The use judgment of the Adjustable Screw Jack rod after rust and pallet deformation?

The use judgment of the Adjustable Screw Jack rod after rust and pallet deformation?

Whether the Adjustable Screw Jack rod can continue to be used after rust and pallet deformation needs to be comprehensively judged in combination with the degree of damage,specification requirements and actual stress scenarios,and it is prohibited to directly use the damaged top support that has not been evaluated,and the specific judgment criteria and treatment methods are as follows:

1.Judgment on the use of rust on the screw rod

Screw rust needs to first clarify the rust depth and impact on structural performance,which cannot be generalized:

Repairable and useable situations:If there is only slight rust on the surface(the rust area accounts for≤10%,the rust depth≤0.5mm),and there is no obvious damage to the thread(no slippage,broken teeth),you can use sandpaper or wire brush to thoroughly remove the rust,and then use a thickness gauge to review the diameter of the screw(such as the diameter of the originalφ30mm screw after rust removal≥29mm,to meet the minimum stress section requirements),and then apply anti-rust paint to protect it,and confirm that the thread adjustment is smooth and there is no jamming lag after inspection.It can be used in non-heavy load support scenarios(such as beam and plate support with a load≤3kN).

Prohibited situations:If the rust depth>0.5mm(such as the diameter of theφ36mm screw after rust removal<35mm,the cross-section is weakened by more than 5%),or the thread has slippage and broken teeth(the number of broken teeth is≥2 or consecutive broken teeth),it will lead to a significant decrease in the load-bearing capacity of the screw and the failure of the adjustment function.

2.Determination of the use of pallet deformation

As a key component of load transmission,pallets need to focus on checking flatness and structural integrity after deformation:

Repairable conditions:If there is only slight deformation(flatness deviation≤2mm,no cracks,no serious warping edges),and there is no cracking or missing welding at the welding between the pallet and the screw rod,it can be corrected by mechanical correction(such as leveling the surface of the pallet with a press),and the flatness can be reviewed with a level after correction to confirm that it meets the requirements and the welding node is stable,and can be used for temporary supports with small loads(such as protective railings and light formwork supports).

Prohibited situations:If the pallet is seriously deformed(flatness deviation>3mm,obvious depression or warping),or there are cracks and cracks at the weld,it will lead to uneven load transfer(local stress concentration),or even the pallet falls off.

3.Core principles and precautions

Priority scrapping principle:For the top support with a vague degree of damage(such as unable to accurately measure the rust depth and difficult to correct after deformation),in order to avoid potential safety hazards,it should be scrapped directly,and it is not recommended to use it riskily.

Prohibition of"diseased"use:rust has not been removed and deformation has not been corrected,which will aggravate the loss in use(such as accelerated thread wear and further deformation of the tray),and cannot meet the requirements of"no damage and deformation of components"in the"Safety Technical Specification for Fastener Steel Pipe Scaffolding for Building Construction"(JGJ130),and must be treated after qualification.

Record and traceability:After inspection,the top support needs to be classified and marked("qualified","to be repaired","scrapped")and made records to avoid scrapped top support from mixing into the construction link and eliminate safety risks from the source.