Improving Pump Reliability Through Vibration and Pulsation Analysis
A client in Texas was challenged with the reliability and performance of their reciprocating injection pumps at multiple sites. Pumps critical to pipeline transfer operations were experiencing repeat failures including seal leaks, tubing failures, and pump seizures.
The client reported multiple issues with their pumps, ranging from excessive vibration and pressure pulsation to physical wear and tear on the equipment. These challenges were constraining the overall performance of the system and leading to frequent failures. Notably, the vibration levels were far above API 674 recommended limits, contributing to recurring, similar failure modes across several gathering sites.
Objective
Assess and improve the reliability of the reciprocating injection pump systems by identifying the root causes of mechanical failures, vibration, and pressure pulsation issues, and develop actionable recommendations that could be applied across all affected sites.
Becht Approach
Becht performed a vibration and pressure pulsation study across the fleet. The analysis confirmed several defects across the various sites, with similar issues having been previously observed by Becht in gathering facilities across the US.
Key findings and observations included:
1. Pressure Pulsation: Pressure pulsation values were repeatedly found to exceed design values. These excessive pulsations showed up as high vibration and were exasperated by poorly designed pulsation dampeners, failed pulsation dampeners, or lack of pulsation dampeners. This was the most common contributor to piping failures upstream and downstream of the pump.
2. Excessive Vibration: Several pumps exhibited high vibration levels, which are detrimental to long-term reliability. Separate from the pulsation cause, typical vibration issues were a product of inadequate design and commissioning hand-over.
The selection process for positive displacement pumps was often flawed by inadequate attention to rod load and NPSH margin. The results are costly to remediate and will permanently affect system performance.
The pumps were consistently operated outside of the design operating envelope and had inadequate setpoint alarms/shutdowns. Training for operators and documented operational procedures were deficient.
3. Foundation and Structural Failures: The concrete foundations had deteriorated at several locations, leading to further alignment and vibration issues that compromised the mechanical integrity of the pumps. The misalignment will contribute to mechanical seal and bearing failure.
4. Maintenance and Operational Gaps: A lack of formal maintenance processes was noted. Without a formal work order system, tracking of leaks and failures was not standardized, resulting in largely reactive maintenance practices. Additionally, issues such as improperly stored parts, missing pipe supports, and poor installation practices were common across sites.
Solution
Becht proposed both short-term and long-term solutions to increase reliability of the pumping systems.
1. Structural Reinforcements: At multiple sites, it was recommended to properly grout the pump baseplates and foundations. Proper support and foundation work are critical to reducing vibration and preventing further mechanical strain. Proper alignment is fundamental to mechanical seal life and bearing health.
2. Pulsation Control: A thorough review and redesign of the pulsation control systems were recommended where pulsation was at its most severe. This would involve inspecting and potentially replacing pulsation accumulators and reviewing the overall piping system design.
3. Operational Procedures: Establishing the operational envelope for the pumps with proportional alarm(s) and operator training on same would increase reliability.
4. Maintenance Training: Emphasis was placed on the relationship between proper installation methods and reliability, particularly with regard to pump alignment.
5. Standardization Across Sites: Implementing consistent design, installation, and maintenance practices across all sites would significantly enhance operational efficiency. Standardizing equipment types, seal designs, and installation would facilitate procedures, spares, and training.
Client Value
The findings from Becht’s analysis revealed several areas where improvements could dramatically enhance the performance and longevity of the client’s pumping systems. By addressing these key issues (including vibration control, pressure pulsation, structural support, installation, and operational practices), the client can significantly improve the reliability of their pumps and reduce costly downtime.