Sunday, June 6, 2010

STEAM HEATING ON CHEMICAL TANKERS-- CAPT AJIT VADAKAYIL




ALL CHEMICALS CARRIED AT SEA ARE HEATED BY HOT WATER AND NOT STEAM.   THE TANK HEATING COILS AT EXIT POINT OF TANK , MUST CONTAIN HOT WATER NOT STEAM.   

THE TEMPERATURE OF WATER IN THE COILS IS ADJUSTED BY THE RETURN VALVE FROM TANK .   THE STEAM INLET VALVE TO TANK MUST BE 100% OPEN ALWAYS .


Heating is done to ----

Reduce viscosity. Viscosity is measured in centistokes. Water is one cst. As the temp rises viscosity reduces at the rate of 2% per degree.

Reduce pour point. Pour point is 3 degrees over temperature were liquid coagulates.

Reduce cloud point. Cloudpoint is the temp where cystallised solids forms inside liquid and settles on bulkheads.

Avoid crystallization. Some cargoes like Caustic Soda require heating to avoid crystallisation.

Avoid freezing of cargo. Some cargoes like Cyclohexane require heat to avoid freezing.

To avoid pre-wash at discharge port. Heating may also be required in order to comply with MARPOL regulation for prewash ( Phenol will have to be prewashed if dischg berth temp is below MP plus 10 deg.

To increase the water solubility.  For example Phenol is soluble in water at a temp of 60 degrees.

To reduce unpumpables at tank sump.

To reduce delivery pressure of the ships centrifugal deepwell pumps.

To avoid claims from the charterers who want a particular voyage and discharge heat. Under heating and over heating will both result in claims from charterers.

To reduce clingage. Clingage does not include the tank bottom

For tank heating coil system the size of the main return line is smaller than that of the steam inlet line. Because the return line is supposed to contain water only, while the main inlet line is supposed to contain steam only. For the steam winches the case is opposite, the return line is bigger as it contains expanded steam.

From the engine room boiler steam arrives on deck through the main inlet steam pipe. Before it enters the deck it has to pass through a PCV or pressure control valve of 1 bar to 7 bar range. There will be a small bypass line around this valve for initial warming prior starting. This bypass must be operated for at least 45 minutes on a small chemical tanker, before the PCV is opened. Heating must be started slowly to reduce thermal stresses.

When not in use the steam coils should be full of fresh water---unless the cargo is water reactive in which case it must be blown dry and blanked.

For initial starting the PCV is put at 1 kg and then slowly increased. Open all drain cocks in the steam inlet line till water is ejected and steam comes out.

Only water should return to engine room through the return line –otherwise it is a huge waste of money. This is one of the energy conservation items . This water must be pure and should not contain any cargo. There is an inspection chamber ( called siphoning drum ) where the first one hour of return water must be monitored. On a chemical tanker you can view through a glass port to check for floating insoluble cargoes, get the odor from the vent to check for volatile soluble cargoes, and drain from the bottom to check for sediments or high SG insoluble chemicals. 

When carrying heating cargoes the return siphoning drum content must be inspected daily check for any traces of cargo—if any are found then the heating coils must be drained individually to find out the culprit. This coil can then be blanked off. The drain valves and siphoning drum must be checked twice daily for ingress of cargo.

Heating of tank is regulated also by the number of active coils from inlet manifold. Temperature of return line has to be taken regularly to find out if you are over heating or under heating. Centre Tanks with double skin has to be heated less than wing tanks who have a cold interface with ballast.

IT IS IMPORTANT TO KNOW HOW TO STOP HEATING. OR YOU DESTROY THE HEATING SYSTEM.  THE IDEA IS TO AVOID TRAPPING HIGH PRESSURE STEAM WHICH ON COOLING WILL CAUSE A HIGH VACUUM BUILD UP . THIS  WILL CAUSE CORROSIVE / EXPLOSIVE/ TOXIC CHEMICALS TO BE SUCKED INTO THE COILS .  First close the inlet valve . Then open drain cock in front of the return valve. Then close return valve.

One single leaking coil can contaminate other clean coils via the return manifold. Steam blow contents must always be checked for pH

If steam heating coils fail ---in an emergency ,use adjacent heat including live steam in ballast water around the tank. When no heating is done temp usually drops 1-2 deg C a day.

When you heat raise the temp to 5 to 6 deg a day---NOT MORE. Many cargoes perish due to indiscriminate overheating . Too high temp causes unacceptable VP or chemical/ physical change which can be permanent. When veg/ animal oils are overheated Carbon Monoxide  is formed which can affect the sweeping party. Overheating luboils can cause oxidation of cargo and colour off spec. Overheating Molasses cause thermal decomposition and total destruction.

