Monitor, or open up

Strictly speaking, German shipowner D. Oltmann Reederei did not need to install engine monitoring systems in its three container ship newbuildings under construction at Hyundai Heavy Industries (HHI). Oltmann, like just about every other shipowner, had never installed the components before, so why start now?

"As a shipowner, we are not likely to change unless there is a benefit, an incident, or both," says Joern Winter, Managing Partner and Director for Fleet Management and Operations at D. Oltmann Reederei in Bremen.

"In this case, there is a clear benefit; with engine monitoring systems, we may be able to forgo the open-up bearing inspection often required by class after five years. And, although we have had no engine failures, we're interested in savings related to extra service calls and inspections."

The designer of the low-speed diesel engines being installed in Oltmann's newbuildings, MAN Diesel, recommends these sensors, but they were not made standard equipment until recently. The systems have become necessary due to the higher power to weight ratio of today's engines, and new metals designed to handle these forces.

MAN Diesel's project guide book for the low-speed diesel engines being installed in Oltmann's ships states: "The ultimate protection against severe bearing damage and the optimum way of providing early warning, is a combined bearing wear and temperature monitoring system." It was the first engine designer to make engine monitoring systems standard equipment, and is thus an early mover on condition-based maintenance.

Dodging a bullet

Data compiled by Swedish Club surveys illustrate damage causes and costs on low-speed engines. Of the five most frequent types of claim, cylinder liner and bearing damages come in at three and four, respectively. In terms of average cost, however, they are the most expensive claims. Thus the downside of a failure provides strong motivation for an engine monitoring system.

Describing Oltmann's motivation, Winter said: "We want increased and improved insight, and a safety margin to react to new requirements. Monitoring is the key to success in terms of efficiency and increased control. Safety and savings are vital to us."

Oltmann originally approached the licensed engine manufacturers at HHI about engine monitoring systems. From there, contact was made to Kongsberg Maritime, which produces a range of sensors for engine monitoring and which was already supplying the ships' propulsion control systems. Arjan Paans of Kongsberg Maritime met with Oltmann in 2008.

"For low-speed engines, a number of monitoring systems are recommended," says Paans. "These include temperature monitoring of crosshead, crank and main bearings, bearing wear monitoring, cylinder liner temperature monitoring and water-in-oil sensors. We expect all of these to become standard equipment soon."

Four core systems

Oltmann's three container ships will each possess a package of engine monitoring systems, which – in addition to a pressure analyzer and the conventional oil mist detection system – result in what Paans has called "one of the best equipped engines in the world today."

Kongsberg's bearing wear sensor was developed in close co-operation with MAN Diesel, and is designed to provide the crew with early warning if any of the crank train bearings have an unexpected wear rate. Basically, a sensor will measure the combined wear of the main bearing, the crosshead and crank bearings at bottom dead center, and trigger an alarm if a problem is developing.

The bearing temperature sensors track metal temperatures in the three bearings. The crosshead and crank head temperature sensors operate wirelessly. The sensor itself has no power demand, and its signals pass via low-energy radar technology.

The cylinder liner monitoring system measures the temperature of the upper part of the cylinder liners. Increased temperatures set off an alarm, so that the crew can respond before excessive scuffing occurs. "Many shipowners have experienced problems of this kind, and they're very interested in avoiding the high costs associated with reconditioning or replacing the cylinder liners," says Paans.

The water-in-oil sensor has earned extra emphasis from engine designers. Water content reduces lubrication, which can cause cavitation and corrosion. Corrosion will result in fatal engine damage very rapidly. "We believe the water-in-oil sensors are a significant improvement on the oil mist detectors," said Winter. These systems fulfil the same functions as today's oil mist detectors, but are quicker and more sensitive.

All of these systems are connected to Kongsberg's AutoChief C20® system via the common (CAN) network. Any failure can have two results: either it will trip off an alarm, or automatically initiate slow-down.

"It's important to understand that these systems can also be used for condition based maintenance, which is getting more and more popular among shipowners," says Paans.

Commercial arguments

Many shipowners want to invest in these systems to skip the kinds of open-up inspections of main engines required by classification societies today. Approximately 70 per cent of bearing seizures occur shortly after an overhaul or open-up inspection. This is simply because conditions during the open-up, and the personnel doing it, are seldom as good as during the engine's production.

"If we can extend the amount of time between open-up inspections, we stand to save a lot of money. This is a very valuable argument for us," says Winter.

He also argues that the systems will provide Oltmann with an advantage on its competitors in terms of reliability, when negotiating with charterers. He continues: "Charterers have different values when it comes to the ship's operations, but many of them aren't interested in your technical issues. Some may choose us partly because we have well-equipped ships; others aren't as interested. But everyone wants reliability, and that's what we aim to offer."

Asked why Oltmann chose Kongsberg to supply the engine monitoring systems (MAN Diesel recommends a handful of suppliers), Winter explained that the company's prior experience with Kongsberg played a big role.

"As a private shipowner, we need to make money on existing vessels, if we want to extend our fleet. Thus we're looking for synergies," says Winter. "If we can combine service calls with one maker, we save money. Also, as a tramp owner, we need to have a global partner, because we don't decide where the ships will be calling."

Inevitable and invaluable

Oltmann is one of a host of shipping companies that is investing in these kinds of systems (Denmark's TORM is putting them on a series of 11 ships), or seriously considering them. The engine manufacturers recommend the systems, classification societies approve them and providers like Kongsberg are steadily improving them. Said Winter: "These have become much more reliable and reasonably priced. Five to ten years ago, this was very fancy kit. Costs have come down and quality has gone up." There is also a manpower and skills side to the picture. Seagoing personnel frequently have less experience than before, and engines are only getting more complex; given the situation, a more intensive alarms strategy mitigates operational risks for shipowners.

"These sensors will result in alarms and/or an automatic response that prevents damage before it happens," said Paans. "This can save you an expensive repair and possible off-hire, at the very least; at the most, it can save your crankshaft."