Around the Bend - Segmentable vs. Piggable Fittings

By Dane Toone, Supply Chain Management Manager, MRC Global
October 25, 2016 Tags: Fitting, Segmentable, Piggable, Elbows
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Our industry has come a long way since the first wooden pipeline was built in 1862, which, at the time, was an upgrade from transporting oil in repurposed whiskey barrels and moved by horse drawn wagons. Advances in technology and best practice are necessary for our industry to operate more efficiently and safely.

One issue at the forefront of pipeline construction improvement is the use of “segmentable” elbows. This is the ability to field cut the elbow with minimal out of roundness (OOR). Industry specification defines this tolerance as 1% OOR.

Why are more and more customers using segmentable elbows? In pipeline construction it is easy to plan for lateral movement but it’s the land topography that sometimes poses problems. Obstacles such as a boulder that they need to maneuver around can quickly interrupt the construction process and potentially cause long, costly delays. Segmentable elbows allow construction crews the flexibility to quickly measure and field cut the desired degree of angle to continue the construction process.

Segmentable elbows are a great option to your typical standard production elbows, and, in addition, we can also offer value added services for shop cut segments to deliver to the customer job site on an expedited basis. If the exact angle of degree is determined then the elbows can either be manufactured as such or be prepared very quickly in a shop controlled environment. This option allows for the highest quality prepared fitting to be delivered to the job site minimizing the amount of field preparation.

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Another popular request is for fittings that are “piggable.” Not to be confused with a segmentable fitting, a piggable fitting gets its name for the ability to run a “pig” or “smart pig” through a pipeline. This is done for a variety of different reasons from pipeline inspection to cleaning. Smart pigs have many different uses and have become a vital component in pipeline maintenance and operation.

The term “piggable” does not have a true industry definition, so it’s important to understand that piggable for fittings means holding an inside diameter (ID) tolerance as close to nominal as possible. We as suppliers of the pipeline components would prefer our customers provide us with the minimum ID tolerance when ordering as piggable. When the ID tolerance is not provided, the manufacturers will generally have their own tolerance based on capabilities or offer to tolerances in MSS SP-75. It is preferred that the ID tolerance be determined by the customer to ensure their requirements are being met.

Our industry is continually coming up with innovative ways to improve the way we transport product to market, and MRC Global is constantly working with the newest advances in both product and manufacturing processes to provide the best solutions to our customers. If your application calls for segmentable or piggable fittings, please contact us to discuss your options. We are here to help.


About the Author

Dane Toone has been with MRC Global since 2014. The University of Oklahoma graduate spent the first seven years of his career with Erne Fittings before joining the MRC Global Supply Chain Management team. Dane is an expert at the many technical solutions available on the manufacturing side of our business, and he leverages that expertise to help our customers choose the right design or material to best meet their need.