Investigation of oxygen-acetylene flashback reactions in welding hoses: Fid-Bau Portal

Investigation of oxygen-acetylene flashback reactions in welding hoses

Newton, Barry E. / Pryor, David / Chiffoleau, Gwenael J.A. / Beeson, Harold

The testing described herein was effective at producing oxyacetylene flashback-initiated deflagration-to-detonation transitions within welding hoses and aided the evaluation of the characteristics of the ruptured hose associated with the incident. The dissimilarity of the ruptures helped to confirm that the welding hose in the actual incident ruptured as a result of a pressure rupture but was not associated with flashback-initiated detonation. Instead, the rupture was more characteristic of a pneumatic overpressure or an old hose rather than a flashback propagating through the torch and into the hose. This conclusion was also consistent with the testimony of the operator which precluded the development of reverse flow of oxygen into the acetylene hose, which thereby precludes flashback. The testing and modelling previously done by the authors had indicated that a backfire into the torch could generate pressures as high as 3963 kPa (563 psig) and the testimony of the operator had indicated that a sustained backfire was occurring at the time of the rupture. Therefore, a pressure distribution would have been expected to develop down the hoses while the sustained backfires were occurring at the mixer. Normally, a good welding hose would not fail due to the pressure piling distubuted down the hose. Consequently, it was suspected that the acetylene hose was deteriorated. This deteriorated condition was confirmed by testing the remainder of the hose after the incident, which indicated that the acetylene welding hose exhibited cracking of the inner liner and pin-hole leaking through the outer liner in at least six locations along the 100-ft length. Therefore, the failure mode for the hose was believed to be related to a pressure rupture due to the use of a deteriorated hose.