Would there be US duty payable on a new pipe organ to be constructed
and built in Germany and installed in a church in the USA? If so what is the rate?

Dear hdmax,

No, a pipe organ made in Germany would not be subject to U.S. import
duty. In their 2002 Tariff Database, the U.S. International Trade
Commission lists the following entry for this kind of product:

HTS Number: 92030040

Brief Description:
Keyboard musical instruments, (...), pipe organs

2002 Normal Trade Relations (NTR) duty rate: 
Duty calculation - 0.00 
Ad Valorem (percent of value) component - 0% 
Specific (per unit) component - $0 
Other duty component - $0 
Ad Valorem equivalent of all rate components
(estimate based on 2002 NTR duty rates and 2001 imports) - 0%  
Binding Status: Bound in World Trade Organization

Source:

U.S. International Trade Commission: 2002 Tariff Database
http://dataweb.usitc.gov/scripts/tariff2002.asp

Hope this answers your question!
Regards,
Scriptor

This answers my question precisely. Because of the importance of the
question I will follow up on the documentation to make an independent
verification of the answer, but I only expect to confirm the answer
which you gave.

Thanks,

HD Maxwell