Your opportunity to influence new in-service radiography standards
11/06/2012
As announced previously, the new EN/ISO standards for weld radiography (prEN ISO 17636-1 for film and prEN ISO 17636-2 digital) are in the final stages of revision. However, these documents are not appropriate for in-service inspection (ISI) of pipes for corrosion/erosion type flaws, which today represents a major application area for both computed and film radiography within the oil and gas industry and elsewhere.For ISI is it generally permissible to use lower quality radiography, but until recently there has been no standardisation of approach. A recommended practice for the in-service radiographic inspection of pipes has recently been developed within the HOIS JIP, as described in the February 2011 issue of Insight, Vol 53, No 2. The HOIS RP can be downloaded from http://www.hoispublications.com following a simple registration process. This document has now been progressed to form the basis for a new two-part draft EN standard.
The new draft standards prEN 16407-1 and prEN 16407-2 cover the radiographic examination of pipes in metallic materials for service-induced flaws such as corrosion pitting, generalised corrosion and erosion. Besides its conventional meaning, ‘pipe’ as used in this standard should be understood to cover other cylindrical bodies such as tubes, penstocks, boiler drums and pressure vessels. Weld inspection for typical welding process-induced flaws is not covered, but weld inspection is included for corrosion/erosion type flaws. The pipes may be insulated or not, and can be assessed where loss of material due, for example, to corrosion or erosion is suspected, either internally or externally. Part 1 of this standard covers the tangential inspection technique for the detection and through-wall sizing of wall loss, including: (a) with the source on the pipe centre line; and (b) with the source offset from it by the pipe radius. Part 2 of this standard covers double-wall radiography, and note that the double-wall double-image technique is often combined with tangential radiography with the source on the pipe centre line. These standards are intended to apply to radiographic inspection using industrial radiographic film techniques, computed digital radiography (CR) and digital detector arrays (DDA).
These draft documents can be viewed and commented on by logging onto the BSI website. Note that a registration process must be completed to view the documents, which can be found at http://drafts.bsigroup.com/Home/Details/31755 and http://drafts.bsigroup.com/Home/Details/31756
The deadline for comments is 14 July. Those in other European countries can contact their national standards organisations regarding arrangements for accessing these standards and making comments.
Steve Burch