Make sure cargo is at the discharge heat four days prior arrival. To expedite the process, remove cold ballast interface.

The heating coils of tanks not required to be heated must be blanked on both entrance and exit and log entry made. In order to avoid confusion, heating coils  should only be used when a cargo requires heating. Any other cargoes on board should have their coils blanked on both the inlet and return side. This is also of paramount importance if the cargo is inhibited, subject to polymerisation ( Styrene Monomer ), or has a violent reaction water ( Sulphuric acid ) etc. 

Tanks which require heating must be pressure tested prior loading and log entry made. If the coils leak –you cannot load unless permanent repairs with proper stainless steel welding is done by chief engineer.

If a heated valve is tight allow it to cool. If you force it , you damage it.

Some ships have deck mounted heat exchangers –Framo pump discharges into a heater at about 60 bars.                       
The two methods for testing steam coils on board are:
Hydraulic testing using water
Steam pressure testing

It is possible to carry out pneumatic testing (air), but this method is considered unreliable and will NOT be considered suitable for meeting company standards, and is NOT to be used.

Hydraulic testing of heating coils is time consuming and cannot be carried out in all tanks on a regular basis. The hydraulic testing of heating coils must be carried out, by ship's engineers, once a year. or as dictated by the company. It is recommended that tank tests are staggered so they are not all due at the same time. Hydraulic testing must also be done by chief engineer after any permanent repairs have been made to the heating coils. The results of all hydraulic tests must be recorded in the log book and the planned maintenance system.
Steam testing of coils is to be carried out before the loading of every heated cargo as a policy.

Thermal oil heating coils are to be hydraulic tested, using oil, every two years. If defects occur, then the coils must be tested annually.The coils must also be tested after any repairs.

All coils must be hydraulically tested when they have been replaced following disassembly for coating work. etc. In a docking situation this should be done before leaving the yard. If this is impossible, then testing should be scheduled for as soon as it is practical.

Any cargo damage due to steam coil leak or ingress into steam coils is un acceptable to us, it is considered as personal failure.

For cold hydraulic testing use Graco pump and a 200 litre FW drum to pressurise to 12 kg.  Do not forget to inspect the riser piping. Testing must be done coil by coil. Also check for loose nuts from steam coil clamps.

It is the more severe of the two test methods due to the fact that when using steam, heat expansion can cause small leaks to seal, and also higher pressure (1.5 times) than working pressure can be used.

When carrying out hydraulic testing, it is important that the tank is completely dry , and cold water ballast interface at the tank bottom is removed. This will make the detection of very small leaks much more easier—any water at the bottom means a leak.
Install blanks to provide the required test boundary. Connect the hydraulic test pump to the coils and install a suitable pressure gauge. Fill the coils with good fresh water. Build up the pressure in the coils to 1.5 times their maximum rated working pressure. Close the hydraulic pump valve to prevent pressure drop. Monitor the pressure of at least 30 minutes, without additional pumping. If a leak is indicated by a pressure drop, then the entire system must be checked until the leak is found.

After 30 minutes, the coils are to be thoroughly examined. The thorough examination must include a very close visual inspection and also feeling by hand under the coils in order to detect any pinhole leaks. Such pinhole leaks may not be indicated by a pressure drop on the manometer and can also be very hard to detect by the eye.

Repair and properly document all leaks detected. Repeat the test procedure after repair.

The testing of coils using steam pressure from the ship's boiler:
Misleading results can be obtained from steam testing due to steam condensation in the coils if the test is not properly conducted as described below. The maximum maximum boiler pressure is to be used . The coils to be tested should be exhausted to atmosphere until live steam is issuing from the return. Close the return against the steam. The steam pressure must be held for 30 minutes prior to inspecting.

Another 2 in one ( DUAL )method is with return valve closed, open the steam inlet at 7 kg . This will then give an easy hydraulic test on coil due to trapped condensate in line. Inspect the coil for water leaks. Following the above, return valve to be opened and steam allowed to flow through the coil via the steam trap. After 30 minutes have elapsed, coils to be inspected for leaks. By shining a torch light along the coil, escaping steam will be highlighted.

If a leak is detected and a section of piping has to be repaired, a proper hydraulic test should be carried out after the repair is completed as a policy. Install blanks to provide the required test boundary, ie isolate only the coil to be tested.

