Heavy duty chain quality inspection and judgment method

Lifting chains can be used for lifting hoists, chain slings and binder chain, which have a wide range of uses, we should have a certain quality judgment method when choosing, to avoid buying bad chains, you can refer to the following two parts of the contents of the two aspects from the appearance and the actual test data to determine whether the quality of the requirements.

Appearance judgment

1. see whether the surface of the chain ring (no matter galvanized, blackened or polished) is smooth or not, and there should be no pits.

2. if it is blackened  G100 link chain, you can wear white gloves, and then rub the chain to see whether the color is off, whether there is black substance on the gloves, or whether there is a lot of oil, a good blackened chain should be black and shiny, and the surface is very clean, with a little bit of oil, can't be off or a small amount of color loss.

3. The typing must be clear.

4. the position of the top bar must not have obvious traces of being topped.

5. the welding position is the welding port, this position welding should be even, burr removal should be clean, welding position can not appear offset, should be in the middle of the chain ring, can not be biased up or down.

6. The chain type should not have high or low angle and one side should be high and the other side should be low.

7. The verticality of the high strength lifting chain, generally speaking, the chain should not be twisted more than 30 degrees under vertical condition.

Method of checking the verticality of the chain:

Testing standard

1. Hardness test

The hardness test is carried out in the process of heat treatment, one of the chain links is randomly intercepted and then polished to a flat surface, and then tested by hardness tester. the normal hardness (Rockwell hardness) of R1 and R2 points is 40-46 degrees, and the hardness of Z1 point is 36-40 degrees.

In addition, EN818-7 type of chain hoist chain requires straight arm 38 degrees (37-40), R angle 42 degrees (40-46), and elongation ≤ 15%; EN818-2 rigging chain requires elongation of 15-20%. R angle is to increase friction and longer use cycle, straight arm in order to elongation rate qualified.

2. Tension test

The test results will appear as follows: 

Under the condition of ensuring the minimum breaking tension and normal elongation of each specification chain:

① Location of breaking point: at the arc (i.e. point R) is qualified product. (The hardness at the arc is high, and the hardness at both sides is low).

② The broken point is unqualified if it is on the welded joint, even if the breaking tension and elongation are reached.

In order to make sure the lifting chain meets the production standard and reaches the breaking requirement of 4 times of the tensile strength test, as a chain rigging supplier, we can provide the following tensile strength test report.

We can provide lifting chain tension test report:

（Description of the contents of the report）

16mm chain tension test

Inspection based on standard: GB/T 20946-2007

Tensile strength：815.25Mpa

Breaking force：327.89KN

Elongation at break：23.32%