The test bend had a 113.6 mm external diameter by 5.8 mm wall thickness giving 102 mm bore, with a ratio of bend radius (to centreline) to pipe bore (R/d) of 3, and operated in a horizontal–to vertically-up orientation. To facilitate accurate measurement of mass loss from the bend, the back section (extrados) of the bend was made as a detachable ‘‘target’’ from thin steel sheet. This reduced its mass so that it could be measured on a balance accurate to 0.1 mg, whereas it would be impossible to measure the whole bend on a balance which is sensitive enough to pick up the mass loss from one test run to the next. The extrados target was a sheet of AISI 304 steel that was 100 mm wide, 250mm long and 0.6 mm thick, hot-worked to an accurate shape to match the bend, and clamped to the remainder of the bend with a gasket between to ensure no air leaks. Fig. 3 shows the arrangement, which was devised to ensure that the whole of the wearing area (identified by inspection of many previously worn bends) was covered.