Vibration Analysis & Solutions
Independant Experts for Engineering Solutions in the field of Machinery and Plant – Worldwide.
Vibration analysis are carried out when vibration problems occur on machines or in industrial plants. The variety of vibration problems and the spectrum of vibration solutions can be illustrated best by means of our project examples. In the following, we have selected some case studies for you:
Project insights – Our short stories.
Click the Story to get an insight into the everyday work of our engineers
People make mistakes
Our story about solving an inexplicable phenonemon.
In a small compressor station a reciprocating compressor is operated with fixed speed in the double-acting mode to transport natural gas to storage. Since the recommissioning after a revision, high pipeline vibrations occur. The operator has no idea about the cause. According to the operator no settings had been changed!
Therefore, our KCE engineer carried out a metrological investigation, clarified all technical details with the responsible engineers and technicians. However, the cause of the problem could not be detected.
After talking to all people being involed in the revision, it turned out that an employee had connected the two cables – one for single-acting mode and one for double-acting mode – the wrong way after revision. By mistake, the cable, responsible for double-acting mode had been connected with the switch, labelled “Single-acting mode”, and vice versa. In fact, the compressor was operated after revision in a permanent single-acting mode, which was normally used in the first minutes when starting the machine.
Solution and Lessons learned.
The problem was quickly solved by reversing the two connections. A detailed expert report, as usually prepared by KCE, including cause, effects and mitigation measures could be kept very short in this case. Sometimes people make mistakes. And the cause of vibration is not always found in the complexity of physical effects and excitation mechanisms, but in two simple cables being exchanged. Important is, not to lose sight of the simple connections…
Many Opportunities for Improvement
An example that shows how false economy can cause bad vibrations.
A chemical plant faced heavy vibration problems concerning failures of the safety valves and the piping system connected to a reciprocating compressor. A first look at the plant revealed many opportunities for improvement. The plant was obviously running for many years and maintenance has been a foreign word in many areas.
Therefore, a first analyze was possible without any technical equipment – High vibrations, cracked pipeline supports, missing or broken screws, loosened pipe clips, obsolete material.
In general, the situation was clear – a lot of components had to be exchanged. Nevertheless, the question of where and how remains. Finally, we decided to proceed as usual and carried out a metrological investigation. Based on these results, detailed instructions for repair and modification measures could be communicated to bring the plant in a safe condition and to allow a reliable operation.
This example shows clearly that a false economy can cause bad vibrations. However, the tricky situation of meeting requirements of reliability, availability, maintainability and safety is a big challenge. Finally, it is important to recognize when it is time to take measures and to know which ones are appropriate. We support you worldwide!
The pulse of your plant
When your machine gets out of rhythm, you will come under pressure.
In the present case, an operator of an LDPE plant is regularly confronted with valve damages, which lead to breakdowns and high and unnecessary costs. The damages go back to high pressure fluctuations caused by a hyper compressor.
To gain control over the pulse of the plant, KÖTTER Consulting Engineers was called to find a quick & sustainable solution. By means of special cables, which are fixed like a blood pressure cuff, it was possible to carry out quickly effective survey measurements to determine the state of the plant.
In a second step, detailed analysis and further targeted metrological investigations followed and formed the basis to elaborate a practicable and economic solution. In this case, the exchange of the orifice and the modified design of the bores led to the goal. Pulse and blood pressure of the plant were calmed down and the plant could be operated again without any problems.
When the pressure is high it is good to know who to call for first aid. And it is even better if first aid is followed by sustainable measures, which do not only treat the symptoms but have impact on the cause of the problem.
Keep the pace
A story about people whose time is money…
A manufacturing company is in a 3-shift operation, producing photographic paper. Suddenly, the number of damages at the gearboxes increases. Sometimes, they fail apart after some days, sometimes, it takes weeks or months and sometimes they run without any problems. The production manager can’t detect any system behind the damages. Actually, the gearboxes should run for 20-30 years.
With the help of strain gauges telemetry KCE is carrying out investigations during three months. No question, the gearboxes are overloaded. But why? Our engineer is checking again the data being provided by the customer, among them the shift schedule. Regardless of the measurement data, it is apparent, that the damages occur exclusively when the first shift is working.
After talking to the employees of this shift, the following explication was given: The employees are working on a piece-rate-basis. Therefore, some of them increased the rotational speed of the machines by hand in order to accomplish more work in less time – and to earn more money, finally. However, the gearboxes were not designed for that pace!
