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 What kind of tests do we carry out ? |
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Hamanaka Quality Control System according
to the classification’s rule shall be strictly applied by carrying out various
tests to ensure consistency of our superior quality.
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Main tests
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| Receiving
Inspection |
Inspect characteristics of bar material before manufacturing
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| Non-Destructive Inspection |
Inspect the interior conditions of chain link by means of Ultrasonic Inspection/etc |
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Visual Inspection
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Inspect the exterior of chain link
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Proof Test
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Secure safety on all the chain links by loading at higher proof load than the operating load
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Mechanical Test
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Secure the internal properties on specimens taken from chain link |
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Breaking Test
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Verify the highest strength on chain link |
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What is Heat Treatment? |
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There are various kinds of Heat Treatments
such as Quenching, Tempering, Normalizing or Annealing. We adopt Quenching and
Tempering.
Usually, Quenching and Tempering are
heating and cooling processes to increase strength and toughness of metal.
Quenching is the
process of a rapid cooling in water after heating chain at 950 degrees C. to 1,000 degrees C., to increase
strength of metal.
Tempering is the process of a normal cooling in water after re-heating chain at 600 degrees C. to 670
degrees C after quenching process, to increase toughness of metal.
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What is the correlation between size of
ship and diameter of chain link?
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The diameter of chain link is, in most cases, corresponded to size of ship.
Here are some examples.
| DWT 40,000 tons Carrier |
Chain Dia. approx. 64mm 〜 66mm |
| DWT 80,000 tons Carrier |
Chain Dia. approx. 81mm |
| DWT 150,000 tons Carrier |
Chain Dia. approx. 107mm |
| DWT 200,000 〜 280,000 tons VLCC |
Chain Dia. approx. 111mm 〜 114mm |
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