As per code & standard it should be 25% at a minimum but in situation I have practiced 10% at a minimum.
Lifting equipment manufacturer keeps a safety margin of 25% with respect to lifting equipment safety, other than that we take another 25% safety margin in rigging studies at a minimum as per code ...

Ben, thank you for such descriptive info.

Actually what I was looking for is an approximate standard working capability so when I compared this formulation with my previous experience, it works indeed.
Anyway thanks for your guidance & time.

Thanks, this operating factor will obviously help me to plan my fabrication and welding accordingly.

If anyone knows about any reference/programe or evaluation method (with the reference of code & standard) to calculate the standard workability of a production welder against different welding methods, also same in case of fabricators that how much Dia Inch one fabricator can perform in 8 hours ...

Qaisar, Infact this is one test which is carried out simultaneosly and is called by Hydro-Pneumatic Test.
The link you have passed is the comparison of Hydro Test & Pneumatic Test.
Kindly update if you find any relevant data on this.

Any one knows about the detailed Hydro Pneumatc Test Procedure For Floating Roof (Double/Single Deck) Storage Tanks & Fix Conical Roof Storage Tanks.

Thanx in anticipation.

Here is a website that has rigging calculation programs that you can try

http://www.maximumreach.com/software.htm

Its very useful indded, if you have basic knowledge about rigging then having this programe you dont need any specialist to consult with.

Gujral.

Its Sadaqa Ja'riya guys, may Allah Almighty award you divine blessings & every success in life ever. (aamin).

Would be Great self-grooming info indeed.