@LittleInch: Thanks for your reply!
Actually one of our fabricator has consulted us for this.
He wants to supply these types of clamps as he has all the facilities for doing so.
He just wants us to design it for them and present the design calculations to the client.
Hence need details for the same.
API 6H provides the general guidelines and directs us to Sect VIII Div 2.
But I am not able to trace any particular design method for this.