How a Deck Steam Drain Valve Caused Main Engine Start Failure

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EXPERIENCE SHARING- CASE STUDY

Around mid 1980s, we experienced an engine failure on a 18 year old crude oil carrier. This vessel was then recently taken over by a new management company.

The owner transferred it to the new management, as the vessel suffered too many breakdowns which the previous management was unable to handle. This 18 year old lady had a lot of ailments. The task was quite a stringent one and no one were interested to take charge of it.

The delivery Chief Engineer resigned within a month of taking up the task, and no other experienced Chief Engineers came forward to take over the task. Eventually, the musical chair stopped, when a less experienced young Chief Engineer came forward to presume charge.

The hand over mentioned that the M/E start failure was the primary problem which needs immediate attention. Furthermore, the air distributor has to be overhauled at every port without fail, and an additional tug has to be ordered for every Arrival and Departure maneuvers.

Situation At Hand

At the next port, the C/E, still with 2/E’s hands on attitude, personally pulled out all pilot valve plungers of the radial starting air distributor. These plunger type pilot valves are pushed on a radial cam under operating air pressure. The pilot air cycles periodically into the cylinder starting valves when pressed down on a negative cam of the radial disc. He noticed the fine oil soaked fibers that was causing the plungers to get stuck, stops it to sit back on the negative cam, under operating air pressure. It was unusual to see such fibers in an air starter system.

While trying to trace the source of fiber, he found that the starting air compressor suction and the air filter box was empty with no filtering element inside. Delivery engineers said that they removed it, because all compressors, when working together were unable to supply enough starting air during ship maneuvers.

Although, some copper wire gauze from a Turbocharger filter was stuffed inside the suction filter to serve this purpose. It worked, well, and there was no more start failure and the compressor was running without any problem. The Vessel was then on a ballast voyage.

Upon arriving at the load port, the deck heating steam was opened, very loud water hammering sound was heard in E/R and all the way upto the accommodation. White dust was all around Engine room with the result of disintegrated lagging of Steam pipes. During departure maneuvering, the compressors were again found not able to cope up with starting air requirement. 2/E ran to C/E and requested permission to remove copper wire gauze. He suspected C/E might have over stuffed compressor suction filters with copper wire gauze. With C/E’s instruction, wire gauze was renewed with a cleaned wire gauze. On inspection of the old wire gauze, it was found wire gauze was badly clogged with the same kind of asbestos fiber that he found in the starting air pilot valve plunger.

Why the persistent water hammer in the steam pipe?

Feed water consumption was very high and the vessel had to lift potable water at every port. A good amount of distilled water was used for the make up feed. The fresh water generated was satisfactory and had no apparent leakage. However, while warming up the deck steam for cargo heating, the water hammer was heard, and engineers had to continuously drain out the condensate to bilge, till the deck heating steam pipe was well warmed up and no more water hammer was heard.

Deck steam pipe lagging was badly damaged and the pipe was bared at many places, throughout the main steam pipe, which runs from the aft to forward sections. No wonder, as the water hammer was prolong in cold weather. There was a condensate drain valve which cross connects the steam pipe and the condensate return pipe at closest dead end . This valve was found shut permanently. The cross connection valve is for the condensate from steam pipe to return and must be shut only after the steam line is fully warmed up.

A proper deck steam warming up procedure was prepared and posted. Also, training was given to both deck officers and engineers on maintaining the condensate return valve operation.

There was no further water hammer, feed water loss or M/E start failure.

Article By Mr. C.K.Murali [ViswaLab]

LESSON TO BE LEARNED:

  1. MACHINERY PROBLEMS COULD BE INDIRECT.
  2. THEY NEED PERSISTENT LOGICAL TRACKING TO FIND OUT ROOT CAUSE.
  3. WHILE 90% OF THE TIME IS SPENT TO DETECT, RECTIFICATION NEED LESS THAN 10%.

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