Workshop «Shaft alignment and dynamic balancing»
We invite technical specialists to participate in the training course on the topic «Shaft alignment and dynamic balancing» which will take place on 12-13 September, 2019 in Germany (Lubeck). The workshop is arranged for specialists in quality, service engineers, mechanics and power engineers who are responsible for the reliability of machines and industrial equipment.

BALTECH GmbH
Kronsforder Allee 45,
23560 Lübeck
Germany
Tel: +49 (0) 451-370-87-700
E-Mail: info@baltech.biz
 
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Articles -- Oher


Defect types of dynamic equipment

Reliability and safety are the key factors for any industrial enterprise. The BALTECH company developed new complex strategy for operation, repair and diagnostics of different types of industrial equipment. The concept "Reliability technologies" is result of our fifteen years' activity, and the next stage in development of our company.
This concept will help to pay attention of experts on all levels of an enterprise to the main problems and tasks which daily disturb normal and trouble-free operation of technical departments of all industrial companies.

In the last years the question of optimization of all industrial assets, optimization and increase of profitability is especially acute for industrial enterprises. Top managers have ideas about increase of production profitability by minimum financial expenses. Optimization of an industrial enterprise is possible in two ways:

1) Increase of labor productivity in all departments. In other words, the same group of employees has to product more products and render more services (repairs) for a standard report period.

2) Reduction of expenses for service of key assets and support of resources (equipment, salary, repairs). This way assumes that by production of constant quantity we reduce and we optimize costs for operation and repair of technical equipment, therefore it causes profitability increase for a report period.

The company BALTECH with fifteen years' experience in technical audit of mechanical and power services developed the second concept, which helps to reduce repair and operation costs for a wide range of equipment by the same reliability factor and in accordance with industrial safety requirements. The new complex strategy was called "Reliability technologies". Many enterprises are familiar with the first version of our standard, which was called "Reliable equipment" and has been developed up to 2013.

The new concept is based on large statistics for defect types of rotor (dynamic) power mechanical equipment (Figure 1). In our client data base there are more than 2500 industrial enterprises and service companies B2B. Statistics were accumulated by our specialists during training and supply of diagnostic equipment for departments of chief engineer and chief power engineer as well as commissioning and start up by our technical department. Our main tasks were set by enterprises in chemical and petrochemical industries, energetic, metallurgy, engineering, paper industry, pipeline industry and other economic branches.

In all branches independent from specific features of rotating (dynamic) equipment its "diseases" and defect types are very similar. According to our statistics we defined the most popular defects on different types of machines: pumps, compressors, fans, electric motors, turbines and gear boxes in per cent ratio.

On the Fig. 1 statistics of the most popular defects are presented:

  • Defects in bearing units (rolling element and slide bearings) - 31%,
  • Misalignment - 26%,
  • Unbalance (rotor unbalance) - 17%,
  • Aging and wear of lubricants - 14%,
  • Inaccurate assembly of units and details (geometry mismatch) - 7%,
  • Looseness caused by wear, remaining life or a human factor - 5%
  • Other defect types related to specific features of a production machine - 3%.

For the statistic analysis we used data of 20 reliability departments from different branches and 20 enterprises which are periodically maintained by the department of technical service of the company Baltech.

The above statistics were based on measurement data of portable measuring devices for technical diagnostics during monthly inspections of mechanical and power equipment:

1) Vibration diagnostics was carried out with BALTECH VP vibration analyzers.

2) Thermography (temperature control) was conducted with by multipurpose thermal imaging cameras BALTECH TR-01500 (Figure 2) and the new camera BALTECH TR-01800 with resolution 640x480 pixels.

3) Tribodiagnostics (the condition analysis of oils and lubricants) of such parameters as viscosity and chemical composition was conducted with a portable minilaboratory.

Thermography, thermal imaging camera, thermal control

Analysis of statistics for several years shows that defects of rolling element bearings remaint the most common today. During detailed analysis and technical audit of units the following reasons of defects in bearing units were detected: purchase of new improper bearings 50%, non-conformance with storage requirements, incorrect mounting of bearings by repairs, load increase by operation.

To detect the problems in the future and to increase reliability of bearing units on rotor equipment you should follow these recommendations: at purchasing stage you should select reliable suppliers, who supply bearing products according to the ISO 199:2005 or arrange a line for incoming bearing check based on the stand BALTECH BCM-6150 for incoming bearing check. To avoid misalignment of inner and outer bearing cups as well as to keep correct adjustments and allowances you should use an induction heater and a special mounting tool kit.

