DUR O LOK® COUPLINGS
INSTALLATION PROCEDURE
1. Prepare DUR O LOK® Coupling for Welding
- The welding surfaces of the coupling and
the mating pipe must be cleaned and prepared for welding. Be sure to remove any dirt,
grease, or other surface contaminants prior to welding. Also, be sure to remove plastic
protective caps prior to welding, as they will melt. If the coupling has a black oxide
finish, lightly grind or sand off the black oxide coating from the welding surfaces of the
coupling. Removal of the black oxide coating from the coupling’s welding end may have
already been done at the factory for your convenience.
- For applications that involve catalyst
transfer (e.g. CCR Platforming), it is recommended that the black oxide coating is removed
from the entire inner surface of the coupling.
2. Weld DUR O LOK® Coupling to Mating Pipe
- It is highly recommended that the DUR O
LOK® Coupling be welded to the mating pipes as an assembled unit when
possible, as this will ensure proper alignment and protect machined surfaces. DUR O LOK®
Couplings have higher installation tolerances than standard flanges, and extra care must
be taken during welding alignment.
Warning: Do not have gasket in place while welding, as damage will
occur.
- For installation of DUR O LOK®
Couplings in catalyst lift lines, or similar services where long piping runs are involved,
tack weld the assembled coupling to both pieces of pipe positioned horizontally along a
flat surface. Care must be taken to ensure that the two pieces of pipe are straight and
aligned prior to welding. 80 feet of (shop floor) space is required to position and weld
two 40 foot sections of pipe to a DUR O LOK® Coupling. The tacked DUR O LOK®
Coupling may be disassembled prior to completing the circumferential weld.
- For pipes involved in catalyst transfer,
a smooth transition at the inside surface for all circumferential welds is mandatory. The
inside diameters of the pipes and welded DUR O LOK® Coupling may require grinding
to remove all ledges to produce a flush transition in the area of the circumferential
welds. The final wall thickness of the pipes and DUR O LOK® Coupling must not be
less than the minimum required wall thickness.
For pipes employing precision bends
(e.g.- CCR catalyst transfer lines and related applications), trial installation in the
shop is highly recommended, as it allows for final adjustments to be made. DUR O LOK®
Couplings have higher installation tolerances than standard flanges, and extra care must
be taken during final alignment. Pipe sections must be match marked after trial fit-up is
complete & on-spec. This will facilitate trouble-free installation of the pipe
assemblies in the field.
- For non-horizontal coupling
installations, ensure that the female hub (hub with gasket cavity) is positioned as the
lower half of the coupling so the gasket cannot fall out of place during assembly.
- Welding of 304SS DUR O LOK®
Couplings to carbon steel pipe is acceptable.
Warning: Protect Machined Surfaces of Coupling from Weld Splatter.
3. Position Tapered Retaining Ring
- Place the tapered retaining ring over
the male hub end and slide it past the grooves on the hub for the split-coupler. The end
with the larger inside diameter must be oriented toward the mating (gasket) surface of the
coupling. The two set screw holes should be located in the half of the tapered retaining
ring closest to the mating surface of the coupling.
- Bring the two hub ends welded to the pipe
segments into approximate assembled position.
4. Install Gasket
- DUR O LOK® Couplings are
offered in a standard and high temperature design. Standard design couplings employ
an elastomeric type o-ring seal and are used for applications typically below 450° F
(232° C). The o-ring material determines the temperature limit. Materials of construction
for o-rings include Viton®, silicone, Kalrez®, and many others depending on the
application requirements. Although o-rings are typically reusable if not damaged, it is
strongly recommended that a used o-ring be replaced.
- BETE offers a high temperature DUR O LOK®
Coupling design which employs a graphite type flat gasket for nominal service
temperatures above 450° F (232° C). A DUR O LOK® installation clamp may be
required to compress the installed gasket and properly assemble the high temperature DUR O
LOK® Coupling. These gaskets are not reusable. These custom sized gaskets are
available only through BETE. Please specify DUR O LOK® Coupling pipe size and pipe
schedule when ordering.
