KEMEL AX Air Seal INSTRUCTION MANUAL
The KEMEL AX Air Seal is a reliable and efficient system for keeping seawater out of the stern tube of a vessel. The system uses compressed air to create a barrier between the seawater and the stern tube oil, minimizing the risk of contamination. The AX Air Seal also automatically regulates the oil pressure based on the ship's draft, minimizing the load on the seal rings and extending their service life.
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KEMEL AIR SEAL Type AX (With Air Relay) INSTRUCTION MANUAL This manual is produced based on a typical lubrication diagram for stern tube system installed with Type AX seals. For correct understanding and operation of the ship’s system, read this booklet together with seal drawing and the piping diagram available in the finished plan. Besides this booklet, read Instruction Manual for KEMEL COMPACT SEAL Type CX, DX & AX included in the finished plan. http://www.kemel.com Contents 1. Outline 1.1 Construction 1.2 Air Control Unit (MU) 1.3 AFT Seal 1.4 S/T L. O. Tank Unit (TU) 1.5 Oil Pressure Unit (OU) 1.6 Drain Collection Unit (CU) -------------------------------------- P. 2 2. Oil Filling & Oil Pressure Test -------------------------------------- P. 5 3. Operation of Air Seal 3.1 Start-up Air Control Unit (MU) 3.2 Operation of Air Seal -------------------------------------- P. 5 4. Daily Maintenance ------------------------------------- P. 8 4.1 Stern Tube System 4.2 Air Control Unit & Drain Collection Unit 5. Trouble Shooting ------------------------------------ P. 10 5.1 Abnormalities of Air Pressures/Air Flow & Actions 5.2 Alarms & Actions 5.3 Other abnormalities & Actions 6. Switch-over to normal Oil Seal System for emergency ---------------- P. 13 7. Operation for Dry-docking, Undocking and Laying-up ---------------- P. 14 7.1 Dry docking & Undocking 7.2 Laying-up -1- 1. OUTLINE 1.1 Construction Air Seal keeps seawater out by blowing air into sea through an air chamber (Air Chamber) provided at the space between the #2 & 3 seal rings in AFT seal, and it keeps oil tight by controlling stern tube oil pressure to follow change of ship’s draft. Segregation of seawater and stern tube oil by Air Chamber minimize the risk of seawater contamination. Besides, a drain line provided at the bottom of Air Chamber collects and recovers leaking oil and water in engine room in case of leakage. At the same time, the system automatically optimizes the oil pressure based on draft pressure detected at Air Chamber and remarkably reduces the pressure load given on AFT seal at all draft levels. The construction of Type DX seal with a stand-by spare seal ring is employed on AFT seal, which enables switching-over to the spare at any time by simple valve operation. FWD seal has a same construction as existing models. The schematic diagram and the components for the system are shown in the sketch below. Component Function Supply air to AFT seal Air Control Unit （MU） Regulate supply air pressure Regulate air flow Pressurize S/T L. O. Tank Clean air pipe by fresh water S/T L. O. Tank Unit （TU） Oil Pressure Unit （OU） Drain Collection Unit （CU） FWD seal L. O. Circulation Unit -2- Supply oil to Pump Pressurize stern tube Circulate stern tube oil - Pump Recover leaking oil/water Recover cleaning fresh water Circulate FWD seal L. O. 1.2 AIR CONTROL UNIT (MU) Air Control Unit (MU) regulates supplied compressed air at the pressure*) set by Air Regulator (R1) and at the flow rate*) set by Air Flow Controller (FC1) after passing Air Filters (F1 & F2). Then the regulated air lead to Air Chamber in AFT seal is blown into sea, called Air Blow Line which has a branch line to Air Relay (AR1) to give the pressure of air blowing as an input signal. Another branch line taken after Air Filters is lead to S/T L. O. Tank Unit (TU) through AR1 to pressurize it, called TU Line. AR1 regulates the pressure in TU Line at the level of the signal pressure from air blowing. AR1 has a hand wheel for fine adjustment of the regulating pressure. TU Line has change lever C2 to bypass AR1, through SUB Line, which gives TU a direct pressure from Air Blow Line. MU has a spare Air Regulator (R2) and a spare Air Flow Controller (FC2) on SUB LINE for switching over from R1 & FC1 on MAIN LINE by C1 Lever. Also MU has Fresh Water Line for periodical cleaning of air purging pipe and has an Alarm Switch for Air Pressure Low. Air Regulators R1 