2016年2月20日星期六

Do you know Marine Anchor Chain ?




The chain is mainly used for connecting anchor and ship hull, transfer in grasping force. Anchorage, in a chain length appropriate, lying part of the seabed anchor chain can also by the friction of contact substrate caught in force.

Chain is connected anchor and ship hull, is mainly used to deliver the anchor grasping force, to offset the external force for the ship's role to ensure that the ship can be safely parked in designated waters. Anchor chain by common link, kenter shackle, joint shackle, swivels composition, according to the structure divided into studlink chain and studless chain. The tensile strength of studlink chain, ship generally uses it; according to the manufacturing method has cast steel chain, welded chain and forging chain. The quality of welding anchor chain better than other chains, low cost, has been widely used.

The size of the chain is expressed as a common link with D diameter. Common link diameter is a measure of cable strength standard. The length of chain as a unit, the whole chain composed of a plurality of chain connection, the 10 section around the anchor chain each side. Our specification of each section of the standard cable length is 27.5m. The detachable connecting links between the sections.

Anchor Chain composition
A root complete anchor chain consists of a plurality of anchor chain by connecting links or joining shackle connected, each section of chain consists of a number of links.

According to the chain structure, the chain is divided into studlink chain and studless chain. Size, material are the same, the strength of studlink chain bigger, small deformation and pile is not easy to tussle, so ships widely used. Studless chain is generally used for small boats. According to the manufacturing method, chain is divided into cast steel and welding anchor chain, forging anchor chain etc. For the production system of the anchor steel grade is divided into AM1, AM2, AM3. AM1 is Killed steel, AM2, AM3 is fine grain steel. On the same ship, if the selection of steel strength, link size can be reduced.

Anchor chain link according to their function points for the common link, enlarged link, swivel, chain end shackle, kenter shackle, end link and connecting links.

The size of chain link with the diameter of D . common link section diameter D, common link length should be link section diameter D 6 times, the width B should is 3.6 times D; enlarged link 6.6d length, width of 4D; powder synthetic type link length of 8D, width of 4D, Kenter shackle for 6D, wide for 4.2d. The standard measure of link cable strength is common link. Common link is a measure of the diameter of cable strength standard.


The length of the cable with "length" as a unit, standard length of each section of chain 27.5m and each section of chain link number should is odd.

The link between the connecting links or connecting shackle. Such as connecting each chain with connecting links, the two ends of the connecting links for the common link. Such as each section of chain connected by a connecting shackle connection at both ends of the shackle are sequentially connected end link (also called studless link), enlarged link and then are connected to a common link to ensure a smooth transition strength.

Studlink anchor chain, each chain consist of end shackle, common links and terminal link. A single complete cable by the common link, enlarged link, end link, connecting links or joining shackles, swivels and end shackle etc.

The anchor end link is the first section of chain, and the anchor connected. The cross pin of the link in the end of the shackle and the anchor shackle anchor should be directed, namely: the arc part toward the intermediate link. The swivel ring bolt should be toward the intermediate links, to reduce friction and resistance. The purpose is to prevent the anchor ring set too twisted.

At end of chain link is the last section is connected with chain stopper. The swivel ring bolt should be toward the intermediate link. Intermediate links such as the connecting shackle connection shackle arc part should be directed toward the anchor, to avoid anchoring the passage to sprocket produce beating, impact and jamming.


Anchorchain selection specification
Ships anchors and anchor chains selection according ships type and navigation waters and ship outfitting number ,according to the specification in the column data to select.

The ship outfitting number, is a parameter that reflects the hull can resist wind, fluid flow force.

Cargo ships, bulk carriers, oil tankers, ferries, trailing suction dredger is equipped with devices according to the selected N. By the number of outfitting look-up table derived from a ship in a matching number of anchor quantity and weight, each anchor and chain level, length and diameter.

If the ship anchor chain node number into the singular, right side should handle one more. Million tons cargo per main anchor with at least 10 length of anchor chain. Ship general unlimited area, each anchor should be equipped with 12 length anchor chain. In addition, ship should reserve at least one anchor shackle and four joining shackle or connecting links, another 1 line cable floating big shackle. Tensile stress less than AM1 of the 400N/mm2 chain can’t be used for large grab force anchor. AM3 chain is only suitable for chain size is 20.5mm or more of the chain.

Anchorchain test
The characteristics of welding anchor chain is: advanced technology, simple manufacture, low cost, quality than other types of chain. At present, for the widespread use of ships. Studlink chian should be used in flash butt welding manufacturing method, link allows drop forging or casting manufacturing. The rung welding should only flash welding seam relative side chain on, between both ends of crosspiece and links should be no visible gap; by qualified welders with suitable material in the welding; all the welding work should be carried out before anchor chain final heat treatment. After welding, there should be no defects that affect the performance of the chain.

The inspection and testing of welding anchor chain including appearance inspection, material test, tensile test, breaking test.

The installation requirements and test method of anchor chain
Anchor and anchor chains, swivel, before connecting the mounting ring should be carefully reproduces the ship inspection product number, manufacturing factory product number and anchor quality. In accordance with the requirements of the drawing, the specification and quantity of the inspection can be shipped on board, and record the number of each.

According to the requirements of the drawing section of chain number, through the connecting ring, swivel connection into the whole chain, chain connect securely installed and poured seals fixed. The connecting ring direction of whole chain should be in the same plane, and through sprocket in a horizontal direction. Check the cable fixed at the root situation and do anchor device decoupling experiment, anchor chain terminal can from abandoned anchor device flexibly disengage .After inspection approval can lock the anchor chain, and check the base of device weld quality and anchor chain in cabin piled up situation. Anchor chains should be paint marks at both ends of each section of chain, throw anchor nodes in order to identify, the work can be put in after the appropriate time to complete.


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