Single pull macgregor type hatch cover.pdf - Cochin University of ...

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CHAPTER 8-TESTS AND TRIALS Since the ship trades in all type of environmental conditions including heavy weather condition etc, there is chance of damage of cargo or goods because of water or moisture entering to the hold. This may even damage the whole ship so in order to avoid this, covers are made water tight and same is tested before proceedings. The two most common leak detection tests are the water hose test and the ultrasonic test. Ultrasonic testing is the preferred method because areas of inadequate hatch sealing are accurately located. Chalk testing (another hatch test) gives only an indication of poor compression and potential leaks. Chalk testing is not a leak detection test. Light testing is also effective but is potentially dangerous because personnel are in a closed, dark hold looking for light infiltration between panels. If hatches are found to leak during a test, make the necessary repairs, then test again. 8.1 WATER HOSE LEAK DETECTION TEST Water hose tests are used to determine weather-tightness of hatch covers. If correctly performed, hose testing will show hatch joints that leak. The general procedure for hose testing is to apply a powerful jet of water from a 20-50 mm diameter hose fitted with a 12 mm diameter nozzle held at a distance of 1-1.5 metres from a hatch joint, moving along the joint at a speed of 1 metre every 2 seconds. The drawbacks of hose testing are: � The hold needs to be empty; � It cannot be performed in sub-zero conditions; � It requires the deck scupper drains to be open (potentially causing pollution); � The test cannot pinpoint leaks on the cross-joint or side joint accurately; � Two people are needed to supervise the test. Care should be taken to avoid excessive nozzle back-pressure. 8.2 ULTRASONIC LEAK DETECTION TEST Ultrasonic leak detection is a viable alternative to the hose test for testing hatch covers, access doors and access hatches for weather tightness, as it accurately locates potential points of leakage. This test should only be carried out using class approved equipment and approved test procedures. 88
The test involves placing (with hatches closed and secure) an electronic signal generator inside the cargo hold. A sensor is then passed around the outside of all compression joints. Readings taken by the sensor indicate points of low compression or potential points of leakage. Ultrasonic testing overcomes the majority of limitations associated with hose testing and can be carried out when holds are loaded. The drawbacks of these section tests are: � The equipment requires an experienced and specialist operator to interpret the readings. � The equipment requires regular calibration; � The equipment is not normally part of the ship’s equipment. 8.3 PUTTY OR MOULDING CLAY TEST This is a maintenance test mainly used by the maker’s representative to precisely determine alignment and clearances. Putty or moulding clay is placed at regular intervals in the packing retaining channels that have no packing in them. The hatch covers are closed then re-opened leaving an indentation. This allows the exact steet- to-steel wear down condition to be calculated and any panel distortion or misalignment to be measured and remedial action taken. 8.4 CHALK TESTING When performing a chalk test, the top edge of every compression bar is covered with chalk. Hatches are then fully closed and reopened. The rubber packing is examined for a chalk mark, which should run continuously along the packing centre. Gaps in the chalk mark indicate lack of compression. Chalk testing merely indicates if hatch panels are aligned and compression achieved. It will not show whether compression is adequate and therefore it is not a test for weather tightness. 8.5 TOLERANCE TEST FOR HATCH COVERS This test is conducted on a jig to check the flatness of adjoining panels, as well as the dimensions and the hinge pin clearances where multiple panels are measured. It also checks cross joint steel to steel contact wear down. 89
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SINGLE PULL MACGREGOR TYPE HATCH CO
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ACKNOWLEDGEMENT First of all we hel
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TABLE OF CONTENTS v Page no. CERTIF
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5.1.4 Hatch Covers Design. 58 5.1.5
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LIST OF FIGURES Figure no: Title Pa
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Figure7.10 Bulwark 84 Figure7.11 Bu
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CHAPTER 1 - INTRODUCTION The classi
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leakage can cause cargo damage and,
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All types of wooden hatch were made
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The first horizontal rolling built
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CHAPTER 2 - TYPES OF HATCH COVERS M
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2.1 SINGLE PULL 2.1.1 Description F
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2.3 FOLDING & MULTI-TYPE 2.3.1 Desc
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2.5 PIGGY BACK 2.5.1 Description Fi
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2.7 REEFERS HATCH COVERS Figure 2.7
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CHAPTER 3 - GENERAL REQUIREMENTS 3.
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secured by tarpaulins and battening
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force by the 1967 Merchant shipping
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3.2.2 Cover Stowage Where a designe
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It is also necessary to provide dra
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Other steel hatch cover secured wea
Page 43 and 44:
Table 3.4 Access equipment strength
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Longitudinal deformation of the top
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(vii) It should retain all the abov
Page 49 and 50: easier to handle without power assi
Page 51 and 52: � Keep wheels, cleats, hinge pins
Page 53 and 54: 4.2.2 Drive Chains; Check their Len
Page 55 and 56: Figure 4.2 Vessel in rough weather
Page 57 and 58: Figure 4.5 Never smoke in a hold. S
Page 59 and 60: Figure 4.9 Always wear protective h
Page 61 and 62: e taken when opening hatch covers e
Page 63 and 64: Remember to carry out a chalk test
Page 65 and 66: 4.6.13 Painting Corrosion occurs ma
Page 67 and 68: 11. Coaming. 12. Sheave. 13. Cross
Page 69 and 70: Breadth: 44.5cm 5.1.3 Hatch Coaming
Page 71 and 72: Slope: 1cm Total number of panels:
Page 73 and 74: Height of jack while normal conditi
Page 75 and 76: Pulley for rope Diameter: 2cm Width
Page 77 and 78: Height from the deck: 7.2cm Height
Page 79 and 80: CHAPTER 6 - FABRICATION The design
Page 81 and 82: 6.3 HATCH COAMING FABRICATION Broug
Page 83 and 84: Using wood cutter length of 320 cm
Page 85 and 86: Plastic wheels (16 pieces), metalli
Page 87 and 88: At the top of the iron plate, rail
Page 89 and 90: Figure 6.12: Crane space Source: Te
Page 91 and 92: CHAPTER 7-ASSEMBLY OF FABRICATED PA
Page 93 and 94: Source: Team 7.3 ASSEMBLY OF SIDE D
Page 95 and 96: 7.6 ASSEMBLY OF HATCH COVER All the
Page 97 and 98: The whole bulwark is placed over th
Page 99: Through the middle top eye bolt rop
Page 103 and 104: CHAPTER 9 - CONCLUSION Right from t
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