Heat responsive backseat for gate valves
US4658848A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 27, 1983 |
| Grant date | Apr 21, 1987 |
| Priority date | — |
| Expiry date | Dec 27, 2003 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T137/1797
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
An improved heat responsive backseat for gate valves which includes a rotating valve stem (50) carried by a bonnet assembly (14) for actuation of a gate member (40). A fusible stem ring (126) supports the valve stem at an outer portion thereof (68) within a roller bearing chamber (56) of the bonnet assembly. The valve stem (50) moves axially outward from the valve chamber (20) when the fusible stem ring (126) melts due to an external fire condition to bring a valve stem backseat portion (64) into sealing engagement with a bonnet seat portion (54). The valve stem (50) moves axially outward from the valve chamber (20) independently of roller bearings (74, 76) contained within roller bearing chamber (56) such that the roller bearings (74, 76) remain axially fixed with respect to the bonnet assembly before, during and after the shifting of the valve stem. Therefore, the valve stem may be easily rotated after the fire condition has been extinguished without the occurrence of cocking or wedging between the bearing means and valve stem. Accordingly, a secondary metal-to-metal seal is provided between the valve stem (50) and bonnet assembly (14) such that if the primary packing (104) is de…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.