Reading Through 3LPE & 3LPP Coatings

3-Layer Polyethylene/Polypropylene (3LPE/3LPP) coatings are capable of withstanding a wide variety of temperatures and environments and as a result 3LPE and 3LPP are the industry standard coatings for the transmission of oil and gas via buried pipeline.

The 3LPE/3LPP coating is a multilayer coating composed, as its name suggests, of three distinct, layered components:

  • A fusion bonded epoxy layer
  • A copolymer adhesive layer
  • A polypropylene or polyethylene layer.

And while the complex nature of the layered coating has huge benefits for protecting the external wall of the pipe, these layers can make it harder for simple, regular inspection of the internal wall – where, corrosion and erosion can be taking place out of sight.

All of Cygnus’ MK5 ultrasonic thickness (UT) gauges use our S2C probes to enable our equipment to penetrate through up to 20mm of coating – with absolutely no need to remove or damage any aspect of the 3LPE / 3LPP coating. This is also the case for the Cygnus 1 Ex UT gauge – the world’s only thickness meter that is certified to ATEX, IECEx, UKEX for Zone 0 and NRTL for Class 1, Division 1 for use in potentially explosive atmospheres.

Cygnus UT gauges are very easy to use; simply place the probe on the outside of the coated pipe and they will ‘read through’ the coating – and present the user with the internal steel thickness only.

As well as this focus on simplicity of use and convenience, the Cygnus MK5 thickness gauges are also versatile and feature-rich. Our PLUS models come equipped with rectified Ascan functionality; these AScans can be read live on site or can be stored (logged) alongside a thickness reading for review at a later date as a part of a predictive maintenance programme.

We know and understand that these are tools that will lead a rough life and so Cygnus gauges are also highly ruggedized; the whole range of units are drop proof, shock proof, can be immersed in water and are dust proof too (all tested to Mil Spec 810G).

A full range of single and dual element probes are also available for a host of other applications.