GirishKamble,
Please tell us why you are trying to design your own Ball Valve?

Is this a School/Class problem?
Do you know what Codes and Standards you need to follow?
Do you think you can build one cheaper that the big guys (existing Ball Valve manufacturers)?
Have you asked the Big Guys for price and delivery for an off-the-shelf Ball Valve"

There are many other questions you will need to answer if you do it on your own.

Sometimes its possible to do all the right things and still get bad results

Why?

Just buy one.

Or look up the design of existing soft seat valves if you really want to know.

There is little value in following the path of many before you unless you somehow have an issue not yet covered by the hundreds of valve manufacturers world wide....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

pennpiper

We are first time dealing with Ball Valves design. We do not want to spend money for buying the of-the shelf valves. Rather wants to understand how the design is.
We are refering standards API 6D, ASME B16.34 B16.5.

GirishKamble'
You wrote:
"We are first time dealing with Ball Valves design."
Based on your previous posts and your profile, it appears that you do not have a real background in Piping, Valves and other related Engineering and Design issues. Why are you trying to design a Ball Valve?

You wrote:
"We do not want to spend money for buying the of-the shelf valves."
You do not need to buy a Ball Valve. You can just contact a local Ball Valve manufacturing Company there in China and ask if you can visit there facility and talk to their Tech people to understand how the different Ball Valves work.

You wrote:
"Rather (we) want to understand how the design is."
See previous response.

You wrote:
"We are referring standards API 6D, ASME B16.34 B16.5."
API 6D: Specification for Pipeline Valves. 1. n. [ Production] API 6D specifies requirements and gives recommendations for the design, manufacturing, testing and documentation of ball, check, gate and plug valves for application in pipeline systems.
Do you have a copy of this Standard? Have you read it? Do you understand everything you read? These same questions also apply for these other Standards: ASME B16.34 and B16.5.

Sometimes its possible to do all the right things and still get bad results

I would have assumed that the company appointed a consultant, which is not too difficult. Also, I am afraid, no recognised end user would want to fit a valve produced in amateur way.

Valve manufacturing activity is quite a mature industry in India and several multinational valve manufacturers have a significant presence.

"Even,if you are a minority of one, truth is the truth."

Mahatma Gandhi.

Thank you all for the pointers.