Pulling forces together (Load Testing)

[steviewinter]

Hello,

Here's my question:

When load testing a lifting lug that is welded to the ceiling, placing it under 5 tonnes of pull, using a chain block to tension and a web sling that is attached to the floor directly below, are you:
A) Pulling 5 tonne down from the lug and 5 tonne up from the floor
B) 2.5 tonne down from the lug and 2.5 tone up from the floor
C) Anything else?

Diagram

_____________________CEILING
Lug ----> ρ
|
|
|
* 5 tonne pull *
|
|
|
__________ρ__________ FLOOR

 

[Andrew Mason]

Hello,

Here's my question:

When load testing a lifting lug that is welded to the ceiling, placing it under 5 tonnes of pull, using a chain block to tension and a web sling that is attached to the floor directly below, are you:
A) Pulling 5 tonne down from the lug and 5 tonne up from the floor
B) 2.5 tonne down from the lug and 2.5 tone up from the floor
C) Anything else?

Diagram

_____________________CEILING
Lug ----> ρ
|
|
|
* 5 tonne pull *
|
|
|
__________ρ__________ FLOOR

It depends on what moves. If nothing moves, all tensions are balanced so everything is being pulled in the opposite directions by equal forces. So the ceiling is pulling the floor up and the floor is pulling the ceiling down, each using 5,000 x 9.8 Newtons of force, and the building structure is pulling down on the floor and up on the ceiling to balance the tension between the floor and ceiling with the same force.

AM

 

[steviewinter]

Nothing moves, the tension is balanced with a chain block pulling 5tonne in the middle. So could you say that both lugs are certified to lift 5 tonne?

 

[Studiot]

The certified load is always less than the test load.

That is you can work at the certified load indefinitely (until the next test) but the actual test is conducted at a higher load. This builds a safety factor into the certification process.

The accuracy of load indicators for chain winches are less than the accuracy achievable by hanging weights from your lug and may not be accurate enough to allow certification.

 

[steviewinter]

I see, so could you tell me, if i tensioned the chain block to 5 tonne on the load test indicator did i, in effect;

Test both lugs to 5 tonnes
or ,
Test them each to 2.5 tonne?

 

[Studiot]

If the test held at 5 tonnes then both floor and ceiling connections were tested to 5 tonnes.

 

[steviewinter]

Thank you very much!