Skip to main content

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.


Popular posts from this blog

Load Line & Why it is Important

Merchant ships have a marking on their hull know as the Plimsoll line or the Plimsoll mark, which indicates the limit until which ships can be loaded with enough cargo, internationally, the Plimsoll line on a ship is officially referred to as the international load line. Every type of ship has a different level of floating and the Plimsoll line on a ship generally varies from one vessel to another.  All vessels of 24 meters and more are required to have this Load line marking at the centre position of the length of summer load water line. There are two types of Load line markings:- Standard Load Line marking – This is applicable to all types of vessels. Timber Load Line Markings – This is applicable to vessels carrying timber cargo. These marks shall be punched on the surface of the hull making it visible even if the ship side paint fades out. The marks shall again be painted with white or yellow colour on a dark background/black on a light background.  The comp

Difference Between A, B & C-Class Divisions?

IMO Symbol A Class Division  IMO Symbol B Class Division  SOLAS has tables for structural fire protection requirement of bulkheads and decks. The requirements depend on the spaces in question and are different for passenger ships and cargo ships. The Administration has required a test of a prototype bulkhead or deck in accordance with the Fire Test Procedures Code to ensure that it meets the above requirements for integrity and temperature rise. Types of Divisions: "A" Class "B" Class "C" Class "A" Class: "A" class divisions are those divisions formed by bulkheads and decks which comply with the following criteria: They are constructed of steel or equivalent material They are suitably stiffened They are constructed as to be capable of preventing the passage of smoke and flame to the end of the one-hour standard fire test. they are insulated with approved non-combustible materials such that the average tempera

Pump Shaft Alignment Procedure

Types of shaft alignment methods: Visual Line-Up Straightedge/Feeler Gauge Rim and Face Cross Dial Reverse Dial Laser Visual Line-Up The visual line-up method is the most common method of alignment. Used in initial installations, visual line-up allows technicians to analyze the working conditions and feasibility of installation. Straightedge/Feeler Gauge Straightedges are used to determine the offset between coupling halves. Corrections are made under all four of the machines feet. Feeler gauges or taper gauges measure the gap between coupling halves at the bottom and top of the coupling. Rim and Face This method is similar in principle to using a straightedge and feeler gauge, but more accurate since dial indicators are used. The rim reading measures the offset between the coupling halves. The face reading measures the angular difference between the faces of the coupling. Changes are calculated with the same formula as the straightedge/feeler gauge met