Hello forum members, we are currently dealing with the issue of cracks in the liners of our 2-stage, 4-cylinder reciprocating compressors used for compressing Boil Off Gas. This problem was discovered during a recent overhaul, with cracks being found in two out of three machines. Has anyone else encountered similar issues before? What could be the possible reasons behind this issue? The operating parameters for the compressors are as follows: - 1st stage suction pressure: 0.15 kg/cm2, temperature: -155 deg. C - 1st stage discharge pressure: 1.7 kg/cm2, temperature: -65 deg. C - 2nd stage suction pressure: 1.7 kg/cm2, temperature: -65 deg. C - 2nd stage discharge pressure: 7 kg/cm2, temperature: 45 deg. C These compressors have non-lubricated cylinders and pressure packings, with no jacket cooling provided. The liners are made of Carbon steel. If anyone has any insights or solutions to share, it would be greatly appreciated. Thank you. Attachment(s): Copy_of_14.07.2010.rar (1.66 MB) - 1 version.
At what stage did this failure occur? Could it be attributed to a null ductility temperature issue? - Irshad
Cracks have been detected exclusively in the second stage liners of one out of three Dresser-Rand machines. Although unfamiliar with "null ductility temperature," it is evident that there is a temperature gradient ranging from -65°C in the suction valve to +45°C in the disc valves of the second stage cylinder.
Before proceeding, Vijay, make sure to verify that the liner material is cast iron instead of carbon steel. Cast iron is prone to cracking under thermal stress (temperature gradients) and caustic stress corrosion. Investigate any presence of caustic substances in the second stage. Occasionally, caustic injection may be necessary between stages. Consult with the original equipment manufacturer (OEM) to confirm the suitability of the material for thermal gradients.
Hi there, from what you've shared, there are several factors that could be contributing to the cracks. Abrupt temperature changes between the stages might induce thermal stress on the liners - especially given that there's no jacket cooling in place. In addition, higher discharge pressures could put additional mechanical stresses on the material. It's also possible that the non-lubricated environment could increase friction and thus wear. The combination of these factors might be triggering fatigue in the Carbon steel liners. If these factors align with your operational parameters, you might consider switching to a more robust material, install jacket cooling to mitigate thermal stress, or revisit the temperature and pressure parameters if possible. It might also be helpful to conduct a thorough stress analysis to identify potential points of failure.
It sounds like thermal fatigue may be causing the cracks in your compressor liners. From the operating parameters you've provided, there are significant temperature changes during compression, from -155 deg. C to 45 deg. C. This continuous extreme temperature fluctuation could lead to cyclic stress in the liner material, causing cracks over time. Additionally, the choice of carbon steel for the liners, without any jacket cooling, may compound the issue as it's less resilient to thermal stress compared to other alloys. Consider assessing the overall thermal efficiency and perhaps transition to a more heat-resistant material for the liners, or review the possibility of adding jacket cooling.
Hi there! It sounds like you're dealing with quite a challenging issue. Cracks in the liners could be attributed to several factors, especially given the extreme temperatures and pressures involved. The transition from extremely low temperatures in the first stage to much higher temperatures in the second stage may be causing thermal cycling stresses, which can lead to material fatigue over time. Additionally, the non-lubricated setup might be increasing wear and tear on the liners. It may be worth investigating the material selection as well; carbon steel can be susceptible to cracking under these conditions. Have you considered looking into alternative materials or coatings that might better handle the thermal fluctuations? Good luck with your overhaul!
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Answer: - The possible reasons behind the issue of cracks in liners could be related to operating parameters, material quality, lack of cooling systems, or other factors impacting the compressors.
Answer: - The operating parameters include 1st stage suction pressure, temperature, discharge pressure, and temperatures for both stages of the compressors.
Answer: - The compressors are 2-stage, 4-cylinder reciprocating compressors used for compressing Boil Off Gas. They have non-lubricated cylinders and pressure packings, with liners made of Carbon steel and no jacket cooling provided.
Answer: - The thread mentions that cracks were found in two out of three machines during a recent overhaul. Seeking input from forum members on similar experiences or solutions is highlighted.
Answer: - Forum members are encouraged to share insights, solutions, or recommendations for addressing the issue of cracks in the liners of 2-stage, 4-cylinder reciprocating compressors used for compressing Boil Off Gas.
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