PLAN PRESENTATION
ABSTRACT
T.D. WILLIAMSON
“HOT-TAP AND STOPPLE PLUGGING SYSTEM”
for modification of repair of pipelines without shutdown or loss of production
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INTRODUCTION
This system has been devised and developed by T.D.Williamson Inc. to enable
pipeline operators to carry out maintenance, modifications and repairs on a planned
basis without the need to consider the effects of interrupted throughput or loss of
production.
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Generally, the system enables large savings to be made on initial installations also,
because it avoids the need to install valves etc., at points where possible future
additions might be necessary.
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The location of pump or compressor stations, and subsequent activities such as road
or rail constructions, or other civil engineering works of a major nature need not be
compromised, as it is relatively simple to relocate the pipeline or make any other
changes necessary without interrupting operations
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The initial cost of the system is extremely low compared to the savings made – for
example the loss of revenue due to a shut-down of a major gas pipeline operating at
high efficiency, would normally pay for the cost of the system in less than 24 hours –
and this period of time is unusually short in terms of the time normally required for a
shut-down.
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Many major gas and oil pipeline operators have also recognized the system as an
invaluable safeguard in terms of their contractual commitments to guarantee supplies
to their customers – such guarantees often incurring penalties far in excess of the
cost of this system for even relatively short interruption of supplies.
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Tapping is the precise process of drilling a hole in an on-stream piping system
without spilling its contents or interrupting its flow. Over the decades, TDW Services,
has performed thousands of successful hot taps onshore and offshore and in nearly
every type of pipeline material. Piping systems are designed to move liquids, gases
or other products in a continuous flow. Shutting down these essential systems, or
even portions of them, can be extremely costly and time consuming. When
alterations or repairs are required in live systems, TDW Services will handle your
assignment from concept to completion, whether the operation calls for common
taps, side taps, angle taps, tank taps or custom designed applications.
PROCEDURE FOR HOT TAP AND STOPPLE PLUGGING
PROCEDURE FOR HOT TAP
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A fitting is permanently secured to the line by welding
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A permanent valve is installed on the fitting
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A TDW tapping machine is installed on the fitting, and the valve is opened. After
pilot drill penetrates, the tapping machine fills with product, and air is purged from
the housing. The tap is made through the line and the coupon is retained
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The valve is closed, and the tapping machine is removed. A branch connection is
added, and the valve is opened. The new connection is ready to put into service.
This field-proven TDW procedure is quick and precise.
Split Tee fittings are supplied in two pieces which are clamped and then welded to the
outside of the pipeline while the flow continues in the line.
(Welding on the outside of pipelines under pressure has been carried out for many years
and has been the subject of satisfactory studies conducted by major research
organizations including the Battelle Memorial Institute, American Petroleum
Institute, British Gas Corporation (Research) etc
SLIDE SHOWING WELDING OF SPLIT TEES
Temporary Sandwich valves are then installed on the fittings and special “Tapping
Machines” are used to cut holes through the pipe wall
SLIDE SHOWING TAPPING OF 2” EQUALIZATION HOLE WITH TM T101
The piece of pipe cut out, is retained inside the cutter and withdrawn
SLIDE SHOWING COUPON AFTER HOT TAP
A temporary bypass is fitted and the Stopple Plugging Machines are placed in position
SLIDE SHOWING STOPPLE PLUGGING IN
The Stopple Plugging Machine lowers the “plugging head” into the pipe completely isolating
the section and diverting all flow into the temporary bypass
SLIDE SHOWING PLUGGING HEAD IN POSITION
When the modifications or repairs are complete, a special plug is locked into the top of the
fitting so that the valves can be recovered
SLIDE SHOWING A SECTIONAL VIEW OF THE PIPE WITH LOR IN PLACE
Blind flanges are installed to complete the job.
Safety and Quality are of prime importance in all T.D.WILLIAMSON products. All designs
undergo complete strain gauge analysis and every component is thoroughly
tested before leaving the factory.
Operators are trained by qualified
WILLIAMSON Engineers and technical advice and equipment maintenance
procedures are available.
SLIDE SHOWING STRAIN GAUGE IN USE
After the isolated section is emptied, the line can be cut and the modifications or repairs
carried out.
SLIDE SHOWING THE PLUGGING HEAD IN POSITION
PROCEDURE FOR STOPPLE PLUGGING
TYPICAL DOUBLE STOPPLE LINE PROCEDURE
(USING FOUR FITTINGS AND A BYPASS)
A TDW plugging machine can temporarily stop the product in an
operating pipeline, by acting as a block valve. When used in
conjunction with a bypass line and another plugging machine,
product can be rerouted around the isolated section of pipeline, while
repairs, alterations, relocations and instrument installations are made
to the piping system.
SLIDE SHOWING TYPICAL DOUBLE LINE PROCEDURE –
USING FOUR FITTINGS AND A BYPASS
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The four fittings are permanently secured to the line.
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Temporary SANDWICH valves are installed on the fittings, and taps
are made through the valves.
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Two STOPPLE Plugging Machines are installed. Product is diverted
through the temporary bypass. The isolated section is purged.
Modifications are made to the isolated pipe section. The new section
is purged and equalized, and the plugging heads are retracted.
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The temporary bypass is removed. LOCK-O-RING Plugs are
installed in the STOPPLE Fittings with a tapping machine. All
equipment is then removed, and blind flanges are installed on the
fittings to complete the job.