What Is The Difference Between Astm A123 And A153
Armanda Kicks
This specification covers the requirements for hot-dip galvanizing on iron and steel products made from rolled pressed and forged shapes, castings, plates, bars, and strips. It does not cover threaded fasteners that are centrifuged or otherwise handled to remove excess zinc.
This ASTM specification covers zinc coatings applied by the hot-dip process on iron and steel hardware. This specification is intended to be applied to hardware items that are centrifuged or otherwise handled to remove excess zinc. A153 is applicable to steel hardware items of Classes A, B, C, and D.
The standard specification that covers the requirements for hot-dip zinc coating applied to carbon steel and alloy steel bolts, screws, washers, nuts, and special threaded fasteners applied by the hot-dip coating process. Nails and rivets are not included in F2329. It is intended to be applicable to fasteners that are centrifuged or otherwise handled to remove excess zinc.
A153 covers galvanizing on many products including fasteners, while F2329 is specific to threaded fasteners, nuts and washers. The two specifications have virtually identical coating thickness requirements. Also, A153 and F2329 have different sampling requirements; F2329 requires more samples per lot than A153. Portland Bolt can meet the requirements for both F2329 and A153 Class C. Portland Bolt performs hot dip galvanizing of threaded fasteners within our 140,000 square foot manufacturing facility. Contact us if you have a need for hot-dip galvanized fasteners or with any technical questions regarding hot-dip galvanizing. One of our experienced sales reps will be happy to answer any of your questions.
@M- The zinc thickness will depend on the process used. Long bar will be galvanized per A123, whereas shorter lengths or bar with threads will be processes per A153/F2329. The two standards have different minimum zinc thickness requirements.
I have one question for valuable advice.from appearance, how to differentiate the memeber is galvanized by ASTM A123 or ASTM A153, for instance, contractor claim that anchor bolt belong to thread hardware, and it is galvanized as per ASTM A153 with lower thickness compared with ASTM A123.In front of such case, how to testify it??
@Lei- If the bolt had threads, and was handled in such a way to remove the excess zinc (like spinning), then A153 is the correct standard to follow. There are small portable devices available that can measure the zinc thickness if there is concern.
@Luis- we are able to certify that the items we manufacture and galvanize in our facility will meet the RoHS requirements. For items that are manufactured by others, it would be on a case by case basis.
Thank you for the useful content. I am having difficulty determining the hot dip zinc coating needed for an anchor bolt 60M(60mm) and 1.75 m in length, as well as the galvanizing coat for its respective hex fasteners. Also a high tension rod( U Bolt) 14mm diameter and 2 meters in length also with its respective fasteners. Any insights would be deeply appreciated. Many thanks
Sal from Dubai
@Sal- Are you asking which galvanizing standard you should be using? The only ones we are familiar with are ASTM A153 and F2329, both of which are the same process. We are are not certain what standards are commonly used in Dubai, so we cannot speak to those.
@Gagan- Sometimes the heat from the hot dip galvanizing operation can slightly soften small hardened items like this. If you are concerned about the hardness dropping, you could look at alternatives platings that do not require heat, like mechanical galvanizing.
@Phil- The hot dip galvanizing process is more or less the same within all of those standards, the difference is how they are handled. Beams and structural members are defined as steel products and are galvanized per A123. Threaded fasteners are handled differently in order to remove the excess zinc from the threads and would fall under A153 or F2329. A153 and F2329 again are more or less the same, F2329 references back to the processes in A153, but goes into more detail with respect to the specifics of threaded fasteners. A153 touches on threaded fasteners, but is not fastener specific. All the ASTM fastener standards refer to F2329 for hot dip galvanizing, so that would be the most appropriate standard to reference.
@Vinay- ASTM A193 and A320 both say that the maximum service temperature for galvanized bolts should not exceed 390F unless caution is used in regard to the potential for liquid hydrogen embirittlement.
