Comments for

Comment on A Good Investment by MONA HUGHES

MONA HUGHES — Tue, 01 Jun 2010 08:43:50 +0000

Every time I come to http://www.pipelineengineering.com there is another remarkable article to read. A friend of mine was talking to me about this topic a few weeks ago. I think I will send my friend the url here and see what they say.

Comment on The right pig for the job by Peter Fretwell

Peter Fretwell — Tue, 14 Jul 2009 13:05:22 +0000

Waxier crudes can be a problem particularly in smaller diameter lines. You did not state what diameter of line or range of diameters you have a particularly interest in so I have assumed it is in the smaller range say 6” through 12” where you have a particular interest. You can contact me again if I have made the wrong assumption.
Some four or five years ago PE developed a cleaning tool to address the problem you have described along with another common problem which is low flow. We discovered while carrying out our extensive trials, that while removing wax from the pipewall, it was also important to keep anything removed in suspension rather than allowing it to building up ahead of the cleaning tool.
We also discovered that a single jet or for that matter multiple jets from the centre front of the tool body did not give the required action to keep the removed debris in suspension. After a number of modifications to the cleaning head we devised a method of directing the bypass to 360 deg of the pipewall and at the point where the wax was being removed. This ensured that everything being removed was kept in suspension.
We already knew that if the percent bypass through or over a cleaning tool was too great then there was a good chance that the tool would not launch from the trap. Knowing this we incorporated a adjustable bypass and also increased the frictional resistance which then required a high differential pressure to move the cleaning tool forward. This also greatly improved the jetting action on the pipewall because rather than it being at 0.5 bar it was now at 2.0 bar.
We call this tool an “Annular Cleaning Tool” and it has been successfully deployed in not only waxy crude lines, but also low flow waxy crude lines with flow rates down as low as 0.2 metres per second. It has also proved very successful in large diameter, 48” and 56” gas lines for the removal of Black Powder.

Comment on Resolving conflicts with pipeline codes and pressure vessel codes by kwilson

kwilson — Thu, 09 Jul 2009 14:58:08 +0000

Chris, many thanks for your comment. It interesting to know that the AS standards are aware of such issues. Pipeline Engineering has in the past provided Pig Launcher/Receivers to the AS2885 specification and hence have experience of its workings. A contract we undertook to supply a 42″x46″ 900# Launcher/Receiver for the LNG4 pipeline was originally specified to the Australian Unfired Pressure Vessel Code AS1210 but later amended to the AS2885 pipeline specification. The only real issue we found with this change was that the pipeline standard required a great many more Weld Procedure Qualifications than the AS Pressure Vessel Specification.

Comment on Resolving conflicts with pipeline codes and pressure vessel codes by Chris Hughes

Chris Hughes — Wed, 08 Jul 2009 22:07:36 +0000

Here in Australia our pipeline standard (AS2885) defines launchers/receivers as “Pipeline Assemblies” designed to the same standard as the pipeline. Our usual practice is not to purchase a proprietary trap but to purchase the closure, high strength reducer and full bore trap valve and free issue these, together with a length of suitable line pipe, to a fabricator for assembly.

Comment on The right pig for the job by George Broze

George Broze — Wed, 08 Jul 2009 17:53:45 +0000

We are beginning to work in waxier fields where pigging intervals are too short to use zero-bypass pigs comfortably. However, we don’t see a lot of standard methodology to design bypass pigs and pigging programs, and we don’t have a good library of field experience with bp pigs. So it is difficult to convince operations to routinely use them. Does anyone have good experience and/or a robust approach for bypass pigs?