becomes expensive.

• Hot dip galvanization is provided with non-uniform coating, while the other one with uniform coating.

• Hot dip galvanization is suitable for all sizes, while electro-galvanization is suitable exclusively for smaller components.

To know more about the differences between hot dip galvanizing and electro-galvanization, it will be useful to take the help of the reputed companies offering top class hot dip galvanizing services.

There are many who would like to know the type of kind of surface preparation of iron and steel is required before it is delivered at any hot dip galvanizing plant. For protective coatings, few of the specifications include Preparation for hot dip galvanizing before coating inspection and application requirements after and during coating application. Usually, for galvanizing, no special preparation is necessary. Speaking with the reputed hot dip galvanizing services can help the person to make a huge difference to the knowledge gained about the same.

Some Specifications

For the batch hot dip galvanizing, ASTM specifications are arranged differently. A153/A153M and ASTM A123/A123M are some of the commonly utilized specifications for Preparation for hot dip galvanizing. They cover all the inspection need of finished galvanized product.  ASTM A385/A385M, A384/A384M and A143/A143M are said to discuss on fabrication process for steel that are to be hot dip galvanized. They also can address few of the surface preparation recommendations before galvanizing.

The process

It is a simple process that batch hot dip galvanizers tend to involve for preparing iron and steel before galvanizing. Once inspection of steel is completed for ensuring presence of adequate drain holes and vent, it gets dipped into cleaning chemical series. The initial chemical is stated to be a degreasing bath to remove organic contaminant like grease, oil and dirt from metal. Pickling acid is the next type of chemical that is used to eliminate rust (oxides) and mill scale from steel. The final step involved prior to galvanizing is to dip the iron or steel into the flux bath. This is to avoid metal oxidization before entering galvanizing bath, as well as to help galvanizing reaction to develop hot dip galvanized coating.

There are not required any specific parameters for ASTM specifications to clean chemicals that are used within the galvanizing process. General concentration tends to make the chemicals quite effective and every galvanizer does optimize its cleaning chemicals, thus providing them with fabulous results to clean the iron or steel. This way, superior quality galvanized hot dip coating is achieved.

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Few materials which cannot be removed by the cleaning chemicals

Several materials do make use of chemical chemicals before the galvanizing process. They may not be able to remove or face difficulty in removing. List of common materials:

• Anti-splatter and weld splatter
• Weld slag as well as welding flux residues
• Burrs (may include those excessive rough edges derived from flame cutting)
• Heavy or probably extremely adherent type of mill scale
• Asphalt, vinyls, epoxies
• Mill coatings like lacquers or varnishes present on several pipe types
• Sand, other impurities present on castings
• Crayon markers
• Markers and oil based paints
• Thick or heavy grease or wax deposits

Such materials are to be eliminated from the metal before it is delivered to galvanizing plant. There are present some commonly used standards to ensure abrasive blast cleaning, powertool cleaning and hand cleaning. These cleaning methods and the hot dip galvanizing services offered are considered to be effective enough to remove these materials. Usually, abrasive blasting is required on castings for removing sand including other impurities from casting process. Moreover, different types of products could be used on iron or steel that is considered to be compatible with hot dip galvanizing method for reducing the requirements for hand or power tool cleaning or blasting.

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