Clump or gravity weight castings - Technical specifications

My first post in this forum seeking some help. I am a casting manufacturer and I have a request for Clump castings weighing from 3 tons to 10 tons per piece.

I have in the past made ballast weights for fpso systems and a for cranes.

I shall be obliged if someone could direct me to DNV or BV standards for these castings. I am sorry, that I have no information about chain , or details of mooring lines.

I shall take the liberty of pasting a representative picture obtained from the internet.

Thanks for your time and looking forward to any assistance.