NEAC once needed a crane to inspect compressor machines. With an API tracker, they just need a rolling case

3D Laser Tracker Systems_372x298NEAC relied on 5-ton coordinate measuring machines to inspect compressors, which run at continuous high speeds constantly and need regular maintenance and checks. The API tracker can measure the full volume of these massive machines portably, saving NEAC and its customers time and money.

The compressors used at NEAC’s Übach-Palenberg, Germany plant run so hard and fast that, if they were the pistons in a car engine, that auto would rack up nearly 500,000 miles every year – representing 333 days of uninterrupted driving. Oh, and the engine would receive only one service check-up each year. This example illustrates the immense stress that NEAC puts on its compressors, which are used in the production of oil and gas, chemicals, food production and renewable energy. It also demonstrates how critical it is for inspections and any overhauls or repairs to be conducted in the shortest amount of time possible, because every minute of downtime costs NEAC money.

Everyone Needs Pressure

Compressors are used in a wide range of industries, and they are critical to the production process for all of them. If this partial step fails, the entire process comes to a halt. To mitigate this, machine maintenance is precisely planned to minimize downtimes and repair costs. The Übach-Palenberg facility, which is a subsidiary company of NEAC Compressor Service GmbH & Co. KG, is involved in the service, installation, commissioning, repair and modernization of NEAC piston compressors as well as those of external manufacturers. Plant managers knew they needed the most effective 3D measurement system possible to use on-site at customer factories. They needed an instrument that was not only portable, but compact enough to take measurements and make calibrations within the customers’ machines themselves.

NEAC managers had stringent accuracy requirements for any system they would consider purchasing. The construction of compressors is so precise that measurements had to be accurate within a few hundredths of a millimeter, roughly the width of a human hair, on a component that can be as large as 50 feet. Two suppliers were brought in, but only one passed NEAC’s tests. An optimal measurement strategy is therefore required for every individual case in order to also achieve the real showpiece discipline of laser trackers: achieving reliable measurements over large distances. The measurements are in any case carried out through interferometry, as, due to the system, this measurement procedure offers the largest accuracy-related reserves. The T3 laser tracker from Automated Precision Inc. (API) proved itself to be the smallest and most accurate measuring system NEAC tested. It achieved further validation by not letting the vibrations in the machine shop disturb its operation. The T3 achieves reliable measurements over large dismeasurement that compares different wavelengths to determine distances.

Everything starts at the foundation

NEAC Compressor Services started using the T3 in September 2010, both in their own machine shop and at customer sites. It has been used in commissioning work, overhauls and repairs. It has also been brought in for re-assemblies, ensuring that even the largest machines are realigned to the foundation within one tenth of a millimeter. This is critical because the connecting pipes of these machines are subject to intense pressures and do not bend. Indeed, the entire assembly of machines today is much flatter and stiffer than in the past. This allows the machines to handle faster running engines and stronger pressures, but it also means that precise positioning is absolutely critical to the machine’s survival. There is no leeway or give anymore in these machines, and an apparatus that occupies 256 square feet must be assembled within an accuracy of about 0.04 inches. If it cannot fit this space the foundation is demolished and partially recast. This is where the laser tracker can offer significant savings, mainly in the form of time. “We used to require up to two weeks for the alignment work on the foundation alone, using leveling units, yardsticks and precision spirit levels” says Stefan Damberg, project engineer at NEAC Compressor Service. “With a laser tracker, however, this task is completed in half a day. In addition, in contrast to earlier times, we also have a meaningful report as evidence for the customer after completing the work.”