and R2 have pressure gauges P2 and P3 for stetting air pressure. *) Set values of Air Regulators and Air Flow Controllers are shown in “Finished Plan – Piping Diagram Fig. 1”. Air Flow Controller MAIN FC1 Air Source Pressure P1 MAIN/SUB Change Lever C1 Air Flow meter FM1 Air Flow Controller TU Air Pressure P5 Differential Pressure Gauge MAIN/SUB Change Lever C2 DP Air Filters Air Regulator SUB R2 & P3 F1・F2 Control wheel Air Relay Air Regulator MAIN R1 & P2 AR1 MU Side View Left FC2 Blowing Air Pressure P4 MU Front View MU Side View Right Air Blow Line OUT1 Test Line OUT3 TU Line OUT2 Fresh Water Line F/W Air Filter Drain Drain Air Source IN MU View Bottom Panel -3- 1.3 AFT Seal Air supplied from MU to AFT Seal blows out underwater through Air Chamber, with the pressure set by Air Regulator. The effects of air blow are explained below; 1) When the pressure in Air Chamber slightly exceeds the tension forces from the #1 & #2 seal rings + seawater pressure from the draft, the air lifts up the #1 & #2 seal lips and starts blowing into sea through the gap, formed by the lift, with the constant rate set by Air Flow Controller. 2) The gap by constant air blow makes Air Chamber being kept opened in-water all the time. 3) By this, Air Chamber pressure is equalized to the level of tension forces from the #1 & #2 seal rings + seawater pressure from the draft or slightly above. Because of the opening underwater, Air Chamber pressure does not go higher up to the pressure set by Air Regulator, and also continual air blowing prevents seawater penetration into Air Chamber. Air Flow Controller keeps constant flow and maintains the gaps under all draft level of the ship. Therefore the pressure in Air Chamber follows water pressure from draft change with no time-delay. In addition, air from MU partly returning to Drain Collection Unit (CU) with slight ventilation in E/R generates low speed air flow to remove leaking oil or water from Air Chamber, through a drain hole provided at the bottom lead into CU. The #3 & #3S seal rings can be switched over by valve operation in E/R. (Valve “C” & “D” shown in the piping diagram P. 6.) Open these valves for the #3 in use and close them for the #3S in use. 1.4 S/T L. O. Tank Unit (TU) TU is an air-tight oil tank having 100 - 200L capacity and is installed to give oil head pressure in stern tube with 2 - 2.5M of the oil height above shaft centerline. In addition, TU is connected with an air pipe via AR1 equalizing the line pressure at Air Chamber Pressure. By the arrangement, stern tube is pressurized at the level of oil head pressure + Air Chamber Pressure which is loaded onto the #3 seal ring, supported at the same time by Air Chamber Pressure from seawater side while air blows out as described in Article 1.3. Because of Air Chamber Pressure at the front face and the back of the #3 seal ring, it counteracts each other cancelling the force. As a result, the actual load remains on the #3 seal ring is oil head pressure of TU constant at all draft. Same effect is available on the #3S seal ring when it is in use. TU is provided with Safety Relief Valve to avoid excessive pressure, and Alarm Switches for Oil Level High & Low. TU is also connected with Oil Pressure Unit (Oil pumps) to circulate stern tube oil. Oil Level High/Low Alarm switches Safety Relief Valve Oil level gauge TU Line connection Drain Valve （N. C.） Air Vent （N. C.） TU Top View TU Front View -4- 1.5 Oil Pressure Unit (OU – Oil Pump) OU circulates lubrication oil via “OU ➔ Stern Tube ➔ TU ➔ OU”. Stern tube oil pressure is measured at the return line from stern tube to TU. The correct pressure is calculated by adding (or deduction on some cases) oil head pressure from the gauge height to the reading value. (See calculation example in P.7.) Periodically examine oil suction & discharge pressures on the pumps, and clean strainers for maintenance whenever is necessary. 