Disaster bushing
Used in A.P.I. glands to support the shaft in the event of a bearing failure, or to prevent product from rushing to atmosphere after a seal failure. The close clearance (0.025 inch or 0.5 mm.) directs most of the leakage through a drain connection in the seal gland to an appropriate container.

open Quench - это, наверное, отковырять этот самый disaster bushing ...

In the seal business, quench (Q) is a term used to describe the introduction of a fluid outside the mechanical seal. We use this fluid to:

To cool the product we are sealing
To dilute any leakage that might migrate across the seal faces.
To introduce low-pressure steam behind the seal to put out a fire.
The Quench connection is labeled (Q). A close fitting bushing (DB) in the end of the gland directs the quench fluid down a drain hole on the opposite side of the seal gland
Steam is the most popular quench medium, but care should be taken that the steam pressure is very low, or the hot steam will penetrate through the nearby bearing seals and contaminate the bearing oil.

QUENCHING - Often called the vent and drain (Q connection on an A.P.I. gland)

Some seal glands have a vent or quench connection provided behind the seal so that steam or some other fluid can be used to control temperature in the seal area. A close fitting carbon ( or any other non sparking material) bushing is installed outboard of this connection to provide a close clearance between the gland and the shaft.
Refinery applications use a version of the quench gland and call it an A.P.I. ( American Petroleum Institute) gland.