If sour service is such a menace to metal and a hazard to operator safety, then is it advisable to use manual operated (Hand opreated) valves in those lines.
Are there any guidelines as to choice of valves in specific services (From Safety aspect)
There is nothing wrong with using manual operated valves as long as the packing is not leaking.
Packing should be "sniffed" periodically to test for leakage.
Use MR-0175 for guidelines on suitable materials.