Tuesday, February 15, 2011

WEDGE FORMULA, ON CHEMICAL TANKERS-- CAPT AJIT VADAKAYIL


              

The UTI tape can measure only what is underneath it. 

If there is an unpumpable wedge of –

1) viscous cargo ( possible if the Framo wear rings are worn out )
2) due to use of portable framo pump
3) excessive back pressure at terminal, and no internal stripping was done.

The ROB quantity inside tank can be calculated as follows using the wedge formula. 

Most surveyors and ships have ready made computer software to do this. The forward part of the aft trimmed tank is empty, and you cannot use the trim tables for ullage volume, that is why you use this formula.

F= distance of ullage pipe from aft bulkhead (metres).
B= breadth of tank (metres)
L= LBP of ship (metres)
T= trim (metres)
S= sounding of liquid (metres)
V=volume of liquid (cum)
C=corrected sounding (metres)
O= trim in degrees
D=depth of tank (metres)

TanO=T/L
C=S+(F - DTanO) TanO ( no UTI tube extension tube )
V=L X B X C/ 2T

Remember—Most of the UTI tubes have a perforated tube extension to the bottom, to prevent the 30 minute moratorium,  after completion of loading static cargoes   ( in absence of inert gas ). 

Wedge formula is applicable for the tape which falls straight through a main deck hole , by gravity-- NOT a tape which lies inside a UTI extension tube at an incline.

The above formula assumes that the vessel is box-shaped. No allowance is made  for the internal structure  or changing shape at the bottom of the wing tanks at ford and aft parts of ship . In the  case of end  wing tanks, the residues could be in error by a considerable amount.

For a square tank, as is usual on chemical tankers with several tanks, it hardly matters if the ship is listed or trimmed--common sense dictates.  

The Chief officer must know the exact position of his MMC / UTI tape inlet, and the fixed ullage float.

Use the wedge formula with commonsense. The out of work mariners who come as cargo measurement surveyors, hardly know the meaning of this term. All this is heavy money.






-------CAPT AJIT VADAKAYIL ( 28 years in command )

2 comments:

  1. sir, this is menon 2/0 who sat next to you during revalidation and now as per your advice am doing my phase 1 and this wedge is there for us and the formula you have given is not getting the needed answer. box shaped v/l 36x27x18 trim 3m,sndg-0.9mtr,LBP-270 mtrs, dist sndg pipe to aft b/hd-5 mtrs and ht of ull pipe from dk -0.9 mt. the reqd answer is 25.19 m3 which is not coming as per this formula - can you please advice ASAP?? best regards and WISHING YOU AND FAMILY A VERY HAPPY VISHU,
    sridhar menon parakkat

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  2. TALKING ABOUT RAFALE FIGHTER JET SIMULATORS--

    I ONCE ATTENDED A SHIP TANKER SIMULATOR COURSE--

    WE HAD TO DISHARGE CLEAN OILS LIKE PETROL , JET FUEL , NAPTHTA ETC

    EVERY CANDIDATE IS TIMED-- AND HIS TIMING AND ADVERSE POINTS LIKE HE LEFT SO MANY TONNES UNPUMPABLE ARE CALCULATED BY THE SOFTWARE.

    SO I ASKED THE TRAINING INSTRUCTOR -- WHAT IS THE NO 1 RECORD TILL NOW.

    HE TOLD ME THE NAME , AND THE PARAMETERS OF THE NO 1 GUY TILL DATE

    I DECLARED -- LISTEN UP ALL-- I WILL EXCEED HIM BY 100%

    THIS WAS CONSIDERED A BOAST BY A COCKY BUGGER

    INDEED , AS DECLARED , I EXCEEDED BY 100% -- BUT I HAD UNPUMPABLE CUBICS IN EACH TANK-- SO MY EVALUATION WAS "FAILED"

    SO I DECLARED-- I HAVE NEVER FAILED IN MY LIFE-- THIS MEANS THE SOFT WARE IS WRONG.

    AND WITHIN 5 MINUTES I POINTED IT OUT

    THE SHIPS TANKS WERE SQUARE WITH A PUMP AT THE AFTER MOST INNER SIDE ON WING TANKS AND AFTER MOST PORT SIDE BULKHEAD FOR CENTRE TANKS

    AS USUAL EVERY BODY WERE TRIMMING THE SHIP BY THE STERN --WHEN IT CAME TO STRIPPING DRY THE TANK USING A SMALL STRIPPER PUMP.

    I DID NOT USE THE SMALL STRIPPER PUMPS, BUT WEDGED THE LIQUID ( IN SQUARE TANKS ) BY BOTH LISTING AND TRIMMING AND USED THE MAIN LARGE PUMP .

    IN A SQUARE TANK , IT MAKES ZILCH DIFFERENCE IF YOU TRIM OR LIST-- I DID BOTH, TO WEDGE THE LIQUID TO A CORNER .

    I DID SIMULTANEOUS BALLASTING TO TRIM/ LIST THE SHIP.

    THE SOFT WARE WAS DEFICIENT- IT WAS MEANT FOR PEA BRAINED CUNTS

    IT HAD NO PLACE FOR A MAN WHO WAS EXTRA SKILLED AND EXTRA COMPETENT.

    IT IS COMMONPLACE FOR ANDRE AGASSI TO FAIL IN TENNIS ELECTRONIC SIMULATOR EXAM.

    NEVER GRADE FIGHTER PILOTS ON THE ELECTRONIC SIMULATOR .

    THEY WILL BE THE BEST OF THE CUNTS , WITH NIL GAAAND MEIN TATTI , INITIATIVE OR SELF CONFIDENCE

    http://ajitvadakayil.blogspot.in/2011/02/wedge-formula-on-chemical-tankers-capt.html

    capt ajit vadakayil
    ..

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