High aspect ratio threadform
View Patent ↗A threadform for a gate valve has a set of threads on a stem that engage a threaded receptacle of the gate. When the stem is rotated, the gate moves. The threads have a thread height to thread base thickness ratio that is at least the inverse of 0.7 times e raised to 0.388 divided by a nominal thread diameter of the threads. That ratio is at least 1.1.
1. In a gate valve having a stem with a set of threads that engage a bushing connected with a gate, so that rotation of the stem moves the gate relative to valve seats, the threads of the stem and bushing comprising:
a threadform wherein a thread height to thread pitch ratio R is at least the following:
R= (0.7 *e (0.388/Td)) −1
where Td is the thread diameter.
2. The gate valve according to claim 1 , wherein the ratio comprises at least 1.1.
3. The gate valve according to claim 1 , wherein each of the threads has a rounded crest.
4. The gate valve according to claim 1 , wherein the threads have an included thread angle of less than 50 degrees.
5. In a gate valve having a stem with a set of threads that engage a bushing connected with a gate, so that rotation of the stem moves the gate relative to valve seats, the threads of the stem and bushing comprising:
a threadform wherein a thread height to a thread pitch ratio R is at least the following:
R= (0.7 *e (0.388/Td)) −1
where Td is the thread diameter; and
wherein the thread height to the thread pitch ratio R for each of the threads is at least 1.1.
6. The gate valve according to claim 5 , wherein each of the threads has a rounded crest.
7. The gate valve according to claim 5 , wherein the threads have an included thread angle of less than 50degrees.
8. In a gate valve having a stem with a set of threads that engage a bushing connected with a gate, so that rotation of the stem moves the gate relative to valve seats, the threads of the stem and bushing comprising:
a threadform with at least two starts and a thread height to thread pitch ratio R that is at least the following:
R= (0.7 *e (0.388/Td)) −1
where Td is the thread diameter;
wherein each of the threads has a rounded crest;
the threads have an included thread angle of less than 50 degrees; and
the thread pitch is equal to a thickness of each of the threads at a base of each of the threads.
9. The gate valve according to claim 1 wherein the thread pitch is equal to a thickness of each of the threads at a base of each of the threads.
10. The gate valve according to claim 5 wherein the thread pitch is equal to a thickness of each of the threads at a base of each of the threads.