Friday, June 15, 2012

SULPHURIC ACID CARRIAGE DANGERS, ON CHEMICAL TANKERS- CAPT AJIT VADAKAYIL

SULPHURIC ACID CARRIAGE DANGERS, ON CHEMICAL TANKERS-  CAPT AJIT VADAKAYIL


The reason why the sea is such an unsafe place now-a-days is due to a strange anomaly.

If you were to witness an international conference of brain surgeons- you can see lot of maturity and respect.

You will never find fossils sitting on administrative chairs, trying to do one-upmanship and showing who is the dang boss around.

After 4 decades at sea , I can vouch that this is NOT the case at sea.

If you were to witness a Maritime seminar you will find the most daft characters trying to show who is boss.

Ego laden ex-sailors sitting on shore chairs , far removed from reality at sea, show a tremendous amount of immaturity.

They assume that they are gold medallists in a IIT entrance exam , while the sailors at sea all got ZERO marks and hence were banished to sea as divine retribution.

This has to be seen to be believed.

The real reason why most of these jokers are ashore is that they were unable to continue at sea ( which allows them to save 6 times more money ) , for whatever reasons - coupled with their ability to compromise.

Below is an exception. 

An actual correspondence where a shore rule making institution wants to consult the people on the field-- the sailors at sea who do the actual job, and hence know what the hell is happening.


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dear XXX,



TO BE FRANK— XXX , WITHOUT SALT SPRAY ON LIPS-- DOES NOT HAVE THE COMPETENCE TO SORT THIS PROBLEM OUT.  



SO READ CAREFULLY.  IT IS ABOUT SAILORS LIVES.



what we must look for here is PREVENTION and not cure.



when you carry sulphuric acid— all ballast interface all around the cargo tank is removed in any case.   
 

in most standard load ports the PSC/ harbor master checks this , and there is hell to pay if he finds some ballast ROB in some SBT after completion of loading..



so checking for pH etc is not gonna be very effective.   why do you want to check the hydrogen ion concentration of a water solution, when there is no water?



WATER WHEN ADDED TO SULPHURIC ACID CAUSED A “EXHOTHERMIC” REACTION AND GENERATION OF TREMENDOUS HEAT , WITH PRODUCTION OF VERY LARGE QUANTITY OF HYDROGEN GAS .  this heat can warp the ship and shear open the welds.



IF THE WATER IS SALTY ( DUE TO INGRESS FROM BUTTERWORTH PORTS ) THEN THERE IS TERRIFIC GALVANIC ACTION WHICH CAN EAT AWAY THE WELDS IN A JIFFY.



this means hydrogen gas value check in ballast tank is gonna be more effective.



when I carry sulphuric acid on my ship there are  a few compulsory check I make personally.



AAA) a sulphuric acid SS ship must have butterworth ports and tank domes with a inner packing of PTFE and a outer packing of viton.  a lot of chemical tankers just have one SINGLE packing of hard Teflon.



BBB) the butterworth port can have butterfly nuts or ordinary nuts/ bolts.   SS has very little friction coefficient . This is why on new Japanese ships the silver bottle screws under the cabin chairs , are not seen after the first voyage. A SS bottle screw is not a bottle screw without a check nut. .  



In case of SS butterfly nuts, there must be no grease on the threads. I usually tell my mate to mix up some epoxy paint with thinner to make a very thin solution and apply a thin veneer on all these threads. this ensures that the butterfly nuts will NOT work loose at sea due to buffeting waves on low freeboard deck , or due to vibrations. in addition I tell him to pass a seizing wire through the butterfly nuts, so that they cant loosen .



in case the tank butterworth ports have nuts and bolts, then I tell him to put check nuts.  this means a same nut put reverse.  vibrations now cause the check nuts to self tighten like magic. the whole idea is NOT to allow a single drop of water to get inside the tank.

This is the reason why all SBT ballast tanks around the acid tanks must be EMPTY, prior starting loading. 

CCC) it is high time passivity of SUS 316 tanks are taken into account. If I work in IMO I will NOT allow sulphuric acid carriage in SUS316 rather - rather I will ask for SUS 316L or SUS 316LN with higher molybdenum content.



