gate valve in refinery

Such gate valves with bellows are more required for critical services than for high pressure or high temperatures.

Critical service like H2S presenting contents and like, where even, occasionally, a drop of leak at gland is intolerable . Bellow is expected to give 100% protection against such gland drips.

But, I've seen when the bellow failed/cracked, the leaks were objectionably very high. This is because the stuffing box elements under the bellow are un-attendable by easy means on service. Failed stuffing box element may even be due to normal wear & tare and ageing.

It is undertood where application involve High Temprature and high reactive medias as mentioned earlier this valve provide more life and less maintenance.

Also the leakage through this valve is off higher degree and to recent enviromental standards.