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What is Phosphate and What it Means for Drill Rod Threads

posted by the Epiroc Exploration & OreBody Solutions team

April 13, 2021

One of the benefits of joining forces with Epiroc is that we're able to share and combine our knowledge, expertise, products and processes. In doing so, we bring our customers the best products. This has happened in our Montreal drill rod plant, in Dollard des Ormeaux (DDO). The engineering team is happy to report that a new phosphate treatment system is up and running. The process has been in place at Epiroc for quite some time, so it was important to implement the process at the Montreal facility.

So, what is a phosphate process and what does it do? First and foremost, it provides more protection to the threads on drill rods and casing. It improves friction properties for parts that slide or thread together. Also, it protects steel against corrosion. Phosphating is a conversion coating that is applied to a metallic surface. Immersing the thread in a near boiling manganese phosphate solution initiates the growth of specific crystals on the face of the metal.

The phosphating process is pretty common for equipment parts that are made of steel because the iron in the steel is necessary for the coating to form.  When resistance to wear and galling is required, manganese phosphate coating is the right coating to apply. There are different phosphate coatings available and manganese coating is the hardest.

Another benefit of this conversion coating is the ability of the crystal structure to retain oil naturally. This provides even more anti-friction properties and improves corrosion resistance.


When drill rods undergo the phosphating process, they look slightly different as you can see in the photo below. The male thread ends appears darker because this is where the phosphate treatment was applied. It is important to remember that even with the phosphate coating, it is essential that you apply adequate rod grease compound before threading rods.

In our DDO plant, the phosphate protection is applied on drill rods as orders come in. The team at DDO has implemented the phosphating process with the support of Epiroc to ensure a high-quality coating and they are using the same supplier. The result is pretty nice.

We drillers know the importance of protecting the threads on drilling equipment. While the phosphating process goes a long way towards adding extra protection, you should still always follow proper handling and maintenance procedures. That means using a high-quality thread compound. Contact our technical support team if you need any additional advice or guidance on how to take care of your drill rods. Our goal is to help you improve your drilling performance while accelerating the transformation of our industry. 

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