1.6 Drain Collection Unit (CU) CU is an air-tight tank with 10L capacity and is located below the shaft level. CU is connected to a drain pipe from Air Chamber in AFT seal. Flow Controller (FC) fitted on CU gives air-flow at a low speed (about 5 L/min.) from Air Chamber towards CU to remove leaking seawater and oil into CU through the pipe. Drain recovered can be discharged by the air pressure in CU, through Drain Valve. (Discharge drain while M/E is stopped.) CU is fitted with Level Gauge and High Level Alarm Switch Joint for AFT seal drain pipe Air Flow Controller FC Air Vent High Level Alarm Switch Level Gauge Drain Valve (N. C.) CU 2. Oil Filling and Oil Pressure Test Procedures for oil filling to stern tube and oil pressure test for Air Seal is described in P. 6. Confirm actual valve operation for oil filling, circulation, draining & etc. in ship’s piping diagram available in finished plan. 3. Operation of Air Seal 3.1 Start-up Air Control Unit (MU) When air supply to Air Seal become available, start-up MU after filling oil in stern tube by the procedures below, 1) Put valve positions in MU for blowing air as per Finished Plan – Piping Diagram Fig. 1. 2) Close Air Vent on TU and Drain Valve on CU. 3) Put valve positions for oil circulation via “TU ➔ OU ➔ Stern Tube ➔ TU”, then start-up OU. 4) Open air source valve for MU. 5) Adjust settings for Air Regulator R1 and Air Flow Controller FC1 if necessary. 6) Confirm air blowing at AFT seal in dry-dock, or at sea surface in stern area after launching. 7) Record all data by using the form shown in P. 7, and examine the system is working right. 8) Adjust stern tube oil pressure Ps/t by operating bypass valve on OU and AR1 on MU if necessary. 9) Put Change Lever C1 on SUB and examine all pressures. (FM1 does not work with SUB in use.) 10) Put Change Lever C2 on SUB and examine all pressures. 11) Put Change Levers C1 & C2 on MAIN for normal operation. In case of launching a new ship with no air blowing, examine CU periodically for possible water penetration after floatation. 3.2 Operation of Air Seal Air Seal System is in operation when blowing air into sea is started. The system automatically controls stern tube oil pressure at the optimum level responding to changes of ship’s draft. Keep blowing air and operating OU all the time while the ship at sea as well as at berth or anchor. OU may be stopped for maintenance etc. while M/E is stopped. In case air source is shut off, stern tube oil pressure stays at the level of oil head pressure from TU. Closely watch seawater penetration in CU in such an event, and recover or establish air supply as soon as possible. Maintenance of stern tube system, MU and CU is done as per the article 4 in P. 8. -5- -6- Leak test via "X"-line Apply oil pressure in stern tube either by X-line or by air pressure, and carry out the test in accordance with the procedure shown in the table. 1) Close valve "G" on oil line. 2) Open valves "A", "B" & "H" on oil line. 3) Keep valves "C" & "D" closed. 4) Close air vent on TU. 5) Operate OU, and circulate oil via TU➟S/T➟TU for test. 6) Set valve positions in MU are for Air Blow. 7) Reduce Regulator setting (0.2 - 0.4MPa) on "MU" to 0.1MPa. 8) 8) Close valve "E", or V4 valve in MU. 9) Check Ps/t shows about 0.1MPa and proceed for the test. Leak test by applying air presssure in MU 1) Close valves "A" & "B". 2) Keep valve "G" opened. Keep valves "C" & "D" closed. 3) Operate OU 4) Circulate oil via Sump Tk➟S/T➟"X"-line➟Sump Tk for test. 1. Valve positions shown above are for "Normal Operating Condition" of Air Seal System. 2. "X"-line is for oil circulation via the gravity line, not in use during operation of Air Seal System. 1) Fill Sump tank, - Open Valve "I". 2) Close air source valve for MU, and open air vent on TU. 3) Close valves "C" & "D", and open valve "G". 4) Keep valves "A" & "H" open, and close valve "B". 5) Fill stern tube and TU with oil by operating OU. 6) Stop OU after TU filled up with half level. 7) Close air vent on TU. 8) Carry out Test Order "1" & "2", either by using; a) "X"-line, or b) Air pressure 9) Fill oil in #3/3S by Test Order "3" after "1" & "2". 10) Fill oil #4/5 by Test Order "6" after "3", "4" & "5". Procedure Oil Filling TYPICAL DIAGRAM - Confirm valve no.s & details in Finished Plan #1 #5 5 6 1) Plug all holes between #4 & 5 on FWD seal casing. 2) Fill #4/5 chamber with oil. 3) Clean up seal casing/liner to remove oil wet. 4) Confirm no oil leaking out. 5) Confirm all oil holes on FWD seal plugged after the test. 1) Same procedures 1) - 5) for testing #2 seal ring above. 2) Confirm no water leaking out. 3) Drain out Fresh Water after the test. 4) Confirm all holes for filling, draining & air venting on AFT seal plugged. 1) Leave bottom plug between #2 & 3 opened. 2) Plug bottom hole between #1 & 2. 3) Remove two plugs on top between #1 & 2, for filling and air venting. 