Fluid ends could be ranked among the components which are constantly under intense stress and are quite prone to wear and tear. They are under this constant pressure due to the unceasing flow of abrasive materials and high-pressure acidic corrosive fluids, and they need to be able to endure the most challenging conditions. Under such circumstances, cutting maintenance and upkeep costs will also maximize profitability, whereas being cheap or failing to prevent problems before they arise could prove to be costly in the long run. Here’s what you need to look out for when it comes to premature failure as well as the adequate methods of prevention.
Washout
Large amounts of fluid can cause significant damage to the sealing surfaces and prevent pressure buildup on the fluid end. The likelihood of this problem arising largely depends on the fluid itself, as highly abrasive, acidic, or proppant fluids can cause considerably more damage. In addition, inadequate maintenance can contribute to the unwanted effects of washout and cause further damage if some valves or seats are not installed properly. These problems can be avoided through the use of top-quality materials and proper training. Applying the best possible maintenance practices, making sure all the valves and seats have successfully gone through the installation process and opting for premium fluid equipment parts are sure ways to extend the lifespan of the fluid end.
Cavitation
Not just the chemical structure of the fluids, but the rhythm of their flow as well can have an unwanted impact on the components. Low-pressure flow can cause cavities to form, which will then implode under the effects of high-pressure flow. That contributes to the effects of washout, imminently leading to failure. Improving the flow characteristics of the components can significantly reduce the negative impact of cavitation, providing a constant flow regardless of the pressure-induced.
Excessive proppant buildup
The buildup of proppant in the intersecting bore of a fluid end can be the cause of various problems, among them the loss of adequate proppant suspension, pony rod and power end problems, as well as difficulties during operations. Proppant buildup is also the cause of unnecessary strain on the fluid pump, already under constant assault from the fluid pressure. The solution to this problem is a design-based one. Make sure to minimise any kind of turbulence and obstructions in the flow to allow the liquid to easily pass around the valves. This will help you avoid proppant settling and accumulating any unwanted materials.
Corrosion of low-quality materials
Contamination of various types of metals through either natural processes (rust) or through corrosion-inducing liquids such as stimulations fluids and uninhibited acids can present serious problems. Here, being cheap is what pays the least since only through the employment of top-quality materials can you ensure protection against corrosion. Choosing to work with materials with qualities such as higher yield strength and corrosion resistance like stainless steel will improve the general durability and minimize the chance of cracks occurring. But even among top-tier materials, there are some better than others. For example, 17-4PH and 15-5PH stainless contain a larger amount of hard spots, delta ferrites and similar “junk” compared to other types. Experience suggests that inferior quality materials have up to ten times shorter lifespans and can last approximately between 100 and 500 pumping hours, in comparison to 1000 to 5000 pumping hours of superior grade materials.
Fatigue
Any exposure to excess pressure, as well as the fluctuations of stress on the fluid end during the loading and unloading processes, can cause localized damage. The prevention process here consists of applying hardening operations on the fluid end materials and smoothing out the edges and blending sharp corners to reduce their ability to cause localized harm to the fluid end metal.
Cracks
Cracks and separations in crucial junction points can be caused by some of the aforementioned issues, like cavitation, fatigue and sand packing or by foreign object impacts or operations not in line with the pump design parameters. Use higher than industry standard yield strength materials to give the fluid end an extra dose of resistance and avoid costly cracks. Also, be sure to perform crack-prevention processes on any material you choose.
Final word
It’s a fact that the wear and tear of the fluid end is unavoidable, as damage and degradation become more likely with use and the passage of time. There are no materials absolutely impervious to all forms of damage, and the causes mentioned in this text are just some that could compromise the quality of your operations. It seems that besides design alterations and processes which are meant to increase the resistance of the fluid end, there is only one way to ensure some manner of protection, and that’s using the most premium quality materials available.
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