(ShareCast News) - The oil and gas industry slowdown has hit revenue growth at technical services firm Diploma, but said it expected revenues for the year to 30 September to be 9% higher.The company also announced that chief operating officer Iain Henderson will step down in January 2016.In a trading update, Diploma said headwinds experienced in the first half of the year had continued and in some cases "strengthened", and on an underlying basis, after adjusting for currency effects and acquisitions, group revenues are expected to increase by around 1%.Diploma's life sciences unit reported trading in line with expectations. The US seals division was hit by the collapsing oil price and subsequent cutbacks in that sector."The further weakening, in the second half of the year, of the Canadian and Australian dollar against the US dollar largely been mitigated by existing currency hedging contract. However this weakening will impact next year's operating margins in the group's Healthcare businesses as existing currency hedging contracts expire and are replaced by more expensive contracts," Diploma said.