Hello, we are currently dealing with frequent failures of the bolts connecting the cylinder to the distance piece and the distance piece to the intermediate casing of the crankshaft on our Single Stage Double acting Reciprocating Compressor. These bolt failures are a result of fatigue, with the bolts shearing off while the nuts remain intact. I am seeking advice on two potential solutions: 1. Upgrading to larger bolts - is this a viable solution to address the issue, and what modifications would be necessary for this change? 2. Using two nuts for tightening instead of one - would this be an effective approach to resolving the problem? I would appreciate any guidance on these proposals to improve the performance and reliability of our compressor.
Failures like these are quite common in industrial settings. They are often caused by fatigue failure due to inadequate fastener tightening. This issue typically arises when fasteners are torqued without proper preload control. Even if a calibrated wrench is used to apply the specified torque, it does not guarantee that the fastener is tightened correctly. Torque simply measures the resistance felt when turning a nut or bolt head, and factors like dirt, damaged threads, and lubrication type can affect the accuracy of torque as an indication of preload. To ensure proper fastener tightness, measuring the stretch of the fastener to achieve the correct elongation is recommended. This can be easily done with specialized ultrasonic equipment. Alternatively, hydraulic nuts can be used to eliminate torsional errors by generating a direct axial load, where hydraulic pressure is directly related to the retained load. While dial indicators can also be utilized, their accuracy may not be ideal. By implementing these solutions, such as measuring fastener stretch and using hydraulic nuts, the risk of fastener failures can be minimized. Wishing you success in overcoming this challenge!
What grade of high tensile strength bolt are you utilizing? Is it 8.8 or higher? Are you considering using double locknuts on the bolt for added security? However, this may not offer any advantages if the bolt itself is failing. Have you ensured that you are using the specific type of bolt recommended by the compressor manufacturer for optimal performance? It's important to avoid overtightening the bolt, as this could lead to yielding and potential breakage caused by thermal expansion of the compressor.
The Tensile Strength grade of the bolt is 8.8, sourced directly from the Compressor manufacturer. My proposal involves adding a nut on each end of the stud to allow for tightening at both ends. It is important not to over-tighten the bolts to the point of yielding, but rather follow the torque specifications provided by the compressor manufacturer. I trust this addresses your concerns and am eager to receive your valuable feedback.
Make sure to check for any signs of liquid entering the cylinder, as compressing liquids can put additional strain on the cylinder fastener bolts. An original equipment manufacturer (OEM) utilizes studs that are pre-stressed to 40,000 psi to handle this pressure.
Jatan, I struggle to see the benefits of using the 2 nut solution. Have you considered opting for a stud with higher tensile strength? Is it consistently the same stud that breaks? If the OEM is providing you with replacements for the weak stud, there may be more to the story. Have you sought the OEM's perspective on this issue?
From a mechanical point of view, using larger bolts may indeed help to mitigate the issue. It could distribute the force over a larger surface area, thus reducing the stress placed on any one point. Of course, this requires adequate space in the bolt holes as well as ensuring the increased size doesn't interfere with other components. As for two nuts instead of one, this approach is commonly referred to as "double nutting." While it can provide some additional stability, it's mostly used to prevent the nut from loosening over time rather than addressing bolt failure. It sounds like your main issue is bolt fatigue, not them coming loose. Therefore, ensuring you're using the right material for your bolts and perhaps considering alternate configurations, like studs and nuts, might be as important as size adjustment and double nutting.
Hello, it sounds like you're dealing with a frustrating situation. I see where you're coming from with both potential solutions. Upgrading to larger bolts could certainly work, but bear in mind it would need some modification of bolt holes. The added material could also increase weight and alter dynamics. The dual-nuts idea is also worth trying, as it can distribute load across more threads but you should be cautious to ensure correct torque. However, it may be more beneficial in the long-term to investigate the root cause of this fatigue - is there unusual vibration, load, or environmental factor causing this issue? The bolts failing could be a symptom of a larger problem, like improper alignment or even a material defect. A more holistic approach might give you a more reliable fix.
It sounds like you’re facing a tough challenge there! Upgrading to larger bolts could definitely help, but you’ll want to ensure that the surrounding components can accommodate the increased size without compromising the assembly’s integrity. You may also need to check the bolt’s tensile strength and how it interacts with the materials of the distance piece and casing. As for using two nuts, that could potentially distribute the load better and allow for more even tension, but make sure the extra nut doesn’t create clearance issues or complicate maintenance. Have you also looked into whether there are any vibrations or misalignments contributing to the fatigue? Addressing those factors might also give you better long-term reliability. Good luck!
It sounds like you’re facing a tough challenge with those bolt failures! Upgrading to larger bolts could definitely help reduce fatigue, but you’ll need to ensure that the surrounding components can accommodate the increased size without compromising structural integrity—this might mean modifying the holes or using spacers. As for the double nut approach, it could provide better load distribution and prevent loosening, but make sure to torque to the proper specifications to avoid any unforeseen issues. Additionally, you might want to consider consulting with a materials engineer to explore options for high-strength materials that could mitigate fatigue better than what you're currently using. Good luck!
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Answer: Answer: Upgrading to larger bolts can be a potential solution to address the issue of bolt failures caused by fatigue. However, it is important to consider the necessary modifications that may be required to accommodate the larger bolts effectively.
Answer: Answer: Using two nuts for tightening instead of one can be a strategy to improve the reliability of the bolted connections. This method can help distribute the load more evenly and reduce the likelihood of bolts shearing off due to fatigue.
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