Evening.im afif.from malaysia.i got problem in my working site.my company now doing the oil offshore platform.im really confius and always asking what is different between hot dip galvanize and hot dip spun galvanize.i received the threaded rod but certificate mention electro plating not hot dip spun as per client requirement.why all fasterner.nut .washer shall be hot dip spun.why cannot hot dip and why people says shall be enough for electroplating only.please explain.
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A 2009 survey conducted by the New Hampshire Department of Transportation (NHDOT) studied the conditions of weathering steel guardrails that had been in service for 10 to 20 years. It discovered a shocking overall failure rate of 25% at the midspan and a failure rate between 50%-71% at connection points. The report also noted that galvanized steel guardrails exposed to the same environments, with an equal number of years in service, showed no decrease in strength or function. The galvanized rail also became less shiny over time, allowing it to better blend into its environment.
Although there are states that permit the use of weathering steel guardrails, many, including California, do not consider it to be a sustainable or safe choice in areas that receive eight or more inches of precipitation per year. (Download the California research summary here.)
According to the most recent available American Community Survey (a yearly review conducted by the U.S. Census Bureau) average annual precipitation in the United States is 30.28 inches, with the highest recording state receiving 59.15 inches of precipitation and the lowest recording state receiving 9.46 inches of precipitation. Based on this data, the use of weathering steel guard rails or bridge components should only be considered for the driest environments in the most arid states.
Take a look at the Time to First Maintenance chart below. Time to first maintenance (TFM) is defined as 5% rusting of the base steel surface, which means 95% of the surface has some zinc coating remaining, and an initial maintenance is recommended to extend the life of the structure.
According to ASTM A123, the governing specification for hot-dip galvanizing, steel -inch thick or greater must have at least 3.9 mils of zinc on the surface, but more often than not, there will be greater than the minimum requirement. Time to first maintenance for galvanized steel is linear and directly related to the zinc coating thickness. Therefore, using the TFM chart, hot-dip galvanized steel >1/4-inch thick that meets ASTM-A123 will provide 70 years or more of service life before first maintenance, even in the most corrosive atmospheres, including marine and industrial environments.
A. This photo shows the need to carefully follow ASTM A385/385M Standard Practice for Providing High-Quality Zinc Coatings (Hot-Dip), also known as the Design Spec, when fabricating steel for galvanizing. Doing so will improve the finished appearance of the job and make for a safer work environment in the galvanizing plant.
When the plate, with holes drilled through it, was attached to the channel, the outside edges of the plate were seal-welded, but the inside edges the holes were not. During the cleaning process (degreasing, rinse, pickling, flux) fluids seeped through unsealed inner edges of the holes and were trapped there between the plate and the channel.
Where surfaces overlap, and the overlapped area is less than 16 sq.in., there are a couple of welding options that meet ASTM A385 and will prevent this problem. One is to provide a gap of at least 3/32-inch (2.5 mm) between the overlapped pieces using an intermittent fillet weld on all sides so that no pocket is formed. This will ensure that all fluids drain out before galvanizing and that the area will be wetted by the molten zinc in the kettle. However, this type of welding may not be suitable for load-bearing members.
In situations where a 3/32-inch gap between overlapping pieces is not suitable, it is important that all edges be completely sealed by welding. If there is any opening, less viscous cleaning solutions will enter the gap but zinc will not. Trapped solutions may cause iron oxide to weep out of any gaps in the joint. Incomplete welds caused the problem in the photos below.
The outcome could also be much worse. Penetration of moisture into the sealed cavity could cause significant safety hazards as the sealed air will greatly expand when the part reaches the galvanizing temperature. This gas expansion can cause the molten zinc to splash out of the bath and endanger galvanizing workers.
Hot-dip galvanizing is a proven corrosion protection system that extends the maintenance-free life of steel in nearly every environment. Following the best design practices as shown in ASTM A385 for items to be hot-dip galvanized will help ensure the highest coating quality and prevent dangerous accidents.
Thank you for your question. I hope you found the answer helpful. The basis information for this answer is available in a brochure from the AGA website. Click here for a free download.
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