4) Fill #1/2 chamber with "Fresh Water" through the top hole. 5) Clean up seal casing/liner/filling holes to remove wet. 6) Confirm no water leaking through the bottom hole between #2 & 3. 1) Plug all oil holes/drain holes between #3 & 3S on AFT seal casing. 2) Open valves "C" & "D", to apply pressure in #3/3S chamber. 3) Close valve "H" for about 30 sec. to direct oil flows into #3/3S chamber. 4) Keep valve "H" open again for the test. 5) Remove bottom plug between #2 & 3 on AFT seal casing. 6) Clean up seal casing/liner/oil holes to remove oil wet. 7) Leave the plug opened for more than 3 hours. 8) Confirm no oil leaking through the bottom hole. 1) Same procedures as 1) & 2) for testing #3S above. 2) Remove bottom plug between #4 & 5 seal rings on FWD seal casing. 3) Clean up seal casing/liner/oil holes to remove oil wet. 4) Leave the plug opened for more than 3 hours. 5) Confirm no oil leaking through the bottom hole. 6) Confirm no oil leaking at other area, i. e. sheet packing, "O" ring & etc. 1) Fill stern tube and TU with oil. - See left "Procedure Oil Filling". 2) Keep valves "C" & "D" closed. 3) Apply oil pressure in stern tube. 4) Remove bottom plug between #3 & 3S seal rings on AFT seal casing. 5) Clean up seal casing/liner/oil holes to remove oil wet. 6) Leave the plug opened for more than 3 hours. 7) Confirm no oil leaking through the bottom hole. 8) Confirm no oil leaking at other area, i. e. sheet packing, "O" ring & etc. Procedure REMARKS 1. Carry out leak test after completion of flushing pipes. 2. Take wear-down readings before and after overhauling AFT seal, for repair ship. 3. Protect seals from sand blasting, painting, welding, chemicals, excessive heat & etc. 4. Use stainless steel fitting bolts (SUS 316 or equivalent) for AFT seal installation. 5. Secure all the fitting bolts and plugs for AFT seal by using stainless steel wire. 6. Put all valves (and regulator setting) back to "Normal Operating Condition" after the test. 7. Check P2 pressure indication for Regulator on the green mark. 8. Oil level may suddenly reduce when air-locking dissolved. Fill oil in such an event. #2 #3 #4 #3S 4 3 2 1 Test Seal Orde Ring LEAK TEST PROCEDURE in dry-dock (AIR Seal Type AX) -7- P2 P3 P4 P5 10.4 0.7 0.3 0 0.11 0.1 0.01 C1 Initial Setting Standard setting Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Main/Sub Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty Clean/Dirty *** *** *** Height of shaft centerline above keel (m) Main Main/Sub Main/Sub Main Clean/Dirty Clean/Dirty 40 Clean/Dirty Clean/Dirty * * * Adjust settings shown in Finishied Plan - Piping Diagram Fig. 1. DP Green range (less than 0.1MPa) FM1 4 0 or 50L/min. P1 More than 0.4MPa P2 0 . 2 5 - 0 . 3 5 M Pa on MAIN, 0MPa on SUB P3 0MPa on MAIN, 0 . 2 5 - 0 . 3 5 M Pa on SUB Symbol C2 flow flow/no flow/no flow/no flow/no flow/no flow/no flow/no flow/no flow/no flow/no flow/no flow/no flow/no flow/no flow/no flow/no empty/oil/sw empty/oil/sw empty/oil/sw empty/oil/sw empty/oil/sw empty/oil/sw empty/oil/sw empty/oil/sw empty/oil/sw empty/oil/sw empty/oil/sw empty/oil/sw empty/oil/sw empty/oil/sw empty/oil/sw empty/oil/sw empty Liquid in tank 0 43 h Ps/t gauge 0.11 Hp Head pressure Ps/t gauge * Differential pressure compensated Δ P + Hp Pd ΔP Differential Pressure Ps/t - Pd Ps/t Symbol Press. in Drain Collection Unit Stern tube oil pressure Check point 2. MPa Remark Variable by draft. Pd shows nearly draft pressure. by calculation 0.03-0.05MPa range Hp Gauge height x 0.009 * * Fill (-) minus value in case the gauge located below shaft level. Head pressure (MPa) Ps/t gauge Gauge height above shaft C/L (m) Calculation of differential pressure at shaft centerline Symbol Value Check point 1. Remark 0.09 Air flow control yy mm 0.17 Example 0.11 0.09 0.02 0.0135 0.0335 Example 1.5 0.0135 0.11 #1 #1/#2 #1/#2 #1/#2 #1/#2 #1/#2 #1/#2 #1/#2 #1/#2 #1/#2 #1/#2 #1/#2 #1/#2 #1/#2 #1/#2 #1/#2 #1/#2 7 0 32 Sample Oil level S/T B'rg FWD M/E S/T oil Oil Oil in Use seal Tk rpm Temp. Remark (Deg.. C) press. press. press. (L) (MPa) (MPa) (MPa) S/T L.O. Tank Unit Oil Pressure Unit Level gauge Ps/t SUC. DISC. Level Level from from Tk Tk bottom bottom (cm) (cm) Drain Collection Unit (10L) FC Level gauge Pd Air flow Air Change Change meter press. lever lever (L/min.) (MPa) FM1 Main/Sub Main/Sub Clean Oil mist filter F2 Clean/Dirty Clean/Dirty Clean Air filter Air Control Unit DP F1 AFT Air Reg. air Reg. air Blow TU line Diff. Draft air air air (M) source press. press. press. Main Sub press. press. press. (MPa) (MPa) (MPa) (MPa) (MPa) (MPa) P1 1. Recording intervals; Once a day 2. P4, P5, Pd & Ps/t pressures automatically follow change of water pressure from the draft. 