There are preceding threads on this tiresome subject. See bottom of page.

Such questions always have the inbuilt afterthoughts. If you want, or really need, to know who has built the longest then you just ask the belt suppliers. There is no point in asking about Pipe diameter; Speed; Material handled or Location since you are only concerned with the longest, Length is sufficient. There can only be one longest: just as there can only be one best. ■