What is the difference between ASTM a123 and a153?

By: Julie PaltrowUpdated: February 12, 2021


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ASTM A153 is the hot-dip galvanizing specification for hardware and fasteners that are spun or otherwise handled (torch and steel brush) after galvanizing to remove excess zinc. ASTM A123 is the hot-dip galvanizing specification for most other items (except single reinforcing bars).

Likewise, how thick is the zinc coating on galvanized steel?

Batch Hot-Dip Galvanizing.
Batch hot-dip galvanizing produces thick coat- ings. The standard coating thickness requirement is 2 oz/ft2 (600 g/m2), 3.3 mils (85 µm). Thicknesses of 6 to 8 mils (150-200 µm) on structural steels are common.

Also to know, what is ASTM a123?

The specification ASTM A123/A123M covers individual steel pieces as well as assemblies of various classes of material. It is the responsibility of the galvanizer to ensure compliance with the specifications, as long as the product has been designed and fabricated in accordance with the supporting specifications.

How do you measure galvanized coating thickness?

There are two methods for measuring the zinc coating thickness of hot-dip galvanized steel; a magnetic thickness gauge and optical microscopy. The simplest and non-destructive way is to utilize a magnetic thickness gauge, as optical microscopy is a destructive test only used to resolve measurement disputes.

Is standard for galvanizing?

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).


What is the thickness of hot dip galvanizing coating?

When it comes to the specification of hot dip galvanizing, most contractors know that to be standards compliant, 7mm steel requires an average coating thickness of '85 microns'. It is a simple industry standard that is easy to retain and is applicable to many construction needs.

How thick is hot dip galvanized coating?

Typical galvanized coatings range from 3-8 mils (75-200 mi- crons) thick. When designing and detailing tapped holes, the increased thickness is important. Best practice suggests that the hole be tapped after galvanizing, removing the coating on the interior mating surface.

Is there a difference between galvanized and hot dipped galvanized?

Difference Between Galvanized and Hot Dip Galvanized. The key difference between galvanized and hot dip galvanized is that most galvanized materials have a smooth and sharp finishing, whereas hot sip galvanized structures have a rough finishing. Galvanization is a process of preventing metal surfaces from corrosion.

Why is zinc good for galvanizing?

Galvanization is the process of applying a protective zinc coating to steel or iron in order to prevent premature rust and corrosion. The corrosion of zinc is very slow, which gives it an extended life while it protects the base metal. Due to the alloying of the Zinc to the iron, cathodic protection occurs.

Why does zinc not rust?

Galvanising is a method of rust prevention. The iron or steel object is coated in a thin layer of zinc. This stops oxygen and water reaching the metal underneath - but the zinc also acts as a sacrificial metal . Zinc is more reactive than iron, so it oxidises in preference to the iron object.

Does Zinc rust in water?

Like all ferrous metals, zinc corrodes when exposed to air and water. However, zinc corrodes at a rate of 1/30 of that for steel. Also like other ferrous metals, zinc corrodes or rusts at different rates depending on its environment (8). The patina layer is the products of zinc corrosion and rust.

What is the difference between zinc coating and galvanizing?

The big difference is thickness: zinc plating is normally 0.2 mils thick. Hot dip galvanizing might be 1.0 mil thick – you get over 5 times the protection with galvanizing. The galvanized product will develop a white protective coating (zinc oxide) that adds to its protective properties.

What type of protection is Galvanising?

Galvanisation or galvanization (or galvanizing as it is most commonly called) is the process of applying a protective zinc coating to iron or steel, to prevent rusting. The most common method is hot dip galvanizing, in which steel sections are submerged in a bath of molten zinc.

Can you electroplated galvanized steel?

Electroplating Galvanizing
The steel used in car bodies is galvanized using electroplate galvanizing because layers of decorative paint can be easily applied. One way zinc is electrodeposited to steel is through the immersion of steel in an electrolyte, a solution of zinc sulfate or cyanide.

What's better zinc or galvanized?

Zinc plating (also known as electro-galvanising) is a process where zinc is applied by using a current of electricity. While is does provide some rust protection, its thinner coating is not as rust resistant as hot dip galvanising. Its main advantage is it is cheaper and easier to weld.

Why is zinc used for coating steel?

Zinc Serves as a Sacrificial Coating
Zinc is more electrochemically active than iron. Zinc also acts as a sacrificial coating that protects the steel via galvanization. Steel will not corrode as quickly when covered with a zinc coating, even when a scratch or cut exposes the steel to air or moisture.

Why are iron washers coated with zinc instead of aluminum?

The corrosion of zinc is very slow, which gives it an extended life while it protects the base metal. Due to the alloying of the Zinc to the iron, cathodic protection occurs. This ensures that small areas of steel which may be exposed through damage are not compromised by rust.