3. Clean filters in case of pressure rise in DP gauge. 4. Clean pump strainers in case of suction pressure drop on Oil Pressure Unit. 5. Put air vent pipe of FC in a water cup to check air flowing at Drain Collection Unit. 6. Use this form in operating the system while the vessel at sea, at berth or in sea trials. 1 Date M/V RECORD FORM - KEMEL Air Seal System 4. Daily Maintenance 4.1 Stern Tube System Record and monitor operation of Air Seal as per the form in P. 7. Also monitor stern tube system as per Operating Guideline shown in KEMEL COMPACT Seal Type CX, DX & AX INSTRUCTION MANUAL. In case of questions on the data or operating condition, send the record to Technical Service Dept. at “techservice＠kemel.com” for examination and comments. 4.2 Air Control Unit & Drain Collection Unit Table below shows maintenance of MU and on CU. Also refer to photo manual in P. 9. Unit Devices Symbol Air Source － Differential Pressure Gauge DP Air Filter F1 F2 Standard Maintenance setting 0.4MPa Min. Fully open air source valve and keep the pressure above 0.4MPa all the time. Less than 0.1MPa in green zone Set Value Air Regulator MU Air Flow Controller Air Flow Meter R1/P2 See Note *) & R2/P3 Allowance ±0.05MPa FC1 Set Value & See Note *) FC2 Allowance ±5L/min. FM1 In red zone ➟ Clean or renew filters. ① Open V10 and close V1 & V2 in MU. ② Open V3 to release air in the line. ③ Remove filter covers. (Secure O-ring fitted) ④ Remove filters. ⑤ Clean & re-set filters, or renew filters. ⑥ Close V3. Open V1 & V2, then close V10. Pressure setting (Set value is shown in Finish Plan – Piping Diagram Fig.1） ① Pull-down the knob to unlock. ② Turn the knob for pressure setting. ③ Push-up the knob to lock. Check positions of Green Markers in P2 & P3 gauges for indication of the set value. Gauge P2 Counter clockwise Mating mark （－） Clockwise Note: Initial setting is made for R1 & R2 at the time of delivery. Flow setting（the value shown in Finished PlanPiping Diagram Fig.1.） ① Pull-up the knob to unlock. ② Check air flow rate at FM1. ③ Turn the knob for flow setting. ④ Push-down the knob to lock. Note: Initial setting is made for FC1 & FC2 at the time of delivery. （＋） Control Knob: Pull Down-Unlock, Up-Lock Counter clockwise （－） Clockwise （＋） Control Knob: Pull Up-Unlock, Down-Lock Counter clockwise（－） Air Relay Change Lever Change Lever AR1 C1 C2 Air Flow Controller FC Level Gauge － "Ps/t -Pd" value in the range 0.03 -0.05 MPa Adjust Ps/t （See P.7 Calculation of differential pressure ） ① Loosen lock-nut for control wheel ② Turn clockwise to increase, conuter clockwise to decrease ③ Adjust stern tube pressure ④ Tighten the lock-nut Clockwise（＋） Control Wheel on MAIN ① On MAIN: Air blows into sea via R1➟P2➟FC1➟FM1. ② On SUB: Air blows into sea via R2➟P3➟FC2, bypassing FM1. ③ SUB is only for temporally use. (FM1 does not work.） ④ Recover MAIN to replace SUB as soon as possible. on MAIN ① Main; AR1 controls air pressure in TU line by using Air Blow Line pressure as a signal. ② Sub; bypass AR1 and pressurize TU line by direct pressure of Air Blow Line. ③ SUB is only for temporally use. ④ Recover MAIN to replace SUB as soon as possible. Slight Open ① Check ventilation through the vent, with low air-speed. ② Turn the knob to adjust flow speed after the lock nut loose, if necessary. ③ Tighten the lock nut after setting air flow. Note: Initial setting is made for FC at the time of delivery. Put air-vent pipe in a water cup to check ventilation bubbles. CU － ① Remove drain in case of high level alarm activated. ② Slight-open drain valve for discharge by air pressure in CU. ③ Discharge while M/E stopped.