DDD ) stainless steel depends on corrosion resistance to a angstrom thin chromic oxide layer.  if this passive layer is NOT there , this SS is as good as mild steel.   most people do NOT understand this.  



on XXX delivery voyage , in 2005, after disch of ex-dumai palm oil fatty acids in bejaya, we had to go to nearby varna to load sulphuric acid. I noticed that the tank passivity has been weakened by long salt water hot wash, and I wanted to passivate with nitric acid BEFORE loading sulphuric acid.   



experienced chemical men do NOT need any aids like passivity meter or palladium chloride to check SS passivity.  they can see it.  XXX did not allow me on email , and were quite sarcastic about a foolish master wanting to passivate tanks after palm oils.



but then I did what I had to.   



I am here to protect the owners asset.  



passive steel does not liberate hydrogen from sulphuric acid.   this is the principle of using palladium chloride . hydrogen reduces palladium chloride to form black palladium metal and hydrogen chloride.  H2+PdCl2= Pd +2HcL



EEE ) Clad stainless steel is just 3 mm thick—integrally bonded. Imagine sea water entering the sulphuric acid tank via loose butterworth port lids. Tremendous heat is generated inside the cargo tank. This heat must trigger off temperature set limit alarms in the CCR.  



Thermal expansion of clad SS is 1.8 times that of mild steel on which it is clad. SS has longer cooling time. There is great distortion and warping. SS tanks which carry sulphuric acid must NOT have secondary welds which are NOT inert gas backed. Rapid chloride corrosion happens in narrow crevices.



FFF ) There must be no water in any steam coils.  for all other chemicals which are NOT water reactive , steam coils contain water.



thanks and best regards



capt. ajit vadakayil

master

XXX ( imo no - XXX )



master's cabin phone : +870 XXX (Inm F77)-- first call

bridge  phone :  +870 XXX (Sing Tel-FBB ) -- second call

bridge phone: +870 XXX (Inm F77)

fax -  : +870 XXX (Inm F77)

tlx ( sat c) : +870 XXX GYKA X


e-mail is not on line.  size must be less than XX




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From: XXX - XXXX Ship Management SG [mailto: XXX]
Sent: XX January 20XX 16:36
To: XXX - MASTER
Cc:  XXX
Subject: FW: Carriage of Acids



Ajit san,



Need your inputs on compliance to the IBC code for carriage of acids for Provision of apparatus to detect leakage of cargo into adjacent spaces when carrying acids in bulk (IBC Code, paragraph 15.11.7)



Regards

XX


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From: XXX


To: ALL MAJOR CHEMICAL TANKER COMPANIES



Sent: Tue Jan XX 06:07:03 20XX
Subject: Carriage of Acids



Dear Member,



Please find attached a submission from Australia to BLG 16 on the subject of the carriage of acids.



As you will see, Australia refers to incidents involving the leakage of acids into ballast tanks and makes suggestions regarding PH monitoring of ballast tanks adjacent to  tanks containing acids. 



We would be grateful if members involved in acid trades  could advise how their vessels comply with para 15.11.7 of the IBC Code, which requires “suitable apparatus to detect leakage of cargo into adjacent spaces” and would welcome comments on any other aspects of this paper, including any information members may have on incidents involving the carriage of acids. 



Unfortunately, papers such as this, providing little information but making what appear to be plausible suggestions have in recent years had a tendency to gather traction and we could foresee this issue being expanded into proposals such as (for example) requiring acid tanks to be fully coffer dammed. 



It is therefore important that we have as much background information as possible at hand to assist in the discussions.



With apologies for the short timeframe (this paper has only recently been circulated) we would ask that any comments be forwarded to the secretariat before the end of this week, since BLG 16 meets next week.



Thanks in advance.



Kind regards,



XXXX


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CAPT AJIT VADAKAYIL
29 YEARS IN COMMAND
..

2 comments:

  1. hi capt,
    i was on a parcel carrier loading MEG from vancouver and discharging in china. It was the supercargo's instruction to put silicon sealant on butterworth pockets before sailing.(it was a 2yr old ship). I did try to reason it out with him but he says we do it all the time!! we used to face extremely bad weather in the pacific ocean(north of aleutian-the favorite of Wx routing guys) but did not fail any sample at the discharge port.i doubt its due to the silicon sealant.
    i liked ur idea regarding the epoxy coating of the bolts.

    regards.

    ReplyDelete
  2. hi anand,

    punch into google search THE NAIVE SAILOR, TURNBUCKLES AND BOTTLE SCREWS - VADAKAYIL.

    capt ajit vadakayil
    ..

    ReplyDelete