When carrying out visual inspections for leaks, look closely for signs of corrosion. Corrosion leaks may require further close examination of the coils to determine the amount of damage. Bad corrosion may mean the whole section may have to be cropped and renewed. All corrosion problems are to be reported to the chemical operator immediately.

Heating coils not in use must be steam pressure tested every 3 months and its results must be recorded. If heating is not to be done the coils must be blanked—and log entry made

If the Master is unable to comply with the charterers heating instructions he must inform the  chemical operator well in advance. Make sure that there is enough bunkers on board to run the boiler.

Under no circumstances should cargo exceeding tank lining resistance tables temperatures be accepted for loading. Be aware of the maximum cargo temperature stipulated in the charter party.

It is the responsibility and duty of chief officer to take the temperature  twice daily—the critical heating log must be signed by him daily without fail—signature must not be postponed to the next day. A signed copy must be hung in CCR bulkhead for Chief engineer to monitor.

The steam valves of wing tanks and forward tanks are usually opened more. The % of the return valve opened must be entered in the log column.

The Chief engineer must log down daily the bunkers used in boiler solely for heating cargo.

Heated cargo temps must be taken at 3 levels inside tanks. As the cargo is discharged , the steam heating into the tank must be reduced. Heated cargoes must be stripped immediately. IT MUST NOT BE POSTPONED.

There must be an action plan ( as part of the pre-load pre-dischg meeting ) to melt solidifying cargoes from inside the pipelines and to prevent valves from getting frozen in place.  If steam hoses have to be used the crew must use PPE and heat resistant gloves.. Steam must be applied at the underside of
the pipes. It is more effective to use hot water on a burlap lagged pipes , especially at bends.

If the pump impeller is frozen steaming into empty DB via sounding pipe can be considered—but inform the chemical operator first.

Before discharging a high MP cargo consider recirculating the cargo before opening the tank delivery valve and the manifold valve.

STEAM TRAPS
Simply put, steam traps are automatic valves that release condensed steam (condensate) from a steam space while preventing the loss of live steam. They also remove air and non-condensables from the steam space.
Once steam has transferred Btus and becomes hot water, it is removed by the trap from the steam side as condensate and either returned to the boiler via condensate return lines. Continuous flow traps will continuously discharge condensate.
Normally there will be no need for level controller of tank cleaning heater if you do not excced 8 machines.

Steam traps on return line coils senses the difference between flow of water and steam. There are filters in front of each steam trap. Clean these filters and also steam traps regularly.

Steam traps must be overhauled regularly to ensure correct function of the steam trap and heating of the cargo. Twice a year and before loading high-heat cargo it is also recommended to open up the steam trap and blow coils through and remove any previous cargo which may have leaked into the coil thereby blocking the trap and narrow parts of coil on deck causing nil heating and subsequent slow discharge claim.


CAPT AJIT VADAKAYIL ( 28 YEARS IN COMMAND )

10 comments:

  1. Thank you for the info. It sounds pretty user friendly. I guess I’ll pick one up for fun. Thank u
    Heating Repairs

    ReplyDelete
  2. Wanted to report on how am I doing after your help for some personal issues.

    - Pranayam has not been regular; but running is (2-3 days a week) The heel pain is not helping.
    - Personal life is getting better but I will report back when it is fully on track.
    - The garlic thing is a magic....I have done it for 8 straight days; at first the stomach remained very heavy for some reason immediately after I chewed the chopped garlic and drank water. BUT THE FRESHNESS IT BRINGS NOW IS AMAZING

    Now about some more personal item and wanted to get your expert advice

    I was diagnosed with Renal Infarction in 2014. Initially the urgent care doctor said Diverticulitis and then after I could not take the pain the ER did MRIs with Bromine dye and identified that 25% of my kidney is blocked (left side). They suspected an infarct dislodging from a blood vessel and stopping at the kidney. If it had happened in the brain or heart (it would have resulted in stroke and heart attack). So soon they put me on Coumidin and indicated that I will have to be on it for life and weekly checks with INR # that should be maintained between 2 -3. BTW I was in the hospital for a week while they did all kinds of scan (brain, heart, MRIs, etc.). The outcome is I have some genetic deficiency of Protien C (not the food one). 6 Months later they did the MRI again and indicated that Protein defficiency may have occurred due the Infarct and now it is gone so you are off Coumidin and I was relived.

    To make the long story short....I had similar pain since 3 days (sam place same Kidney) and I rode it out (not extreme like before) but since they did not find anything prior to this I don't know what they will find now. I don't have that pain anymore.

    The only change or items that I am taking is B12 tablets (41667% of daily value) as I have throbbing pain in my left leg heel while I walk and in the morning.