（Do not open the valve when M/E in operation.） Note *) Adjust settings shown in Finished Plan - Piping Diagram Fig. 1. -8- -9- - 10 - TU ・ OU CU MU Unit Fully open valve “A”, shown in P. 2 diagram. Re-adjust the bypass valve. Adjust TU line pressure by AR1 hand wheel. Valve “A” on return line to TU is not fully opened. Bypass valve on OU is fully closed. Tu Line pressure too high. Low, or “Zero” pressure. P3 Ps/t “Ps/t – Pd” value is greater than 0.05 MPa, with compensation of Ps/t gauge height. Ps/t stays at head pressure of TU, or does not rise. Pressure does not follow change of draft. Level Filled with seawater. Gauge Filled with oil. Pressure low. Out of setting range. FM1 Pd Indicator needle in “Red Zone”. Considerably higher than P4 pressure. DP P5 Considerably lower than P4 pressure. Gets higher pressure in the same draft level before. Low, or “Zero” pressure. The pressure does not follow change of draft. Air leakage from air pipes P4 gauge malfunction Pressure gauge malfunction. Wrong setting AR1. Air leakage on TU line Malfunction AR1. Pressure gauge malfunction Wrong setting AR1. Malfunction AR1. Dirty filters F1 & F2. Air Flow Controller FC1 setting changed. Air Flow Controller FC1malfunction. Air Flow Meter FM1 malfunction. Drain valve or Air Flow Controller FC fully opened. Blockage or air leakage at drain pipe lead to CU. Pd gauge malfunction Seawater leakage through the #1 & 2 seal rings. Oil leakage through the #3 seal ring. Air vent valve on TU is opened. Air leakage at the pipe lead to TU or TU itself. Ps/t gauge malfunction. Blockade proceeding in Air Blow Line. No action required. Keep C1 on MAIN. Re-adjust R2 setting. Replace P3 gaugeReplace R2. Open the valves. Put 3-way valve in direction of air blowing. Clean pipe by using fresh water line in MU, while M/E stopped. Check pipes by spraying soap water, and repair. Replace P4 gauge. Replace pressure gauges. Re-adjust AR1. Check pipes by spraying soap water, and repair. Put C2 on Sub. Replace AR1. Replace pressure gauges. Re-adjust AR1. Put C2 on Sub. Replace AR1. Clean or replace filters. Re-adjust FC1 setting. Put C1on SUB. Replace FC1. Put C1on SUB. Replace FM1. Close drain valve or re-adjust FC slight open. Clean pipe by fresh water line in MU, repair pipe. Replace Pd gauge Remove water. Record daily amount and report. Remove oil. Record daily amount and report. Close air vent valve. Check pipes by spraying soap water, and repair. Replace Ps/t gauge Change Lever C1 is on MAIN. Air Regulator R2 setting changed. P3 gauge malfunction. Air regulator R2 malfunction. Valves on Air Blow Line are closed. 3-way valve on Air Blow Line in direction F/W cleaning. Low, or “Zero” pressure. P2 P4 Put C1 on MAIN, if it works. Re-adjust R1 setting. Replace P2 gauge Put C1 on Sub. Replace R1. Change Lever C1 is on SUB. Air Regulator R1 setting changed. P2 gauge malfunction. Air regulator R1 malfunction. Rises up to R1 (or R2) set pressure. Open air source valve. Keep the pressure above 0.4MPa. Replace P1 gauge. Action Air source valve closed. Air source pressure low. P1 gauge malfunction. Possible Cause Low, or “Zero” pressure. （Minimum 0.4MPa required.） Abnormality P1 Gauge 5.1 Abnormalities of Air Pressures/Air Flow & Actions 5. Trouble Shooting - 11 - FM1 setting changed Malfunction FM1. Flow rate is below the minimum value. (see Finished Plan – Piping Diagram Fig. 1) Wrong position. (see Finished Plan – Piping Diagram Fig. 1) The relief valve activates at lower pressure. Air leakage. (Check by spraying liquid soap.) Air vent valve opened. FM1 Flow Meter Valve positions Safety relief valve Air pipe joints Air vent Level gauge FWD Level gauge seal CU CU Level Gauge Drain Damage of the #1 & 2 seal rings Damage of the #3 seal ring Recovery of oil over 2L/day Leakage from the #4 seal ring Oil level increases over 2L/day. Continuous seawater recovery. Filled with seawater in a day. Loose joint Leakage from the #3 seal ring Oil leakage Oil level increases over 2L/day. The differtial pressure "Ps/t - Pd" should not exceed 0.05MPa. (See P. 7 Calculation of pressures) *** Increase oil pressure by operating Air Realy “AR1” on MU. A3 （CU） Liquid Level High AFT seal damage Setting changed. Loose joints etc. － － Dirty strainer Particles in S/T oi Air inclusion Air-pocket in S/T. Malfunction valve. Loose joints etc. － Decrease oil level in FWD seal tank, and increase the Pressure fluctuation in S/T. level in TU with same amount. (Pumping effect.) Filled with seawater immediately after draining. Excessive air flow at FC. Air leakage. (Check by spraying liquid soap.) Drain valve left opened. Loss of air source pressure. Negative pressure at pump suction, causes air sucking. Dirty strainer. Air bubbles（Increased oil volume by air inclusion.） Level increase in shallow draft and decrease in deep draft Sign of seawater penetration. R1 setting changed. Malfunction R1. Malfunction P2. P2 indicates below the minimum set pressure. (see Finished Plan – Piping Diagram Fig. 1) P2 Gauge － Dirty filters. Possible Cause The indicator in Red