The second part of defects (misalignment and unbalance) is mostly connected with initial use of inaccurate methods for alignment and repair of equipment or with development of such defects at operation of a machine (e.g. metal pickup or wear of impellers). We recommend to use hereof laser alignment systems with calibrated shims and portable devices for balancing in own bearings as well as balancing machines. ISO 1940-1-2007 includes requirements for residual unbalance specified for different machines and devices according to their accuracy grade G0.4, G1, G2.5, G6.3,..., G4000. For balancing of rigid rotors we recommend to use horizontal balancing machines BALTECH HBM series.

The third part of defects is related to the quality of lubricants, which assures reliability and long life of industrial equipment. Only application of qualitative oils and lubricants can increase working capacity and trouble-free operation of power mechanical and hydraulic equipment. Analysis of reasons makes it clear, that the main problem is due to improper lubrication, incorrect periodicity of lubrication or application of wrong kinds of oils and lubricants. As for recommendations we offer a new time schedule of diagnostic measurements with portable minilaboratories, advice to change lubricants, to replace sealings and to install a stationary system of automatic lubrication, which allows to reduce annual amount of used lubricants 3-4 times due to exact dosing.

Temperature control and periodic monitoring of heat sports with thermal imaging cameras detect heating trends of electric motors. Defect growth in electric magnet systems of electric machines appeared as a result of primary defects and were diagnosed as secondary defects. Primary defects are mechanical problems as well as defects of oils and lubricants. Temperature parameter is more inactive and develops not so fast as other parameters (e.g. vibration or tribological parameters). Thermography is used for diagnostics for electric equipment, thermotechnical equipment as well as energy audit as a main method for technical diagnostics. For mechanical equipment monitoring with thermal imaging cameras is an additional method, which helps to detect a defect recognized with another device.

On our opinion, to the last part of defects belong the problems of wear and remaining life, looseness of mechanical couplings on worn out equipment, defects of supports and foundations as well as piping defects.

Appearance origin of such defects cab be due to imperfection of repair technology and periodic metrological certification of machines. For example, flatness of foundations was checked with laser systems for geometry check. According to the construction requirements allowable deviation from reference horizon should be not more than 0,4mm/m. But this tolerance was kept not everywhere, because foundations were poured more than 20 years ago, and nobody has checked them.

Geometry check (including check of straightness, flatness, squareness, parallelism) is a very important metrological task for machines and machineries, which are worn out (usually operation life is more than 15 years). The requirements of ISO 230-2-1997 and ISO 1101-2004 regulate the accuracy of mating parts.

On the Figure 3 you can see recommended areas of diagnostics, which can provide reliability of dynamic equipment. By applying the complex strategy "Reliability technologies" each industrial enterprise can significantly reduce financial expenses for operation, reduce repair intervals, decrease a required amount of spare part storage as well as provide a safe and trouble-free work of power mechanical equipment.

The company BALTECH recommends all technical departments to order our service of technical audit or to perform this procedure by themselves with help of our experienced analytics for analysis of statistics for defect types on different kinds of machines. You should make a time group of specialists for reliability increase and detection of the "weakest links" of equipment. It's not a secret, that reliability of any technically complex system is equal to reliability of the weakest unit. The most important is to increase work efficiency of specialist with system of motivation and stimulation. it should be based on integration of the final most profitable results obtained during technical audit.

The last recommendation of our company is review of economical and production factors and precise analysis of all resources (personal, tools, wear coefficient of equipment, equipment record, commonality of equipment in use). You should in advance calculate profitability of usage of devices for technical diagnostics and new repair technologies, otherwise you have to switch to outsourcing. If for you it is more profitable to invite other service companies, you should step by step conduct reorganization of your company.

Certification of specialists and periodic personal development are to be performed in science-based and approved companies, which should provide both theoretical and practical training. Our company invites all interested technical specialists to our professional courses. Timetable of the courses you can see on our website on the tab "Training".

Summary

The concept "Reliability technologies" is a complex strategy providing reliability of industrial equipment, but we do not claim to be perfect. If you have a lot of statistics according to your technical equipment as well as positive experience in application of other means of technical diagnostics (e.g., defect detection, acoustic emission monitoring systems, parametric diagnostic etc.), you can make your own scheme of reliability support of technically complex systems.
Each enterprise as a living body is constantly developing and changing, so you should promptly react and measure reliability level of any technical equipment. We wish you good luck in finding solutions for interesting engineering tasks.