Fault Finding

[Big Pete]

A couple of years ago I was Chief Engineer on a Platform Supply Vessel.
The ship was fitted with 3 identical Mitsubishi Purifiers (Westfalia clones) one for the L.O. on each main engine and one for Gas Oil.
All 3 were supplied with a common high pressure water supply from the Hydrophore/ Pneupress system and all 3 were supplied with a common low pressure fresh water supply from a header tank with float operated level control.
The following happenned when I was on leave.
One of the Purifiers was opened up for routine overhaul and cleaning, on reassembly it was not working correctly (dumping oil).
The other 2 Purifiers were working correctly.
The Chief Engineer raised the set point on the Hydrophore pump pressure switch until the safety valve on the hydrophore tanks lifted.
He then screwed down the safety valve and continued to raise the hydrophore pressure until the centrifugal pumps were running continuously.
Two of the purifiers were still working correctly, but the overhauled one wasn't.
My relief then made an urgent Purchase Order to the company for 2 new Hydrophore pumps " Because the old ones were worn out and he couldn't get the purifier to work without more pressure on the FW system".

I then rejoined.

Has anyone got any thoughts on this sorry tale?

BP

[JK]

Interesting that they immediately jumped at the hydrophore pump as the cause even though 2 other purifiers are working correctly and presumably the rebuilt purifier worked before the work.
Westfalia has a very good trouble shooting section in their manual. I would assume Mitsibishi does as well.

[Matthias]

I'm more familiar with Alfa Laval purifiers, but one thing I would have checked is the amount of operating water actually making it to the purifier. There are usually specifications for required amount of flow. Also, if it was working before the routine overhaul/cleaning, then I would take the purifier apart again and inspect all of the operating water passages and holes. Sounds like the closing water passages may be blocked.

[The Dieselduck]

Giacomo (jack), was an Italian second engineer with Disney, I was working with him on watch. He had, what appeared to me, to have this obsession about always testing the water flow to the purifier. I always thought he was a bit extreme with this obsession until I started being in charge of ten purifiers as a second, later on in my career. I came to appreciate that this system was often overlooked... for years, but was a major source of problems not easily thought of.

I too became obsessive, always checking the strainers on the supply side, looking for the hidden ones - which were often clogged - making sure the float system was in good working order. Like Matthias I had dealings with Alfa Laval predominately so I learned the controller and how to run the opening water, sealing water solenoids test electronically and with my stopwatch and a "special bucket" (which may seem silly - but on large ship you're always looking for a clean bucket), which was clearly marked with all my appropriate quantities, I would go around religiously testing the water flow and quantity to the manual's specs. Then trouble shoot from there. Sometimes I would have to rebuild a solenoid block, or the flexible steel lines had become clogged, or more often, been crushed, after so many service periods of mishandling. Lo and behold, over a couple of contracts, I went from several complaints per watch "marty, your bloody purifiers tripped on me again", to only a handful of complaints over a 14 week contract, which was quite nice.

Now, whenever I sign on a new ship, operating water for the purifier is a priority check at the earliest convenience, as the importance of the operating water seems to be often overlooked. Of course also making sure the operating water passages are cleared like Matthias mentioned, and that the proper orings are in their proper grooves. Of course these checks are alot easier to do then replacing pumps, so I am anxiously waiting to find out out what Big Pete's problems was in the first place. Good topic by the way.

[JK]

I would shut off all of the automatics functions and run the purifier manually and see if it was correctly reassembled, then I would open it and check the slide bowl.
If I remember the Westfalias correctly there where teflon nozzles fitted in the bowl bottoms that needed to be replaced for proper operation. I'd check the slide bowl o-rings as well to make sure the right ones where in the right slots.
I hope you don't come back and say they re-used all of the o-rings because they still looked good.
It was pretty hard to not put a Westfalia together correctly, I actually liked them better then the Alfa Lavals.

Now back to my real job.

[TxMarEng]

Blockages in the operating water system is one of the most common separator problems. All it takes is a bit of scale in an orifice or on a bowl surface to cause a problem with bowl opening and closing. Installation of a good demineralizing filter in the operating water supply is a good way to get around some of these problems.

