In some application, a narrow groove is cut into the piston above the topring to serve as a "heat dam" to reduce the amount of heat reaching the top ring.
在一些实际结构中，一条窄槽切入顶端活塞环的上部，其作用是充当“隔热槽”以减少达到顶端活塞环的热量。
2
The gap in the topringgroove had exceeded the requirement.
第一道环槽的天地间隙超过了请求。
3
Time for the third kind of closing well is so long that flange steel ringgroove on the top of casing-head is heavily corroded in M4 well being situated in Tarim basin.