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Proof Load Test - Anchor

Most of the modern anchors for large ships are now made of cast steel so that they are tough and can resist shock loading and breakage especially if the anchor strikes a rock or rocky surface whilst anchoring.
About 80 years back all anchors were made of cast iron and the method of testing them were by dropping them on hard prepared ground from a height of 75 feet. If it survived this test without breaking or cracking, it was sent to the ship and if it cracked or broke it went back to the foundry for recasting. This is destructive testing and not used now.
Modern anchors are subjected to non-destructive testing and the procedure is as follows.

The anchor is placed on the test bed of a chain testing machine. The shank end is connected to either the fixed end of the machine and the head is connected to the ram end of the machine which moves inwards by hydraulic pressure. The pressure is monitored on the pressure gauge fitted to the hydraulic cylinder. The required proof load is given by P* machine constant in tons or KN as required.  The proof load is kept for half hour to one hour as per class regulations and any deformity in shape of flukes or any crack formation is to be observed before approving the anchor.

An old anchor obtained from a ship scrap yard can be used as a replacement anchor provided the following conditions are met:
  • The selected anchor conforms to the mass requirement as per the equipment letter
  • The general inspection reveals no flukes or cracks.
  • The anchor is to be subjected to a proof load test as per the proof load given in the tables and witnessed by the class The testing machine should be approved by class.

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