Good Shipbuilding Practice vs Requirement

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Brad
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Good Shipbuilding Practice vs Requirement

Postby Brad » Mon Nov 16, 2015 10:34 pm

Quick question for the wealth of knowledge and experience on here.

Is there any class (any society) or statutory rule stipulating that a fresh water cooling system is to be a higher pressure than the sea water system?

We are in the final fitting out stage of a newbuild, and run up and testing of systems have proven the FW system to be lower than SW. Now this is not as designed, and that is the feedback to the yard of course, with system rejected.
However, in their argument, they are stating that there is no rule requirement for the FW needing to be higher pressure than the SW.
They are offering to fit salinometers (sp?), header high level alarms, and all sorts to keep from lifting header tanks or replacing pumps at this late stage.

While we will get there in the end, I am looking for the smoking gun if you will, to shorten this long drawn out nonsense.
It does raise the question of how to enforce 'good shipbuilding practice' and common sense, without having a build spec the size of War and Peace!

I look forward to hearing everyone's thoughts while I bang my head against the Ulsan wall.

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JK
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Re: Good Shipbuilding Practice vs Requirement

Postby JK » Tue Nov 17, 2015 2:17 am

If it is designed, specified, bid on and contracted, it is a deliverable. IMO. If the spec is not clear on a point, they will use it to their advantage. I'll have a look when I get into the office. ETA, I had a look at LR and didn't see anything.
It is always entertaining how the yards use Rules for their benefit and ignore them when It is also to their benefit.
BTW, there is no such thing as good shipbuilding practice. You put that in a spec and you're already in trouble.

Brad
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Re: Good Shipbuilding Practice vs Requirement

Postby Brad » Tue Nov 17, 2015 9:17 am

I agree with everything you say. Unfortunately I wasn't involved in the project during the spec discussions or agreement, yet there it is on occasion, along with 'builders standard' which is another way for them to come up with magical reasons for doing it there way which suits the mistakes made.
It is quiet shocking actually how far they will go to alter and work around a mistake instead of just fixing it. The cost over runs for the yard at this point are well in the tens of millions...50
The funny part is that they think we will just accept...
Comical to a point.
Fact is though the spec is the spec, signed by both parties. They don't like it and nor do we. But that's true compromise...
When both parties leave equally disappointed.
I'm still looking myself, nothing yet.

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JK
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Re: Good Shipbuilding Practice vs Requirement

Postby JK » Tue Nov 17, 2015 2:57 pm

Add to that, the Yard hires Class which makes it even more difficult

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D Winsor
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Re: Good Shipbuilding Practice vs Requirement

Postby D Winsor » Wed Nov 18, 2015 4:23 am

Is the fresh water cooling system in question for an engine or some other piece of equipment? Have you checked to see if the engine or equipment manufacturer has it in their design specifications the required differential pressure between the systems? If so they could help resolve the issue.
If this is a new installation I would also verify with the engine or equipment manufacturer that the piping and all fresh water cooling system components, including the pumps, were the correct specified size and installed correctly.
If this was a retrofit I would also check the components in the Raw Water system to insure that there isn't some kind of blockage in a valve or piping, such as a rag or improperly installed gasket, or there is some other improperly installed component such as a valve, gasket or orifice on the discharge side after the engine that is causing back pressure in the raw water system. I would also verify the flow capacity requirements of the new equipment such as the coolers and compare to that of the original equipment to insure they are the same. If the flow capacity is lower for the new equipment, the issue can be resolved with some sort of bypass regulator on the raw water supply to the engine or equipment in question.
Troubleshooting 101 "Don't over think it - K.I.S.S. it"

Revolver
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Re: Good Shipbuilding Practice vs Requirement

Postby Revolver » Mon Nov 30, 2015 6:45 pm

Not a class req, just proper design.

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Big Pete
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Re: Good Shipbuilding Practice vs Requirement

Postby Big Pete » Mon Nov 30, 2015 10:42 pm

It is really just common sense, but that can be in remarkably short supply!!
It is always better to ask a stupid question than to do a stupid thing.

Revolver
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Re: Good Shipbuilding Practice vs Requirement

Postby Revolver » Tue Dec 01, 2015 4:31 pm

Common sense, not so common anymore.

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JK
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Re: Good Shipbuilding Practice vs Requirement

Postby JK » Tue Dec 01, 2015 4:37 pm

Not when a yard is involved

Brad
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Re: Good Shipbuilding Practice vs Requirement

Postby Brad » Wed Dec 02, 2015 10:03 am

After much posturing and crying in their Soju, they are agreeing to relocate the header tanks from the upper tween decks into the funnel at a suitable height to reach design pressure of LT system.

The resistance effectively boiled down to them not knowing how they could fit new tanks through the funnel doors!

It still amazes me how far (time and money) a shipyard will go to work around a mistake, instead of sticking a hand up and fixing it correctly straight away.

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Big Pete
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Re: Good Shipbuilding Practice vs Requirement

Postby Big Pete » Thu Dec 03, 2015 12:53 am

Glad to hear that you wore them down eventually.
BP
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JK
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Re: Good Shipbuilding Practice vs Requirement

Postby JK » Sun Mar 06, 2016 1:38 am

We had header tanks installed too high in a vessel. For years the ship engineers struggled with high temperatures in the central cooling because of the head pressure on the pumps. I had them dropped down 2 decks in a refit and voila, end of heating issues. Another shipyard workaround. The ship had a heating arrangement on the engine room intakes to warm supply air in the Arctic. Instead of installing another aux system and pump for the heat exchanger they tried to shoehorn it into the existing system somehow. Nothing really worked well.


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