Warning: Low Temperature (OR76) and High Temperature (GRF100) Design DUR O LOK®
Couplings and their Gaskets are NOT Interchangeable.
- Closely examine the gasket cavity of
the female hub. Ensure that the cavity is free from oil, debris, scratches, or anything
that may affect the quality of the seal.
- Place the gasket in the gasket cavity of
the female hub.
- Handle gaskets with care in order to
avoid damage.
Warning: Damaged gaskets must not be used, as they will not seal
properly.
Always Replace Used Gaskets to Ensure Proper Seal.
High Temperature (GRF100) Gaskets are for One-Time Use Only.
5. Assemble Coupling
BETE offers a special clamp used to bring together hubs that are
slightly misaligned. If this clamp is to be used follow step 5b, otherwise proceed with
step 5a (and then skip 5b.)
5a. Assemble Coupling
Warning: The tapered retaining ring must be fully engaged to
attain the design compression and pressure rating for the desired service. The tips of the
set screws must fit completely inside the split coupler’s set screw groove. The
coupling could become inadvertently disassembled from vibration during use if not
assembled properly. The result may be process material leakage.
Figure 1
Shop-made DUR O LOK® Coupling Clamp Constructed from Riser Clamps
DUR O LOK® CLAMP
Figure 2
5b. Assemble Coupling Using Clamp
Couplings that are excessively out of alignment will require
removal, repositioning, and re-welding. It is best to take care to align the piping and
couplings prior to welding.
Select the appropriate size clamp for each application. See Figure 3
for the location of the DUR O LOK® size marking. Use size 1 for 1", 1
¼", and 1 ½" DUR O LOK® couplings. Use a size 2 clamp for 2", 2
½" and 3" DUR O LOK® couplings.
Determine the appropriate adjustable hinge slot for each location. See
Figure 4 for the location and description of the adjustable hinge slots. Set the
adjustable hinge to slot 1 for a 1" or 2" DUR O LOK, slot 2 for a 1 ¼" or
2 ½" DUR O LOK®, and slot 3 for a 1 ½" or 3" DUR O LOK®.
Remove the secondary driver. Place clamp around DUR O LOK®.
Hold the lower jaw flush with the lower hub collar on the DUR O LOK® and tighten the
knurled knob. Loosely engage the upper jaw around the upper DUR O LOK® hub. Use
the primary driver to lower the upper jaws until they come into contact with the upper hub
collar. Replace the secondary driver. Tighten the knurled knob on the upper jaw while
holding the upper jaw flush against the upper hub collar.
Using the primary driver, tighten the clamp until the hubs come into
contact. Use the secondary driver to level the hubs as needed.
Place the two split couplers in position with the set screw groove in
the split couplers being positioned over the female hub (hub with the gasket).
Loosen the jaws using the knurled knobs, and then loosen the clamp and
remove.
Slide the tapered retaining ring over the split couplers until it is in
position with the set screw holes directly over the set screw groove in the split
couplers. Use a soft faced hammer (e.g. -nylon or rubber) to drive the tapered retaining
ring into a fully engaged position.
DUR O LOK® Clamp Part Identification
Figure 3
Clamp
Figure 4
Adjustable Hinge
6. Secure Coupling
- Install and hand tighten the set
screws with the supplied 3/16" hex key (allen wrench). The function of the set screws
is to prevent the tapered collar from becoming disengaged. The set screws do not function
to pull the tapered retaining ring into position. Do not over-tighten, as damage to the
threads may occur.
- Install the safety wire through the holes
in both set screws and wrap the wire once around coupling.
- Twist the safety wire a minimum of five
times such that the set screws can not work loose during operation. Safety wire
twisting-cutting pliers are available for this purpose.
- The presence of the safety wire generally
is indicative that a gasket is in place. The DUR O LOK® Couplings can also be
tagged or marked to indicated "gasket installed".
Figure 5
Exploded View of DUR O LOK® Coupling
Dur O Lok® manufactured by 