Zone, exceeding 0.1MPa. Abnormal Condition DP Gauge Check Point Flow Controller FC CU Air pipe joints Drain Valve Air Source Pressure gauge OU Strainer Oil color TU Level gauge S/T Stern tube drain TU MU Unit TU Oil pipe joint A2 CU Level gauge （TU） Oil Level FWD Level gauge Low seal A2 （TU） Oil Level High A1 (MU) Air pressure Low ALARM 5.2 Alarms & Actions Activate the #3S seal ring. Increase air flow rate at 60－80L/min. Conduct diver inspection. Repair AFT seal. Recovery. Repair the #4 seal ring. Repair pipe joints. Activate the #3S seal ring. Increase S/T oil pressure. *** Re-fill oil in FWD seal, whenever is necessary. Dissolve air-pocket. Increase air flow rate at 60－80L/min. Conduct diver inspection. Repair AFT seal. Clean strainers. Re-adjust FC with 2-3 air bubbles/sec. Repair leaking joints/pipes. Close drain valve. Take actions in P. 13. Recovery of air Repair/Replace the relief valve. Repair leaking joints/pipes. Close the valve. Clean or replace filter elements. Re-adjust R1 setting. Put C1 on SUB. Replace R1. Replace P2. Re-adjust FC1 setting. Put C1 on SUB. Replace FC1. Correct valve positions. Action Yes Yes Yes Yes Yes Yes Yes Report to KEMEL - 12 - Open the valves. Clean pipe by using Fresh Water Line in MU. Activate the #3S seal ring and keep monitoring. Cleaning Air pipe by Fresh Water. Increase air flow rate at 60－80L/min. Clean pipe by using Fresh Water Line in MU. Conduct diver inspection, if necessary. Actions Yes Yes Yes Report to KEMEL Note1. When 3-way Valve is turned to the direction of Fresh Water, Air Blow line is shut off and air pressure set by R1 is directly given to TU. This may cause activation of Safety Relief Valve on TU, which is not harmful. The activation of Safety Relief Valve may be stopped by reducing R1 setting during Fresh Water Cleaning. However, do not reduce R1 setting in case of continual seawater leakage into CU. Also make sure R1 should be back to the set value after the cleaning. Note2. It takes a time to have cleaning water coming out at CU drain. (Flow Control Valve on fresh water line is initially set and locked at very slow speed so that the water does not penetrate into stern tube by sudden rise of water pressure. In case the initial setting is lost, fully close the control valve then turn the wheel 180 degree, half-turn, for re-setting. Procedure for Fresh Water Cleaning (To be done while M/E stopped or on turning gear.) 1) Open drain valve on CU. 2) Turn 3-Way Valve in MU, to the direction of Fresh Water Line. - Note 1 3) Open the valve and start supply fresh water. 4) Clean the air pipe till fresh water coming out from the drain valve on CU. - Note 2 5) Stop fresh water supply. 6) Turn 3-Way Valve in MU, to the direction of Air Blow Line. 7) Close the drain valve on CU after blowing out water by the air. 8) Examine all pressures and air flow being in normal condition. Cleaning Air Pipe by Fresh Water In case P4 pressure become higher than Pd over 0.03MPa difference, it is possible that air flow pipes started to have blockage due to extraction of salt etc. MU has a fresh water line to dissolve the blockage and to clean the pipe. It is recommended that the ship clean the pipe by using the line with 6months intervals. Air pressure high alarm (Option) from Valve position on Air Blow Line. Valves remain closed. A1. P4 pressure on MU. Blockade in Air Blow Line. Broken pipe in stern tube Blockage in drain pipe. Stern tube oil leak with no collection Pressure in CU. of oil in CU. Oil level in TU. Possible Cause Blockade in drain pipe. Check Point Seawater penetration into stern tube Air pressure in CU. with no seawater collected in CU. Stern tube oil condition. Abnormalities 5.3 Other abnormalities & Actions 6. Switch-over to Oil Seal System for emergency Losing air supply to AFT seal causes oil pressure drop in stern tube. In case of air lost while the vessel is at sea, immediately examine seawater penetration in CU. It is possible to operate the system without air if no seawater is observed in CU. Air supply, however, should be recovered to raise the oil pressure at the earliest possible. During the operation with no air, keep monitoring CU by frequent examination of the drain. In case no air supply to MU may continue for a long period, study possibilities of slow-down or stop M/E till air supply is recovered. If seawater continuously fills CU in a short time, conduct protection of stern tube bearing from seawater by switching Air Seal system over to normal oil seal system as per the procedures below, 1) Switch-off all alarms on MU, TU and CU and stop air supply. 