In fact, a metrological investigation would not have been necessary in this case. It was more a human-made problem that could be solved by a simple talk. However, even for this kind of problem a “neutral third party” can be a helpful hand in order to detect the “weak points” in a running system.
If you want to increase performance, take care that men & machine are ready to keep the pace.
Case of Emergency
In the present case the commissioning of a new LDPE plant failed due to exceeded pipeline vibrations and crack of pipeline supports. The cause was unknown! After taking care of all paperwork in a record time our engineer dived into the crucial phase of the project. Heat – regarding the temperatures on site but also regarding the heated debate about time and cost pressure passed on from all parties concerned – determined this project work.
Nevertheless, it was possible to find the cause within only one day. Vibrations could be traced to a divergence between the original pulsation study done by the manufacturer and the implementation of the operator. To sum it up: A “Wrong support construction in the wrong position” caused this uncomfortable delay in commissioning. Detailed instructions regarding the refitting and the modification of the supports were the quick and cost-effective solution! In the second attempt, commissioning was performed without any problems and the plant could be operated as expected.
When the problem is big, it does not mean that the solution must be complicated and expensive. Even in case of emergency it can be possible to find a quick solution, with moderate costs and sustainable impact. At least in this case, we could keep it simple by achieving a 100% benefit for our customer.
A story about positive side effects of vibrations.
For doubling the capacity, an additional 4 MW reciprocating compressor was installed in an underground gas storage. Afterwards , several members of the staff in the administration building complained about vibrating desks, computer screens etc.
Furthermore, very disagreeable vibrations occurred in the private home of a neighbor, 160 m away from the compressor. F.ex. the central-heating boiler was making an annoying noise that was strongly inconvenient for sleep during the night.
The operator confirmed that in this residence “flowers were dancing in the window and the clothes horse was trembling like a guitar”.
So, a comprehensive metrological investigation was carried out by KÖTTER Consulting Engineers. Here the most important points in a short summary:
- Although there were high vibrations in the neighborhood, no exceeding vibrations occured at the foundation itself
- The decision was taken to design an extension of the foundation in order to improve the vibration situation in the neighbouring buildings
- A Finite-element calculations including the soil-structure interaction was the basis for the decision to install additionally a pile foundation below the extended concrete slabs.
- Control measurements confirmed a successful reduction of the vibration level in the offices and in the neighbouring residential building. A good basis to work and to sleep…
The Side Effect
The pleasing side effect: After the vibration reducing measures by means of an optimized installation, the compressor could be operated by a reduced driving power. These significant energy savings generated consequently cost saving of a middle 5-digit figure.
Be aware: Sometimes, it is worth to see vibrations with different eyes – as they can have positive side effects!
Read the full article about this project with all technical details:
Vibrations in the Environment – Remedial Actions at a New Compressor Foundation
The following article gives you some background information:
Excursion – The effect behind the story: The Sommerfeld Effect
All aboard for a specific solution
No space for extension? Create one!
When a higher performance requires bigger machines, you need space to install them.
The present case is one example of how limited availability of space requires extraordinary solutions and of how beneficial even significant investigations can be.
To increase the exploration capacity on a platform for drilling and mining of petroleum, the installation of three heavy reciprocating mud pumps on offshore constructions was planned replacing old and smaller ones.
Such a project demands a special attention regarding the foundation and the dynamic loads which will be induced into the substructure below the installation.
How the idea was born…
Normally, block foundations made of concrete cannot be used because of their heavy weight and shortage of space on site.
The singular solution, born from a first idea and growing into a concrete project caused many sleepless nights also for our engineers.
Read more how the idea was born to relocate the mud tanks, the pump installation, the silos for auxiliary flushing and parts of the electrical installation (SCR-unit) above the area of the “coffer dam”, ending up in a framework of steel covering 8 damping elements under the concrete platform…
This routine maintenance avoided a desaster
How routine maintenance can avoid a desaster
For a routine maintenance of large air coolers in a chemical plant our engineer is fixing the measurement equipment. The fan blades have a length of 5 meters, one fan has the weight of 1 ton. The coolers are installed on a gear, which is surrounded by a separate concrete ring. The gear is operated by a motor, installed outside of the concrete ring and connected with the gear by a cardan shaft lead through a hole. Acces during operation is impossible and strictly forebidden.
Normally, we measure vibration with 2-3 mm/s. This time, vibration with 20 mm/s have been recorded.