    Please let me know if there is something else I should do.

    Please delete the comment when I reply back to you. When you get a chance.

    Kind Regards,
    Saurin

    ReplyDelete
    Replies
    1. hi sp,

      https://www.youtube.com/watch?v=fSZa4tGnuRo

      Pain on the bottom of the heel is plantar fasciitis or better known as heel spur syndrome. Another common cause is nerve entrapment ( more than 70% of patients have both plantar fasciitis and nerve entrapment) .

      A sharp stabbing pain, like a nail going into the bottom of the heel when first stepping on the foot after getting out of bed or after sitting for period of time, is the most common description for plantar fasciitis or heel spur syndrome. Typically the pain eases off as the day goes on but it may not go away completely. A thick ligament that attaches to the bottom of the heel and runs the length of the foot to the toes can become inflamed and swollen at the attachment site. This tends to be an overuse type of injury where poor foot structure is involved; also, wearing of shoe gear that lacks adequate support (ie: worn out shoes, boots and flip-flops) and prolonged standing or walking are often implicated.

      A throbbing pain that gets worse as the day goes on and can be worse at night when laying in bed is most often associated with an irritated or entrapped nerve on the inside of the ankle or heel. This is similar to carpel tunnel syndrome in the wrist and hand. Approximately 70% patients with heel pain have a component of nerve entrapment as the cause of their heel pain. This is also one of the most common causes of chronic heel pain because it is often missed as a diagnosis

      Posterior Heel Pain (Retrocalcaneal):- This is pain in the back of the heel that flares up when first starting an activity. It is often associated with a large bump that can be irritated by shoes. The Achilles tendon attaches to the back of the heel and, like on the bottom, this attachment site can often become inflamed; a spur may or may not be present. Another painful area is a sac of fluid (bursa) that sits between the tendon and bone to act as a cushion for the tendon. This bursa can become inflamed often leading to significant pain called retrocalcaneal bursitis.
      Rest– reducing activities for a few days can help to reduce the most severe pain.
      Avoid going barefoot – when without shoes excessive stress and strain is placed on the plantar fascia.
      Proper shoe gear – supportive shoes that fit and are not too worn along with good arch support help to reduce the stress and strain on the plantar fascia over time.
      Medications – non-steroidal anti-inflammatory medication, such as Motrin (ibuprofen), may help to reduce inflammation.

      The plantar fascia is made of dense, fibrous connective tissue that will stretch very little. It acts something like a shock absorber. As the foot impacts the ground with each step, it flattens out lengthening the foot. This action pulls on the plantar fascia, which stretches slightly. When the heel comes off the ground the tension on the ligament is released. Anything that causes the foot to flatten excessively will cause the plantar fascia to stretch greater that it is accustom to doing. One consequence of this is the development of small tears where the ligament attaches into the heel bone. When these small tears occur, a very small amount of bleeding occurs and the tension of the plantar fascia on the heel bone produces a spur on the bottom of the heel to form. Pain experienced in the bottom of the heel is not produced by the presence of the spur. The pain is due to excessive tension of the plantar fascia as it tears from its attachment into the heel bone

      GARLIC MANAGES THIS AILMENT

      capt ajit vadakayil
      ..

      Delete
  3. Thanks a lot Captain. Very helpful. Garlic thing is continuing. Please let me know if you can comment on the Kidney issue (Renal Infarction.) Understood when you get a chance as you are preparing for the new post on Hinduism.

    ReplyDelete
  4. STOP PRESS:

    SOMETIMES MY READERS WONDER HOW I GET SO MUCH OF UNKNOWN INFORMATION..

    A CHUNK OF IT CAME BY "SHAKING DOWN " PEOPLE.

    MAKE SOMEONE FEEL THAT IF HE DOES NOT CONFESS- HE WILL GO TO JAIL-- AND I HAVE THE POWER TO DO IT.

    THIS IS WHO I CAME TO KNOW SECRETS OF "INDIAN SHIP MANAGEMENT COMPANIES "

    EXAMPLE?

    ONCE I WAS PUT IN A HOTEL ROOM WITH SAME SEROUS DEFICIENCIES --SAY THE ROOM DID NOT HAVE A WINDOW

    I WOULD CALL FOR THE TOP MANAGER AND SHAKE HIM DOWN.

    BUT HEY--

    BUT I MAY RE-CONSIDER , IF HE TELLS ME HOW MUCH KICK BACK PERCENTAGE HE GIVES TO THE MANNING OFFICE WHO PUTS SHIP OFFICERS IN HIS HOTEL.

