Flowserve High Temperature Metal Bellows Seals - Manual (Page 7)

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5.9.3 Process fluid must flood and pressurize the seal chamber at all
times for single and dual non-pressurized (tandem) seals. Barrier/
buffer fluid must flood dual seals at all times during equipment
operation and pressurized seals must be pressurized above the
process pressure at all times.
5.10 Steam seal requirements (Plan 72, 74):
5.10.1 Clean, dry, superheated steam is required.
5.10.2 Pressurized steam seals (e.g. GTSP) require 3.4 bar (50 psi)
greater than seal chamber pressure supplied to the seal at all
times.
5.10.3 Containment seals (e.g. GSDH) require a steam purge up to
0.7 barg (10 psig) supplied to the seal at all times.
5.10.4 Take proper precautions to prevent steam condensate from
entering the seal. Steam traps should be located at low points
in the piping. Steam should be taken from the top of the steam
header to prevent contaminants from entering the steam barrier
stream. Contact your Flowserve representative to review piping
runs and ensure that minimum requirements for satisfactory seal
performance have been met.
5.11 Steam quench requirements (Plan 62):
5.11.1 Dry steam should be supplied to the seal gland quench
connection.
5.11.2 Use a needle valve (or other flow restriction) to provide less than
0.2 bar (3 psi) steam to the quench connection of the seal gland.
5.11.3 Ensure that all condensate is drained from the supply line and
open the supply slowly before the pump is preheated to prevent
thermal shock.
5.11.4 Proper pressure and steam condition should result in wisps of
steam exiting the seal gland area.
5.12 Startup equipment in accordance with normal operating procedures
unless specifically requested otherwise by Flowserve. If the equipment is
not operating correctly, shut down the equipment, investigate and remove
the cause.