Flowserve Durco User Manual

Durco® G4 Full Area Plug Valves

Non-Lubricated Plug Valves

for Chemical Service

Durco® G4 Full Area Plug Valves

Flowserve, which has supplied the highest quality plug valves for the most corrosive and difficult chemical
services, is now pleased to offer the Durco G4 Full Area Sleeveline Plug Valves These valves offer greatly expanded
port areas to permit greatly increased flow of process fluid. All of the proven features of the standard G4 remain
with the full area model.

Special Configuration Valves

The G4 Full Area valve is available in a wide number of variations including designs for the following:

• Firesealed

• Chlorine service

• HF alkylation

• Weld end

• 3-way configurations

Double D Plug Stem

Accepts most standard
actuation equipment.

In-Line Adjustment

Prevents thru-line leakage.

Actuator Mounting Pads

Mounts directly on flanges
for solid support.

PTFE Sleeve

Large seal area offers
positive shutoff and
extended service life.

Expanded ports

offer low pressure drop
and high CV.

2

Raised Locking Ribs

Along with grooves and recesses positively
lock sleeve in body.

Rugged, Heavy-Duty Body

Limited lifetime casting
guarantee. ANSI (ASA) or
DIN flanges standard. N.P.T.
screwed, socket and butt weld
available.

Rated to ANSI Class 150
lb and 300 lb designs at
pressures to 740 psi (5102
kPa) and vacuum
to 1 micron (0.133 kPa).

Tapered Plug

Assures reduced turning torque and in-line seal adjustment
and wear. Adjustment is independent of stem seals. With ± 3⁄16
in (± 5 mm) adjustment, plug cannot bottom out.

Marathon Option offers High Cycle Positive Stem Sealing

G4B Marathon Valve

PPM

flowserve.com

3-Year Performance Guarantee

Unprecedented limited warranty. The valve will be repaired
or replaced if stem seal fails within 3 years after installation.

Unique Stem-Sealing Design

The G4B Marathon
valve can be used with
confidence in chemical
processing applications
where tight shutoff and
emissions containment
are priority requirements.
As a bonus, its very
design assures long-lived,
high cycle performance.

New Welded Diaphragm

The integral thrust
collar/alloy diaphragm
is a third line of defense
against leakage to
the atmosphere. The
underside of the metal
bellows-like diaphragm
acts as an expansion
joint by allowing the PFA
diaphragm to adjust to
plug movement and pressure changes. The Hastelloy C
diaphragm provides an impermeable barrier to chlorine as
well as many other services.

Available for G4Z, MG4, FJG and other models.

Viton O-Rings

A pair of Viton
O-rings prevents
stem leakage while
containing line
pressure. They also
protect the thrust
collar against attack
from atmospheric
corrosion. PTFE
back-up rings firmly
lock the Viton
O-rings in the stem
grooves and serve
as anti-extrusion
devices.

Optional Kalrez O-rings are available for special services.

Without
back-up rings

With back-up
rings

Proven High Cyclability

Lab and field tests have proven that the G4B Marathon can
cycle as many as three-to-five times more than a standard
PTFE sleeved quarter-turn valve before it begins to show
stem seal wear.

Passing The Test

Lab technicians defeated the PTFE sleeve and PFA
diaphragm, the G4B’s primary and secondary stem seals, by
cutting both of them in four places. They operated the valve
to 160,000 cycles. Rather than using the standard Method
21 methane emissions test, they chose the more demanding
helium emissions test. The results were impressive.

Viton O-Rings and welded metal diaphragm stem seals
Sleeve and diaphragm cut in four places

20

10

0

10 20

Cycles (x 1000)

Conventional Plug Valve > 2000 PPM

140 160

G4EB Valve

3