Appropriate use of materials??

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Big Pete
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Appropriate use of materials??

Postby Big Pete » Tue Jul 13, 2010 10:50 pm

d it
P1000499.JPG
Silly **** sealant in action!
P1000499.JPG (333.09 KiB) Viewed 2960 times


I have just joined a "new ship", to me anyway. I thought that this picture might raise a smile. It is a 25/30 bar discharge line from the main starting air compressor. There is a slight leak of air and condensate, and some one thought silicon sealant was just the product to fix it!!!
(Personally I call it silly Cxxx sealant)

It reminds me of the time I joined a ship and found all the engine room pumps were leaking heavily from the stuffing boxes. Investigation showed they had all been packed using wire reinforced valve packing intended for superheated steam!!! The pump shafts were all totally destroyed, by friction with the wire.

Someone told me about a ship he joined where the engineers had used wire reinforced superheated steam jointing on a low pressure saturated steam system. Of course superheated steam is totally dry and saturated steam is wet. The jointing turned into a soggy pulp and the wire reinforcing rusted through, and there were leaks everywhere.

Someone else told me about a Saudi Aramco jack up rig he worked on. Someone decided it would be a good idea to lubricate the jack up legs with Copaslip, and ordered several tons of it. Apparently it came in 200 litre drums. Most experienced Engineers know that Copaslip is an high temperature anti sieze compound and has absolutely no lubricating properties. (if you don't believe me , google "Copaslip" and see what the makers say!!!)

Another mistake is to use copaslip on fuel injection equipment (apart from the outside of the injector nozzle and nut to stop it siezing in the pocke). Copaslip contains large chunks of copper compound which are large enough to cause fuel injectors and fuel pumps to sieze if they get into the fuel system.
The only assembly compound permitted on fuel pipe work, fuel injectors, pumps etc is the aerosol Molybdenum Di Sulphide spray.

Molybdenum DiSulphide compounds such as MolyKote and Molyslip, unlike Copaslip, have extremely good lubricating properties. In fact they are so good that Salesmen used to demonstarte by getting Engineers to tighten a nut bolt as hard as they could, dry, and then lubricate the threads with MoS2 when the bolt was tightened again, because the friction on the threads was so greatly reduced, the tensile force created in the bolt was sufficient to shear the head off the bolt!!!
This illustrates how important it is to check tightening procedures and toques. Some things are specified to be tightened dry, some with ordinary oil and some with Noybdenum Di Sulphide. The tension in the bolt and the compression on whatever is being tightened will vary enormously for the same torque, depending on the lubrication used.


BP.
It is always better to ask a stupid question than to do a stupid thing.

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JK
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Re: Appropriate use of materials??

Postby JK » Wed Jul 14, 2010 3:24 am

LOL, that is funny in a train-wreck sort of way!

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D Winsor
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Re: Appropriate use of materials??

Postby D Winsor » Wed Jul 14, 2010 10:49 am

I've forgotten how many times I've seen leaks in pipes and other equipment repaired in what is known in Canada as a "Red Green Special". A rag or some other material over the leak held on with many turns of Duct Tape!

I have also seen a hydraulic control valve seal leak declared "Fixed" with silicone. Works great until the valve handle is pulled or turned!
Troubleshooting 101 "Don't over think it - K.I.S.S. it"

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JK
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Re: Appropriate use of materials??

Postby JK » Wed Jul 14, 2010 11:50 am

Surely Dave you have seen the SW line leak repaired with many,many turns of twine neatly tied off!!

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Big Pete
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Re: Appropriate use of materials??

Postby Big Pete » Thu Jul 15, 2010 2:56 am

I used to despair on some ships, where you saw little baked bean tins or whatever, carefully wired up underneath a small leak to catch the drips. It was so much more work than taking a shifter out of your pocket and nipping up the leaking gland!!!
The best was when the first tin overflowed, and then the crew would wire a larger tin in place to catch the overflow from the first one!!!
BP
It is always better to ask a stupid question than to do a stupid thing.

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JK
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Re: Appropriate use of materials??

Postby JK » Thu Jul 15, 2010 4:06 am

I briefly worked on a ship with 7 cylinder Cooper Bessimers. Amazing engines....I never knew something could leak so profusely. Every joint had a little soup can neatly wired under it and under the LO Pump, a 5 gallon bucket . The oiler would drain everything off into a big bucket and dump it back into the diesel tank or sump, depending on the buckets contents. The paxman generators weren't much better. I was only there 2 weeks before I moved to another ship, hardly time to find anything.
I also worked on another ship briefly that had Vivian (sewing machine) engines. Standing orders were to keep the LO temp to 100*F. After I was there a couple of days, I found out that they keep the LO temps low to prevent oil from running everywhere. I was very glad to leave there.


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