We have a cylindrical housing with 16 3/4"-16 UNF 2B threaded holes. The housing and port are coated with manganese phosphate. A 3/4"-16 UNF 3A nozzle (pin) thread made with D2 Tool Steel and no coating is called out to make up into the hole. Our Supply Chain Manager says he is having hell trying to make up this threaded connection. I looked into this and believe that there are two problems.
1) the phosphate thickness in the holes and ability to control inside the threaded ports
and
2) the thread class 3A external thread should not make up to a 2B internal thread.
I propose changing the external 3/4-16 UNF Nozzle to a 2A class and leaving the threaded ports in the housing class 2B. Is this the proper solution? Can someone enlighten me about how to check thread class make-up. Do you compare PD, and Major diameters to verify there is no interference? Thanks.
- CJ
1) the phosphate thickness in the holes and ability to control inside the threaded ports
and
2) the thread class 3A external thread should not make up to a 2B internal thread.
I propose changing the external 3/4-16 UNF Nozzle to a 2A class and leaving the threaded ports in the housing class 2B. Is this the proper solution? Can someone enlighten me about how to check thread class make-up. Do you compare PD, and Major diameters to verify there is no interference? Thanks.
- CJ