After starting the measurement our engineer has doubts with regards to the accurateness of the figures: Vibration values with 20 mm/s are recorded – that would be more than alarming. However, the measurement setup is correct! An optical inspection through the hole with the cardan shaft provides a view into the inner circle and shows the distaster! It was frightened to see how the fans were tumbling. Even the gear, on which the fan blades were installed was nearly „walking away“… Immediately and in the last minute, a shut-down was realised. What happened? A screw on the gear disengaged and the whole construction became inbalanced due to the extreme stress caused by the rotational movement. Thanks to the weight of the construction, the installation has not yet been broken apart…Otherwise, the throwing capacity of the fun blades would have caused a disaster.
Sometimes, you need luck: In this case, the maintenance was done at the right moment. Our engineer and the staff reacted promptly. A shut-down could avoid bigger damages or even worse. Be aware: The initial phase of a disaster if often marked by a flood of data. If we succeed in interpreting them correctly and in reacting accordingly, we can avoid the disaster.
Vibrations - but no access to the plant?
Vibrations – but no access to the plant?
In the present case “dancing cooler racks” in a LDPE plant were the reason for the operator to call KÖTTER Consulting Engineers for a vibration analyze. However, The piping system of such a plant is set up in an EX-rated environment inside of a bunker, which is normally prohibited to enter during operation.
Therefore, vibration issues are often tackled with either simplified spot measurements at distinct locations or extremely complex and expensive measurement setups. Nevertheless, it is more or less impossible to get a full picture including operational deflection shapes as well as reliable and comprehensive assessments.
Measurement from a safe position with precise results.
To overcome this, we carried out the vibration measurement by means of a laser. The main advantage of this technique is the possibility to acquire mechanical vibrations at almost every object in the line of sight of the sensor from a safe, non-EX zone far from outside of the bunker. An additional advantage is, that the method is almost independent from the surface temperature.
Result & Lessons Learned
Based on the results, it was decided in this case to increase the stiffness of the racks by installation of additional beams. The vibration level at the rack was decreased to 30 % of the original value. The pulsations at the discharge flanges of the compressor and close to the reactor bay were within the limits defined by the original pulsation study.
When the access to certain areas in a plant is restricted or even forbitten (ex-zones, too high temperatures, too high buildings etc.) KCE provides technical solutions to overcome these obstacles.
Less can be more
The idea is to get the optimal result with minimal expense.
In the present case the operator of a compressor station faced significant vibrations in an office building nearby, so that it was impossible for the employees to work on their CAD-workstations. The vibrations arise from two compressors, sharing one foundation.
„Creative“ ideas have been worked out to solve the problem, but they were far from reality.
After several investigations of third parties, all possible solutions seemed to be exhausted – unfortunately, all of them have been considered to be too expensive (between 250.000 and 500.000 EUR) and impractical (f.ex. building an earth wall between the station and the office) for the operator.
So, our task was to fulfill three wishes at once: a practical, affordable and sustainable solution.
And we did! Our engineers found out that the operation of one compressor generates more vibrations than the operation of two compressors. At a fixed phase shift between both compressors, there was a minimum of vibrations in the neighbourhood.
Curious what measures were taken? Read the details here.
Sometimes, less can be more! In this case, it was less efforts and less expenses for our customer with the result to realise a more practical and sustainable solution.
Here you can see that it can be worth to invest time & know-how in the investigation phase to come out with a solution being perfect for the customer.
Further Case Studies
Further project examples with more technical background information can be found here:
Vibration Limits – Order your free poster
- Vibration Limits for Reciprocating Compressors
- Vibration Limits for Screw Compressors
- Vibration Limits for typical Machine types
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- Worldwide troubleshooting in case of interruptions in the operating procedure or damages
- Root cause analysis and elaboration of mitigation measures
- Plant Optimization for high performance operation and reliability
- Elaboration of vibration reduction measures
- Pulsation Studies according to API 618 / API 674
- Measurement of material stress with the aid of a mobile strain gauge system
- Carrying out of torsional vibration and torque measurements at drive trains
- Plans for the installation of machinery, e.g. on customised foundations
- Static and dynamic analysis of complex piping systems
- Advice on the vibration characteristics of different machine types
- Avoidance of machine downtimes due to vibrations
- The maximum possible vibration reduction in/from rotating and oscillating machines
- Reduction damage to machines and decrease wear and tear
- Best planning reliability
- Optimised conditions for performance and service life, e.g. of your machine.
- Increase work safety
- Reduction of production losses
- Development of timely solutions that can be easily implemented
- The best possible solution on cost effective terms
- Rapid troubleshooting virtually anywhere in the world, even when there are complex travel restrictions
- Staff with international in the areas of oil and natural gas production, power plant operations, chemical industry, commercial vehicle engineering, as well as the paper, packaging and food industries