Inspection of two 70 Year Old Marine Engines in Switzerland

One of our most-seasoned engineers recently had the rare opportunity to carry out an inspection and condition assessment on two 70-year old main engines installed on an inland cargo vessel in Switzerland. During its long history, the ship changed ownership two or three times and now belongs to one of Switzerland’s prime construction companies and is used to transport construction gravel to a cement plant, where the gravel gets recycled.

The vessel was originally built in 1948/49 in a shipyard in The Netherlands as an inland cargo vessel. She is a twin-screw design.

When she was built, she had a displacement of 1’246 metric tons, an overall length of 83 meters, a beam of 9 meters and a draught of 2.6 meters. In 1969/1970, she was converted to a self-unloading gravel carrier. Her length was extended by 8 meters, resulting in a new tonnage of 1’447 metric tons.

The two main engines were build by Sulzer Brothers in Winterthur, Switzerland, in 1948 and are connected to the propeller shafts through reversible gearboxes. The engines are of the two-stroke, trunk-piston type and have the following specification:

  • Engine Type: Sulzer 6TW24
  • Bore: 240 mm
  • Rated Speed: 400 rpm
  • Rated Output: 450 hp each

As can be seen in the cross-sectional view on the right, the engines are equipped with piston-type scavenge pumps, which explains the for the time considerable power output of 450 horse power per engine, or 900 horse power (671 kW) in total.

Our engineer spent a few days on board, compiled an extensive report and after the visit continued to support the customer, for example to identify spare parts.

Because we have a soft spot for antique marine installations, we carried out this assignment and the subsequent customer support activities pro-bono.

An early picture of the vessel on the Rhine river
An early picture of the vessel on the Rhine river
One of the two main engines, photo taken in 2020
One of the two main engines, photo taken in 2020
Top view of the engine room, photo taken in 2020
Top view of the engine room, photo taken in 2020

Photo credits:

  • www.commons.wikimedia.org/w/index.php?curid=59313086
  • www.swiss-ships.ch
  • QuantiServ own

Cooling Water System Reverse Engineering

After 25 years of intermittent operation and of being exposed to the elements, the cooling water radiators of an 3500 kW emergency diesel generator installed in a thermal power plant in Macau had degraded considerably. Thus, the power plant owner decided to replace them.
Unfortunately, the original documentation and specification were not available anymore. Therefore, QuantiServ reverse engineered them and got 12 new elements made by a specialized manufacturer.
The new radiators have just been installed and commissioned and will provide reliable cooling for many years to come.
Although this was a small case, it illustrates the important advantages that reverse engineering provides. Many of the industrial plants that we maintain and repair on behalf of our customers have a lifetime of many decades. But that does not mean that the documentation always survives that long, or that spare parts are still available. And sometimes even the OEM himself, or his sub-supplier, may not exist anymore.
It is thus comforting to know that QuantiServ has the skills, tools and experience to reverse engineer and reproduce all kinds of machinery components, even very complex ones and entire systems.

Our Brand-new Case Study Page is now Online!

The new QuantiServ Case Study page is now online. It introduces recent work that we have done for customers coming from a variety of industries ranging from Marine, Mining, Hydro and Thermal Power Plants to Oil & Gas.

The cases are sortable by industry and cover services such as in-situ machining, metal stitching, reconditioning and many more. They each include a short description of the problem that the customer was facing, the solution and include many before/after and in-process pictures.

Case Studies

 

Be Aware of Cam Effect/Ridge Wear that Affects Four-Stroke Crankshafts!

Whenever a four-stroke engine has accumulated around 60,000 running hours or more, then its crank pins are in all likelihood affected by what is called the “cam effect” or “ridge wear”.

This phenomenon develops over time and manifests itself in an uneven wear pattern that is, with the right tools, easily detectable as a protruding band (“cam”) that goes around the circumference of the crank pin. It usually only develops on engines equipped with grooved bearing shells and its development is a function of time. The more impurities (abrasive particles) the lubricating oil contains, the faster the cam effect develops.

The two major makers of medium-speed diesel engines, MAN Diesel & Turbo and Wärtsilä, have booth issued Service Letters to make their customers aware.

The following pictures are typical and exemplify well how the cam effect develops and what damage it can cause. The pictures were taken during an attendance on a German-owned small tanker, where QuantiServ’s specialists machined one crank pin and polished all the others on the vessel’s single 50/54 main engine. The damage was in fact so severe that in-situ heat treatment (annealing) had to be performed too in order to reduce the crankpin’s hardness, which had increased as a result of the failure.

QuantiServ very much recommends to all owners and operators of medium-speed four-stroke engines to keep a close eye on the condition of the crankpins and to regularly inspect them once they have surpassed around 60,000 running hours. The cost of rectifying the pin geometry in good time pales in comparison to the cost of a repairing a failed crankpin bearing. And fail they will, if no action is taken.

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