T.D. Williamson Global Solutions- March 2006

by Bob Warterfield

Test results are almost startling. The numbers are so significant that V-Jet™ pigs may
be facing a very busy future as the primary global workhorse for drastically reducing corrosion in gas pipelines. Findings indicate that the difference between using a V-Jet pig and not using one is quite remarkable. In the most stringently applied testing program to date, V-Jet usage reduced metal loss due to corrosion by a factor of between 10 and 12. What does that mean in plain English? Simply this - by switching to V-Jet pigs, it could take 80 to 100 years to see the same amount of corrosion damage presently occurring within eight short years in today's pipelines using what until now has been the best anti-corrosion pigs and pigging practices. Exactly what these test results mean to every gas pipeline operator in terms of extended pipeline service life, reduced repair and maintenance, reduced man-hour involvement and reduced chemical inhibitor use is, to say the least, considerable. V-Jet test results are particularly meaningful to operators with hard to access pipelines.

Companies who have previously conducted their own tests are ordering additional V-Jet pigs for various sized gas pipelines around the world, and especially for those lines that are most affected by corrosion problems. Word is spreading about the extraordinary effectiveness of V-Jet pigs and a rising tide of orders is being filled.

The historical development of V-Jet technology has followed a familiar path at TDW.
It starts with someone contacting TDW with an unusually troublesome problem to solve. Organizations who are familiar with TDW engineering capabilities and long history of creating custom solutions for unique jobsite situations frequently treat TDW as an extension of their own engineering departments and feel comfortable contacting TDW
to discuss particular needs and desires.

The case for designing V-Jet pigs started with a major European company facing a serious top of line corrosion situation in Southeast Asia. During conversations at a NACE conference, the corrosion problem was discussed with TDW Pipeline Integrity Sales Manager, Larry Payne. A corrosion engineer from the European company asked if TDW could help. Within a short period of time, TDW was at work on a solution.

The concept of creating a tool that re-uses/re-distributes injected corrosion inhibitor fluids that pool on the bottom of gas pipelines was an immediate consideration. TDW Senior Engineering Designer, Rick Pruett was deeply involved with the concept, design and testing process. Working closely with his engineering counterpart from Europe, the first tool prototypes were modified sponge pigs built to swab up chemicals and, theoretically, recoat the pipe. They did not work. Focus then centered on physical methods for moving chemicals from the bottom of a pipe to the top. Numerous drawings were made and three promising concepts were selected for additional development.

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During the design and development phase, parts of several "next generation" prototypes were literally hand-carved out of solid urethane. One of the tool concepts configured to literally suck up fluids and spray them upward through an array of nozzles performed extremely well and emerged as the primary design direction for solving top of line corrosion problems. Anticipating uneven distribution of inhibitor fluid within a pipeline, the V-Jet pig was designed to act as its own short term reservoir in the event that it should pass through a section of pipe void of corrosion inhibitor fluid, such as during an incline or decline in elevation.

Preliminary testing confirmed that the V-Jet fluid redistribution process worked. Next, a real world pipeline environment provided genuine challenges for V-Jet pigs and served to verify the spectacular degree of effectiveness that the tool was capable of producing. The challenge came from a large energy corporation who heard about the development of a new TDW tool and its potential for reducing line corrosion. Operating a 10" natural gas pipeline in Texas that is perfectly suited for monitoring top of line corrosion rates, the company and TDW teamed together for a yearlong stint of real time field testing to analyze actual corrosion rates and scientifically measure metal loss on removable coupons. The effects of varying combinations of pigging tools, pigging schedules and chemicals were tested.

Metal Loss

Values Measured in MPY (Mills Per Year)

Coupon Time In Pipeline

Top

Chemical Application & Process

Coupon #1

Coupon # 2

Coupon # 3

( 1 Mile Mark )

( 3 Mile Mark )

( 7 Mile Mark )

PERIOD 1:
(Chemical "A" w/o The V-Jet)

91 days

0.26

4.56

3.43

The pipeline was dewatered every Monday & Friday with a typical batching pig. Three batch treatments were run using a chemical slug between two typical batching pigs.

PERIOD 2:
(Chemical "A" With The V-Jet)

47 days

0.18

0.39

0.33

The pipeline was dewatered every Monday and Friday with a V-Jet pig. One batch treatment was run using the V-Jet pig.

PERIOD 3:
(Chemical "A" With The V-Jet)

41 days

0.27

0.43

0.28

The pipeline was dewatered every Monday and Friday with a V-Jet pig. No batch treatment was used.

PERIOD 4:
(Chemical "B")

34 days

0.47

1.14

0.81

The pipeline was dewatered every Monday & Friday with a typical batching pig. One batch treatment was run using the V-Jet pig.

PERIOD 5:
(Chemical "B" With The V-Jet)

36 days

0.37

0.76

0.57

The pipeline was dewatered every Monday and Friday with a V-Jet pig. No batch treatment was used.

V-Jet Test Results

The above pigging test results indicate:

When standard pigs were removed from all or part of the corrosion inhibitor process and V-Jet pigs took their place, corrosion reduction improved significantly.
Regardless of which corrosion inhibitor chemical was used, results consistently improved when a V-Jet pig was used.
It is possible to eliminate the use of corrosion inhibitor batching pigs and still realize superior corrosion reduction results.

Rigorous testing has allowed
TDW to realize additional benefits. After each series of pipeline runs, TDW engineers carefully analyzed the V-Jet pigs. Findings were used
to refine and toughen V-Jet structural elements so they can withstand the most demanding pipeline environments. Engineers also used lessons learned in testing to develop a quick-change spray head and simplify V-Jet nozzle cleaning and maintenance procedures. Cups and disks made of new TDW Formula SI™ Urethane used on V-Jet pigs also held up extremely well and performed perfectly over the course of multiple runs.

The patented V-Jet™ emerges from Field Testing

Every new V-Jet usage report that is received from pipeline operators further confirms that a new age of gas pipeline corrosion protection has arrived. TDW V-Jet pigs are now available in standard sizes ranging from 8" to 24". Sizes that are larger or smaller are only produced on a custom design basis.

Additional V-Jet information is available by going to www.tdwilliamson.com
or by calling 918-447-5500 or 800-695-0535.