    PAT- THE ANSWER WILL COME-- 40 %

    THIS MEANS IN A HOTEL ROOM COSTING 5000 BUCKS A DAY 2000 BUCKS GOES TO THE POCKET OF OWNER/ MANAGER OF THE MANNING OFFICE.

    I HAVE SHAKEN DOWN SHIPPING ACCOUNTANTS IN FOREIGN NATIONS . NOBODY LIKES JAIL

    I HAVE COME TO KNOW OF SLIMY SHIP MAMANGEMENT INDIAN COMPANIES WHO PAY AN OFFICER 6000 DOLLARS A MONTH-- BUT THEY FORGE THE WHOLE SIGNED SHEET AGAIN ( ENTIRE CREW ) IN THE OFFICE , AND CHARGE THE JAPANESE SHIP OWNER 30% EXTRA.

    THAT MEANS IF THE ACTUAL WAGES GIVEN ARE 2 LAKHS DOLLARS PER MONTH 60,000 DOLLARS ARE SKIMMED OFF BY THE INDIAN SHIPMANAGEMENT COMPANY--WITHOUT THE CREW OR THE JAP SHIPOWNER KNOWING.

    OFFICERS AND CREW ARE MADE TO PAY FOR THE "FLAG DOCUMENTATION" SAY--PANAMA/ MONROVIA ETC SAY 800 DOLLARS-- BUT THEY COLLECT THIS MONEY FROM THE JAP OWNERS TOO--

    FLAG DOCUMENTATION-- CERTIFICATE OF COMPETENCY, CDC, SPECIAL VERTIFICATES LIKE OIL / CHEMICAL/ GAS ADVANCED COURSEs ETC

    I HAVE THE POWER TO JAIL SEVERAL HIGH FLYING MAHA MERUS WITH PROOF. I HAVE REVEALED JUST 2%.

    SOME OF THEM ARE IMMORAL SONS OF BITCHES-- THEY WILL SELL THEIR OWN MOTHERS TO WHORE HOUSES.

    WELL THEY WILL READ THIS TODAY--AND ALL WILL SHIT IN THEIR LANGOTS AND SPEND SEVERAL SLEEPLESS NIGHTS

    capt ajit vadakayil
    ..


    Capt. Ajit VadakayilFebruary 26, 2016 at 2:31 PM
    SOMEBODY CALLED –

    ASKED ME CAN YOU REVEAL SOME MORE ABOUT THESE BASTARDS RUNNING INDIAN SHIP MANAGEMENT COMPANIES—

    OK— TWO MORE

    AAA- MONTHLY ALLOTMENTS TO HOME BANK REACHING LATE.
    ##################################

    LET US SAY THAT I SENT 15000 USD AS MONTHLY ALLOTMENT TO MY WIFE

    IT WILL REACH MY HOME ONLY AFTER 20 DAYS

    THE FIRST 20 DAYS , THEY MILK OFF THE INTEREST ( HUGE AMOUNT FOR THE WHOLE CREW ) IN SOME BANK.

    AS A BONUS TO THESE BASTARDS I WILL NOT REVEAL THEIR FCNR / NRE MONEY CHANNELING VIA THE MAURITIUS ROUTE OR WHATEVER -- FERA - AS OF NOW


    BBB- A LOT OF COMPANIES DEMAND THE FIRST MONTHs SALARY AS BRIBE.
    ######################################

    I STOPPED THIS WHEN I CAME TO KNOW ABOUT THIS.

    EXAMPLE: I HAD A BANGLADESI OFFICER WHO HAD TO PAY HIS RECRUITING MANNING AGENT ( A SHORE CAPTAIN ) AT DHAKA , HIS FIRST MONTHs SALARY- BEFORE BOARDING THE SHIP.

    THIS MEANS YOU WORK THE FIRST MONTH WITHOUT SALARY.

    I CALLED UP THE TOP HONCHO IN DENMARK ( MY DIEHARD FAN ) AND STOPPED THIS NONSENSE , THAT VERY MINUTE.

    Capt ajit vadakayil
    ..

    ReplyDelete
  5. Hello Captain,

    I had sent a comment 2 times at various intervals to get your advice and guidance. Please let me know if you did not get it and wish not to comment.

    I really wanted to get your advice on leaky gut syndrome.

    Thanks
    Saurin

    ReplyDelete
    Replies
    1. I HAVE COMMENTED ON CHRONS AND LEAKY GUT SYNDROME SEVERAL TIMES.

      google-

      LEAKY GUT VADAKAYIL

      Delete