Technical Report Page 1

TECHNICAL REPORT

EXAMINATION OF

TUBE CLEANER SYSTEM

J CAMPBELL

SYNOPSIS

We were asked to examine the tube cleaning process carried out by Rico Limited to determine in detail the quality of the tube bore after the process had been carried out. The purpose of tests was to establish how much of the tube surface is lost, and how the condition of the tube is left after cleaning takes place.

The cleaning operation is performed by using water under pressure which pushes a cleaning plug or ‘pig' through the tube. The pig design incorporates a series of overlapping spring-loaded metal flights, which align themselves down the bore and give 100% coverage of the bore surface. Rico use phosphor bronze flights on copper based tubes, but the testing included a series of tests using steel flights, to ascertain the extent of damage from the contact with the steel.

METALLUGICAL EXAMINATION

Samples of each tube were cut through the wall, then mounted and polished to reveal the metallurgical microstructure of the tube. The surface which had been cleaned was examined at up to a thousand times magnification and no sign of any material damage to the grain structure was noted in any of the tubes.

Samples of the tube that were cleaned with the steel flighted plugs were also examined and here there was some surface deformation of the grain structure in the vicinity of the contact areas with the steel flights.

TESTING PROCEDURE

The cleaning equipment was set up under normal conditions, with fresh mains water feeding the Rico pump and cleaning gun. No chemical additives were used.The tube used was new tube that had been left standing for some time, so it was oxidised, but the bore was not fouled, as the tube had not been in service. Several tubes were provided so that a fresh tube could be used for each series of tests.The intention was to carry out multiple cleaning passes of the pig so that any surface damage or loss would be accentuated. One length of tube was cleaned repetitively, with the end cut off each time a measurement was taken. This yielded a series of tube samples with progressive numbers of cleaning passes. For example, one pass was made, the tube end was cut off, another pass was made, another tube sample was cut (2 passes this sample), then three more passes were made (5 passes this sample) and so on. A sample of the tube was also removed prior to any cleaning, to act as a datum.

Also, several pig options were carried out as follows:

next