Relieving the strain on the stationary measuring machine

The T3’s portability also offered substantial savings on transportation by allowing inspections to take place on-site, rather than forcing NEAC operators to haul their components over to a stationary measuring machine, usually by crane. And even these heavy coordinate measuring machines could not take measurements on NEAC’s largest engine frames or cylinders, which weigh more than 5 tons. Only a laser tracker could do that. The ability of laser trackers to carry out real-time measurements becomes especially important when it is necessary to reduce web deflection – which is the tendency of the crankshaft to rise at its weakest spot (its hub) if it has not been optimally aligned. To do this, the motor and compressor must be aligned as accurately as possible to each other using a laser tracker, while the web deflection is measured using a dial gauge. The T3’s compactness and versatility allows it to measure virtually every component of the compressor assembly. However, some elements remain too small for any 3D measurement to be exclusively used. These areas, with a diameter of less than 400 millimeters in the smaller machines, are too tight for anyone to get through and measure the interior. In these cases, additional 2D measuring equipment is used.

…And They Are Still Running Today

Remember the car that has to run 333 days straight to match the annual performance of NEAC’s compressors? Now imagine this car running for 30 or 40 years. This is quite common among compressor machines. As long as the parts are regularly serviced and properly replaced, these machines have an almost limitless capacity. The engineers from NEAC make this service available worldwide – not only for their own machines, but also for third-party products of the KSB, Linde, Halberg, Demag or Borsig companies. Some of these manufacturers no longer exist, but NEAC engineers can continue to service and maintain their machines. This requires a great deal of know-how and a little gut instinct, especially when they are working on machines from the 1960s, for which no CAD drawings exist, giving the engineers no information on their tolerances. An extensive stock of replacement and wearing parts for piston compressors for both NEAC and third-party models guarantees that services can take place any time, any day.

Time-Consuming Measurements

Measuring the parts themselves is quite time-consuming. Typically, the measuring machines collect hundreds of data points. For maximum accuracy, they are processed with single-point measurements.

For example, the measurement of a bearing hole with a diameter of 1.3 meters requires up to 160 individually measured points. Given this meticulousness, it is a great benefit that the laser tracker requires only one person to carry out the measurement. In this manner, a comprehensive measurement of a complete engine for shape and position will only take around two to three days. For large units, the tracker will be set up inside the engine itself, if, for example, it is necessary to measure the perpendicularity of the cross-head slipway. The low installation height of the T3 tracker head of 17 inches is an advantage here, while its light weight of only 18.7 pounds facilitates the set-up inside machines. The NEAC use SpatialAnalyzer to interpret the measurement data. NEAC employees were trained on the laser tracker and software by API.

It’s the Measurement Strategy that Counts

“A laser tracker is basically simple to operate, but a great deal depends in the optimal measurement strategy.” says Stefan Damberg. “In doing this, it is important to exclude as many possible sources of error as possible from the very start. These are mainly unfavorable set-ups and environmental conditions that can cause measurement errors; we have learned a great deal in this area in the past.”

In order to set up the ideal measuring conditions and eliminate environmental influences on t In order to exclude the special environmental influences on these machines, many of which are installed in the open air, a special makeshift structure is put up for the measurements and subsequent work. Depending on the size of the machines, a maintenance platform as tall as 20 feet might be installed.

A Growing Global Market

Demand for NEAC Compressor Services is growing worldwide, as piston compressors are not only required in the petrochemical industry, but also in the construction of solar panels. Stefan Damberg said NEAC will further expand its customer service support by providing faster turnaround for service using a transportable flangeturning machine and bearing machinery – along with the help of laser-based measurements. This emphasis on being an on-the-move service provider makes portability even more important. Stamberg would like to see his laser tracker so small it can be considered carry-on luggage when flying. Portability is simply infectious.


With service centers worldwide, NEAC Compressor Service supports its customer as a specialist for installations, commissioning, repair work and modernization. Together with the customer, solutions are drawn up for the minimization of downtimes and repair costs in order to guarantee the longest and most accurate operation runs. These solutions include tailor-made service contracts, project management during repair work and the registration of the overall machine status, including the 3D laser measurements. Further services include the diagnosis and analysis of vibrations, vibrations and engineering studies, as well as customer training courses and seminars in the NEAC Training Center.

Stefan Damberg | Certified Engineer | NEAC Compressor Service GmbH & Co. KG | | Phone: 02451/481-323