[JK]

Big Pete is keeping us in suspense!!

[Big Pete]

When my relief explained the situation to me he was unable to give any logical reason why the problem was caused by low water pressure. He just kept insisting that the problem was due to low water pressure.
My first concern was safety, the hydrophore tank is a pressure vessel and its working pressure had been increased by 50%, so I readjusted the pressure switches and safety valve settings back to what they had been marked up as being set on Sea trials, 16 years before. My Second Engineer and Motorman stripped down and checked the purifier, found a missing "O" ring and replaced it.
All 3 purifiers worked normally after that.

Further investigation failed to show any paperwork relating to the safe working pressure / Hydraulic Test Pressure of the hydrophore/ Pneupress tank, and there was no test stamp visible on the tank.
However, it did reveal that the fresh water pumps had been working at their maximum designed pressure, so fitting new pumps would not have changed the system pressure.

[JK]

Big Pete, if that is the trouble shooting being employed by the other engineers, I hope you never have any major issues.
A missing Oring is basic and would have been picked up immediately if they had looked at the purifier again.
Pretty darn scarey

[Big Pete]

Every time I rejoined that ship there was a "surprise" for me.
One time I joined and the other crew had had problms with one Electric Stern Thruster tripping out on overload. The ship hads been working for 16 years in the North Sea, and it was Summer time. There were 4 identical thrusters, all consisting of an electric motor driving a 90 degree gearbox with a CPP prop on the end. There was a small servo pump producing high pressure oil for pitch control and low pressure oil for bearing lubrication, gears were spllash lubricated.
The other crew decided the cause was due to the viscosity of the oil being too high (Castroil SP150) and ordered enough oil of lower viscosity (SP100) to change all the thrusters oil. SP100 being recommemnded for Arctic operation.....
The other Chief had many years experience as Chief on a Baltic ferry and before that he had been a Political Commissar.

[JK]

a Political Commissar to a Chief Engineer....I'll bet there is an interesting story in there somewhere!!
Good reasoning, if there was absolutely no other reason for the motor trips and you were somewhere handy to the North Pole.

That is right up there with our Captains who like to run the bow thruster in the ice. Why? We are quite not sure.

[Big Pete]

There were 4 identical thrusters and only one was tripping out....
Eventually I found the problem was a faulty overload unit in the main breaker.

The common problem I found with most ex Communist block Engineers is that they are unable to see that some problems would affect all identical pieces of machinery on board and some would be specific to one machine. To me that is the first stage of the process of elimination, to eventually determine the fault.

[ArkSeaJumper]

We have a lot of problems with the water side. Some of the Engineers are slow to stripp the machine all the way down to the water distributer.

Because most of our vessels are on shorts sea trade, the fresh water is shore water, full of limescale, can be very hard water.
On some of these machines ther is a water 'Pump' in the verticial shaft, to pump up the operating water. This quite ofter is also overlooked.
I say 'Pump' because it is a slightly bent piece of flat metal.

We have started to fit water softeners to the systems.

[Big Pete]

I agree with you, I think that if you don't have distilled water for operating the purifiers then it is better to fit water softeners.
One alternative I have seen, where the operating water is supplied from open tanks, is to dose them daily with a few milli litres of Evaperator treatment, that will prevent scale formation in the purifiers as well as in evaporators.
Of course most modern purifiers operate direct from the mains.

[Pacific Barbarian]

Sad to say that most decent purifiers come with an intermediate and major service kit. When performing the service, the kit is to be used in its ENTIRETY

So after boxing up the machine, look for any o-rings left in the kit? Seems like a good idea to me

Scale build up on the operating water side is a problem, especially up that vertical shaft you guys were talking about, got the t-shirt, after a good acid bath of the shaft.

Cheap and easy way to solve this problem: everyday put a little (as in not a lot!) of dish washing soap in the operating water cistern to keep it soft. Not too much, or else it will start foaming and all pressure will be lost!

When stripping down the bowl you shall find the operating side of the bowl....well.... you guessed it....SPOTLESS AND SHINING

Hydropohore pumps? WTF?

Just my humble opinion.