초록 ▼

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 threa

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.

대표청구항 ▼

We claim: 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

We claim: 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.