Ship maintenance

Ship maintenance goes high tech




June 19, 2014

Machine reliability is a top priority and an ongoing challenge in marine applications, which operate in harsh conditions and in locations far from ports and repair facilities. Ship operators can help keep machinery running smoothly by equipping their maintenance departments and crews with a full range of next-generation maintenance tools. These tools, which range from high-precision alignment systems to precise automatic lubricators, can help prevent premature failures and reduce the need for repairs at sea.


Tanker operator improves pulley alignment

Many ship operators have modernized their maintenance practices and tools as part of overall reliability efforts. A case in point is a major tanker operator with a fleet of 55 vessels, based in the UK. Pulley alignment was a pressing area of ​​concern for the operator. Belt failures in key machinery had caused costly downtime and sometimes reduced a ship’s operational efficiency. The root cause was usually a misalignment.
The company decided to upgrade its existing alignment practices, which were cumbersome and lacked the necessary degree of precision.
The operator evaluated several advanced alignment systems and ultimately settled on a laser-equipped belt alignment system consisting of a laser emitting unit and a receiving unit. Both units are securely positioned in the pulley grooves during operation, allowing alignment of pulleys with varying widths and different faces. Users can detect horizontal, vertical and parallel misalignments and adjust belts and pulleys accordingly. The system design is intuitive, requiring minimal training for the ship’s engineers.
After the upgrade, company officials reported an immediate improvement in alignment accuracy. The end result was more reliable machine operation across the entire fleet.

Tailored solutions
Different types of rotating machinery have varying operating parameters and maintenance requirements. Assembling a set of solutions that match the requirements of key application platforms before leaving port is good maintenance practice. For example, next-generation maintenance solutions, such as single-point lubricators, can help optimize vibrating screen performance and reduce the risk of failure. Vibrating screens are used to sort catches on fishing vessels and to transport certain bulk materials. In addition to the harsh conditions, the screens experience high temperatures, accelerations and speeds ranging from 1,000 to 2,000 rpm. Common causes of failure include fretting corrosion on the shafts and problems with lubrication and bearing cage.
Single-point lubricators attach directly to bearing positions in screens and provide precise, regulated flow of lubricant. A popular type consists of a transparent cartridge filled with up to 125 milliliters of lubricant. When activated, a built-in plunger propels lubricant at the user’s predetermined setting from the cartridge. Depending on application and flow rate, lubricators can operate for six months or more without refilling. This long life can help avoid the need for relubrication at sea, which is time consuming and can introduce contaminants into the screen bearings.
Vibrating screens are usually driven and coupled to electric motors and gearboxes. Like pulleys, they must be properly aligned with the mated machinery for efficient operation. New handheld shaft alignment tools generate real-time alignment values, allowing users to gradually adjust coupled machines until they are properly aligned.
During screen operation, vibration monitors and electric shock detectors allow workers to assess the condition of the machine in real time. Vibration devices typically collect enveloped speed and acceleration data, automatically compare it with pre-programmed guidelines, and give early indications of conditions that could cause failure. Discharge detectors monitor operating electric motors, such as those driving vibrating screens, and identify potentially damaging electrical erosion. A similar set of maintenance solutions can be used for other marine applications including refrigeration and ice making equipment, conveyors, cranes, pumps and fans.

Assembly/Dismantling
Vessel maintenance departments can benefit from the ability to mount and dismount rotating components at sea. Applications with large components can be designed in advance to allow mounting/dismounting by oil injection. Oil injection uses a thin film of pressurized oil to drive components onto shafts or safely remove them. For smaller components, portable induction heaters are ideal for on-board use. A ship operator in the Middle East, for example, acquired 20 high-frequency induction heaters for mounting bearings in small motors. The heaters weigh only 10 pounds. and are easy to handle and store. They heat bearings in bore sizes from 0.8 to 4 inches and weighing up to 11 lbs. An additional advantage is that the heating elements do not magnetize the bearings when heating them. This reduces the risk of contamination from small particles and makes a degaussing cycle unnecessary.

The author
Paul Michalicka is North American Sales Manager for Maintenance Products, SKF USA Inc., Lansdale, Pennsylvania. He can be contacted at

e : [email protected]
: 416-806-6723

(As published in the June 2014 edition of Maritime Reporter & Engineering News – http://magazines.marinelink.com/Magazines/MaritimeReporter)