The answer to your question varies significantly for each factory. The limit is determined by the casting weight limit of the foundry used, the maximum amount of weight the cranes in the factory can lift, and the size of the doors on the factory. The limit is also influenced by the amount of money in the customers wallet. For $10 million and 2 years time, I will find a way to make it in my garage.

Dear bcd

Thank you for your reply.
I am asking the question because of Engineering Design perspective( commercial availability / cost / Necessity of usage) .

NPS 36 line containing Class 900 pressures is very rare. There will be no "commercially" available valve. Whatever is selected will be especially designed and made. When pipe sizes get this large, the normal preference is to look to butterfly valves to minimize the amount of metal and weight. However, Class 900 is a high pressure rating for butterfly valves. You should be able to find a manufacturer more willing to quote a butterfly. Your other choice could be a typical 3-piece end entry pipeline ball valve. Since you asked for top loaded, my guess is the customer is looking for weld end. You can get either with butterfly or the typical trunnion pipeline ball valve.

The designer's emphasis is due to maintenance issues
This is why that they chosen Top Entry type
Concerning butterfly valve, am not sure about Custom Design Process.

Dear Peter,

What sort of industry is this valve for? Upstream or downstream oil and gas, pipeline, mining, etc.?
Aside from manufacturing/workshop constraint, metal seated ball valve is so complex, it might scare even the well known manufacturer to reply back to you. Or provide you with price overestimation.
Seems like your client performed mainly desktop review prior deciding they will go for 36” ball valve, butt welded top entry. Criteria such as maintainable, full bore (PIGable), quarter turn (faster opening/closing) by text book will lead mainly to ball valve. While in practice this is not entirely true.
Our engineering contractor (EC) also did similar things for our 12”-20” pipeline, end up with late delivery, metal seated excessive leak rate, and there was no clear guideline for maintenance. If I were you, I would challenge whether this is necessity. Butterfly valve or flanged trunnion mounted pipeline ball valve (not top entry) as bcd suggested would be better option wrt reliability.

Proper maintenance is better if valve can be blocked (by for instance by two gate valves before and after), removed from line for proper workshop repair, install spare valve for the next xyz years. Lifting ball only (for maintenance as your end user suggested) would require at least same effort or even bigger shall compared to lifting the whole valve.
Clarify acceptance criteria to the manufacturer prior your inquiry. PR2 requirement will spook most of them. Or is this just API6D or API598

MOGAS and Cameron have years of experience in metal seated ball valve. brochure below indicates that they can make 36”-900# ball valve.
https://www.mogas.com/en-us/resources/media-centre...)
Not really sure who supplied ball valves for South Stream transport.

PS: Unless there is a fundamental requirement of using biggest size top entry butt welded metal seated ball valve, I personally would avoid this.

Good luck

Regards

Dear Danlap,

Fist of all thank you so much for sharing such a information :

In this regard,We have also another Issues as below :

1)The estimated break torque for this 36" 900# ball valve is 91000N.M
2)The estimated weight is about 21 tons
3)Actuator type selection
4)Test bench facilities for testing
5)Design a Die Casting Mold(costly)
6)Seat Design
7)Factories previous experience

A 36" class 900 top entry is a rare beast alright, but if you spend the money you can get one.

Valve manufacturers have all consolidated over the years so what seems like dozens of suppliers are often only one or two large companies.

Have you done any real research into suppliers?

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

Dear LittleInch

Thank you your reply.
I have already searched,and got offer from 148.000$/230,000$ cast quality to 480,000$ forge quality,(not first class factories!)
But non of them have previous experience in design & manufacturing.
Just say custom Design.!

Refer to Cameron or Flowserve valves who are making all sorts of large valves for the projects in the past.

Quote:

https://www.control-associates.com/getattachment/e...

Quote:

https://www.ibasa.com.mx/manuales/flowserve/valbar...

I think for a class 900 36" valve I would want a 1st class factory....

I agree with mk3223.

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