2) Stop OU, and then take action 3) with no delay. 3) Change oil circulation l via X-line as per “Valve Operation for switching to X-line” shown below 4) Re-start OU with no delay. While operation with X-line, keep OU running all the time to maintain the oil head pressure which minimizes the chance of seawater penetration into stern tube. Strengthen examination of stern tube oil drain and remove contaminated oil when it is found. It is necessary to recover air source failure as soon as possible. At the same time, investigate possibility of earlier inspection and repair of AFT seal for seawater leakage. Valve Operation for switching to X-line MU CU Valve V11 E F Operation Close Close Close A Close TU B Close Air Vent Open OU I Open X-line G Open Note 1. V11 valve is located in MU, on the line to pressurize TU. Note 2. Confirm detail valve operation in Finished Plan - Piping Diagram Fig. 2. Valve Operation for switching back to Air Seal X-line OU TU Valve G I Air Vent B Operation Close Close Close Open - 13 - A Open CU F Open MU E Open V11 Open 7. Operation for Dry-docking, Undocking and Laying-up 7.1 Dry-docking & Undocking In case of dry-docking and undocking, shut-down and re-start Air Seal system as the manners below, 1) Stop all alarms on MU, TU and CU, and then stop air supply to CU to shut-down before entering dock. 2) Discharge oil in stern tube, AFT seal and FWD seal for seal repair after dry-up. 3) Carry out inspection or repair of the seal unit as necessary. 4) Fill stern tube and carry out oil pressure test as necessary. (See P. 6 for oil filling and pressure test.) 5) Re-start the system before undocking. (See articles 2 & 3 for the procedures.) 7.2 Laying-up In case of laying-up the ship with no power and no air, shut-down Air Seal system as the manners below, 1) Stop all alarms on MU, TU and CU. 2) Stop OU to shut-down the system. 3) Examine existence of seawater in CU through the drain valve. 4) In case of no seawater observed, carry out drain check once a week after the shut-down. 5) In case seawater fills CU in a short time, conduct protection of stern tube bearing from seawater by switching Air Seal system over to normal oil seal system using X-line as per article 6. 6) Circulate stern tube oil via X-line by operating OU. 7) Check oil pressure at Ps/t gauge. 8) Stop OU to shut-down the system. 9) Confirm the oil head is maintained. 10)Examine Ps/t once a week and stern tube drain. 11)Recover the pressure by the procedures 6) – 9), if necessary. Re-start Air Seal after the laying-up period as the manners below, 1) Operate the valves as per article 6 “Valve operation for switching back to Air Seal”. 2) Confirm drain valve on CU is closed. 3) Operate OU. 4) Supply air to MU and activate all alarms on MU, TU and CU to re-start. 5) Examine all pressures and air flow of the system. It is possible that marine growths around AFT seal area during laying-up period may cause reduction of seal tightness. Recommend cleaning and overhaul inspection of the seal at the earliest opportunity after re-activation of the system. - 14 - ">
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Key features
- Air-operated seal for stern tube
- Minimizes seawater contamination
- Automatic oil pressure regulation
- Stand-by spare seal ring
- Fresh water cleaning for air purging pipes
- High and low level alarms for oil tank
- Switch-over to normal oil seal system for emergency
Frequently asked questions
The Air Seal keeps seawater out of the stern tube by blowing air into sea through an air chamber provided at the space between the #2 & #3 seal rings in AFT seal. This helps to prevent seawater contamination of the stern tube oil.
The Air Seal automatically optimizes the oil pressure based on draft pressure detected at Air Chamber. This remarkably reduces the pressure load given on AFT seal at all draft levels.
The daily maintenance requirements include recording and monitoring the operation of the Air Seal as per the form in P. 7. You should also monitor the stern tube system as per the Operating Guideline shown in KEMEL COMPACT Seal Type CX, DX & AX INSTRUCTION MANUAL. In case of questions on the data or operating condition, send the record to Technical Service Dept. at “techservice＠kemel.com” for examination and comments.
