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What kind of tests do we carry out?

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.

Main tests
Receiving Inspection

Inspect characteristics of bar material before manufacturing

Non-Destructive Inspection Inspect the interior conditions of chain link by means of Ultrasonic Inspection/etc
Visual Inspection
Inspect the exterior of chain link
Proof Test

Secure safety on all the chain links by loading at higher proof load than the operating load

Mechanical Test
Secure the internal properties on specimens taken from chain link
Breaking Test
Verify the highest strength on chain link

What is Heat Treatment?

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.

What is the correlation between size of ship and diameter of chain link?

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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